Make TargetPattern evaluation during query evaluation more parallel-friendly by introducing TargetPattern#parEval, which allows TargetPatterns' evaluations to explicitly have parallel implementations (no need to secretly use a FJP).

--
MOS_MIGRATED_REVID=139101922

3 files changed, 39 insertions, 7 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryEnvironment.java
index 5cf7c6efbc..9245a68972 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryEnvironment.java
@@ -159,6 +159,16 @@ public interface QueryEnvironment<T> {
   void getTargetsMatchingPattern(QueryExpression owner, String pattern, Callback<T> callback)
       throws QueryException, InterruptedException;
 
+  /**
+   * Same as {@link #getTargetsMatchingPattern}, but optionally making use of the given
+   * {@link ForkJoinPool} to achieve parallelism.
+   */
+  void getTargetsMatchingPatternPar(
+      QueryExpression owner,
+      String pattern,
+      ThreadSafeCallback<T> callback,
+      ForkJoinPool forkJoinPool) throws QueryException, InterruptedException;
+
   /** Ensures the specified target exists. */
   // NOTE(bazel-team): this method is left here as scaffolding from a previous refactoring. It may
   // be possible to remove it.
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/TargetLiteral.java b/src/main/java/com/google/devtools/build/lib/query2/engine/TargetLiteral.java
index 8b718ab01a..aeace9aa70 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/TargetLiteral.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/TargetLiteral.java
@@ -17,6 +17,7 @@ import com.google.devtools.build.lib.util.Preconditions;
 
 import java.util.Collection;
 import java.util.Set;
+import java.util.concurrent.ForkJoinPool;
 
 /**
  * A literal set of targets, using 'blaze build' syntax.  Or, a reference to a
@@ -44,23 +45,42 @@ public final class TargetLiteral extends QueryExpression {
     return LetExpression.isValidVarReference(pattern);
   }
 
+  private <T> void evalVarReference(VariableContext<T> context, Callback<T> callback)
+      throws QueryException, InterruptedException {
+    String varName = LetExpression.getNameFromReference(pattern);
+    Set<T> value = context.get(varName);
+    if (value == null) {
+      throw new QueryException(this, "undefined variable '" + varName + "'");
+    }
+    callback.process(value);
+  }
+
   @Override
   protected <T> void evalImpl(
       QueryEnvironment<T> env, VariableContext<T> context, Callback<T> callback)
           throws QueryException, InterruptedException {
     if (isVariableReference()) {
-      String varName = LetExpression.getNameFromReference(pattern);
-      Set<T> value = context.get(varName);
-      if (value == null) {
-        throw new QueryException(this, "undefined variable '" + varName + "'");
-      }
-      callback.process(value);
+      evalVarReference(context, callback);
     } else {
       env.getTargetsMatchingPattern(this, pattern, callback);
     }
   }
 
   @Override
+  protected <T> void parEvalImpl(
+      QueryEnvironment<T> env,
+      VariableContext<T> context,
+      ThreadSafeCallback<T> callback,
+      ForkJoinPool forkJoinPool)
+      throws QueryException, InterruptedException {
+    if (isVariableReference()) {
+      evalVarReference(context, callback);
+    } else {
+      env.getTargetsMatchingPatternPar(this, pattern, callback, forkJoinPool);
+    }
+  }
+
+  @Override
   public void collectTargetPatterns(Collection<String> literals) {
     if (!isVariableReference()) {
       literals.add(pattern);
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/ThreadSafeCallback.java b/src/main/java/com/google/devtools/build/lib/query2/engine/ThreadSafeCallback.java
index d39172819f..950335e38a 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/ThreadSafeCallback.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/ThreadSafeCallback.java
@@ -14,8 +14,10 @@
 package com.google.devtools.build.lib.query2.engine;
 
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
+import com.google.devtools.build.lib.util.ThreadSafeBatchCallback;
 
 /** Marker interface for a {@link Callback} that is {@link ThreadSafe}. */
 @ThreadSafe
-public interface ThreadSafeCallback<T> extends Callback<T> {
+public interface ThreadSafeCallback<T>
+    extends Callback<T>, ThreadSafeBatchCallback<T, QueryException> {
 }