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140 Zeilen
3.5 KiB
140 Zeilen
3.5 KiB
// Copyright (c) 2018 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#ifndef STORAGE_LEVELDB_PORT_PORT_STDCXX_H_
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#define STORAGE_LEVELDB_PORT_PORT_STDCXX_H_
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// port/port_config.h availability is automatically detected via __has_include
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// in newer compilers. If LEVELDB_HAS_PORT_CONFIG_H is defined, it overrides the
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// configuration detection.
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#if defined(LEVELDB_HAS_PORT_CONFIG_H)
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#if LEVELDB_HAS_PORT_CONFIG_H
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#include "port/port_config.h"
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#endif // LEVELDB_HAS_PORT_CONFIG_H
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#elif defined(__has_include)
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#if __has_include("port/port_config.h")
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#include "port/port_config.h"
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#endif // __has_include("port/port_config.h")
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#endif // defined(LEVELDB_HAS_PORT_CONFIG_H)
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#if HAVE_CRC32C
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#include <crc32c/crc32c.h>
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#endif // HAVE_CRC32C
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#if HAVE_SNAPPY
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#include <snappy.h>
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#endif // HAVE_SNAPPY
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#include <stddef.h>
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#include <stdint.h>
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#include <cassert>
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#include <condition_variable> // NOLINT
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#include <mutex> // NOLINT
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#include <string>
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#include "port/atomic_pointer.h"
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#include "port/thread_annotations.h"
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namespace leveldb {
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namespace port {
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static const bool kLittleEndian = !LEVELDB_IS_BIG_ENDIAN;
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class CondVar;
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// Thinly wraps std::mutex.
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class LOCKABLE Mutex {
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public:
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Mutex() = default;
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~Mutex() = default;
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Mutex(const Mutex&) = delete;
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Mutex& operator=(const Mutex&) = delete;
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void Lock() EXCLUSIVE_LOCK_FUNCTION() { mu_.lock(); }
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void Unlock() UNLOCK_FUNCTION() { mu_.unlock(); }
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void AssertHeld() ASSERT_EXCLUSIVE_LOCK() { }
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private:
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friend class CondVar;
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std::mutex mu_;
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};
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// Thinly wraps std::condition_variable.
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class CondVar {
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public:
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explicit CondVar(Mutex* mu) : mu_(mu) { assert(mu != nullptr); }
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~CondVar() = default;
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CondVar(const CondVar&) = delete;
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CondVar& operator=(const CondVar&) = delete;
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void Wait() {
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std::unique_lock<std::mutex> lock(mu_->mu_, std::adopt_lock);
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cv_.wait(lock);
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lock.release();
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}
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void Signal() { cv_.notify_one(); }
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void SignalAll() { cv_.notify_all(); }
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private:
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std::condition_variable cv_;
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Mutex* const mu_;
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};
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using OnceType = std::once_flag;
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#define LEVELDB_ONCE_INIT {}
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// Thinly wraps std::call_once.
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inline void InitOnce(OnceType* once, void (*initializer)()) {
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std::call_once(*once, *initializer);
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}
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inline bool Snappy_Compress(const char* input, size_t length,
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::std::string* output) {
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#if HAVE_SNAPPY
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output->resize(snappy::MaxCompressedLength(length));
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size_t outlen;
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snappy::RawCompress(input, length, &(*output)[0], &outlen);
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output->resize(outlen);
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return true;
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#endif // HAVE_SNAPPY
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return false;
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}
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inline bool Snappy_GetUncompressedLength(const char* input, size_t length,
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size_t* result) {
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#if HAVE_SNAPPY
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return snappy::GetUncompressedLength(input, length, result);
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#else
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return false;
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#endif // HAVE_SNAPPY
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}
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inline bool Snappy_Uncompress(const char* input, size_t length, char* output) {
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#if HAVE_SNAPPY
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return snappy::RawUncompress(input, length, output);
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#else
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return false;
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#endif // HAVE_SNAPPY
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}
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inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
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return false;
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}
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inline uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size) {
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#if HAVE_CRC32C
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return ::crc32c::Extend(crc, reinterpret_cast<const uint8_t*>(buf), size);
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#else
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return 0;
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#endif // HAVE_CRC32C
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}
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} // namespace port
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_PORT_PORT_STDCXX_H_
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