fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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574 lines
17 KiB
574 lines
17 KiB
// 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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//
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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 "cache/lru_cache.h"
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#include <assert.h>
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#include <stdio.h>
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#include <string>
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#include "util/mutexlock.h"
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namespace ROCKSDB_NAMESPACE {
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LRUHandleTable::LRUHandleTable() : list_(nullptr), length_(0), elems_(0) {
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Resize();
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}
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LRUHandleTable::~LRUHandleTable() {
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ApplyToAllCacheEntries([](LRUHandle* h) {
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if (!h->HasRefs()) {
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h->Free();
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}
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});
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delete[] list_;
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}
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LRUHandle* LRUHandleTable::Lookup(const Slice& key, uint32_t hash) {
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return *FindPointer(key, hash);
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}
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LRUHandle* LRUHandleTable::Insert(LRUHandle* h) {
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LRUHandle** ptr = FindPointer(h->key(), h->hash);
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LRUHandle* old = *ptr;
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h->next_hash = (old == nullptr ? nullptr : old->next_hash);
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*ptr = h;
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if (old == nullptr) {
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++elems_;
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if (elems_ > length_) {
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// Since each cache entry is fairly large, we aim for a small
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// average linked list length (<= 1).
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Resize();
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}
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}
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return old;
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}
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LRUHandle* LRUHandleTable::Remove(const Slice& key, uint32_t hash) {
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LRUHandle** ptr = FindPointer(key, hash);
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LRUHandle* result = *ptr;
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if (result != nullptr) {
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*ptr = result->next_hash;
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--elems_;
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}
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return result;
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}
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LRUHandle** LRUHandleTable::FindPointer(const Slice& key, uint32_t hash) {
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LRUHandle** ptr = &list_[hash & (length_ - 1)];
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while (*ptr != nullptr && ((*ptr)->hash != hash || key != (*ptr)->key())) {
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ptr = &(*ptr)->next_hash;
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}
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return ptr;
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}
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void LRUHandleTable::Resize() {
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uint32_t new_length = 16;
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while (new_length < elems_ * 1.5) {
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new_length *= 2;
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}
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LRUHandle** new_list = new LRUHandle*[new_length];
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memset(new_list, 0, sizeof(new_list[0]) * new_length);
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uint32_t count = 0;
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for (uint32_t i = 0; i < length_; i++) {
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LRUHandle* h = list_[i];
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while (h != nullptr) {
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LRUHandle* next = h->next_hash;
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uint32_t hash = h->hash;
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LRUHandle** ptr = &new_list[hash & (new_length - 1)];
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h->next_hash = *ptr;
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*ptr = h;
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h = next;
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count++;
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}
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}
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assert(elems_ == count);
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delete[] list_;
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list_ = new_list;
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length_ = new_length;
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}
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LRUCacheShard::LRUCacheShard(size_t capacity, bool strict_capacity_limit,
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double high_pri_pool_ratio,
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bool use_adaptive_mutex,
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CacheMetadataChargePolicy metadata_charge_policy)
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: capacity_(0),
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high_pri_pool_usage_(0),
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strict_capacity_limit_(strict_capacity_limit),
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high_pri_pool_ratio_(high_pri_pool_ratio),
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high_pri_pool_capacity_(0),
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usage_(0),
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lru_usage_(0),
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mutex_(use_adaptive_mutex) {
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set_metadata_charge_policy(metadata_charge_policy);
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// Make empty circular linked list
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lru_.next = &lru_;
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lru_.prev = &lru_;
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lru_low_pri_ = &lru_;
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SetCapacity(capacity);
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}
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void LRUCacheShard::EraseUnRefEntries() {
