From 8f429bd30146ed064f37440312548d5fcde20a9b Mon Sep 17 00:00:00 2001
From: Julien HENRY <julien.henry@sonarsource.com>
Date: Mon, 2 Jan 2017 16:55:57 +0100
Subject: SONAR-8567 Improve logging API to accept a lambda as argument

---
 .../main/java/org/sonar/api/utils/log/Logger.java  | 37 ++++++++++++++-
 .../org/sonar/api/utils/log/LogTesterTest.java     | 53 ++++++++++++++++++++++
 2 files changed, 89 insertions(+), 1 deletion(-)

(limited to 'sonar-plugin-api')

diff --git a/sonar-plugin-api/src/main/java/org/sonar/api/utils/log/Logger.java b/sonar-plugin-api/src/main/java/org/sonar/api/utils/log/Logger.java
index 36665b990a6..3fd95e6ec55 100644
--- a/sonar-plugin-api/src/main/java/org/sonar/api/utils/log/Logger.java
+++ b/sonar-plugin-api/src/main/java/org/sonar/api/utils/log/Logger.java
@@ -19,6 +19,7 @@
  */
 package org.sonar.api.utils.log;
 
+import java.util.function.Supplier;
 import javax.annotation.Nullable;
 
 /**
@@ -59,6 +60,23 @@ public interface Logger {
    */
   void trace(String msg);
 
+  /**
+   * Logs a TRACE message, which is only to be constructed if the logging level
+   * is such that the message will actually be logged.
+   * <p>
+   * TRACE messages must
+   * be valuable for diagnosing production problems. They must not be used for development debugging.
+   * They can significantly slow down performances. The standard use-case is logging of
+   * SQL and Elasticsearch requests.
+   * @param msgSupplier A function, which when called, produces the desired log message
+   * @since 6.3
+   */
+  default void trace(Supplier<String> msgSupplier) {
+    if (isTraceEnabled()) {
+      trace(msgSupplier.get());
+    }
+  }
+
   /**
    * Logs an TRACE parameterized message according to the specified format and argument. Example:
    * <code>trace("Value is {}", value)</code>
@@ -99,11 +117,28 @@ public interface Logger {
   boolean isDebugEnabled();
 
   /**
-   * Logs a DEBUG message. Debug messages must
+   * Logs a DEBUG message. 
+   * <p>
+   * DEBUG messages must
    * be valuable for diagnosing production problems. They must not be used for development debugging.
    */
   void debug(String msg);
 
+  /**
+   * Logs a DEBUG message which is only to be constructed if the logging level
+   * is such that the message will actually be logged.
+   * <p>
+   * DEBUG messages must
+   * be valuable for diagnosing production problems. They must not be used for development debugging.
+   * @param msgSupplier A function, which when called, produces the desired log message
+   * @since 6.3
+   */
+  default void debug(Supplier<String> msgSupplier) {
+    if (isDebugEnabled()) {
+      debug(msgSupplier.get());
+    }
+  }
+
   /**
    * Logs an DEBUG parameterized message according to the specified format and argument. Example:
    * <code>debug("Value is {}", value)</code>
diff --git a/sonar-plugin-api/src/test/java/org/sonar/api/utils/log/LogTesterTest.java b/sonar-plugin-api/src/test/java/org/sonar/api/utils/log/LogTesterTest.java
index 0521837bc3b..e94f797ac44 100644
--- a/sonar-plugin-api/src/test/java/org/sonar/api/utils/log/LogTesterTest.java
+++ b/sonar-plugin-api/src/test/java/org/sonar/api/utils/log/LogTesterTest.java
@@ -19,6 +19,7 @@
  */
 package org.sonar.api.utils.log;
 
+import java.util.concurrent.atomic.AtomicBoolean;
 import org.junit.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -63,4 +64,56 @@ public class LogTesterTest {
     underTest.after();
     assertThat(LogInterceptors.get()).isSameAs(NullInterceptor.NULL_INSTANCE);
   }
+
+  @Test
+  public void use_suppliers() throws Throwable {
+    // when LogTester is used, then info logs are enabled by default
+    underTest.before();
+    AtomicBoolean touchedTrace = new AtomicBoolean();
+    AtomicBoolean touchedDebug = new AtomicBoolean();
+    Loggers.get("logger1").trace(() -> {
+      touchedTrace.set(true);
+      return "a trace information";
+    });
+    Loggers.get("logger1").debug(() -> {
+      touchedDebug.set(true);
+      return "a debug information";
+    });
+
+    assertThat(underTest.logs()).isEmpty();
+    assertThat(touchedTrace.get()).isFalse();
+    assertThat(touchedDebug.get()).isFalse();
+
+    // change level to DEBUG
+    underTest.setLevel(LoggerLevel.DEBUG);
+    Loggers.get("logger1").trace(() -> {
+      touchedTrace.set(true);
+      return "a trace information";
+    });
+    Loggers.get("logger1").debug(() -> {
+      touchedDebug.set(true);
+      return "a debug information";
+    });
+
+    assertThat(underTest.logs()).containsOnly("a debug information");
+    assertThat(touchedTrace.get()).isFalse();
+    assertThat(touchedDebug.get()).isTrue();
+    touchedDebug.set(false);
+    underTest.logs().clear();
+
+    // change level to TRACE
+    underTest.setLevel(LoggerLevel.TRACE);
+    Loggers.get("logger1").trace(() -> {
+      touchedTrace.set(true);
+      return "a trace information";
+    });
+    Loggers.get("logger1").debug(() -> {
+      touchedDebug.set(true);
+      return "a debug information";
+    });
+
+    assertThat(underTest.logs()).containsExactly("a trace information", "a debug information");
+    assertThat(touchedTrace.get()).isTrue();
+    assertThat(touchedDebug.get()).isTrue();
+  }
 }
-- 
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