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-rw-r--r--src/rocksdb/cache/lru_cache.cc574
1 files changed, 574 insertions, 0 deletions
diff --git a/src/rocksdb/cache/lru_cache.cc b/src/rocksdb/cache/lru_cache.cc
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index 000000000..987417806
--- /dev/null
+++ b/src/rocksdb/cache/lru_cache.cc
@@ -0,0 +1,574 @@
+// 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.
+
+#include "cache/lru_cache.h"
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string>
+
+#include "util/mutexlock.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+LRUHandleTable::LRUHandleTable() : list_(nullptr), length_(0), elems_(0) {
+ Resize();
+}
+
+LRUHandleTable::~LRUHandleTable() {
+ ApplyToAllCacheEntries([](LRUHandle* h) {
+ if (!h->HasRefs()) {
+ h->Free();
+ }
+ });
+ delete[] list_;
+}
+
+LRUHandle* LRUHandleTable::Lookup(const Slice& key, uint32_t hash) {
+ return *FindPointer(key, hash);
+}
+
+LRUHandle* LRUHandleTable::Insert(LRUHandle* h) {
+ LRUHandle** ptr = FindPointer(h->key(), h->hash);
+ LRUHandle* old = *ptr;
+ h->next_hash = (old == nullptr ? nullptr : old->next_hash);
+ *ptr = h;
+ if (old == nullptr) {
+ ++elems_;
+ if (elems_ > length_) {
+ // Since each cache entry is fairly large, we aim for a small
+ // average linked list length (<= 1).
+ Resize();
+ }
+ }
+ return old;
+}
+
+LRUHandle* LRUHandleTable::Remove(const Slice& key, uint32_t hash) {
+ LRUHandle** ptr = FindPointer(key, hash);
+ LRUHandle* result = *ptr;
+ if (result != nullptr) {
+ *ptr = result->next_hash;
+ --elems_;
+ }
+ return result;
+}
+
+LRUHandle** LRUHandleTable::FindPointer(const Slice& key, uint32_t hash) {
+ LRUHandle** ptr = &list_[hash & (length_ - 1)];
+ while (*ptr != nullptr && ((*ptr)->hash != hash || key != (*ptr)->key())) {
+ ptr = &(*ptr)->next_hash;
+ }
+ return ptr;
+}
+
+void LRUHandleTable::Resize() {
+ uint32_t new_length = 16;
+ while (new_length < elems_ * 1.5) {
+ new_length *= 2;
+ }
+ LRUHandle** new_list = new LRUHandle*[new_length];
+ memset(new_list, 0, sizeof(new_list[0]) * new_length);
+ uint32_t count = 0;
+ for (uint32_t i = 0; i < length_; i++) {
+ LRUHandle* h = list_[i];
+ while (h != nullptr) {
+ LRUHandle* next = h->next_hash;
+ uint32_t hash = h->hash;
+ LRUHandle** ptr = &new_list[hash & (new_length - 1)];
+ h->next_hash = *ptr;
+ *ptr = h;
+ h = next;
+ count++;
+ }
+ }
+ assert(elems_ == count);
+ delete[] list_;
+ list_ = new_list;
+ length_ = new_length;
+}
+
+LRUCacheShard::LRUCacheShard(size_t capacity, bool strict_capacity_limit,
+ double high_pri_pool_ratio,
+ bool use_adaptive_mutex,
+ CacheMetadataChargePolicy metadata_charge_policy)
+ : capacity_(0),
+ high_pri_pool_usage_(0),
+ strict_capacity_limit_(strict_capacity_limit),
+ high_pri_pool_ratio_(high_pri_pool_ratio),
+ high_pri_pool_capacity_(0),
+ usage_(0),
+ lru_usage_(0),
+ mutex_(use_adaptive_mutex) {
+ set_metadata_charge_policy(metadata_charge_policy);
+ // Make empty circular linked list
+ lru_.next = &lru_;
+ lru_.prev = &lru_;
+ lru_low_pri_ = &lru_;
+ SetCapacity(capacity);
+}
+
+void LRUCacheShard::EraseUnRefEntries() {
+ autovector<LRUHandle*> last_reference_list;
+ {
+ MutexLock l(&mutex_);
+ while (lru_.next != &lru_) {
+ LRUHandle* old = lru_.next;
+ // LRU list contains only elements which can be evicted
+ assert(old->InCache() && !old->HasRefs());
+ LRU_Remove(old);
+ table_.Remove(old->key(), old->hash);
+ old->SetInCache(false);
