commit c49e874a6e7fcf4a75342ef3f55a7387567b0af8
author nharmata <nharmata@google.com> Thu Sep 27 11:27:41 2018 -0700
committer Copybara-Service <copybara-piper@google.com> Thu Sep 27 11:28:50 2018 -0700
tree c670b346c1e19bf7b55a6297a9ee3466593f028a
parent 3e0f5203058dc1bb9d98002b1a0bc4d43cf5113d

When we already know query evaluation will produce unique results, don't bother
using a Uniquifier in BatchStreamedCallback.

RELNOTES: None
PiperOrigin-RevId: 214807126

src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java

diff --git a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
index ca2ff3d..9bb1e30 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
@@ -76,6 +76,7 @@
 import com.google.devtools.build.lib.query2.engine.QueryExpressionMapper;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.MinDepthUniquifierImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.MutableKeyExtractorBackedMapImpl;
+import com.google.devtools.build.lib.query2.engine.QueryUtil.NonExceptionalUniquifier;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.ThreadSafeMutableKeyExtractorBackedSetImpl;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.UniquifierImpl;
 import com.google.devtools.build.lib.query2.engine.StreamableQueryEnvironment;
@@ -402,7 +403,7 @@
     BatchStreamedCallback batchCallback = new BatchStreamedCallback(
         callback,
         BATCH_CALLBACK_SIZE,
-        createUniquifier());
+        createUniquifierForOuterBatchStreamedCallback(expr));
     return super.evaluateQuery(expr, batchCallback);
   }
 
@@ -633,8 +634,14 @@
   }
 
   @ThreadSafe
+  protected NonExceptionalUniquifier<Target> createUniquifierForOuterBatchStreamedCallback(
+      QueryExpression expr) {
+    return createUniquifier();
+  }
+
+  @ThreadSafe
   @Override
-  public UniquifierImpl<Target, ?> createUniquifier() {
+  public NonExceptionalUniquifier<Target> createUniquifier() {
     return new UniquifierImpl<>(TargetKeyExtractor.INSTANCE);
   }
 
@@ -1168,7 +1175,7 @@
     // memory. We should have a threshold for when to invoke the callback with a batch, and also a
     // separate, larger, bound on the number of targets being processed at the same time.
     private final ThreadSafeOutputFormatterCallback<Target> callback;
-    private final UniquifierImpl<Target, ?> uniquifier;
+    private final NonExceptionalUniquifier<Target> uniquifier;
     private final Object pendingLock = new Object();
     private List<Target> pending = new ArrayList<>();
     private int batchThreshold;
@@ -1176,7 +1183,7 @@
     private BatchStreamedCallback(
         ThreadSafeOutputFormatterCallback<Target> callback,
         int batchThreshold,
-        UniquifierImpl<Target, ?> uniquifier) {
+        NonExceptionalUniquifier<Target> uniquifier) {
       this.callback = callback;
       this.batchThreshold = batchThreshold;
       this.uniquifier = uniquifier;

src/main/java/com/google/devtools/build/lib/query2/engine/QueryUtil.java

diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryUtil.java b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryUtil.java
index 120d53b..fe072b6 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/QueryUtil.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/QueryUtil.java
@@ -218,8 +218,48 @@
     }
   }
 
+  /** A {@link Uniquifier} whose methods do not throw {@link QueryException}. */
+  public interface NonExceptionalUniquifier<T> extends Uniquifier<T> {
+    @Override
+    boolean unique(T newElement);
+
+    @Override
+    ImmutableList<T> unique(Iterable<T> newElements);
+  }
+
+  /**
+   * A {@link NonExceptionalUniquifier} that doesn't do anything and always says an element is
+   * unique.
+   */
+  public static class NullUniquifierImpl<T> implements NonExceptionalUniquifier<T> {
+    private static final NullUniquifierImpl<Object> INSTANCE = new NullUniquifierImpl<>();
+
+    private NullUniquifierImpl() {
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> NullUniquifierImpl<T> instance() {
+      return (NullUniquifierImpl<T>) INSTANCE;
+    }
+
+    @Override
+    public boolean uniquePure(T newElement) {
+      return true;
+    }
+
+    @Override
+    public boolean unique(T newElement) {
+      return true;
+    }
+
+    @Override
+    public ImmutableList<T> unique(Iterable<T> newElements) {
+      return ImmutableList.copyOf(newElements);
+    }
+  }
+
   /** A trivial {@link Uniquifier} implementation. */
-  public static class UniquifierImpl<T, K> implements Uniquifier<T> {
+  public static class UniquifierImpl<T, K> implements NonExceptionalUniquifier<T> {
     private final KeyExtractor<T, K> extractor;
     private final Set<K> alreadySeen;