51 lines
1.6 KiB
C++
51 lines
1.6 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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//
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// Copyright (c) 2011 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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#include "util/concurrent_arena.h"
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#include <thread>
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#include "port/likely.h"
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#include "port/port.h"
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#include "util/random.h"
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namespace rocksdb {
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#if ROCKSDB_SUPPORT_THREAD_LOCAL
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__thread uint32_t ConcurrentArena::tls_cpuid = 0;
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#endif
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ConcurrentArena::ConcurrentArena(size_t block_size, size_t huge_page_size)
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: shard_block_size_(block_size / 8), arena_(block_size, huge_page_size) {
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// find a power of two >= num_cpus and >= 8
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auto num_cpus = std::thread::hardware_concurrency();
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index_mask_ = 7;
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while (index_mask_ + 1 < num_cpus) {
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index_mask_ = index_mask_ * 2 + 1;
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}
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shards_.reset(new Shard[index_mask_ + 1]);
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Fixup();
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}
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ConcurrentArena::Shard* ConcurrentArena::Repick() {
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int cpuid = port::PhysicalCoreID();
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if (UNLIKELY(cpuid < 0)) {
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// cpu id unavailable, just pick randomly
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cpuid =
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Random::GetTLSInstance()->Uniform(static_cast<int>(index_mask_) + 1);
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}
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#if ROCKSDB_SUPPORT_THREAD_LOCAL
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// even if we are cpu 0, use a non-zero tls_cpuid so we can tell we
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// have repicked
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tls_cpuid = cpuid | (static_cast<int>(index_mask_) + 1);
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#endif
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return &shards_[cpuid & index_mask_];
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}
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} // namespace rocksdb
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