Add "allrdeps" function that computes rdeps in whatever universe happens to be loaded.

This avoids having to materialize the full universe scope in memory when doing an rdeps query over "//...".

Another option considered was special-casing the string "//..." if it was the first argument to rdeps, but this seemed cleaner.

--
MOS_MIGRATED_REVID=96878999

3 files changed, 110 insertions, 38 deletions

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 44db228fdd..8a6e5dc38a 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
@@ -39,6 +39,7 @@ import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.pkgcache.PathPackageLocator;
 import com.google.devtools.build.lib.pkgcache.TargetPatternEvaluator;
+import com.google.devtools.build.lib.query2.engine.AllRdepsFunction;
 import com.google.devtools.build.lib.query2.engine.QueryEvalResult;
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
@@ -460,4 +461,10 @@ public class SkyQueryEnvironment extends AbstractBlazeQueryEnvironment<Target> {
   public Target getOrCreate(Target target) {
     return target;
   }
+
+  @Override
+  public Iterable<QueryFunction> getFunctions() {
+    return ImmutableList.<QueryFunction>builder()
+        .addAll(super.getFunctions()).add(new AllRdepsFunction()).build();
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/AllRdepsFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/AllRdepsFunction.java
new file mode 100644
index 0000000000..5f1493e54b
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/AllRdepsFunction.java
@@ -0,0 +1,96 @@
+// Copyright 2015 Google Inc. 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.query2.engine;
+
+import com.google.common.base.Predicate;
+import com.google.common.base.Predicates;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Iterables;
+import com.google.devtools.build.lib.query2.engine.QueryEnvironment.Argument;
+import com.google.devtools.build.lib.query2.engine.QueryEnvironment.ArgumentType;
+import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryFunction;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * An "allrdeps" query expression, which computes the reverse dependencies of the argument within
+ * the currently known universe. An optional integer-literal second argument may be specified; its
+ * value bounds the search from the arguments.
+ *
+ * <pre>expr ::= ALLRDEPS '(' expr ')'</pre>
+ * <pre>       | ALLRDEPS '(' expr ',' WORD ')'</pre>
+ */
+// Public because SkyQueryEnvironment needs to refer to it directly.
+public class AllRdepsFunction implements QueryFunction {
+  public AllRdepsFunction() {}
+
+  @Override
+  public String getName() {
+    return "allrdeps";
+  }
+
+  @Override
+  public int getMandatoryArguments() {
+    return 1;  // last argument is optional
+  }
+
+  @Override
+  public List<ArgumentType> getArgumentTypes() {
+    return ImmutableList.of(ArgumentType.EXPRESSION, ArgumentType.INTEGER);
+  }
+
+  /**
+   * Breadth-first search from the argument while sticking to nodes satisfying the {@param universe}
+   * predicate.
+   */
+  protected <T> Set<T> eval(QueryEnvironment<T> env, List<Argument> args, Predicate<T> universe)
+      throws QueryException {
+    Set<T> argumentValue = args.get(0).getExpression().eval(env);
+    int depthBound = args.size() > 1 ? args.get(1).getInteger() : Integer.MAX_VALUE;
+    Set<T> visited = new LinkedHashSet<>();
+    Collection<T> current = argumentValue;
+
+    // We need to iterate depthBound + 1 times.
+    for (int i = 0; i <= depthBound; i++) {
+      List<T> next = new ArrayList<>();
+      // Restrict to nodes satisfying the universe predicate.
+      Iterable<T> currentInUniverse = Iterables.filter(current, universe);
+      // Filter already visited nodes: if we see a node in a later round, then we don't need to
+      // visit it again, because the depth at which we see it must be greater than or equal to
+      // the last visit.
+      next.addAll(env.getReverseDeps(Iterables.filter(currentInUniverse,
+          Predicates.not(Predicates.in(visited)))));
+      Iterables.addAll(visited, currentInUniverse);
+      if (next.isEmpty()) {
+        // Exit when there are no more nodes to visit.
+        break;
+      }
+      current = next;
+    }
+
+    return visited;
+
+  }
+
+  /** Breadth-first search from the argument. */
+  @Override
+  public <T> Set<T> eval(QueryEnvironment<T> env, QueryExpression expression, List<Argument> args)
+      throws QueryException {
+    return eval(env, args, Predicates.<T>alwaysTrue());
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/query2/engine/RdepsFunction.java b/src/main/java/com/google/devtools/build/lib/query2/engine/RdepsFunction.java
index 9c61139700..68d0d8b7b2 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/engine/RdepsFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/engine/RdepsFunction.java
@@ -15,14 +15,9 @@ package com.google.devtools.build.lib.query2.engine;
 
