Introduce a specialized SkyFunctionEnvironment method for a single value.

Delegating to `getOrderedValuesAndExceptions` costs significant overhead.

PiperOrigin-RevId: 468196750
Change-Id: I26cc97b9db485a35f2992f114b088f20ea68349f

Author: justinhorvitz

src/main/java/com/google/devtools/build/lib/skyframe/SkyFunctionEnvironmentForTesting.java

@@ -50,6 +50,12 @@ public final class SkyFunctionEnvironmentForTesting extends AbstractSkyFunctionE
     this.skyframeExecutor = skyframeExecutor;
   }
 
+  @Override
+  protected ValueOrUntypedException getSingleValueOrUntypedException(SkyKey depKey)
+      throws InterruptedException {
+    return getOrderedValueOrUntypedExceptions(ImmutableList.of(depKey)).get(0);
+  }
+
   @Override
   protected Map<SkyKey, ValueOrUntypedException> getValueOrUntypedExceptions(
       Iterable<? extends SkyKey> depKeys) {

src/main/java/com/google/devtools/build/skyframe/AbstractSkyFunctionEnvironment.java

@@ -14,7 +14,6 @@
 package com.google.devtools.build.skyframe;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.collect.ImmutableSet;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.devtools.build.lib.util.GroupedList;
 import java.util.ArrayList;
@@ -40,11 +39,11 @@ public abstract class AbstractSkyFunctionEnvironment implements SkyFunction.Envi
   @Nullable private final GroupedList<SkyKey> temporaryDirectDeps;
   @Nullable protected List<ListenableFuture<?>> externalDeps;
 
-  public AbstractSkyFunctionEnvironment(@Nullable GroupedList<SkyKey> temporaryDirectDeps) {
+  protected AbstractSkyFunctionEnvironment(@Nullable GroupedList<SkyKey> temporaryDirectDeps) {
     this.temporaryDirectDeps = temporaryDirectDeps;
   }
 
-  public AbstractSkyFunctionEnvironment() {
+  protected AbstractSkyFunctionEnvironment() {
     this(null);
   }
 
@@ -53,31 +52,47 @@ public GroupedList<SkyKey> getTemporaryDirectDeps() {
     return temporaryDirectDeps;
   }
 
-  /** Implementations should set {@link #valuesMissing} as necessary. */
+  /**
+   * Gets a single value or exception.
+   *
+   * <p>Implementations should set {@link #valuesMissing} as necessary.
+   */
+  protected abstract ValueOrUntypedException getSingleValueOrUntypedException(SkyKey depKey)
+      throws InterruptedException;
+
+  /**
+   * Gets a map of values or exceptions.
+   *
+   * <p>Implementations should set {@link #valuesMissing} as necessary.
+   */
   protected abstract Map<SkyKey, ValueOrUntypedException> getValueOrUntypedExceptions(
       Iterable<? extends SkyKey> depKeys) throws InterruptedException;
 
-  /** Implementations should set {@link #valuesMissing} as necessary. */
+  /**
+   * Gets a list of values or exceptions parallel to the given keys.
+   *
+   * <p>Implementations should set {@link #valuesMissing} as necessary.
+   */
   protected abstract List<ValueOrUntypedException> getOrderedValueOrUntypedExceptions(
       Iterable<? extends SkyKey> depKeys) throws InterruptedException;
 
   @Override
   @Nullable
-  public SkyValue getValue(SkyKey depKey) throws InterruptedException {
+  public final SkyValue getValue(SkyKey depKey) throws InterruptedException {
     return getValueOrThrowHelper(depKey, null, null, null, null);
   }
 
   @Override
   @Nullable
-  public <E extends Exception> SkyValue getValueOrThrow(SkyKey depKey, Class<E> exceptionClass)
-      throws E, InterruptedException {
+  public final <E extends Exception> SkyValue getValueOrThrow(
+      SkyKey depKey, Class<E> exceptionClass) throws E, InterruptedException {
     SkyFunctionException.validateExceptionType(exceptionClass);
     return getValueOrThrowHelper(depKey, exceptionClass, null, null, null);
   }
 
   @Override
   @Nullable
-  public <E1 extends Exception, E2 extends Exception> SkyValue getValueOrThrow(
+  public final <E1 extends Exception, E2 extends Exception> SkyValue getValueOrThrow(
       SkyKey depKey, Class<E1> exceptionClass1, Class<E2> exceptionClass2)
       throws E1, E2, InterruptedException {
     SkyFunctionException.validateExceptionType(exceptionClass1);
@@ -87,7 +102,7 @@ public <E1 extends Exception, E2 extends Exception> SkyValue getValueOrThrow(
 
   @Override
   @Nullable
-  public <E1 extends Exception, E2 extends Exception, E3 extends Exception>
+  public final <E1 extends Exception, E2 extends Exception, E3 extends Exception>
       SkyValue getValueOrThrow(
           SkyKey depKey,
           Class<E1> exceptionClass1,
@@ -102,7 +117,8 @@ SkyValue getValueOrThrow(
 