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autovector<LRUHandle*> last_reference_list;
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{
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MutexLock l(&mutex_);
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while (lru_.next != &lru_) {
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LRUHandle* old = lru_.next;
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// LRU list contains only elements which can be evicted
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assert(old->InCache() && !old->HasRefs());
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LRU_Remove(old);
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table_.Remove(old->key(), old->hash);
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old->SetInCache(false);
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size_t total_charge = old->CalcTotalCharge(metadata_charge_policy_);
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assert(usage_ >= total_charge);
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usage_ -= total_charge;
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last_reference_list.push_back(old);
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}
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}
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for (auto entry : last_reference_list) {
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entry->Free();
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}
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}
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void LRUCacheShard::ApplyToAllCacheEntries(void (*callback)(void*, size_t),
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bool thread_safe) {
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const auto applyCallback = [&]() {
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table_.ApplyToAllCacheEntries(
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[callback](LRUHandle* h) { callback(h->value, h->charge); });
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};
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if (thread_safe) {
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MutexLock l(&mutex_);
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applyCallback();
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} else {
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applyCallback();
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}
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}
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void LRUCacheShard::TEST_GetLRUList(LRUHandle** lru, LRUHandle** lru_low_pri) {
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MutexLock l(&mutex_);
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*lru = &lru_;
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*lru_low_pri = lru_low_pri_;
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}
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size_t LRUCacheShard::TEST_GetLRUSize() {
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MutexLock l(&mutex_);
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LRUHandle* lru_handle = lru_.next;
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size_t lru_size = 0;
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while (lru_handle != &lru_) {
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lru_size++;
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lru_handle = lru_handle->next;
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}
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return lru_size;
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}
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double LRUCacheShard::GetHighPriPoolRatio() {
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MutexLock l(&mutex_);
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return high_pri_pool_ratio_;
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}
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void LRUCacheShard::LRU_Remove(LRUHandle* e) {
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assert(e->next != nullptr);
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assert(e->prev != nullptr);
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if (lru_low_pri_ == e) {
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lru_low_pri_ = e->prev;
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}
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e->next->prev = e->prev;
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e->prev->next = e->next;
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e->prev = e->next = nullptr;
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size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
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assert(lru_usage_ >= total_charge);
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lru_usage_ -= total_charge;
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if (e->InHighPriPool()) {
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assert(high_pri_pool_usage_ >= total_charge);
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high_pri_pool_usage_ -= total_charge;
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}
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}
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void LRUCacheShard::LRU_Insert(LRUHandle* e) {
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assert(e->next == nullptr);
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assert(e->prev == nullptr);
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size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
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if (high_pri_pool_ratio_ > 0 && (e->IsHighPri() || e->HasHit())) {
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// Inset "e" to head of LRU list.
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e->next = &lru_;
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e->prev = lru_.prev;
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e->prev->next = e;
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e->next->prev = e;
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e->SetInHighPriPool(true);
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high_pri_pool_usage_ += total_charge;
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MaintainPoolSize();
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} else {
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// Insert "e" to the head of low-pri pool. Note that when
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// high_pri_pool_ratio is 0, head of low-pri pool is also head of LRU list.
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e->next = lru_low_pri_->next;
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e->prev = lru_low_pri_;
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e->prev->next = e;
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e->next->prev = e;
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e->SetInHighPriPool(false);
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lru_low_pri_ = e;
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}
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lru_usage_ += total_charge;
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}
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void LRUCacheShard::MaintainPoolSize() {
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while (high_pri_pool_usage_ > high_pri_pool_capacity_) {
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// Overflow last entry in high-pri pool to low-pri pool.
