create module sonar-ce-task

31 files changed, 1822 insertions, 0 deletions

diff --git a/server/sonar-ce-task/build.gradle b/server/sonar-ce-task/build.gradle
new file mode 100644
index 00000000000..66ad1d81185
--- /dev/null
+++ b/server/sonar-ce-task/build.gradle
@@ -0,0 +1,66 @@
+description = 'Definition of a Compute Engine task and utility "framework" and classes to code one'
+
+sonarqube {
+  properties {
+    property 'sonar.projectName', "${projectTitle} :: Compute Engine :: Task"
+  }
+}
+
+sourceSets {
+  test {
+    resources {
+      srcDirs += ['src/test/projects']
+    }
+  }
+}
+
+
+import org.apache.tools.ant.filters.ReplaceTokens
+processResources {
+  filesMatching('build.properties') {
+    filter ReplaceTokens, tokens: [
+      'buildNumber': release ? 'git rev-parse HEAD'.execute().text.trim() : 'N/A'
+    ]
+  }
+}
+
+dependencies {
+  // please keep the list grouped by configuration and ordered by name
+
+  compile 'org.picocontainer:picocontainer'
+  compile 'org.slf4j:jul-to-slf4j'
+  compile 'org.slf4j:slf4j-api'
+
+  compile project(':server:sonar-process')
+  compile project(':sonar-core')
+  compileOnly project(path: ':sonar-plugin-api')
+
+  compileOnly 'com.google.code.findbugs:jsr305'
+
+  testCompile 'ch.qos.logback:logback-access'
+  testCompile 'ch.qos.logback:logback-classic'
+  testCompile 'ch.qos.logback:logback-core'
+  testCompile 'com.google.code.findbugs:jsr305'
+  testCompile 'com.h2database:h2'
+  testCompile 'com.tngtech.java:junit-dataprovider'
+  testCompile 'junit:junit'
+  testCompile 'org.apache.logging.log4j:log4j-api'
+  testCompile 'org.apache.logging.log4j:log4j-core'
+  testCompile 'org.assertj:assertj-core'
+  testCompile 'org.assertj:assertj-guava'
+  testCompile 'org.mockito:mockito-core'
+  testCompile 'org.reflections:reflections'
+}
+
+task testJar(type: Jar) {
+  classifier = 'tests'
+  from sourceSets.test.output
+}
+
+configurations {
+  tests
+}
+
+artifacts {
+ tests testJar
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/CeTask.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/CeTask.java
new file mode 100644
index 00000000000..f0d4f06ddcf
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/CeTask.java
@@ -0,0 +1,166 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation;
+
+import com.google.common.base.MoreObjects;
+import javax.annotation.CheckForNull;
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+import static com.google.common.base.Strings.emptyToNull;
+import static java.util.Objects.requireNonNull;
+
+@Immutable
+public class CeTask {
+
+  private final String organizationUuid;
+  private final String type;
+  private final String uuid;
+  private final String componentUuid;
+  private final String componentKey;
+  private final String componentName;
+  private final String submitterUuid;
+
+  private CeTask(Builder builder) {
+    this.organizationUuid = requireNonNull(emptyToNull(builder.organizationUuid), "organizationUuid can't be null nor empty");
+    this.uuid = requireNonNull(emptyToNull(builder.uuid), "uuid can't be null nor empty");
+    this.type = requireNonNull(emptyToNull(builder.type), "type can't be null nor empty");
+    this.componentUuid = emptyToNull(builder.componentUuid);
+    this.componentKey = emptyToNull(builder.componentKey);
+    this.componentName = emptyToNull(builder.componentName);
+    this.submitterUuid = emptyToNull(builder.submitterUuid);
+  }
+
+  public String getOrganizationUuid() {
+    return organizationUuid;
+  }
+
+  public String getUuid() {
+    return uuid;
+  }
+
+  public String getType() {
+    return type;
+  }
+
+  @CheckForNull
+  public String getComponentUuid() {
+    return componentUuid;
+  }
+
+  @CheckForNull
+  public String getComponentKey() {
+    return componentKey;
+  }
+
+  @CheckForNull
+  public String getComponentName() {
+    return componentName;
+  }
+
+  @CheckForNull
+  public String getSubmitterUuid() {
+    return submitterUuid;
+  }
+
+  @Override
+  public String toString() {
+    return MoreObjects.toStringHelper(this)
+      .add("organizationUuid", organizationUuid)
+      .add("type", type)
+      .add("uuid", uuid)
+      .add("componentUuid", componentUuid)
+      .add("componentKey", componentKey)
+      .add("componentName", componentName)
+      .add("submitterUuid", submitterUuid)
+      .toString();
+  }
+
+  @Override
+  public boolean equals(@Nullable Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    CeTask ceTask = (CeTask) o;
+    return uuid.equals(ceTask.uuid);
+  }
+
+  @Override
+  public int hashCode() {
+    return uuid.hashCode();
+  }
+
+  public static final class Builder {
+    private String organizationUuid;
+    private String uuid;
+    private String type;
+    private String componentUuid;
+    private String componentKey;
+    private String componentName;
+    private String submitterUuid;
+
+    public Builder setOrganizationUuid(String organizationUuid) {
+      this.organizationUuid = organizationUuid;
+      return this;
+    }
+
+    // FIXME remove this method when organization support is added to the Compute Engine queue
+    public boolean hasOrganizationUuid() {
+      return organizationUuid != null;
+    }
+
+    public Builder setUuid(String uuid) {
+      this.uuid = uuid;
+      return this;
+    }
+
+    public Builder setType(String type) {
+      this.type = type;
+      return this;
+    }
+
+    public Builder setComponentUuid(String componentUuid) {
+      this.componentUuid = componentUuid;
+      return this;
+    }
+
+    public Builder setComponentKey(@Nullable String s) {
+      this.componentKey = s;
+      return this;
+    }
+
+    public Builder setComponentName(@Nullable String s) {
+      this.componentName = s;
+      return this;
+    }
+
+    public Builder setSubmitterUuid(@Nullable String s) {
+      this.submitterUuid = s;
+      return this;
+    }
+
+    public CeTask build() {
+      return new CeTask(this);
+    }
+  }
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/CeTaskResult.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/CeTaskResult.java
new file mode 100644
index 00000000000..73dcb927513
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/CeTaskResult.java
@@ -0,0 +1,33 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation;
+
+import java.util.Optional;
+
+/**
+ * Represents the result of the processing of a {@link CeTask}.