 import com.google.common.base.Predicates;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.query2.engine.QueryEnvironment.Argument;
 import com.google.devtools.build.lib.query2.engine.QueryEnvironment.ArgumentType;
-import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryFunction;
 
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 
@@ -34,9 +29,8 @@ import java.util.Set;
  * <pre>expr ::= RDEPS '(' expr ',' expr ')'</pre>
  * <pre>       | RDEPS '(' expr ',' expr ',' WORD ')'</pre>
  */
-final class RdepsFunction implements QueryFunction {
-  RdepsFunction() {
-  }
+final class RdepsFunction extends AllRdepsFunction {
+  RdepsFunction() {}
 
   @Override
   public String getName() {
@@ -45,13 +39,13 @@ final class RdepsFunction implements QueryFunction {
 
   @Override
   public int getMandatoryArguments() {
-    return 2;  // last argument is optional
+    return super.getMandatoryArguments() + 1;  // +1 for the universe.
   }
 
   @Override
   public List<ArgumentType> getArgumentTypes() {
-    return ImmutableList.of(
-        ArgumentType.EXPRESSION, ArgumentType.EXPRESSION, ArgumentType.INTEGER);
+    return ImmutableList.<ArgumentType>builder()
+        .add(ArgumentType.EXPRESSION).addAll(super.getArgumentTypes()).build();
   }
 
   /**
@@ -62,34 +56,9 @@ final class RdepsFunction implements QueryFunction {
   public <T> Set<T> eval(QueryEnvironment<T> env, QueryExpression expression, List<Argument> args)
       throws QueryException {
     Set<T> universeValue = args.get(0).getExpression().eval(env);
-    Set<T> argumentValue = args.get(1).getExpression().eval(env);
-    int depthBound = args.size() > 2 ? args.get(2).getInteger() : Integer.MAX_VALUE;
-
     env.buildTransitiveClosure(expression, universeValue, Integer.MAX_VALUE);
 
-    Set<T> visited = new LinkedHashSet<>();
-    Set<T> reachableFromUniverse = env.getTransitiveClosure(universeValue);
-    Collection<T> current = argumentValue;
-
-    // We need to iterate depthBound + 1 times.
-    for (int i = 0; i <= depthBound; i++) {
-      List<T> next = new ArrayList<>();
-      // Restrict to nodes in our universe.
-      Iterable<T> currentInUniverse = Iterables.filter(current,
-          Predicates.in(reachableFromUniverse));
-      // Filter already visited nodes: if we see a node in a later round, then we don't need to
-      // visit it again, because the depth at which we see it at must be greater than or equal to
-      // the last visit.
-      next.addAll(env.getReverseDeps(Iterables.filter(currentInUniverse,
-          Predicates.not(Predicates.in(visited)))));
-      Iterables.addAll(visited, currentInUniverse);
-      if (next.isEmpty()) {
-        // Exit when there are no more nodes to visit.
-        break;
-      }
-      current = next;
-    }
-
-    return visited;
+    return eval(env, args.subList(1, args.size()),
+        Predicates.in(env.getTransitiveClosure(universeValue)));
   }
 }