SONAR-6397 Use a cache when reading SCM info to reduce db calls

2 files changed, 41 insertions, 2 deletions

diff --git a/server/sonar-server/src/main/java/org/sonar/server/computation/scm/ScmInfoRepositoryImpl.java b/server/sonar-server/src/main/java/org/sonar/server/computation/scm/ScmInfoRepositoryImpl.java
index 7ac532af8aa..20a7e1d88b9 100644
--- a/server/sonar-server/src/main/java/org/sonar/server/computation/scm/ScmInfoRepositoryImpl.java
+++ b/server/sonar-server/src/main/java/org/sonar/server/computation/scm/ScmInfoRepositoryImpl.java
@@ -20,6 +20,8 @@
 package org.sonar.server.computation.scm;
 
 import com.google.common.base.Optional;
+import java.util.HashMap;
+import java.util.Map;
 import org.sonar.api.utils.log.Logger;
 import org.sonar.api.utils.log.Loggers;
 import org.sonar.batch.protocol.output.BatchReport;
@@ -40,6 +42,8 @@ public class ScmInfoRepositoryImpl implements ScmInfoRepository {
   private final DbClient dbClient;
   private final SourceService sourceService;
 
+  private final Map<Component, ScmInfo> scmInfoCache = new HashMap<>();
+
   public ScmInfoRepositoryImpl(BatchReportReader batchReportReader, DbClient dbClient, SourceService sourceService) {
     this.batchReportReader = batchReportReader;
     this.dbClient = dbClient;
@@ -49,17 +53,30 @@ public class ScmInfoRepositoryImpl implements ScmInfoRepository {
   @Override
   public Optional<ScmInfo> getScmInfo(Component component) {
     checkNotNull(component, "Component cannot be bull");
+    initializeScmInfoForComponent(component);
+    return Optional.fromNullable(scmInfoCache.get(component));
+  }
+
+  private void initializeScmInfoForComponent(Component component) {
+    if (scmInfoCache.containsKey(component)) {
+      return;
+    }
+    Optional<ScmInfo> scmInfoOptional = getScmInfoForComponent(component);
+    scmInfoCache.put(component, scmInfoOptional.isPresent() ? scmInfoOptional.get() : null);
+  }
+
+  private Optional<ScmInfo> getScmInfoForComponent(Component component) {
     BatchReport.Changesets changesets = batchReportReader.readChangesets(component.getReportAttributes().getRef());
     if (changesets == null) {
       LOGGER.trace("Reading SCM info from db for file '{}'", component);
-      return getFromDb(component);
+      return getScmInfoFromDb(component);
     } else {
       LOGGER.trace("Reading SCM info from report for file '{}'", component);
       return Optional.<ScmInfo>of(new ReportScmInfo(changesets));
     }
   }
 
-  private Optional<ScmInfo> getFromDb(Component component){
+  private Optional<ScmInfo> getScmInfoFromDb(Component component) {
     DbSession dbSession = dbClient.openSession(false);
     try {
       Optional<Iterable<DbFileSources.Line>> linesOpt = sourceService.getLines(dbSession, component.getUuid(), 1, Integer.MAX_VALUE);
diff --git a/server/sonar-server/src/test/java/org/sonar/server/computation/scm/ScmInfoRepositoryImplTest.java b/server/sonar-server/src/test/java/org/sonar/server/computation/scm/ScmInfoRepositoryImplTest.java
index 04c0166a372..6108f9f640d 100644
--- a/server/sonar-server/src/test/java/org/sonar/server/computation/scm/ScmInfoRepositoryImplTest.java
+++ b/server/sonar-server/src/test/java/org/sonar/server/computation/scm/ScmInfoRepositoryImplTest.java
@@ -24,6 +24,7 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.sonar.api.utils.System2;
+import org.sonar.api.utils.log.LogTester;
 import org.sonar.batch.protocol.output.BatchReport;
 import org.sonar.db.DbClient;
 import org.sonar.db.DbTester;
@@ -35,11 +36,15 @@ import org.sonar.server.source.SourceService;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.guava.api.Assertions.assertThat;
+import static org.sonar.api.utils.log.LoggerLevel.TRACE;
 import static org.sonar.server.computation.component.ReportComponent.builder;
 
 public class ScmInfoRepositoryImplTest {
 
   @Rule
+  public LogTester logTester = new LogTester();
+
+  @Rule
   public ExpectedException thrown = ExpectedException.none();
 
   static final int FILE_REF = 1;
@@ -61,6 +66,8 @@ public class ScmInfoRepositoryImplTest {
 
     ScmInfo scmInfo = underTest.getScmInfo(FILE).get();
     assertThat(scmInfo.getAllChangesets()).hasSize(1);
+
+    assertThat(logTester.logs(TRACE)).containsOnly("Reading SCM info from report for file 'ReportComponent{ref=1, key='FILE_KEY', type=FILE}'");
   }
 
   @Test
@@ -69,6 +76,8 @@ public class ScmInfoRepositoryImplTest {
 
     ScmInfo scmInfo = underTest.getScmInfo(FILE).get();
     assertThat(scmInfo.getAllChangesets()).hasSize(1);
+
+    assertThat(logTester.logs(TRACE)).containsOnly("Reading SCM info from db for file 'ReportComponent{ref=1, key='FILE_KEY', type=FILE}'");
   }
 
   @Test
@@ -111,6 +120,19 @@ public class ScmInfoRepositoryImplTest {
     underTest.getScmInfo(null);
   }
 
+  @Test
+  public void load_scm_info_from_cache_when_already_read() throws Exception {
+    addChangesetInReport("john", 123456789L, "rev-1");
+    ScmInfo scmInfo = underTest.getScmInfo(FILE).get();
+    assertThat(scmInfo.getAllChangesets()).hasSize(1);
+
+    assertThat(logTester.logs(TRACE)).hasSize(1);
+    logTester.clear();
+
+    underTest.getScmInfo(FILE);
+    assertThat(logTester.logs(TRACE)).isEmpty();
+  }
+
   private void addChangesetInDb(String author, Long date, String revision) {
     DbFileSources.Data.Builder fileDataBuilder = DbFileSources.Data.newBuilder();
     fileDataBuilder.addLinesBuilder()