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// Copyright 2017 The Bazel Authors. 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.syntax;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import java.util.ArrayList;
import java.util.List;
/**
* Holds the Skylark callstack in thread-local storage. Contains all Expressions and BaseFunctions
* currently being evaluated.
*
* <p>This is needed for memory tracking, since the evaluator is not available in the context of
* instrumentation. It should not be used by normal Skylark interpreter logic.
*/
public class Callstack {
// This field should be read, but not written, directly in order to avoid the overhead of a
// method call.
static boolean enabled;
private static final ThreadLocal<List<Object>> callstack =
ThreadLocal.withInitial(ArrayList::new);
public static void setEnabled(boolean enabled) {
Callstack.enabled = enabled;
}
public static void push(ASTNode node) {
callstack.get().add(node);
}
public static void push(BaseFunction function) {
callstack.get().add(function);
}
public static void pop() {
List<Object> threadStack = callstack.get();
threadStack.remove(threadStack.size() - 1);
}
public static List<Object> get() {
Preconditions.checkState(enabled, "Must call Callstack#setEnabled before getting");
return callstack.get();
}
@VisibleForTesting
public static void resetStateForTest() {
enabled = false;
callstack.get().clear();
}
}