Introduce a Builder for ForkJoinQuiescingExecutor.

--
MOS_MIGRATED_REVID=133714902

1 files changed, 61 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/concurrent/ForkJoinQuiescingExecutor.java b/src/main/java/com/google/devtools/build/lib/concurrent/ForkJoinQuiescingExecutor.java
index 45132a1cb7..b012ac18ef 100644
--- a/src/main/java/com/google/devtools/build/lib/concurrent/ForkJoinQuiescingExecutor.java
+++ b/src/main/java/com/google/devtools/build/lib/concurrent/ForkJoinQuiescingExecutor.java
@@ -13,6 +13,7 @@
 // limitations under the License.
 package com.google.devtools.build.lib.concurrent;
 
+import com.google.devtools.build.lib.util.Preconditions;
 import java.util.concurrent.ForkJoinPool;
 import java.util.concurrent.ForkJoinTask;
 
@@ -23,15 +24,73 @@ import java.util.concurrent.ForkJoinTask;
 // maintaining AQV.remainingTasks.
 public class ForkJoinQuiescingExecutor extends AbstractQueueVisitor {
 
-  public ForkJoinQuiescingExecutor(ForkJoinPool forkJoinPool, ErrorClassifier errorClassifier) {
+  private ForkJoinQuiescingExecutor(
+      ForkJoinPool forkJoinPool, ErrorClassifier errorClassifier, boolean shutdownOnCompletion) {
     super(
         /*concurrent=*/ true,
         forkJoinPool,
-        /*shutdownOnCompletion=*/ true,
+        shutdownOnCompletion,
         /*failFastOnException=*/ true,
         errorClassifier);
   }
 
+  /** Builder for {@link ForkJoinQuiescingExecutor}. */
+  public static class Builder {
+    private ForkJoinPool forkJoinPool = null;
+    private boolean owned = false;
+    private ErrorClassifier errorClassifier = ErrorClassifier.DEFAULT;
+
+    private Builder() {
+    }
+
+    /**
+     * Sets the {@link ForkJoinPool} that will be used by the to-be-built
+     * {@link ForkJoinQuiescingExecutor}. The given {@link ForkJoinPool} will _not_ be shut down on
+     * completion of the {@link ForkJoinQuiescingExecutor}.
+     */
+    public Builder withoutOwnershipOf(ForkJoinPool forkJoinPool) {
+      Preconditions.checkState(this.forkJoinPool == null);
+      this.forkJoinPool = forkJoinPool;
+      this.owned = false;
+      return this;
+    }
+
+    /**
+     * Sets the {@link ForkJoinPool} that will be used by the to-be-built
+     * {@link ForkJoinQuiescingExecutor}. The given {@link ForkJoinPool} will be shut down on
+     * completion of the {@link ForkJoinQuiescingExecutor}.
+     */
+    public Builder withOwnershipOf(ForkJoinPool forkJoinPool) {
+      Preconditions.checkState(this.forkJoinPool == null);
+      this.forkJoinPool = forkJoinPool;
+      this.owned = true;
+      return this;
+    }
+
+    /**
+     * Sets the {@link ErrorClassifier} that will be used by the to-be-built
+     * {@link ForkJoinQuiescingExecutor}.
+     */
+    public Builder setErrorClassifier(ErrorClassifier errorClassifier) {
+      this.errorClassifier = errorClassifier;
+      return this;
+    }
+
+    /**
+     * Returns a fresh {@link ForkJoinQuiescingExecutor} using the previously given options.
+     */
+    public ForkJoinQuiescingExecutor build() {
+      Preconditions.checkNotNull(forkJoinPool);
+      return new ForkJoinQuiescingExecutor(
+          forkJoinPool, errorClassifier, /*shutdownOnCompletion=*/ owned);
+    }
+  }
+
+  /** Returns a fresh {@link Builder}. */
+  public static Builder newBuilder() {
+    return new Builder();
+  }
+
   @Override
   protected void executeRunnable(Runnable runnable) {
     if (ForkJoinTask.inForkJoinPool()) {