+ */
+@FunctionalInterface
+public interface CeTaskResult {
+  /**
+   * The UUID of the analysis created, if any, for the Component in {@link CeTask}
+   */
+  Optional<String> getAnalysisUuid();
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/log/CeTaskLogging.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/log/CeTaskLogging.java
new file mode 100644
index 00000000000..8f1dbba3ced
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/log/CeTaskLogging.java
@@ -0,0 +1,37 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.log;
+
+import org.slf4j.MDC;
+import org.sonar.server.computation.CeTask;
+
+public class CeTaskLogging {
+
+  public static final String MDC_CE_TASK_UUID = "ceTaskUuid";
+
+  public void initForTask(CeTask task) {
+    MDC.put(MDC_CE_TASK_UUID, task.getUuid());
+  }
+
+  public void clearForTask() {
+    MDC.remove(MDC_CE_TASK_UUID);
+  }
+
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/log/package-info.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/log/package-info.java
new file mode 100644
index 00000000000..1088bac9be7
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/log/package-info.java
@@ -0,0 +1,23 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+@ParametersAreNonnullByDefault
+package org.sonar.server.computation.log;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/package-info.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/package-info.java
new file mode 100644
index 00000000000..2b97ccbf4fc
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/package-info.java
@@ -0,0 +1,23 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+@ParametersAreNonnullByDefault
+package org.sonar.server.computation;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/EagerStart.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/EagerStart.java
new file mode 100644
index 00000000000..10ab10abf01
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/EagerStart.java
@@ -0,0 +1,33 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.container;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Components with this annotation will be eagerly started when loaded into the {@link TaskContainerImpl}.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+public @interface EagerStart {
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/TaskContainer.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/TaskContainer.java
new file mode 100644
index 00000000000..ba9a14b28c0
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/TaskContainer.java
@@ -0,0 +1,50 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.container;
+
+import org.picocontainer.PicoContainer;
+import org.sonar.server.computation.CeTask;
+import org.sonar.core.platform.ComponentContainer;
+import org.sonar.core.platform.ContainerPopulator;
+
+/**
+ * The Compute Engine task container. Created for a specific parent {@link ComponentContainer} and a specific {@link CeTask}.
+ */
+public interface TaskContainer extends ContainerPopulator.Container, AutoCloseable {
+
+  ComponentContainer getParent();
+
+  /**
+   * Starts task container, starting any startable component in it.
+   */
+  void bootup();
+
+  /**
+   * Cleans up resources after process has been called and has returned.
+   */
+  @Override
+  void close();
+
+  /**
+   * Access to the underlying pico container.
+   */
+  PicoContainer getPicoContainer();
+
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/TaskContainerImpl.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/TaskContainerImpl.java
new file mode 100644
index 00000000000..3902a1b9709
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/TaskContainerImpl.java
@@ -0,0 +1,93 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.container;
+
+import java.util.List;
+import org.picocontainer.ComponentAdapter;
+import org.picocontainer.ComponentMonitor;
+import org.picocontainer.DefaultPicoContainer;
+import org.picocontainer.MutablePicoContainer;
+import org.picocontainer.behaviors.OptInCaching;
+import org.picocontainer.lifecycle.ReflectionLifecycleStrategy;
+import org.picocontainer.monitors.NullComponentMonitor;
+import org.sonar.api.config.PropertyDefinitions;
+import org.sonar.api.utils.log.Loggers;
+import org.sonar.core.platform.ComponentContainer;
+import org.sonar.core.platform.ContainerPopulator;
+import org.sonar.core.platform.Module;
+import org.sonar.core.platform.StopSafeReflectionLifecycleStrategy;
+
+import static java.util.Objects.requireNonNull;
+
+public class TaskContainerImpl extends ComponentContainer implements TaskContainer {
+
+  public TaskContainerImpl(ComponentContainer parent, ContainerPopulator<TaskContainer> populator) {
+    super(createContainer(requireNonNull(parent)), parent.getComponentByType(PropertyDefinitions.class));
+
+    populateContainer(requireNonNull(populator));
+  }
+
+  private void populateContainer(ContainerPopulator<TaskContainer> populator) {
+    populator.populateContainer(this);
+    populateFromModules();
+  }
+
+  private void populateFromModules() {
+    List<Module> modules = getComponentsByType(Module.class);
+    for (Module module : modules) {
+      module.configure(this);
+    }
+  }
+
+  /**
+   * Creates a PicContainer which extends the specified ComponentContainer <strong>but is not referenced in return</strong>
+   * and lazily starts its components.
