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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* This file incorporates work covered by the following license notice:
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you 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 .
*/
#include <ThreadedDeflater.hxx>
#include <zlib.h>
#include <com/sun/star/packages/zip/ZipConstants.hpp>
#include <sal/log.hxx>
using namespace com::sun::star::packages::zip::ZipConstants;
using namespace com::sun::star;
namespace ZipUtils
{
const sal_Int64 MaxBlockSize = 128 * 1024;
// Parallel ZLIB compression using threads. The class internally splits the data into
// blocks and spawns ThreadPool tasks to process them independently. This is achieved
// in a similar way how pigz works, see comments from Mark Adler at
// https://stackoverflow.com/questions/30294766/how-to-use-multiple-threads-for-zlib-compression
// and
// https://stackoverflow.com/questions/30794053/how-to-use-multiple-threads-for-zlib-compression-same-input-source
// Everything here should be either read-only, or writing to distinct data, or atomic.
class ThreadedDeflater::Task : public comphelper::ThreadTask
{
z_stream stream;
ThreadedDeflater* deflater;
int sequence;
int blockSize;
public:
Task(ThreadedDeflater* deflater_, int sequence_, int blockSize_)
: comphelper::ThreadTask(deflater_->threadTaskTag)
, deflater(deflater_)
, sequence(sequence_)
, blockSize(blockSize_)
{
}
private:
virtual void doWork() override;
};
ThreadedDeflater::ThreadedDeflater(sal_Int32 nSetLevel)
: zlibLevel(nSetLevel)
, threadTaskTag(comphelper::ThreadPool::createThreadTaskTag())
, pendingTasksCount(0)
{
}
ThreadedDeflater::~ThreadedDeflater()
{
waitForTasks();
clear();
}
void ThreadedDeflater::startDeflate(const uno::Sequence<sal_Int8>& rBuffer)
{
inBuffer = rBuffer;
sal_Int64 size = inBuffer.getLength();
int tasksCount = (size + MaxBlockSize - 1) / MaxBlockSize;
tasksCount = std::max(tasksCount, 1);
pendingTasksCount = tasksCount;
outBuffers.resize(pendingTasksCount);
for (int sequence = 0; sequence < tasksCount; ++sequence)
{
sal_Int64 thisSize = std::min(MaxBlockSize, size);
size -= thisSize;
comphelper::ThreadPool::getSharedOptimalPool().pushTask(
std::make_unique<Task>(this, sequence, thisSize));
}
assert(size == 0);
}
bool ThreadedDeflater::finished() const { return pendingTasksCount == 0; }
css::uno::Sequence<sal_Int8> ThreadedDeflater::getOutput() const
{
assert(finished());
sal_Int64 totalSize = 0;
for (const auto& buffer : outBuffers)
totalSize += buffer.size();
uno::Sequence<sal_Int8> outBuffer(totalSize);
auto pos = outBuffer.begin();
for (const auto& buffer : outBuffers)
pos = std::copy(buffer.begin(), buffer.end(), pos);
return outBuffer;
}
void ThreadedDeflater::waitForTasks()
{
comphelper::ThreadPool::getSharedOptimalPool().waitUntilDone(threadTaskTag);
}
void ThreadedDeflater::clear()
{
assert(finished());
inBuffer = uno::Sequence<sal_Int8>();
outBuffers.clear();
}
#if defined Z_PREFIX
#define deflateInit2 z_deflateInit2
#define deflateBound z_deflateBound
#define deflateSetDictionary z_deflateSetDictionary
#define deflate z_deflate
#define deflateEnd z_deflateEnd
#endif
void ThreadedDeflater::Task::doWork()
{
stream.zalloc = nullptr;
stream.zfree = nullptr;
stream.opaque = nullptr;
// -MAX_WBITS means 32k window size and raw stream
if (deflateInit2(&stream, deflater->zlibLevel, Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL,
Z_DEFAULT_STRATEGY)
!= Z_OK)
{
SAL_WARN("package.threadeddeflate", "deflateInit2() failed");
abort();
}
// Find out size for our output buffer to be large enough for deflate() needing to be called just once.
sal_Int64 outputMaxSize = deflateBound(&stream, blockSize);
// add extra size for Z_SYNC_FLUSH
outputMaxSize += 20;
deflater->outBuffers[sequence].resize(outputMaxSize);
sal_Int64 myInBufferStart = sequence * MaxBlockSize;
// zlib doesn't handle const properly
unsigned char* inBufferPtr = reinterpret_cast<unsigned char*>(
const_cast<signed char*>(deflater->inBuffer.getConstArray()));
if (sequence != 0)
{
// the window size is 32k, so set last 32k of previous data as the dictionary
assert(MAX_WBITS == 15);
assert(MaxBlockSize >= 32768);
deflateSetDictionary(&stream, inBufferPtr + myInBufferStart - 32768, 32768);
}
stream.next_in = inBufferPtr + myInBufferStart;
stream.avail_in = blockSize;
stream.next_out = reinterpret_cast<unsigned char*>(deflater->outBuffers[sequence].data());
stream.avail_out = outputMaxSize;
bool last = sequence == int(deflater->outBuffers.size() - 1); // Last block?
// The trick is in using Z_SYNC_FLUSH instead of Z_NO_FLUSH. It will align the data at a byte boundary,
// and since we use a raw stream, the data blocks then can be simply concatenated.
int res = deflate(&stream, last ? Z_FINISH : Z_SYNC_FLUSH);
assert(stream.avail_in == 0); // Check that everything has been deflated.
if (last ? res == Z_STREAM_END : res == Z_OK)
{ // ok
sal_Int64 outSize = outputMaxSize - stream.avail_out;
deflater->outBuffers[sequence].resize(outSize);
--deflater->pendingTasksCount;
}
else
{
SAL_WARN("package.threadeddeflate", "deflate() failed");
abort();
}
deflateEnd(&stream);
}
} // namespace
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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