Provide more reporting options to SkyFunctions

With more specific information to be reported by Skyfunctions, e.g.,
to inform the build-event protocol on missing files, the EventHandler
interface is no longer enough. Therefore, provide an enriched context
for reporting events.

--
Change-Id: I2d06166fe4d5b9054e24ad8c752fafc039e3f9f8
Reviewed-on: https://cr.bazel.build/8794
PiperOrigin-RevId: 148463437
MOS_MIGRATED_REVID=148463437

6 files changed, 63 insertions, 41 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/events/DelegatingEventHandler.java b/src/main/java/com/google/devtools/build/lib/events/DelegatingEventHandler.java
index 9b09d23bb9..84858e328b 100644
--- a/src/main/java/com/google/devtools/build/lib/events/DelegatingEventHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/events/DelegatingEventHandler.java
@@ -17,13 +17,13 @@ package com.google.devtools.build.lib.events;
 import com.google.devtools.build.lib.util.Preconditions;
 
 /**
- * An EventHandler which delegates to another EventHandler.
- * Primarily useful as a base class for extending behavior.
+ * An EventHandler which delegates to another EventHandler. Primarily useful as a base class for
+ * extending behavior.
  */
-public class DelegatingEventHandler implements EventHandler {
-  protected final EventHandler delegate;
+public class DelegatingEventHandler implements ExtendedEventHandler {
+  protected final ExtendedEventHandler delegate;
 
-  public DelegatingEventHandler(EventHandler delegate) {
+  public DelegatingEventHandler(ExtendedEventHandler delegate) {
     super();
     this.delegate = Preconditions.checkNotNull(delegate);
   }
@@ -32,4 +32,9 @@ public class DelegatingEventHandler implements EventHandler {
   public void handle(Event e) {
     delegate.handle(e);
   }
+
+  @Override
+  public void post(ExtendedEventHandler.Postable obj) {
+    delegate.post(obj);
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/events/ErrorSensingEventHandler.java b/src/main/java/com/google/devtools/build/lib/events/ErrorSensingEventHandler.java
index fb12d76cc3..3286efad0a 100644
--- a/src/main/java/com/google/devtools/build/lib/events/ErrorSensingEventHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/events/ErrorSensingEventHandler.java
@@ -22,7 +22,7 @@ public final class ErrorSensingEventHandler extends DelegatingEventHandler {
 
   private volatile boolean hasErrors;
 
-  public ErrorSensingEventHandler(EventHandler eventHandler) {
+  public ErrorSensingEventHandler(ExtendedEventHandler eventHandler) {
     super(eventHandler);
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/events/ExtendedEventHandler.java b/src/main/java/com/google/devtools/build/lib/events/ExtendedEventHandler.java
index 1457b58846..f05cbab716 100644
--- a/src/main/java/com/google/devtools/build/lib/events/ExtendedEventHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/events/ExtendedEventHandler.java
@@ -16,13 +16,13 @@ package com.google.devtools.build.lib.events;
 
 /**
  * Interface for reporting events during the build. It extends the {@link EventHandler} by also
- * allowing posting arbitrary objects on the event bus.
+ * allowing posting more structured information.
  */
 public interface ExtendedEventHandler extends EventHandler {
 
   /** Interface for declaring events that can be posted via the extended event handler */
   public interface Postable {}
 
-  /** Report arbitrary information over the event bus. */
+  /** Post an postable object with more refined information about an important build event */
   void post(Postable obj);
 }
diff --git a/src/main/java/com/google/devtools/build/lib/events/NullEventHandler.java b/src/main/java/com/google/devtools/build/lib/events/NullEventHandler.java
index c606219566..522d350b62 100644
--- a/src/main/java/com/google/devtools/build/lib/events/NullEventHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/events/NullEventHandler.java
@@ -14,15 +14,16 @@
 
 package com.google.devtools.build.lib.events;
 
-/**
- * An ErrorEventListener which does nothing.
- */
-public final class NullEventHandler implements EventHandler {
-  public static final EventHandler INSTANCE = new NullEventHandler();
+/** An ErrorEventListener which does nothing. */
+public final class NullEventHandler implements ExtendedEventHandler {
+  public static final ExtendedEventHandler INSTANCE = new NullEventHandler();
 
   private NullEventHandler() {}  // Prevent instantiation
 
   @Override
   public void handle(Event e) {
   }
+
+  @Override
+  public void post(ExtendedEventHandler.Postable e) {}
 }
diff --git a/src/main/java/com/google/devtools/build/lib/events/Reporter.java b/src/main/java/com/google/devtools/build/lib/events/Reporter.java
index a970d586ac..12039e3340 100644
--- a/src/main/java/com/google/devtools/build/lib/events/Reporter.java
+++ b/src/main/java/com/google/devtools/build/lib/events/Reporter.java
@@ -13,31 +13,29 @@
 // limitations under the License.
 package com.google.devtools.build.lib.events;
 
+import com.google.common.eventbus.EventBus;
 import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.util.io.OutErr;
-
 import java.io.PrintStream;
 import java.util.ArrayList;
 import java.util.List;
 