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lru_low_pri_ = lru_low_pri_->next;
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assert(lru_low_pri_ != &lru_);
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lru_low_pri_->SetInHighPriPool(false);
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size_t total_charge =
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lru_low_pri_->CalcTotalCharge(metadata_charge_policy_);
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assert(high_pri_pool_usage_ >= total_charge);
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high_pri_pool_usage_ -= total_charge;
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}
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}
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void LRUCacheShard::EvictFromLRU(size_t charge,
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autovector<LRUHandle*>* deleted) {
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while ((usage_ + charge) > capacity_ && lru_.next != &lru_) {
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LRUHandle* old = lru_.next;
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// LRU list contains only elements which can be evicted
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assert(old->InCache() && !old->HasRefs());
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LRU_Remove(old);
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table_.Remove(old->key(), old->hash);
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old->SetInCache(false);
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size_t old_total_charge = old->CalcTotalCharge(metadata_charge_policy_);
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assert(usage_ >= old_total_charge);
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usage_ -= old_total_charge;
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deleted->push_back(old);
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}
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}
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void LRUCacheShard::SetCapacity(size_t capacity) {
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autovector<LRUHandle*> last_reference_list;
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{
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MutexLock l(&mutex_);
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capacity_ = capacity;
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high_pri_pool_capacity_ = capacity_ * high_pri_pool_ratio_;
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EvictFromLRU(0, &last_reference_list);
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}
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// Free the entries outside of mutex for performance reasons
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for (auto entry : last_reference_list) {
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entry->Free();
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}
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}
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void LRUCacheShard::SetStrictCapacityLimit(bool strict_capacity_limit) {
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MutexLock l(&mutex_);
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strict_capacity_limit_ = strict_capacity_limit;
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}
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Cache::Handle* LRUCacheShard::Lookup(const Slice& key, uint32_t hash) {
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MutexLock l(&mutex_);
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LRUHandle* e = table_.Lookup(key, hash);
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if (e != nullptr) {
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assert(e->InCache());
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if (!e->HasRefs()) {
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// The entry is in LRU since it's in hash and has no external references
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LRU_Remove(e);
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}
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e->Ref();
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e->SetHit();
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}
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return reinterpret_cast<Cache::Handle*>(e);
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}
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bool LRUCacheShard::Ref(Cache::Handle* h) {
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LRUHandle* e = reinterpret_cast<LRUHandle*>(h);
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MutexLock l(&mutex_);
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// To create another reference - entry must be already externally referenced
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assert(e->HasRefs());
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e->Ref();
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return true;
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}
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void LRUCacheShard::SetHighPriorityPoolRatio(double high_pri_pool_ratio) {
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MutexLock l(&mutex_);
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high_pri_pool_ratio_ = high_pri_pool_ratio;
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high_pri_pool_capacity_ = capacity_ * high_pri_pool_ratio_;
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MaintainPoolSize();
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}
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bool LRUCacheShard::Release(Cache::Handle* handle, bool force_erase) {
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if (handle == nullptr) {
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return false;
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}
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LRUHandle* e = reinterpret_cast<LRUHandle*>(handle);
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bool last_reference = false;
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{
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MutexLock l(&mutex_);
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last_reference = e->Unref();
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if (last_reference && e->InCache()) {
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// The item is still in cache, and nobody else holds a reference to it
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if (usage_ > capacity_ || force_erase) {
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// The LRU list must be empty since the cache is full
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assert(lru_.next == &lru_ || force_erase);
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// Take this opportunity and remove the item
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table_.Remove(e->key(), e->hash);
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e->SetInCache(false);
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} else {
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// Put the item back on the LRU list, and don't free it
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LRU_Insert(e);
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last_reference = false;
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}
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}
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if (last_reference) {
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size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
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assert(usage_ >= total_charge);
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usage_ -= total_charge;
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}
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}
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// Free the entry here outside of mutex for performance reasons
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if (last_reference) {
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e->Free();
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}
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return last_reference;
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}
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Status LRUCacheShard::Insert(const Slice& key, uint32_t hash, void* value,
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size_t charge,
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void (*deleter)(const Slice& key, void* value),
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Cache::Handle** handle, Cache::Priority priority) {
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// Allocate the memory here outside of the mutex
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// If the cache is full, we'll have to release it
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// It shouldn't happen very often though.
