blob: e4eff0ff141f090c4d9246a3ed217a101d1fe376 [file] [log] [blame]
// Copyright 2018 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.skyframe.actiongraph.v2;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
/**
* Basic class to abstract action graph cache functionality.
*/
abstract class BaseCache<K, P> {
private final Map<K, Integer> cache = new HashMap<>();
protected final AqueryOutputHandler aqueryOutputHandler;
BaseCache(AqueryOutputHandler aqueryOutputHandler) {
this.aqueryOutputHandler = aqueryOutputHandler;
}
private int generateNextId() {
// protobuf interprets the value 0 as "default value" for uint64, thus treating the field as
// "unset". We should start from 1 instead.
return cache.size() + 1;
}
protected K transformToKey(K data) {
// In most cases, the data is the key but it can be overridden by subclasses.
return data;
}
/**
* Store the data in the internal cache, if it's not yet present. Return the generated id. Ids are
* positive and unique.
*
* <p>Stream the proto to output, the first time it's generated.
*/
int dataToIdAndStreamOutputProto(K data) throws IOException, InterruptedException {
K key = transformToKey(data);
Integer id = cache.get(key);
if (id == null) {
// Note that this cannot be replaced by computeIfAbsent since createProto is a recursive
// operation for the case of nested sets which will call dataToId on the same object and thus
// computeIfAbsent again.
id = generateNextId();
cache.put(key, id);
P proto = createProto(data, id);
toOutput(proto);
}
return id;
}
abstract P createProto(K key, int id) throws IOException, InterruptedException;
abstract void toOutput(P proto) throws IOException;
}