Revision 0d4a2b733070a1bd52f981313f9e17f126701407 authored by Yi Wu on 04 August 2017, 20:09:56 UTC, committed by Facebook Github Bot on 04 August 2017, 20:12:07 UTC
Summary: The FsyncFiles background job call Fsync() periodically for blob files. However it can access WritableFileWriter concurrently with a Put() or Write(). And WritableFileWriter does not support concurrent access. It will lead to WritableFileWriter buffer being flush with same content twice, and blob file end up corrupted. Fixing by simply let FsyncFiles hold write_mutex_. Closes https://github.com/facebook/rocksdb/pull/2685 Differential Revision: D5561908 Pulled By: yiwu-arbug fbshipit-source-id: f0bb5bcab0e05694e053b8c49eab43640721e872
1 parent 627c9f1
core_local.h
// Copyright (c) 2017-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#include <cstddef>
#include <thread>
#include <utility>
#include <vector>
#include "port/likely.h"
#include "port/port.h"
#include "util/random.h"
namespace rocksdb {
// An array of core-local values. Ideally the value type, T, is cache aligned to
// prevent false sharing.
template <typename T>
class CoreLocalArray {
public:
CoreLocalArray();
size_t Size() const;
// returns pointer to the element corresponding to the core that the thread
// currently runs on.
T* Access() const;
// same as above, but also returns the core index, which the client can cache
// to reduce how often core ID needs to be retrieved. Only do this if some
// inaccuracy is tolerable, as the thread may migrate to a different core.
std::pair<T*, size_t> AccessElementAndIndex() const;
// returns pointer to element for the specified core index. This can be used,
// e.g., for aggregation, or if the client caches core index.
T* AccessAtCore(size_t core_idx) const;
private:
std::unique_ptr<T[]> data_;
int size_shift_;
};
template <typename T>
CoreLocalArray<T>::CoreLocalArray() {
int num_cpus = static_cast<int>(std::thread::hardware_concurrency());
// find a power of two >= num_cpus and >= 8
size_shift_ = 3;
while (1 << size_shift_ < num_cpus) {
++size_shift_;
}
data_.reset(new T[static_cast<size_t>(1) << size_shift_]);
}
template <typename T>
size_t CoreLocalArray<T>::Size() const {
return static_cast<size_t>(1) << size_shift_;
}
template <typename T>
T* CoreLocalArray<T>::Access() const {
return AccessElementAndIndex().first;
}
template <typename T>
std::pair<T*, size_t> CoreLocalArray<T>::AccessElementAndIndex() const {
int cpuid = port::PhysicalCoreID();
size_t core_idx;
if (UNLIKELY(cpuid < 0)) {
// cpu id unavailable, just pick randomly
core_idx = Random::GetTLSInstance()->Uniform(1 << size_shift_);
} else {
core_idx = static_cast<size_t>(cpuid & ((1 << size_shift_) - 1));
}
return {AccessAtCore(core_idx), core_idx};
}
template <typename T>
T* CoreLocalArray<T>::AccessAtCore(size_t core_idx) const {
assert(core_idx < static_cast<size_t>(1) << size_shift_);
return &data_[core_idx];
}
} // namespace rocksdb
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