+   */
+  private static MutablePicoContainer createContainer(ComponentContainer parent) {
+    ComponentMonitor componentMonitor = new NullComponentMonitor();
+    ReflectionLifecycleStrategy lifecycleStrategy = new StopSafeReflectionLifecycleStrategy(componentMonitor) {
+      @Override
+      public boolean isLazy(ComponentAdapter<?> adapter) {
+        return adapter.getComponentImplementation().getAnnotation(EagerStart.class) == null;
+      }
+    };
+
+    return new DefaultPicoContainer(new OptInCaching(), lifecycleStrategy, parent.getPicoContainer(), componentMonitor);
+  }
+
+  @Override
+  public void bootup() {
+    startComponents();
+  }
+
+  @Override
+  public String toString() {
+    return "TaskContainerImpl";
+  }
+
+  @Override
+  public void close() {
+    try {
+      stopComponents();
+    } catch (Throwable t) {
+      Loggers.get(TaskContainerImpl.class).error("Cleanup of container failed", t);
+    }
+  }
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/package-info.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/package-info.java
new file mode 100644
index 00000000000..f01956fbb38
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/container/package-info.java
@@ -0,0 +1,23 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+@ParametersAreNonnullByDefault
+package org.sonar.server.computation.task.container;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ComputationStep.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ComputationStep.java
new file mode 100644
index 00000000000..f8fd66fe961
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ComputationStep.java
@@ -0,0 +1,31 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.step;
+
+/**
+ * A way of splitting the processing of a task into smaller items which can be executed sequencially
+ * by {@link ComputationStepExecutor}.
+ */
+public interface ComputationStep {
+
+  void execute();
+
+  String getDescription();
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ComputationStepExecutor.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ComputationStepExecutor.java
new file mode 100644
index 00000000000..536121f29ca
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ComputationStepExecutor.java
@@ -0,0 +1,83 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.step;
+
+import javax.annotation.CheckForNull;
+import javax.annotation.Nullable;
+import org.sonar.api.utils.log.Logger;
+import org.sonar.api.utils.log.Loggers;
+import org.sonar.core.util.logs.Profiler;
+
+public final class ComputationStepExecutor {
+  private static final Logger LOGGER = Loggers.get(ComputationStepExecutor.class);
+
+  private final ComputationSteps steps;
+  @CheckForNull
+  private final Listener listener;
+
+  /**
+   * Used when no {@link ComputationStepExecutor.Listener} is available in pico
+   * container.
+   */
+  public ComputationStepExecutor(ComputationSteps steps) {
+    this(steps, null);
+  }
+
+  public ComputationStepExecutor(ComputationSteps steps, @Nullable Listener listener) {
+    this.steps = steps;
+    this.listener = listener;
+  }
+
+  public void execute() {
+    Profiler stepProfiler = Profiler.create(LOGGER);
+    boolean allStepsExecuted = false;
+    try {
+      executeSteps(stepProfiler);
+      allStepsExecuted = true;
+    } finally {
+      if (listener != null) {
+        executeListener(allStepsExecuted);
+      }
+    }
+  }
+
+  private void executeSteps(Profiler stepProfiler) {
+    for (ComputationStep step : steps.instances()) {
+      stepProfiler.start();
+      step.execute();
+      stepProfiler.stopDebug(step.getDescription());
+    }
+  }
+
+  private void executeListener(boolean allStepsExecuted) {
+    try {
+      listener.finished(allStepsExecuted);
+    } catch (Throwable e) {
+      // any Throwable throws by the listener going up the stack might hide an Exception/Error thrown by the step and
+      // cause it be swallowed. We don't wan't that => we catch Throwable
+      LOGGER.error("Execution of listener failed", e);
+    }
+  }
+
+  @FunctionalInterface
+  public interface Listener {
+    void finished(boolean allStepsExecuted);
+  }
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ComputationSteps.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ComputationSteps.java
new file mode 100644
index 00000000000..c35ca8f6a38
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ComputationSteps.java
@@ -0,0 +1,39 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.step;
+
+import java.util.List;
+
+/**
+ * Ordered list of steps classes and instances to be executed in a Compute Engine process.
+ */
+public interface ComputationSteps {
+  /**
+   * List of all {@link ComputationStep},
+   * ordered by execution sequence.
+   */
+  List<Class<? extends ComputationStep>> orderedStepClasses();
+
+  /**
+   * List of all {@link ComputationStep},
+   * ordered by execution sequence.
+   */
+  Iterable<ComputationStep> instances();
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ExecuteStatelessInitExtensionsStep.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ExecuteStatelessInitExtensionsStep.java
new file mode 100644
index 00000000000..b587083d88b
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/ExecuteStatelessInitExtensionsStep.java
@@ -0,0 +1,56 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.step;
+
+import org.sonar.api.ce.ComputeEngineSide;
+
+/**
+ * Execute {@link StatelessInitExtension} instances in no specific order.
+ * If an extension fails (throws an exception), consecutive extensions
+ * won't be called.
+ */
+@ComputeEngineSide
+public class ExecuteStatelessInitExtensionsStep implements ComputationStep {
+
+  private final StatelessInitExtension[] extensions;
+
+  public ExecuteStatelessInitExtensionsStep(StatelessInitExtension[] extensions) {
+    this.extensions = extensions;
+  }
+
+  /**
+   * Used when zero {@link StatelessInitExtension} are registered into container.
+   */
+  public ExecuteStatelessInitExtensionsStep() {
+    this(new StatelessInitExtension[0]);
+  }
+
+  @Override
+  public void execute() {
+    for (StatelessInitExtension extension : extensions) {
+      extension.onInit();
+    }
+  }
+
+  @Override
+  public String getDescription() {
+    return "Initialize";
+  }
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/StatelessInitExtension.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/StatelessInitExtension.java
new file mode 100644
index 00000000000..aedc81e8347
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/StatelessInitExtension.java
@@ -0,0 +1,41 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.step;
+
+import org.sonar.api.ExtensionPoint;
+import org.sonar.api.ce.ComputeEngineSide;
+
+/**
+ * Extension point that is called during processing of a task
+ * by {@link ExecuteStatelessInitExtensionsStep}.
+ * It is stateless, the same instance is reused for all tasks.
+ * As a consequence Compute Engine task components can't be injected
+ * as dependencies.
