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https://github.com/facebook/rocksdb.git
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82 lines
2 KiB
C++
82 lines
2 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same 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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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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}
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ColumnFamilyData* FlushScheduler::TakeNextColumnFamily() {
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while (true) {
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if (Empty()) {
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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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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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assert(rv == checking_set_.empty());
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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(Empty());
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}
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} // namespace rocksdb
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