   @Override
   @Nullable
-  public <E1 extends Exception, E2 extends Exception, E3 extends Exception, E4 extends Exception>
+  public final <
+          E1 extends Exception, E2 extends Exception, E3 extends Exception, E4 extends Exception>
       SkyValue getValueOrThrow(
           SkyKey depKey,
           Class<E1> exceptionClass1,
@@ -127,28 +143,48 @@ SkyValue getValueOrThrowHelper(
           @Nullable Class<E3> exceptionClass3,
           @Nullable Class<E4> exceptionClass4)
           throws E1, E2, E3, E4, InterruptedException {
-    SkyframeIterableResult result = getOrderedValuesAndExceptions(ImmutableSet.of(depKey));
-    return result.nextOrThrow(exceptionClass1, exceptionClass2, exceptionClass3, exceptionClass4);
+    ValueOrUntypedException voe = getSingleValueOrUntypedException(depKey);
+    SkyValue value = voe.getValue();
+    if (value != null) {
+      return value;
+    }
+    Exception e = voe.getException();
+    if (e != null) {
+      if (exceptionClass1 != null && exceptionClass1.isInstance(e)) {
+        throw exceptionClass1.cast(e);
+      }
+      if (exceptionClass2 != null && exceptionClass2.isInstance(e)) {
+        throw exceptionClass2.cast(e);
+      }
+      if (exceptionClass3 != null && exceptionClass3.isInstance(e)) {
+        throw exceptionClass3.cast(e);
+      }
+      if (exceptionClass4 != null && exceptionClass4.isInstance(e)) {
+        throw exceptionClass4.cast(e);
+      }
+    }
+    valuesMissing = true;
+    return null;
   }
 
   @Override
-  public SkyframeLookupResult getValuesAndExceptions(Iterable<? extends SkyKey> depKeys)
+  public final SkyframeLookupResult getValuesAndExceptions(Iterable<? extends SkyKey> depKeys)
       throws InterruptedException {
     Map<SkyKey, ValueOrUntypedException> valuesOrExceptions = getValueOrUntypedExceptions(depKeys);
     return new SkyframeLookupResult(() -> valuesMissing = true, valuesOrExceptions::get);
   }
 
   @Override
-  public SkyframeIterableResult getOrderedValuesAndExceptions(Iterable<? extends SkyKey> depKeys)
-      throws InterruptedException {
+  public final SkyframeIterableResult getOrderedValuesAndExceptions(
+      Iterable<? extends SkyKey> depKeys) throws InterruptedException {
     List<ValueOrUntypedException> valuesOrExceptions = getOrderedValueOrUntypedExceptions(depKeys);
     Iterator<ValueOrUntypedException> valuesOrExceptionsi = valuesOrExceptions.iterator();
     return new SkyframeIterableResult(() -> valuesMissing = true, valuesOrExceptionsi);
   }
 
   @Override
-  public boolean valuesMissing() {
-    return valuesMissing || (externalDeps != null);
+  public final boolean valuesMissing() {
+    return valuesMissing || externalDeps != null;
   }
 
   @Override

src/main/java/com/google/devtools/build/skyframe/SkyFunctionEnvironment.java

@@ -428,6 +428,30 @@ private static SkyValue getValueOrNullMarker(@Nullable NodeEntry nodeEntry)
     return valueMaybeWithMetadata;
   }
 
+  @Override
+  protected ValueOrUntypedException getSingleValueOrUntypedException(SkyKey depKey)
+      throws InterruptedException {
+    checkActive();
+    checkState(
+        !depKey.equals(ErrorTransienceValue.KEY),
+        "Error transience key cannot be in requested deps of %s",
+        skyKey);
+    SkyValue depValue = maybeGetValueFromErrorOrDeps(depKey);
+    if (depValue == null) {
+      NodeEntry depEntry = evaluatorContext.getGraph().get(skyKey, Reason.DEP_REQUESTED, depKey);
+      depValue = getValueOrNullMarker(depEntry);
+      newlyRequestedDepsValues.put(depKey, depValue);
+      if (depValue != NULL_MARKER) {
+        maybeUpdateMaxTransitiveSourceVersion(depEntry);
+      }
+    }
+    if (!previouslyRequestedDepsValues.containsKey(depKey)) {
+      newlyRequestedDeps.add(depKey);
+    }
+    processDepValue(depKey, depValue);
+    return transformToValueOrUntypedException(depValue);
+  }
+
   @Override
   protected Map<SkyKey, ValueOrUntypedException> getValueOrUntypedExceptions(
       Iterable<? extends SkyKey> depKeys) throws InterruptedException {

src/test/java/com/google/devtools/build/lib/actions/util/ActionsTestUtil.java

@@ -333,6 +333,12 @@ private BlockingSkyFunctionEnvironment(
       this.eventHandler = eventHandler;
     }
 
+    @Override
+    protected ValueOrUntypedException getSingleValueOrUntypedException(SkyKey depKey)
+        throws InterruptedException {
+      return getOrderedValueOrUntypedExceptions(ImmutableList.of(depKey)).get(0);
+    }
+
     @Override
     protected Map<SkyKey, ValueOrUntypedException> getValueOrUntypedExceptions(
         Iterable<? extends SkyKey> depKeys) {