commit bc47f40b0dd352d3bf9dc8228fbf0279ac67e907
author Nathan Harmata <nharmata@google.com> Wed Jul 13 16:22:30 2016 +0000
committer Kristina Chodorow <kchodorow@google.com> Thu Jul 14 11:12:15 2016 +0000
tree 93ac0e8ae932517d4b080769b95345fd338767c7
parent 80d1e16b7ae1d04fa2fa4c561588fe9fdbaefc41

Re-implement variables in the blaze query language. Instead of using a mutable global context of variable bindings, pass around immutable local contexts.

The motivation is so we can safely evaluate all blaze query expressions concurrently under the hood. A global context is hostile to this goal.

--
MOS_MIGRATED_REVID=127324600

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

diff --git a/src/main/java/com/google/devtools/build/lib/query2/AbstractBlazeQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/AbstractBlazeQueryEnvironment.java
index 0292f08..07df0c6 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/AbstractBlazeQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/AbstractBlazeQueryEnvironment.java
@@ -31,13 +31,12 @@
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpression;
 import com.google.devtools.build.lib.query2.engine.QueryUtil.AggregateAllCallback;
+import com.google.devtools.build.lib.query2.engine.VariableContext;
 import com.google.devtools.build.lib.util.Preconditions;
 
 import java.util.Collection;
-import java.util.HashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
-import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
@@ -49,7 +48,6 @@
 public abstract class AbstractBlazeQueryEnvironment<T>
     implements QueryEnvironment<T>, AutoCloseable {
   protected final ErrorSensingEventHandler eventHandler;
-  private final Map<String, Set<T>> letBindings = new HashMap<>();
   protected final boolean keepGoing;
   protected final boolean strictScope;
 
@@ -117,7 +115,7 @@
         throw new QueryException(expr, e.getMessage());
       }
       try {
-        this.eval(expr, new Callback<T>() {
+        this.eval(expr, VariableContext.<T>empty(), new Callback<T>() {
           @Override
           public void process(Iterable<T> partialResult)
               throws QueryException, InterruptedException {
@@ -169,16 +167,6 @@
 
   public abstract Target getTarget(Label label) throws TargetNotFoundException, QueryException;
 
-  @Override
-  public Set<T> getVariable(String name) {
-    return letBindings.get(name);
-  }
-
-  @Override
-  public Set<T> setVariable(String name, Set<T> value) {
-    return letBindings.put(name, value);
-  }
-
   protected boolean validateScope(Label label, boolean strict) throws QueryException {
     if (!labelFilter.apply(label)) {
       String error = String.format("target '%s' is not within the scope of the query", label);