+ */
+@ComputeEngineSide
+@ExtensionPoint
+public interface StatelessInitExtension {
+
+  /**
+   * This method can make the task fail by throwing a {@link RuntimeException}
+   */
+  void onInit();
+
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/TypedException.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/TypedException.java
new file mode 100644
index 00000000000..b600f90f7e3
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/TypedException.java
@@ -0,0 +1,33 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.step;
+
+/**
+ * This interface is implemented by the exceptions
+ * that provide a type of error when failing
+ * a Compute Engine task.
+ * The error type is persisted and available in
+ * the tasks returned by the web services api/ce.
+ */
+public interface TypedException {
+
+  String getType();
+
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/package-info.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/package-info.java
new file mode 100644
index 00000000000..5868b7cccc4
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/task/step/package-info.java
@@ -0,0 +1,23 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+@ParametersAreNonnullByDefault
+package org.sonar.server.computation.task.step;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/taskprocessor/MutableTaskResultHolder.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/taskprocessor/MutableTaskResultHolder.java
new file mode 100644
index 00000000000..5e4409b1b73
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/taskprocessor/MutableTaskResultHolder.java
@@ -0,0 +1,30 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.taskprocessor;
+
+import org.sonar.server.computation.CeTaskResult;
+
+public interface MutableTaskResultHolder extends TaskResultHolder {
+  /**
+   * @throws NullPointerException if {@code taskResult} is {@code null}
+   * @throws IllegalStateException if a {@link CeTaskResult} has already been set in the holder
+   */
+  void setResult(CeTaskResult taskResult);
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/taskprocessor/MutableTaskResultHolderImpl.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/taskprocessor/MutableTaskResultHolderImpl.java
new file mode 100644
index 00000000000..6fe1e53913e
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/taskprocessor/MutableTaskResultHolderImpl.java
@@ -0,0 +1,44 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.taskprocessor;
+
+import javax.annotation.CheckForNull;
+import org.sonar.server.computation.CeTaskResult;
+
+import static com.google.common.base.Preconditions.checkState;
+import static java.util.Objects.requireNonNull;
+
+public class MutableTaskResultHolderImpl implements MutableTaskResultHolder {
+  @CheckForNull
+  private CeTaskResult result;
+
+  @Override
+  public CeTaskResult getResult() {
+    checkState(this.result != null, "No CeTaskResult has been set in the holder");
+    return this.result;
+  }
+
+  @Override
+  public void setResult(CeTaskResult taskResult) {
+    requireNonNull(taskResult, "taskResult can not be null");
+    checkState(this.result == null, "CeTaskResult has already been set in the holder");
+    this.result = taskResult;
+  }
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/taskprocessor/TaskResultHolder.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/taskprocessor/TaskResultHolder.java
new file mode 100644
index 00000000000..b4c3e978150
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/taskprocessor/TaskResultHolder.java
@@ -0,0 +1,29 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.taskprocessor;
+
+import org.sonar.server.computation.CeTaskResult;
+
+public interface TaskResultHolder {
+  /**
+   * @throws IllegalStateException if holder holds no CeTaskResult
+   */
+  CeTaskResult getResult();
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/util/InitializedProperty.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/util/InitializedProperty.java
new file mode 100644
index 00000000000..01170eb9fde
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/util/InitializedProperty.java
@@ -0,0 +1,43 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.util;
+
+import javax.annotation.CheckForNull;
+import javax.annotation.Nullable;
+
+public class InitializedProperty<E> {
+  private E property;
+  private boolean initialized = false;
+
+  public InitializedProperty<E> setProperty(@Nullable E property) {
+    this.property = property;
+    this.initialized = true;
+    return this;
+  }
+
+  @CheckForNull
+  public E getProperty() {
+    return property;
+  }
+
+  public boolean isInitialized() {
+    return initialized;
+  }
+}
diff --git a/server/sonar-ce-task/src/main/java/org/sonar/server/computation/util/package-info.java b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/util/package-info.java
new file mode 100644
index 00000000000..415bc7b76f9
--- /dev/null
+++ b/server/sonar-ce-task/src/main/java/org/sonar/server/computation/util/package-info.java
@@ -0,0 +1,24 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+@ParametersAreNonnullByDefault
+package org.sonar.server.computation.util;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+
diff --git a/server/sonar-ce-task/src/test/java/org/sonar/server/computation/CeTaskTest.java b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/CeTaskTest.java
new file mode 100644
index 00000000000..b42261f5eb7
--- /dev/null
+++ b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/CeTaskTest.java
@@ -0,0 +1,148 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class CeTaskTest {
+  @Rule
+  public ExpectedException expectedException = ExpectedException.none();
+
+  private CeTask.Builder underTest = new CeTask.Builder();
+
+  @Test
+  public void build_fails_with_NPE_if_organizationUuid_is_null() {