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LRUHandle* e = reinterpret_cast<LRUHandle*>(
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new char[sizeof(LRUHandle) - 1 + key.size()]);
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Status s = Status::OK();
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autovector<LRUHandle*> last_reference_list;
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e->value = value;
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e->deleter = deleter;
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e->charge = charge;
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e->key_length = key.size();
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e->flags = 0;
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e->hash = hash;
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e->refs = 0;
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e->next = e->prev = nullptr;
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e->SetInCache(true);
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e->SetPriority(priority);
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memcpy(e->key_data, key.data(), key.size());
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size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
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{
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MutexLock l(&mutex_);
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// Free the space following strict LRU policy until enough space
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// is freed or the lru list is empty
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EvictFromLRU(total_charge, &last_reference_list);
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if ((usage_ + total_charge) > capacity_ &&
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(strict_capacity_limit_ || handle == nullptr)) {
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if (handle == nullptr) {
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// Don't insert the entry but still return ok, as if the entry inserted
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// into cache and get evicted immediately.
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e->SetInCache(false);
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last_reference_list.push_back(e);
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} else {
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delete[] reinterpret_cast<char*>(e);
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*handle = nullptr;
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s = Status::Incomplete("Insert failed due to LRU cache being full.");
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}
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} else {
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// Insert into the cache. Note that the cache might get larger than its
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// capacity if not enough space was freed up.
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LRUHandle* old = table_.Insert(e);
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usage_ += total_charge;
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if (old != nullptr) {
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s = Status::OkOverwritten();
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assert(old->InCache());
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old->SetInCache(false);
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if (!old->HasRefs()) {
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// old is on LRU because it's in cache and its reference count is 0
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LRU_Remove(old);
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size_t old_total_charge =
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old->CalcTotalCharge(metadata_charge_policy_);
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assert(usage_ >= old_total_charge);
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usage_ -= old_total_charge;
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last_reference_list.push_back(old);
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}
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}
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if (handle == nullptr) {
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LRU_Insert(e);
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} else {
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e->Ref();
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*handle = reinterpret_cast<Cache::Handle*>(e);
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}
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}
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}
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// Free the entries here outside of mutex for performance reasons
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for (auto entry : last_reference_list) {
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entry->Free();
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}
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return s;
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}
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void LRUCacheShard::Erase(const Slice& key, uint32_t hash) {
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LRUHandle* e;
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bool last_reference = false;
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{
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MutexLock l(&mutex_);
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e = table_.Remove(key, hash);
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if (e != nullptr) {
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assert(e->InCache());
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e->SetInCache(false);
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if (!e->HasRefs()) {
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// The entry is in LRU since it's in hash and has no external references
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LRU_Remove(e);
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size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
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assert(usage_ >= total_charge);
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usage_ -= total_charge;
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last_reference = true;
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}
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}
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}
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// Free the entry here outside of mutex for performance reasons
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// last_reference will only be true if e != nullptr
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if (last_reference) {
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e->Free();
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}
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}
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size_t LRUCacheShard::GetUsage() const {
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MutexLock l(&mutex_);
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return usage_;
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}
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size_t LRUCacheShard::GetPinnedUsage() const {
