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b2584577fa
Summary: FlushScheduler's methods are instrumented with debug-time locks to check the scheduler state against a simple container definition. Since https://github.com/facebook/rocksdb/pull/2286 the scope of such locks are widened to the entire methods' body. The result is that the concurrency tested during testing (in debug mode) is stricter than the concurrency level manifested at runtime (in release mode). The patch reverts this change to reduce the scope of such locks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5372 Differential Revision: D15545831 Pulled By: maysamyabandeh fbshipit-source-id: 01d69191afb1dd807d4bdc990fc74813ae7b5426
91 lines
2.5 KiB
C++
91 lines
2.5 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#include "db/flush_scheduler.h"
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#include <cassert>
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#include "db/column_family.h"
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namespace rocksdb {
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void FlushScheduler::ScheduleFlush(ColumnFamilyData* cfd) {
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#ifndef NDEBUG
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{
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std::lock_guard<std::mutex> lock(checking_mutex_);
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assert(checking_set_.count(cfd) == 0);
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checking_set_.insert(cfd);
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}
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#endif // NDEBUG
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cfd->Ref();
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// Suppress false positive clang analyzer warnings.
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#ifndef __clang_analyzer__
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Node* node = new Node{cfd, head_.load(std::memory_order_relaxed)};
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while (!head_.compare_exchange_strong(
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node->next, node, std::memory_order_relaxed, std::memory_order_relaxed)) {
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// failing CAS updates the first param, so we are already set for
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// retry. TakeNextColumnFamily won't happen until after another
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// inter-thread synchronization, so we don't even need release
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// semantics for this CAS
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}
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#endif // __clang_analyzer__
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}
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ColumnFamilyData* FlushScheduler::TakeNextColumnFamily() {
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while (true) {
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if (head_.load(std::memory_order_relaxed) == nullptr) {
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return nullptr;
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}
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// dequeue the head
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Node* node = head_.load(std::memory_order_relaxed);
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head_.store(node->next, std::memory_order_relaxed);
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ColumnFamilyData* cfd = node->column_family;
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delete node;
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#ifndef NDEBUG
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{
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std::lock_guard<std::mutex> lock(checking_mutex_);
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auto iter = checking_set_.find(cfd);
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assert(iter != checking_set_.end());
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checking_set_.erase(iter);
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}
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#endif // NDEBUG
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if (!cfd->IsDropped()) {
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// success
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return cfd;
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}
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// no longer relevant, retry
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if (cfd->Unref()) {
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delete cfd;
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}
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}
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}
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bool FlushScheduler::Empty() {
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auto rv = head_.load(std::memory_order_relaxed) == nullptr;
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#ifndef NDEBUG
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std::lock_guard<std::mutex> lock(checking_mutex_);
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// Empty is allowed to be called concurrnetly with ScheduleFlush. It would
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// only miss the recent schedules.
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assert((rv == checking_set_.empty()) || rv);
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#endif // NDEBUG
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return rv;
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}
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void FlushScheduler::Clear() {
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ColumnFamilyData* cfd;
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while ((cfd = TakeNextColumnFamily()) != nullptr) {
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if (cfd->Unref()) {
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delete cfd;
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}
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}
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assert(head_.load(std::memory_order_relaxed) == nullptr);
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}
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} // namespace rocksdb
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