+    expectedException.expect(NullPointerException.class);
+    expectedException.expectMessage("organizationUuid can't be null nor empty");
+
+    underTest.build();
+  }
+
+  @Test
+  public void build_fails_with_NPE_if_organizationUuid_is_empty() {
+    underTest.setOrganizationUuid("");
+
+    expectedException.expect(NullPointerException.class);
+    expectedException.expectMessage("organizationUuid can't be null nor empty");
+
+    underTest.build();
+  }
+
+  @Test
+  public void build_fails_with_NPE_if_uid_is_null() {
+    underTest.setOrganizationUuid("org1");
+
+    expectedException.expect(NullPointerException.class);
+    expectedException.expectMessage("uuid can't be null nor empty");
+
+    underTest.build();
+  }
+
+  @Test
+  public void build_fails_with_NPE_if_uuid_is_empty() {
+    underTest.setOrganizationUuid("org1").setUuid("");
+
+    expectedException.expect(NullPointerException.class);
+    expectedException.expectMessage("uuid can't be null nor empty");
+
+    underTest.build();
+  }
+
+  @Test
+  public void build_fails_with_NPE_if_type_is_null() {
+    underTest.setOrganizationUuid("org1").setUuid("uuid");
+
+    expectedException.expect(NullPointerException.class);
+    expectedException.expectMessage("type can't be null nor empty");
+
+    underTest.build();
+  }
+
+  @Test
+  public void build_fails_with_NPE_if_type_is_empty() {
+    underTest.setOrganizationUuid("org1").setUuid("uuid").setType("");
+
+    expectedException.expect(NullPointerException.class);
+    expectedException.expectMessage("type can't be null nor empty");
+
+    underTest.build();
+  }
+
+  @Test
+  public void verify_getters() {
+    underTest.setOrganizationUuid("org1");
+    underTest.setType("TYPE_1");
+    underTest.setUuid("UUID_1");
+    underTest.setSubmitterUuid("LOGIN_1");
+    underTest.setComponentKey("COMPONENT_KEY_1");
+    underTest.setComponentUuid("COMPONENT_UUID_1");
+    underTest.setComponentName("The component");
+
+    CeTask task = underTest.build();
+
+    assertThat(task.getOrganizationUuid()).isEqualTo("org1");
+    assertThat(task.getUuid()).isEqualTo("UUID_1");
+    assertThat(task.getType()).isEqualTo("TYPE_1");
+    assertThat(task.getSubmitterUuid()).isEqualTo("LOGIN_1");
+    assertThat(task.getComponentKey()).isEqualTo("COMPONENT_KEY_1");
+    assertThat(task.getComponentUuid()).isEqualTo("COMPONENT_UUID_1");
+    assertThat(task.getComponentName()).isEqualTo("The component");
+  }
+
+  @Test
+  public void empty_in_component_properties_is_considered_as_null() {
+    CeTask ceTask = underTest.setOrganizationUuid("org1").setUuid("uuid").setType("type")
+      .setComponentKey("")
+      .setComponentName("")
+      .setComponentUuid("")
+      .build();
+
+    assertThat(ceTask.getComponentKey()).isNull();
+    assertThat(ceTask.getComponentName()).isNull();
+    assertThat(ceTask.getComponentUuid()).isNull();
+  }
+
+  @Test
+  public void empty_in_submitterLogin_is_considered_as_null() {
+    CeTask ceTask = underTest.setOrganizationUuid("org1").setUuid("uuid").setType("type")
+      .setSubmitterUuid("")
+      .build();
+
+    assertThat(ceTask.getSubmitterUuid()).isNull();
+  }
+
+  @Test
+  public void equals_and_hashCode_on_uuid() {
+    underTest.setOrganizationUuid("org1").setType("TYPE_1").setUuid("UUID_1");
+    CeTask task1 = underTest.build();
+    CeTask task1bis = underTest.build();
+    CeTask task2 = new CeTask.Builder().setOrganizationUuid("org1").setType("TYPE_1").setUuid("UUID_2").build();
+
+    assertThat(task1.equals(task1)).isTrue();
+    assertThat(task1.equals(task1bis)).isTrue();
+    assertThat(task1.equals(task2)).isFalse();
+    assertThat(task1.hashCode()).isEqualTo(task1.hashCode());
+    assertThat(task1.hashCode()).isEqualTo(task1bis.hashCode());
+  }
+}
diff --git a/server/sonar-ce-task/src/test/java/org/sonar/server/computation/log/CeTaskLoggingTest.java b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/log/CeTaskLoggingTest.java
new file mode 100644
index 00000000000..5193eb1efd8
--- /dev/null
+++ b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/log/CeTaskLoggingTest.java
@@ -0,0 +1,78 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.log;
+
+import ch.qos.logback.core.joran.spi.JoranException;
+import org.junit.After;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.mockito.Mockito;
+import org.slf4j.MDC;
+import org.sonar.process.logging.LogbackHelper;
+import org.sonar.server.computation.CeTask;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.when;
+import static org.sonar.server.computation.log.CeTaskLogging.MDC_CE_TASK_UUID;
+
+public class CeTaskLoggingTest {
+
+  @Rule
+  public ExpectedException expectedException = ExpectedException.none();
+
+  private LogbackHelper helper = new LogbackHelper();
+  private CeTaskLogging underTest = new CeTaskLogging();
+
+  @After
+  public void resetLogback() throws JoranException {
+    helper.resetFromXml("/logback-test.xml");
+  }
+
+  @After
+  public void cleanMDC() {
+    MDC.clear();
+  }
+
+  @Test
+  public void initForTask_stores_task_uuid_in_MDC() {
+    String uuid = "ce_task_uuid";
+
+    underTest.initForTask(createCeTask(uuid));
+
+    assertThat(MDC.get(MDC_CE_TASK_UUID)).isEqualTo(uuid);
+  }
+
+  private CeTask createCeTask(String uuid) {
+    CeTask ceTask = Mockito.mock(CeTask.class);
+    when(ceTask.getUuid()).thenReturn(uuid);
+    return ceTask;
+  }
+
+  @Test
+  public void clearForTask_removes_task_uuid_from_MDC() {
+    MDC.put(MDC_CE_TASK_UUID, "some_value");
+
+    underTest.clearForTask();
+
+    assertThat(MDC.get(MDC_CE_TASK_UUID)).isNull();
+  }
+
+}
diff --git a/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/ChangeLogLevel.java b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/ChangeLogLevel.java
new file mode 100644
index 00000000000..3260b7263cd
