Add a LoadingProgressReceiver class

Instances of this class keep track of the packages already loaded and those
currently being loaded. This information can be useful for UIs.

--
Change-Id: Ifd380dd2129d11181ad4a31ecbb71d142825df61
Reviewed-on: https://bazel-review.googlesource.com/#/c/3267
MOS_MIGRATED_REVID=119252784

1 files changed, 76 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/LoadingProgressReceiver.java b/src/main/java/com/google/devtools/build/lib/skyframe/LoadingProgressReceiver.java
new file mode 100644
index 0000000000..4a828b3cb3
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/LoadingProgressReceiver.java
@@ -0,0 +1,76 @@
+// Copyright 2016 The Bazel Authors. 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.skyframe;
+
+import com.google.common.base.Supplier;
+import com.google.common.collect.Sets;
+import com.google.devtools.build.skyframe.EvaluationProgressReceiver;
+import com.google.devtools.build.skyframe.SkyKey;
+import com.google.devtools.build.skyframe.SkyValue;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.Set;
+
+/**
+ * An {@link EvaluationProgressReceiver} used during loading phase
+ *
+ * It receives updates about progress in the loading phase via the
+ * {@link EvaluationProgressReceiver} interface. These updates get aggregated
+ * and a summary of the current state of the loading phase can be obtained via
+ * and provides a summary about the current state via the {@link #progressState}
+ * method.
+ */
+public class LoadingProgressReceiver implements EvaluationProgressReceiver {
+
+  private final Set<SkyKey> enqueuedPackages = Sets.newConcurrentHashSet();
+  private final Set<SkyKey> completedPackages = Sets.newConcurrentHashSet();
+  private final Deque<SkyKey> pending = new ArrayDeque<>();
+
+  @Override
+  public void invalidated(SkyKey skyKey, InvalidationState state) {}
+
+  @Override
+  public synchronized void enqueueing(SkyKey skyKey) {
+    if (skyKey.functionName().equals(SkyFunctions.PACKAGE)) {
+      enqueuedPackages.add(skyKey);
+      pending.addLast(skyKey);
+    }
+  }
+
+  @Override
+  public void computed(SkyKey skyKey, long elapsedTimeNanos) {}
+
+  @Override
+  public synchronized void evaluated(
+      SkyKey skyKey, Supplier<SkyValue> valueSupplier, EvaluationState state) {
+    if (skyKey.functionName().equals(SkyFunctions.PACKAGE)) {
+      completedPackages.add(skyKey);
+      pending.remove(skyKey);
+    }
+  }
+
+  public synchronized String progressState() {
+    long completed = completedPackages.size();
+    long enqueued = enqueuedPackages.size();
+    String answer = "" + completed + " / " + enqueued;
+    if (enqueued > completed) {
+      answer += " " + pending.peekFirst().toString();
+      if (enqueued > completed + 1) {
+        answer += " ...";
+      }
+    }
+    return answer;
+  }
+}