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
thread_local.h
// Copyright (c) 2011-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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <atomic>
#include <functional>
#include <memory>
#include <unordered_map>
#include <vector>
#include "util/autovector.h"
#include "port/port.h"
namespace rocksdb {
// Cleanup function that will be called for a stored thread local
// pointer (if not NULL) when one of the following happens:
// (1) a thread terminates
// (2) a ThreadLocalPtr is destroyed
typedef void (*UnrefHandler)(void* ptr);
// ThreadLocalPtr stores only values of pointer type. Different from
// the usual thread-local-storage, ThreadLocalPtr has the ability to
// distinguish data coming from different threads and different
// ThreadLocalPtr instances. For example, if a regular thread_local
// variable A is declared in DBImpl, two DBImpl objects would share
// the same A. However, a ThreadLocalPtr that is defined under the
// scope of DBImpl can avoid such confliction. As a result, its memory
// usage would be O(# of threads * # of ThreadLocalPtr instances).
class ThreadLocalPtr {
public:
explicit ThreadLocalPtr(UnrefHandler handler = nullptr);
~ThreadLocalPtr();
// Return the current pointer stored in thread local
void* Get() const;
// Set a new pointer value to the thread local storage.
void Reset(void* ptr);
// Atomically swap the supplied ptr and return the previous value
void* Swap(void* ptr);
// Atomically compare the stored value with expected. Set the new
// pointer value to thread local only if the comparison is true.
// Otherwise, expected returns the stored value.
// Return true on success, false on failure
bool CompareAndSwap(void* ptr, void*& expected);
// Reset all thread local data to replacement, and return non-nullptr
// data for all existing threads
void Scrape(autovector<void*>* ptrs, void* const replacement);
typedef std::function<void(void*, void*)> FoldFunc;
// Update res by applying func on each thread-local value. Holds a lock that
// prevents unref handler from running during this call, but clients must
// still provide external synchronization since the owning thread can
// access the values without internal locking, e.g., via Get() and Reset().
void Fold(FoldFunc func, void* res);
// Add here for testing
// Return the next available Id without claiming it
static uint32_t TEST_PeekId();
// Initialize the static singletons of the ThreadLocalPtr.
//
// If this function is not called, then the singletons will be
// automatically initialized when they are used.
//
// Calling this function twice or after the singletons have been
// initialized will be no-op.
static void InitSingletons();
class StaticMeta;
private:
static StaticMeta* Instance();
const uint32_t id_;
};
} // namespace rocksdb
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