BuildEventStreamer: allow final messages

After receiving a BuildCompletingEvent, allow some final late messages,
but only those not yet seen and announced by that BuildCompletingEvent.
This mechanism will be used in a follow-up change to add a message with
tool statistics.

Change-Id: I979bec5bd946208068faff9a4ddd5245a769f096
PiperOrigin-RevId: 173514552

3 files changed, 69 insertions, 14 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildCompletingEvent.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildCompletingEvent.java
index a1b5b284d3..72b6e085f1 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildCompletingEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/BuildCompletingEvent.java
@@ -27,10 +27,17 @@ import java.util.Collection;
 public abstract class BuildCompletingEvent implements BuildEvent {
   private final ExitCode exitCode;
   private final long finishTimeMillis;
+  private final Collection<BuildEventId> children;
 
-  public BuildCompletingEvent(ExitCode exitCode, long finishTimeMillis) {
+  public BuildCompletingEvent(
+      ExitCode exitCode, long finishTimeMillis, Collection<BuildEventId> children) {
     this.exitCode = exitCode;
     this.finishTimeMillis = finishTimeMillis;
+    this.children = children;
+  }
+
+  public BuildCompletingEvent(ExitCode exitCode, long finishTimeMillis) {
+    this(exitCode, finishTimeMillis, ImmutableList.of());
   }
 
   public ExitCode getExitCode() {
@@ -44,7 +51,7 @@ public abstract class BuildCompletingEvent implements BuildEvent {
 
   @Override
   public Collection<BuildEventId> getChildrenEvents() {
-    return ImmutableList.of();
+    return children;
   }
 
   @Override
diff --git a/src/main/java/com/google/devtools/build/lib/buildtool/buildevent/BuildCompleteEvent.java b/src/main/java/com/google/devtools/build/lib/buildtool/buildevent/BuildCompleteEvent.java
index d1c2cb79d4..3c63692c41 100644
--- a/src/main/java/com/google/devtools/build/lib/buildtool/buildevent/BuildCompleteEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/buildtool/buildevent/BuildCompleteEvent.java
@@ -16,8 +16,11 @@ package com.google.devtools.build.lib.buildtool.buildevent;
 
 import static com.google.devtools.build.lib.util.Preconditions.checkNotNull;
 
+import com.google.common.collect.ImmutableList;
 import com.google.devtools.build.lib.buildeventstream.BuildCompletingEvent;
+import com.google.devtools.build.lib.buildeventstream.BuildEventId;
 import com.google.devtools.build.lib.buildtool.BuildResult;
+import java.util.Collection;
 
 /**
  * This event is fired from BuildTool#stopRequest().
@@ -27,14 +30,16 @@ import com.google.devtools.build.lib.buildtool.BuildResult;
 public final class BuildCompleteEvent extends BuildCompletingEvent {
   private final BuildResult result;
 
-  /**
-   * Construct the BuildCompleteEvent.
-   */
-  public BuildCompleteEvent(BuildResult result) {
-    super(result.getExitCondition(), result.getStopTime());
+  /** Construct the BuildCompleteEvent. */
+  public BuildCompleteEvent(BuildResult result, Collection<BuildEventId> children) {
+    super(result.getExitCondition(), result.getStopTime(), children);
     this.result = checkNotNull(result);
   }
 
+  public BuildCompleteEvent(BuildResult result) {
+    this(result, ImmutableList.<BuildEventId>of());
+  }
+
   /**
    * @return the build summary
    */
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/BuildEventStreamer.java b/src/main/java/com/google/devtools/build/lib/runtime/BuildEventStreamer.java
index 33adad0aab..109065385b 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/BuildEventStreamer.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/BuildEventStreamer.java
@@ -44,6 +44,7 @@ import com.google.devtools.build.lib.buildeventstream.BuildEventTransport;
 import com.google.devtools.build.lib.buildeventstream.BuildEventTransportClosedEvent;
 import com.google.devtools.build.lib.buildeventstream.BuildEventWithConfiguration;
 import com.google.devtools.build.lib.buildeventstream.BuildEventWithOrderConstraint;
+import com.google.devtools.build.lib.buildeventstream.ChainableEvent;
 import com.google.devtools.build.lib.buildeventstream.LastBuildEvent;
 import com.google.devtools.build.lib.buildeventstream.NullConfiguration;
 import com.google.devtools.build.lib.buildeventstream.ProgressEvent;
@@ -98,6 +99,14 @@ public class BuildEventStreamer implements EventHandler {
   // Will be set to true if the build was invoked through "bazel test".
   private boolean isTestCommand;
 
