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// Copyright 2014 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;
import java.io.Serializable;
import java.util.Objects;
/**
* In case we can't get a fast digest from the filesystem, we store this metadata as a proxy to
* the file contents. Currently it is a pair of the mtime and "value id" (which is right now just
* the ivalue number). We may wish to augment this object with the following data:
* a. the device number
* b. the ctime, which cannot be tampered with in userspace
*
* <p>For an example of why mtime alone is insufficient, note that 'mv' preserves timestamps. So if
* files 'a' and 'b' initially have the same timestamp, then we would think 'b' is unchanged after
* the user executes `mv a b` between two builds.
*/
public final class FileContentsProxy implements Serializable {
private final long mtime;
private final long valueId;
public FileContentsProxy(long mtime, long valueId) {
this.mtime = mtime;
this.valueId = valueId;
}
public static FileContentsProxy create(long mtime, long valueId) {
return new FileContentsProxy(mtime, valueId);
}
public long getMtime() {
return mtime;
}
public long getValueId() {
return valueId;
}
@Override
public boolean equals(Object other) {
if (other == this) {
return true;
}
if (!(other instanceof FileContentsProxy)) {
return false;
}
FileContentsProxy that = (FileContentsProxy) other;
return mtime == that.mtime && valueId == that.valueId;
}
@Override
public int hashCode() {
return Objects.hash(mtime, valueId);
}
@Override
public String toString() {
return prettyPrint();
}
public String prettyPrint() {
return String.format("mtime of %d and nodeId of %d", mtime, valueId);
}
}
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