--- /dev/null
+++ b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/ChangeLogLevel.java
@@ -0,0 +1,40 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task;
+
+import org.sonar.api.utils.log.Logger;
+import org.sonar.api.utils.log.LoggerLevel;
+import org.sonar.api.utils.log.Loggers;
+
+public final class ChangeLogLevel implements AutoCloseable {
+  private final Logger logger;
+  private final LoggerLevel previous;
+
+  public ChangeLogLevel(Class<?> clazz, LoggerLevel newLevel) {
+    this.logger = Loggers.get(clazz);
+    this.previous = logger.getLevel();
+    logger.setLevel(newLevel);
+  }
+
+  @Override
+  public void close() {
+    logger.setLevel(previous);
+  }
+}
diff --git a/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/container/TaskContainerImplTest.java b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/container/TaskContainerImplTest.java
new file mode 100644
index 00000000000..debaac8a916
--- /dev/null
+++ b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/container/TaskContainerImplTest.java
@@ -0,0 +1,114 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.container;
+
+import org.junit.Test;
+import org.picocontainer.Startable;
+import org.sonar.core.platform.ComponentContainer;
+import org.sonar.core.platform.ContainerPopulator;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+public class TaskContainerImplTest {
+  private ComponentContainer parent = new ComponentContainer();
+  private ContainerPopulator populator = mock(ContainerPopulator.class);
+
+  @Test(expected = NullPointerException.class)
+  public void constructor_fails_fast_on_null_container() {
+    new TaskContainerImpl(null, mock(ContainerPopulator.class));
+  }
+
+  @Test(expected = NullPointerException.class)
+  public void constructor_fails_fast_on_null_item() {
+    new TaskContainerImpl(new ComponentContainer(), null);
+  }
+
+  @Test
+  public void calls_method_populateContainer_of_passed_in_populator() {
+    TaskContainerImpl ceContainer = new TaskContainerImpl(parent, populator);
+
+    verify(populator).populateContainer(ceContainer);
+  }
+
+  @Test
+  public void ce_container_is_not_child_of_specified_container() {
+    TaskContainerImpl ceContainer = new TaskContainerImpl(parent, populator);
+
+    assertThat(parent.getChildren()).isEmpty();
+    verify(populator).populateContainer(ceContainer);
+  }
+
+  @Test
+  public void bootup_starts_components_lazily_unless_they_are_annotated_with_EagerStart() {
+    final DefaultStartable defaultStartable = new DefaultStartable();
+    final EagerStartable eagerStartable = new EagerStartable();
+    TaskContainerImpl ceContainer = new TaskContainerImpl(parent, container -> {
+      container.add(defaultStartable);
+      container.add(eagerStartable);
+    });
+    ceContainer.bootup();
+
+    assertThat(defaultStartable.startCalls).isEqualTo(0);
+    assertThat(defaultStartable.stopCalls).isEqualTo(0);
+    assertThat(eagerStartable.startCalls).isEqualTo(1);
+    assertThat(eagerStartable.stopCalls).isEqualTo(0);
+  }
+
+  @Test
+  public void close_stops_started_components() {
+    final DefaultStartable defaultStartable = new DefaultStartable();
+    final EagerStartable eagerStartable = new EagerStartable();
+    TaskContainerImpl ceContainer = new TaskContainerImpl(parent, container -> {
+      container.add(defaultStartable);
+      container.add(eagerStartable);
+    });
+    ceContainer.bootup();
+
+    ceContainer.close();
+
+    assertThat(defaultStartable.startCalls).isEqualTo(0);
+    assertThat(defaultStartable.stopCalls).isEqualTo(0);
+    assertThat(eagerStartable.startCalls).isEqualTo(1);
+    assertThat(eagerStartable.stopCalls).isEqualTo(1);
+  }
+
+  public static class DefaultStartable implements Startable {
+    protected int startCalls = 0;
+    protected int stopCalls = 0;
+
+    @Override
+    public void start() {
+      startCalls++;
+    }
+
+    @Override
+    public void stop() {
+      stopCalls++;
+    }
+  }
+
+  @EagerStart
+  public static class EagerStartable extends DefaultStartable {
+  }
+
+
+}
diff --git a/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/step/ComputationStepExecutorTest.java b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/step/ComputationStepExecutorTest.java
new file mode 100644
index 00000000000..19050a279bf
--- /dev/null
+++ b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/step/ComputationStepExecutorTest.java
@@ -0,0 +1,166 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.step;
+
+import java.util.Arrays;
+import java.util.List;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.mockito.InOrder;
+import org.sonar.api.utils.log.LogTester;
+import org.sonar.api.utils.log.LoggerLevel;
+import org.sonar.server.computation.task.ChangeLogLevel;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+import static org.mockito.ArgumentMatchers.anyBoolean;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.inOrder;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
+
+public class ComputationStepExecutorTest {
+  @Rule
+  public LogTester logTester = new LogTester();
+  @Rule
+  public ExpectedException expectedException = ExpectedException.none();
+
+  private final ComputationStepExecutor.Listener listener = mock(ComputationStepExecutor.Listener.class);
+  private final ComputationStep computationStep1 = mockComputationStep("step1");
+  private final ComputationStep computationStep2 = mockComputationStep("step2");
+  private final ComputationStep computationStep3 = mockComputationStep("step3");
+
+  @Test
+  public void execute_call_execute_on_each_ComputationStep_in_order_returned_by_instances_method() {
+    new ComputationStepExecutor(mockComputationSteps(computationStep1, computationStep2, computationStep3))
+      .execute();
+
+    InOrder inOrder = inOrder(computationStep1, computationStep2, computationStep3);
