dwarfs/include/dwarfs/zstd_context_manager.h

99 lines
2.6 KiB
C++

/* vim:set ts=2 sw=2 sts=2 et: */
/**
* \author Marcus Holland-Moritz (github@mhxnet.de)
* \copyright Copyright (c) Marcus Holland-Moritz
*
* This file is part of dwarfs.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the “Software”), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* SPDX-License-Identifier: MIT
*/
#pragma once
#include <mutex>
#include <vector>
#include <zstd.h>
namespace dwarfs {
class zstd_context_manager;
class zstd_scoped_context {
friend class zstd_context_manager;
public:
~zstd_scoped_context();
zstd_scoped_context(zstd_scoped_context&&) = default;
zstd_scoped_context& operator=(zstd_scoped_context&&) = default;
ZSTD_CCtx* get() const { return ctx_; }
private:
explicit zstd_scoped_context(zstd_context_manager* mgr);
zstd_context_manager* mgr_;
ZSTD_CCtx* ctx_;
};
class zstd_context_manager {
friend class zstd_scoped_context;
public:
zstd_context_manager() = default;
~zstd_context_manager() {
for (auto ctx : ctx_) {
ZSTD_freeCCtx(ctx);
}
}
zstd_scoped_context make_context() { return zstd_scoped_context(this); }
private:
ZSTD_CCtx* acquire() {
std::lock_guard lock(mx_);
if (ctx_.empty()) {
return ZSTD_createCCtx();
}
auto ctx = ctx_.back();
ctx_.pop_back();
return ctx;
}
void release(ZSTD_CCtx* ctx) {
std::lock_guard lock(mx_);
ctx_.push_back(ctx);
}
std::mutex mx_;
std::vector<ZSTD_CCtx*> ctx_;
};
inline zstd_scoped_context::zstd_scoped_context(zstd_context_manager* mgr)
: mgr_{mgr}
, ctx_{mgr_->acquire()} {}
inline zstd_scoped_context::~zstd_scoped_context() { mgr_->release(ctx_); }
} // namespace dwarfs