+  // After a BuildCompetingEvent we might expect a whitelisted set of events. If non-null,
+  // the streamer is restricted to only allow those events and fully close after having seen
+  // them.
+  private Set<BuildEventId> finalEventsToCome = null;
+
+  // True, if we already closed the stream.
+  private boolean closed;
+
   private static final Logger logger = Logger.getLogger(BuildEventStreamer.class.getName());
 
   /**
@@ -289,7 +298,7 @@ public class BuildEventStreamer implements EventHandler {
    * Clear all events that are still announced; events not naturally closed by the expected event
    * normally only occur if the build is aborted.
    */
-  private void clearAnnouncedEvents() {
+  private void clearAnnouncedEvents(Collection<BuildEventId> dontclear) {
     if (announcedEvents != null) {
       // create a copy of the identifiers to clear, as the post method
       // will change the set of already announced events.
@@ -298,7 +307,9 @@ public class BuildEventStreamer implements EventHandler {
         ids = Sets.difference(announcedEvents, postedEvents);
       }
       for (BuildEventId id : ids) {
-        post(new AbortedEvent(id, abortReason, ""));
+        if (!dontclear.contains(id)) {
+          post(new AbortedEvent(id, abortReason, ""));
+        }
       }
     }
   }
@@ -320,7 +331,18 @@ public class BuildEventStreamer implements EventHandler {
         TimeUnit.SECONDS);
   }
 
+  public boolean isClosed() {
+    return closed;
+  }
+
   private void close() {
+    synchronized (this) {
+      if (closed) {
+        return;
+      }
+      closed = true;
+    }
+
     ScheduledExecutorService executor = null;
     try {
       executor = Executors.newSingleThreadScheduledExecutor();
@@ -407,6 +429,17 @@ public class BuildEventStreamer implements EventHandler {
 
   @Subscribe
   public void buildEvent(BuildEvent event) {
+    if (finalEventsToCome != null) {
+      synchronized (this) {
+        BuildEventId id = event.getEventId();
+        if (finalEventsToCome.contains(id)) {
+          finalEventsToCome.remove(id);
+        } else {
+          return;
+        }
+      }
+    }
+
     if (isActionWithoutError(event)
         || bufferUntilPrerequisitesReceived(event)
         || isVacuousTestSummary(event)) {
@@ -451,14 +484,18 @@ public class BuildEventStreamer implements EventHandler {
     }
 
     if (event instanceof BuildCompletingEvent) {
-      buildComplete();
+      buildComplete(event);
     }
 
     if (event instanceof NoBuildEvent) {
       if (!((NoBuildEvent) event).separateFinishedEvent()) {
-        buildComplete();
+        buildComplete(event);
       }
     }
+
+    if (finalEventsToCome != null && finalEventsToCome.isEmpty()) {
+      close();
+    }
   }
 
   private synchronized BuildEvent flushStdoutStderrEvent(String out, String err) {
@@ -496,7 +533,7 @@ public class BuildEventStreamer implements EventHandler {
     return ImmutableSet.copyOf(transports);
   }
 
-  private void buildComplete() {
+  private void buildComplete(ChainableEvent event) {
     clearPendingEvents();
     String out = null;
     String err = null;
@@ -505,8 +542,14 @@ public class BuildEventStreamer implements EventHandler {
       err = outErrProvider.getErr();
     }
     post(ProgressEvent.finalProgressUpdate(progressCount, out, err));
-    clearAnnouncedEvents();
-    close();
+    clearAnnouncedEvents(event.getChildrenEvents());
+
+    finalEventsToCome = new HashSet<>(announcedEvents);
+    finalEventsToCome.removeAll(postedEvents);
+
+    if (finalEventsToCome.isEmpty()) {
+      close();
+    }
   }
 
   /**