Update from Google.

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MOE_MIGRATED_REVID=85702957

1 files changed, 71 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/runtime/RateLimitingEventHandler.java b/src/main/java/com/google/devtools/build/lib/runtime/RateLimitingEventHandler.java
new file mode 100644
index 0000000000..5e90f2ecf2
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/runtime/RateLimitingEventHandler.java
@@ -0,0 +1,71 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.runtime;
+
+import com.google.devtools.build.lib.events.Event;
+import com.google.devtools.build.lib.events.EventHandler;
+import com.google.devtools.build.lib.util.BlazeClock;
+import com.google.devtools.build.lib.util.Clock;
+
+/**
+ * An event handler that rate limits events.
+ */
+public class RateLimitingEventHandler implements EventHandler {
+
+  private final EventHandler outputHandler;
+  private final double intervalMillis;
+  private final Clock clock;
+  private long lastEventMillis = -1;
+
+  /**
+   * Creates a new Event handler that rate limits the events of type PROGRESS
+   * to one per event "rateLimitation" seconds.  Events that arrive too quickly are dropped;
+   * all others are are forwarded to the handler "delegateTo".
+   *
+   * @param delegateTo  The event handler that ultimately handles the events
+   * @param rateLimitation The minimum number of seconds between events that will be forwarded
+   *                    to the delegateTo-handler.
+   *                    If less than zero (or NaN), all events will be forwarded.
+   */
+  public static EventHandler create(EventHandler delegateTo, double rateLimitation) {
+    if (rateLimitation < 0.0 || Double.isNaN(rateLimitation)) {
+      return delegateTo;
+    }
+    return new RateLimitingEventHandler(delegateTo, rateLimitation);
+  }
+
+  private RateLimitingEventHandler(EventHandler delegateTo, double rateLimitation) {
+    clock = BlazeClock.instance();
+    outputHandler = delegateTo;
+    this.intervalMillis = rateLimitation * 1000;
+  }
+
+  @Override
+  public void handle(Event event) {
+    switch (event.getKind()) {
+      case PROGRESS:
+      case START:
+      case FINISH:
+        long currentTime = clock.currentTimeMillis();
+        if (lastEventMillis + intervalMillis <= currentTime) {
+          lastEventMillis = currentTime;
+          outputHandler.handle(event);
+        }
+        break;
+      default:
+        outputHandler.handle(event);
+        break;
+    }
+  }
+}