 /**
- * The reporter is the primary means of reporting events such as errors,
- * warnings, progress information and diagnostic information to the user.  It
- * is not intended as a logging mechanism for developer-only messages; use a
- * Logger for that.
+ * The reporter is the primary means of reporting events such as errors, warnings, progress
+ * information and diagnostic information to the user. It is not intended as a logging mechanism for
+ * developer-only messages; use a Logger for that.
  *
- * <p>The reporter instance is consumed by the build system, and passes events to
- * {@link EventHandler} instances. These handlers are registered via {@link
- * #addHandler(EventHandler)}. The reporter's main use is in the blaze runtime
- * and its lifetime is the lifetime of the blaze server.
+ * <p>The reporter instance is consumed by the build system, and passes events to {@link
+ * EventHandler} instances. These handlers are registered via {@link #addHandler(EventHandler)}. The
+ * reporter's main use is in the blaze runtime and its lifetime is the lifetime of the blaze server.
  *
- * <p>Thread-safe: calls to {@code #report} may be made on any thread.
- * Handlers may be run in an arbitary thread (but right now, they will not be
- * run concurrently).
+ * <p>Thread-safe: calls to {@code #report} may be made on any thread. Handlers may be run in an
+ * arbitary thread (but right now, they will not be run concurrently).
  */
-public final class Reporter implements EventHandler, ExceptionListener {
+public final class Reporter implements ExtendedEventHandler, ExceptionListener {
 
   private final List<EventHandler> handlers = new ArrayList<>();
+  private EventBus eventBus;
 
   /** An OutErr that sends all of its output to this Reporter.
    * Each write will (when flushed) get mapped to an EventKind.STDOUT or EventKind.STDERR event.
@@ -48,7 +46,9 @@ public final class Reporter implements EventHandler, ExceptionListener {
   private EventHandler ansiStrippingHandler;
   private boolean ansiAllowingHandlerRegistered;
 
-  public Reporter() {}
+  public Reporter(EventBus eventBus) {
+    this.eventBus = eventBus;
+  }
 
   public static OutErr outErrForReporter(EventHandler rep) {
     return OutErr.create(
@@ -64,12 +64,12 @@ public final class Reporter implements EventHandler, ExceptionListener {
    */
   public Reporter(Reporter template) {
     handlers.addAll(template.handlers);
+    this.eventBus = template.eventBus;
   }
 
-  /**
-   * Constructor which configures a reporter with the specified handlers.
-   */
-  public Reporter(EventHandler... handlers) {
+  /** Constructor which configures a reporter with the specified handlers. */
+  public Reporter(EventBus eventBus, EventHandler... handlers) {
+    this.eventBus = eventBus;
     for (EventHandler handler: handlers) {
       addHandler(handler);
     }
@@ -111,6 +111,17 @@ public final class Reporter implements EventHandler, ExceptionListener {
     }
   }
 
+  @Override
+  public void post(ExtendedEventHandler.Postable obj) {
+    if (eventBus != null) {
+      eventBus.post(obj);
+    }
+  }
+
+  public void clearEventBus() {
+    eventBus = null;
+  }
+
   /**
    * Reports the start of a particular task.
    * Is a wrapper around report() with event kind START.
diff --git a/src/main/java/com/google/devtools/build/lib/events/StoredEventHandler.java b/src/main/java/com/google/devtools/build/lib/events/StoredEventHandler.java
index 9edea8d9eb..e68c5d2a6c 100644
--- a/src/main/java/com/google/devtools/build/lib/events/StoredEventHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/events/StoredEventHandler.java
@@ -14,16 +14,14 @@
 package com.google.devtools.build.lib.events;
 
 import com.google.common.collect.ImmutableList;
-
 import java.util.ArrayList;
 import java.util.List;
 
-/**
- * Stores error and warning events, and later replays them. Thread-safe.
- */
-public class StoredEventHandler implements EventHandler {
+/** Stores error and warning events, and later replays them. Thread-safe. */
+public class StoredEventHandler implements ExtendedEventHandler {
 
   private final List<Event> events = new ArrayList<>();
+  private final List<ExtendedEventHandler.Postable> posts = new ArrayList<>();
   private boolean hasErrors;
 
   public synchronized ImmutableList<Event> getEvents() {
@@ -32,7 +30,7 @@ public class StoredEventHandler implements EventHandler {
 
   /** Returns true if there are no stored events. */
   public synchronized boolean isEmpty() {
-    return events.isEmpty();
+    return events.isEmpty() && posts.isEmpty();
   }
 
 
@@ -42,11 +40,17 @@ public class StoredEventHandler implements EventHandler {
     events.add(e);
   }
 
-  /**
-   * Replay all events stored in this object on the given eventHandler, in the same order.
-   */
-  public synchronized void replayOn(EventHandler eventHandler) {
+  @Override
+  public synchronized void post(ExtendedEventHandler.Postable e) {
+    posts.add(e);
+  }
+
+  /** Replay all events stored in this object on the given eventHandler, in the same order. */
+  public synchronized void replayOn(ExtendedEventHandler eventHandler) {
     Event.replayEventsOn(eventHandler, events);
+    for (ExtendedEventHandler.Postable obj : posts) {
+      eventHandler.post(obj);
+    }
   }
 
   /**
@@ -58,6 +62,7 @@ public class StoredEventHandler implements EventHandler {
 
   public synchronized void clear() {
     events.clear();
+    posts.clear();
     hasErrors = false;
   }
 }