logger: 'trace' level added

jps/standalone-builder/src/com/intellij/openapi/diagnostic/CompositeLogger.java

@@ -61,6 +61,23 @@ public class CompositeLogger extends Logger {
     }
   }
 
+  @Override
+  public boolean isTraceEnabled() {
+    for (Logger logger : myLoggers) {
+      if (logger.isTraceEnabled()) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  @Override
+  public void trace(String message) {
+    for (Logger logger : myLoggers) {
+      logger.trace(message);
+    }
+  }
+
   @Override
   public void info(@NonNls String message) {
     for (Logger logger : myLoggers) {

platform/platform-impl/src/com/intellij/idea/RareLogger.java

@@ -132,6 +132,16 @@ public class RareLogger extends Logger {
     process(Level.DEBUG, message, t);
   }
 
+  @Override
+  public boolean isTraceEnabled() {
+    return myLogger.isTraceEnabled();
+  }
+
+  @Override
+  public void trace(String message) {
+    process(Level.TRACE, message, null);
+  }
+
   @Override
   public void error(@NonNls String message, @Nullable Throwable t, @NotNull @NonNls String... details) {
     process(Level.ERROR, message, t, details);

platform/util/src/com/intellij/openapi/diagnostic/Log4jBasedLogger.java

@@ -51,6 +51,16 @@ public class Log4jBasedLogger extends Logger {
     myLogger.debug(message, t);
   }
 
+  @Override
+  public boolean isTraceEnabled() {
+    return myLogger.isTraceEnabled();
+  }
+
+  @Override
+  public void trace(String message) {
+    myLogger.trace(message);
+  }
+
   @Override
   public void info(@NonNls String message) {
     myLogger.info(message);

platform/util/src/com/intellij/openapi/diagnostic/Logger.java

@@ -93,6 +93,18 @@ public abstract class Logger {
     }
   }
 
+  public boolean isTraceEnabled() {
+    return isDebugEnabled();
+  }
+
+  /**
+   * Log a message with 'trace' level which finer-grained than 'debug' level. Use this method instead of {@link #debug(String)} for internal
+   * events of a subsystem to avoid overwhelming the log if 'debug' level is enabled.
+   */
+  public void trace(String message) {
+    debug(message);
+  }
+
   public void info(@NotNull Throwable t) {
     info(t.getMessage(), t);
   }