+    inOrder.verify(computationStep1).execute();
+    inOrder.verify(computationStep1).getDescription();
+    inOrder.verify(computationStep2).execute();
+    inOrder.verify(computationStep2).getDescription();
+    inOrder.verify(computationStep3).execute();
+    inOrder.verify(computationStep3).getDescription();
+    inOrder.verifyNoMoreInteractions();
+  }
+
+  @Test
+  public void execute_let_exception_thrown_by_ComputationStep_go_up_as_is() {
+    String message = "Exception should go up";
+
+    ComputationStep computationStep = mockComputationStep("step1");
+    doThrow(new RuntimeException(message))
+      .when(computationStep)
+      .execute();
+
+    ComputationStepExecutor computationStepExecutor = new ComputationStepExecutor(mockComputationSteps(computationStep));
+
+    expectedException.expect(RuntimeException.class);
+    expectedException.expectMessage(message);
+
+    computationStepExecutor.execute();
+  }
+
+  @Test
+  public void execute_does_not_log_end_timing_for_each_ComputationStep_called_when_level_is_INFO() {
+    List<String> infoLogs = execute_logs_end_timing_for_each_ComputationStep_called_when_(LoggerLevel.INFO);
+    assertThat(infoLogs).isEmpty();
+  }
+
+  @Test
+  public void execute_logs_end_timing_for_each_ComputationStep_called_when_level_is_DEBUG() {
+    List<String> infoLogs = execute_logs_end_timing_for_each_ComputationStep_called_when_(LoggerLevel.DEBUG);
+    assertThat(infoLogs).hasSize(2);
+    assertThat(infoLogs.get(0)).contains("step1 | time=");
+    assertThat(infoLogs.get(1)).contains("step2 | time=");
+  }
+
+  @Test
+  public void execute_logs_end_timing_for_each_ComputationStep_called_when_level_is_TRACE() {
+    List<String> infoLogs = execute_logs_end_timing_for_each_ComputationStep_called_when_(LoggerLevel.TRACE);
+    assertThat(infoLogs).hasSize(2);
+    assertThat(infoLogs.get(0)).contains("step1 | time=");
+    assertThat(infoLogs.get(1)).contains("step2 | time=");
+  }
+
+  private List<String> execute_logs_end_timing_for_each_ComputationStep_called_when_(LoggerLevel level) {
+    try (ChangeLogLevel executor = new ChangeLogLevel(ComputationStepExecutor.class, level);
+      ChangeLogLevel step1 = new ChangeLogLevel(computationStep1.getClass(), level);
+      ChangeLogLevel step2 = new ChangeLogLevel(computationStep2.getClass(), level)) {
+      new ComputationStepExecutor(mockComputationSteps(computationStep1, computationStep2))
+        .execute();
+
+      return logTester.logs(LoggerLevel.DEBUG);
+    }
+  }
+
+  @Test
+  public void execute_calls_listener_finished_method_with_all_step_runs() {
+    new ComputationStepExecutor(mockComputationSteps(computationStep1, computationStep2), listener)
+      .execute();
+
+    verify(listener).finished(true);
+    verifyNoMoreInteractions(listener);
+  }
+
+  @Test
+  public void execute_calls_listener_finished_method_even_if_a_step_throws_an_exception() {
+    RuntimeException toBeThrown = new RuntimeException("simulating failing execute Step method");
+    doThrow(toBeThrown)
+      .when(computationStep1)
+      .execute();
+
+    try {
+      new ComputationStepExecutor(mockComputationSteps(computationStep1, computationStep2), listener)
+        .execute();
+      fail("exception toBeThrown should have been raised");
+    } catch (RuntimeException e) {
+      assertThat(e).isSameAs(toBeThrown);
+      verify(listener).finished(false);
+      verifyNoMoreInteractions(listener);
+    }
+  }
+
+  @Test
+  public void execute_does_not_fail_if_listener_throws_Throwable() {
+    ComputationStepExecutor.Listener listener = mock(ComputationStepExecutor.Listener.class);
+    doThrow(new Error("Facking error thrown by Listener"))
+        .when(listener)
+        .finished(anyBoolean());
+
+    new ComputationStepExecutor(mockComputationSteps(computationStep1), listener).execute();
+  }
+
+  private static ComputationSteps mockComputationSteps(ComputationStep... computationSteps) {
+    ComputationSteps steps = mock(ComputationSteps.class);
+    when(steps.instances()).thenReturn(Arrays.asList(computationSteps));
+    return steps;
+  }
+
+  private static ComputationStep mockComputationStep(String desc) {
+    ComputationStep mock = mock(ComputationStep.class);
+    when(mock.getDescription()).thenReturn(desc);
+    return mock;
+  }
+}
diff --git a/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/step/ExecuteStatelessInitExtensionsStepTest.java b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/step/ExecuteStatelessInitExtensionsStepTest.java
new file mode 100644
index 00000000000..fdf4049bf35
--- /dev/null
+++ b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/step/ExecuteStatelessInitExtensionsStepTest.java
@@ -0,0 +1,89 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.step;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.mockito.InOrder;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.fail;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.inOrder;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
+public class ExecuteStatelessInitExtensionsStepTest {
+
+  @Rule
+  public ExpectedException expectedException = ExpectedException.none();
+
+  @Test
+  public void test_getDescription() {
+    ExecuteStatelessInitExtensionsStep underTest = new ExecuteStatelessInitExtensionsStep();
+
+    assertThat(underTest.getDescription()).isEqualTo("Initialize");
+  }
+
+  @Test
+  public void do_nothing_if_no_extensions() {
+    ExecuteStatelessInitExtensionsStep underTest = new ExecuteStatelessInitExtensionsStep();
+
+    // no failure
+    underTest.execute();
+  }
+
+  @Test
+  public void execute_extensions() {
+    StatelessInitExtension ext1 = mock(StatelessInitExtension.class);
+    StatelessInitExtension ext2 = mock(StatelessInitExtension.class);
+
