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/*
* Copyright (C) 2016 The Android Open Source Project
*
* 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.android.apkzlib.zip.utils;
import com.google.common.io.ByteSource;
import com.google.common.io.ByteStreams;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.annotation.Nonnull;
/**
* Keeps track of used bytes allowing gauging memory usage.
*/
public class ByteTracker {
/**
* Number of bytes currently in use.
*/
private long bytesUsed;
/**
* Maximum number of bytes used.
*/
private long maxBytesUsed;
/**
* Creates a new byte source by fully reading an input stream.
*
* @param stream the input stream
* @return a byte source containing the cached data from the given stream
* @throws IOException failed to read the stream
*/
public CloseableDelegateByteSource fromStream(@Nonnull InputStream stream) throws IOException {
byte[] data = ByteStreams.toByteArray(stream);
updateUsage(data.length);
return new CloseableDelegateByteSource(ByteSource.wrap(data), data.length) {
@Override
public synchronized void innerClose() throws IOException {
super.innerClose();
updateUsage(-sizeNoException());
}
};
}
/**
* Creates a new byte source by snapshotting the provided stream.
*
* @param stream the stream with the data
* @return a byte source containing the cached data from the given stream
* @throws IOException failed to read the stream
*/
public CloseableDelegateByteSource fromStream(@Nonnull ByteArrayOutputStream stream)
throws IOException {
byte[] data = stream.toByteArray();
updateUsage(data.length);
return new CloseableDelegateByteSource(ByteSource.wrap(data), data.length) {
@Override
public synchronized void innerClose() throws IOException {
super.innerClose();
updateUsage(-sizeNoException());
}
};
}
/**
* Creates a new byte source from another byte source.
*
* @param source the byte source to copy data from
* @return the tracked byte source
* @throws IOException failed to read data from the byte source
*/
public CloseableDelegateByteSource fromSource(@Nonnull ByteSource source) throws IOException {
return fromStream(source.openStream());
}
/**
* Updates the memory used by this tracker.
*
* @param delta the number of bytes to add or remove, if negative
*/
private synchronized void updateUsage(long delta) {
bytesUsed += delta;
if (maxBytesUsed < bytesUsed) {
maxBytesUsed = bytesUsed;
}
}
/**
* Obtains the number of bytes currently used.
*
* @return the number of bytes
*/
public synchronized long getBytesUsed() {
return bytesUsed;
}
/**
* Obtains the maximum number of bytes ever used by this tracker.
*
* @return the number of bytes
*/
public synchronized long getMaxBytesUsed() {
return maxBytesUsed;
}
}
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