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MutexLock l(&mutex_);
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assert(usage_ >= lru_usage_);
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return usage_ - lru_usage_;
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}
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std::string LRUCacheShard::GetPrintableOptions() const {
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const int kBufferSize = 200;
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char buffer[kBufferSize];
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{
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MutexLock l(&mutex_);
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snprintf(buffer, kBufferSize, " high_pri_pool_ratio: %.3lf\n",
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high_pri_pool_ratio_);
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}
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return std::string(buffer);
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}
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LRUCache::LRUCache(size_t capacity, int num_shard_bits,
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bool strict_capacity_limit, double high_pri_pool_ratio,
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std::shared_ptr<MemoryAllocator> allocator,
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bool use_adaptive_mutex,
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CacheMetadataChargePolicy metadata_charge_policy)
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: ShardedCache(capacity, num_shard_bits, strict_capacity_limit,
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std::move(allocator)) {
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num_shards_ = 1 << num_shard_bits;
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shards_ = reinterpret_cast<LRUCacheShard*>(
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port::cacheline_aligned_alloc(sizeof(LRUCacheShard) * num_shards_));
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size_t per_shard = (capacity + (num_shards_ - 1)) / num_shards_;
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for (int i = 0; i < num_shards_; i++) {
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new (&shards_[i])
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LRUCacheShard(per_shard, strict_capacity_limit, high_pri_pool_ratio,
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use_adaptive_mutex, metadata_charge_policy);
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}
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}
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LRUCache::~LRUCache() {
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if (shards_ != nullptr) {
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assert(num_shards_ > 0);
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for (int i = 0; i < num_shards_; i++) {
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shards_[i].~LRUCacheShard();
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}
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port::cacheline_aligned_free(shards_);
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}
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}
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CacheShard* LRUCache::GetShard(int shard) {
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return reinterpret_cast<CacheShard*>(&shards_[shard]);
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}
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const CacheShard* LRUCache::GetShard(int shard) const {
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return reinterpret_cast<CacheShard*>(&shards_[shard]);
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}
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void* LRUCache::Value(Handle* handle) {
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return reinterpret_cast<const LRUHandle*>(handle)->value;
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}
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size_t LRUCache::GetCharge(Handle* handle) const {
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return reinterpret_cast<const LRUHandle*>(handle)->charge;
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}
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|
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uint32_t LRUCache::GetHash(Handle* handle) const {
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return reinterpret_cast<const LRUHandle*>(handle)->hash;
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}
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|
|
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void LRUCache::DisownData() {
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// Do not drop data if compile with ASAN to suppress leak warning.
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#if defined(__clang__)
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#if !defined(__has_feature) || !__has_feature(address_sanitizer)
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shards_ = nullptr;
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num_shards_ = 0;
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#endif
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#else // __clang__
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#ifndef __SANITIZE_ADDRESS__
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shards_ = nullptr;
|
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num_shards_ = 0;
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#endif // !__SANITIZE_ADDRESS__
|
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#endif // __clang__
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}
|
|
|
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size_t LRUCache::TEST_GetLRUSize() {
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|
size_t lru_size_of_all_shards = 0;
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|
for (int i = 0; i < num_shards_; i++) {
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lru_size_of_all_shards += shards_[i].TEST_GetLRUSize();
|
|
}
|
|
return lru_size_of_all_shards;
|
|
}
|
|
|
|
double LRUCache::GetHighPriPoolRatio() {
|
|
double result = 0.0;
|
|
if (num_shards_ > 0) {
|
|
result = shards_[0].GetHighPriPoolRatio();
|
|
}
|
|
return result;
|
|
}
|
|
|
|
std::shared_ptr<Cache> NewLRUCache(const LRUCacheOptions& cache_opts) {
|
|
return NewLRUCache(cache_opts.capacity, cache_opts.num_shard_bits,
|
|
cache_opts.strict_capacity_limit,
|
|
cache_opts.high_pri_pool_ratio,
|
|
cache_opts.memory_allocator, cache_opts.use_adaptive_mutex,
|
|
cache_opts.metadata_charge_policy);
|
|
}
|
|
|
|
std::shared_ptr<Cache> NewLRUCache(
|
|
size_t capacity, int num_shard_bits, bool strict_capacity_limit,
|
|
double high_pri_pool_ratio,
|
|
std::shared_ptr<MemoryAllocator> memory_allocator, bool use_adaptive_mutex,
|
|
CacheMetadataChargePolicy metadata_charge_policy) {
|
|
if (num_shard_bits >= 20) {
|
|
return nullptr; // the cache cannot be sharded into too many fine pieces
|
|
}
|
|
if (high_pri_pool_ratio < 0.0 || high_pri_pool_ratio > 1.0) {
|
|
// invalid high_pri_pool_ratio
|
|
return nullptr;
|
|
}
|
|
if (num_shard_bits < 0) {
|
|
num_shard_bits = GetDefaultCacheShardBits(capacity);
|
|
}
|
|
return std::make_shared<LRUCache>(
|
|
capacity, num_shard_bits, strict_capacity_limit, high_pri_pool_ratio,
|
|
std::move(memory_allocator), use_adaptive_mutex, metadata_charge_policy);
|
|
}
|
|
|
|
} // namespace ROCKSDB_NAMESPACE
|
|
|