+    ExecuteStatelessInitExtensionsStep underTest = new ExecuteStatelessInitExtensionsStep(
+      new StatelessInitExtension[] {ext1, ext2});
+    underTest.execute();
+
+    InOrder inOrder = inOrder(ext1, ext2);
+    inOrder.verify(ext1).onInit();
+    inOrder.verify(ext2).onInit();
+  }
+
+  @Test
+  public void fail_if_an_extension_throws_an_exception() {
+    StatelessInitExtension ext1 = mock(StatelessInitExtension.class);
+    StatelessInitExtension ext2 = mock(StatelessInitExtension.class);
+    doThrow(new IllegalStateException("BOOM")).when(ext2).onInit();
+    StatelessInitExtension ext3 = mock(StatelessInitExtension.class);
+
+    ExecuteStatelessInitExtensionsStep underTest = new ExecuteStatelessInitExtensionsStep(
+      new StatelessInitExtension[] {ext1, ext2, ext3});
+
+    try {
+      underTest.execute();
+      fail();
+    } catch (IllegalStateException e) {
+      assertThat(e).hasMessage("BOOM");
+      verify(ext1).onInit();
+      verify(ext3, never()).onInit();
+    }
+  }
+
+}
diff --git a/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/step/StepsExplorer.java b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/step/StepsExplorer.java
new file mode 100644
index 00000000000..1f836dee41c
--- /dev/null
+++ b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/task/step/StepsExplorer.java
@@ -0,0 +1,68 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.task.step;
+
+import com.google.common.base.Function;
+import com.google.common.base.Predicate;
+import java.lang.reflect.Modifier;
+import java.util.Set;
+import javax.annotation.Nonnull;
+import org.reflections.Reflections;
+
+import static com.google.common.base.Predicates.notNull;
+import static com.google.common.collect.FluentIterable.from;
+
+public class StepsExplorer {
+  /**
+   * Compute set of canonical names of classes implementing ComputationStep in the specified package using reflection.
+   */
+  public static Set<String> retrieveStepPackageStepsCanonicalNames(String packageName) {
+    Reflections reflections = new Reflections(packageName);
+
+    return from(reflections.getSubTypesOf(ComputationStep.class))
+        .filter(NotAbstractClass.INSTANCE)
+        .transform(ClassToCanonicalName.INSTANCE)
+        // anonymous classes do not have canonical names
+        .filter(notNull())
+        .toSet();
+  }
+
+  private enum NotAbstractClass implements Predicate<Class<? extends ComputationStep>> {
+    INSTANCE;
+
+    @Override
+    public boolean apply(Class<? extends ComputationStep> input) {
+      return !Modifier.isAbstract(input.getModifiers());
+    }
+  }
+
+  public static Function<Class<?>, String> toCanonicalName() {
+    return ClassToCanonicalName.INSTANCE;
+  }
+
+  private enum ClassToCanonicalName implements Function<Class<?>, String> {
+    INSTANCE;
+
+    @Override
+    public String apply(@Nonnull Class<?> input) {
+      return input.getCanonicalName();
+    }
+  }
+}
diff --git a/server/sonar-ce-task/src/test/java/org/sonar/server/computation/taskprocessor/MutableTaskResultHolderImplTest.java b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/taskprocessor/MutableTaskResultHolderImplTest.java
new file mode 100644
index 00000000000..f81de440ad6
--- /dev/null
+++ b/server/sonar-ce-task/src/test/java/org/sonar/server/computation/taskprocessor/MutableTaskResultHolderImplTest.java
@@ -0,0 +1,70 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2018 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.taskprocessor;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.sonar.server.computation.CeTaskResult;
+
+import static org.mockito.Mockito.mock;
+
+public class MutableTaskResultHolderImplTest {
+  @Rule
+  public ExpectedException expectedException = ExpectedException.none();
+
+  private MutableTaskResultHolder underTest = new MutableTaskResultHolderImpl();
+
+  @Test
+  public void getResult_throws_ISE_if_no_CeTaskResult_is_set() {
+    expectedException.expect(IllegalStateException.class);
+    expectedException.expectMessage("No CeTaskResult has been set in the holder");
+
+    underTest.getResult();
+  }
+
+  @Test
+  public void getResult_returns_object_set_with_setResult() {
+    CeTaskResult taskResult = mock(CeTaskResult.class);
+
+    underTest.setResult(taskResult);
+
+    Assertions.assertThat(underTest.getResult()).isSameAs(taskResult);
+  }
+
+  @Test
+  public void setResult_throws_NPE_if_CeTaskResult_argument_is_null() {
+    expectedException.expect(NullPointerException.class);
+    expectedException.expectMessage("taskResult can not be null");
+
+    underTest.setResult(null);
+  }
+
+  @Test
+  public void setResult_throws_ISE_if_called_twice() {
+    underTest.setResult(mock(CeTaskResult.class));
+
+    expectedException.expect(IllegalStateException.class);
+    expectedException.expectMessage("CeTaskResult has already been set in the holder");
+
+    underTest.setResult(mock(CeTaskResult.class));
+  }
+}
diff --git a/server/sonar-ce-task/src/test/resources/logback-test.xml b/server/sonar-ce-task/src/test/resources/logback-test.xml
new file mode 100644
index 00000000000..3e34b0f9fc8
--- /dev/null
+++ b/server/sonar-ce-task/src/test/resources/logback-test.xml
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<configuration debug="false">
+  <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator"/>
+
+  <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
+    <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
+      <pattern>
+        %d{yyyy.MM.dd HH:mm:ss} %-5level %msg%n
+      </pattern>
+    </encoder>
+  </appender>
+
+  <root>
+    <level value="INFO"/>
+    <appender-ref ref="CONSOLE"/>
+  </root>
+
+  <logger name="ch.qos.logback">
+    <level value="WARN"/>
+  </logger>
+
+  <logger name="okhttp3.mockwebserver">
+    <level value="WARN"/>
+  </logger>
+
+</configuration>