+ size_t total_charge = old->CalcTotalCharge(metadata_charge_policy_);
+ assert(usage_ >= total_charge);
+ usage_ -= total_charge;
+ last_reference_list.push_back(old);
+ }
+ }
+
+ for (auto entry : last_reference_list) {
+ entry->Free();
+ }
+}
+
+void LRUCacheShard::ApplyToAllCacheEntries(void (*callback)(void*, size_t),
+ bool thread_safe) {
+ const auto applyCallback = [&]() {
+ table_.ApplyToAllCacheEntries(
+ [callback](LRUHandle* h) { callback(h->value, h->charge); });
+ };
+
+ if (thread_safe) {
+ MutexLock l(&mutex_);
+ applyCallback();
+ } else {
+ applyCallback();
+ }
+}
+
+void LRUCacheShard::TEST_GetLRUList(LRUHandle** lru, LRUHandle** lru_low_pri) {
+ MutexLock l(&mutex_);
+ *lru = &lru_;
+ *lru_low_pri = lru_low_pri_;
+}
+
+size_t LRUCacheShard::TEST_GetLRUSize() {
+ MutexLock l(&mutex_);
+ LRUHandle* lru_handle = lru_.next;
+ size_t lru_size = 0;
+ while (lru_handle != &lru_) {
+ lru_size++;
+ lru_handle = lru_handle->next;
+ }
+ return lru_size;
+}
+
+double LRUCacheShard::GetHighPriPoolRatio() {
+ MutexLock l(&mutex_);
+ return high_pri_pool_ratio_;
+}
+
+void LRUCacheShard::LRU_Remove(LRUHandle* e) {
+ assert(e->next != nullptr);
+ assert(e->prev != nullptr);
+ if (lru_low_pri_ == e) {
+ lru_low_pri_ = e->prev;
+ }
+ e->next->prev = e->prev;
+ e->prev->next = e->next;
+ e->prev = e->next = nullptr;
+ size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
+ assert(lru_usage_ >= total_charge);
+ lru_usage_ -= total_charge;
+ if (e->InHighPriPool()) {
+ assert(high_pri_pool_usage_ >= total_charge);
+ high_pri_pool_usage_ -= total_charge;
+ }
+}
+
+void LRUCacheShard::LRU_Insert(LRUHandle* e) {
+ assert(e->next == nullptr);
+ assert(e->prev == nullptr);
+ size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
+ if (high_pri_pool_ratio_ > 0 && (e->IsHighPri() || e->HasHit())) {
+ // Inset "e" to head of LRU list.
+ e->next = &lru_;
+ e->prev = lru_.prev;
+ e->prev->next = e;
+ e->next->prev = e;
+ e->SetInHighPriPool(true);
+ high_pri_pool_usage_ += total_charge;
+ MaintainPoolSize();
+ } else {
+ // Insert "e" to the head of low-pri pool. Note that when
+ // high_pri_pool_ratio is 0, head of low-pri pool is also head of LRU list.
+ e->next = lru_low_pri_->next;
+ e->prev = lru_low_pri_;
+ e->prev->next = e;
+ e->next->prev = e;
+ e->SetInHighPriPool(false);
+ lru_low_pri_ = e;
+ }
+ lru_usage_ += total_charge;
+}
+
+void LRUCacheShard::MaintainPoolSize() {
+ while (high_pri_pool_usage_ > high_pri_pool_capacity_) {
+ // Overflow last entry in high-pri pool to low-pri pool.
+ lru_low_pri_ = lru_low_pri_->next;
+ assert(lru_low_pri_ != &lru_);
+ lru_low_pri_->SetInHighPriPool(false);
+ size_t total_charge =
+ lru_low_pri_->CalcTotalCharge(metadata_charge_policy_);
+ assert(high_pri_pool_usage_ >= total_charge);
+ high_pri_pool_usage_ -= total_charge;
+ }
+}
+
+void LRUCacheShard::EvictFromLRU(size_t charge,
+ autovector<LRUHandle*>* deleted) {
+ while ((usage_ + charge) > capacity_ && lru_.next != &lru_) {
+ LRUHandle* old = lru_.next;
+ // LRU list contains only elements which can be evicted
+ assert(old->InCache() && !old->HasRefs());
+ LRU_Remove(old);
+ table_.Remove(old->key(), old->hash);
+ old->SetInCache(false);
+ size_t old_total_charge = old->CalcTotalCharge(metadata_charge_policy_);
+ assert(usage_ >= old_total_charge);
+ usage_ -= old_total_charge;
+ deleted->push_back(old);
+ }
+}
+
+void LRUCacheShard::SetCapacity(size_t capacity) {
+ autovector<LRUHandle*> last_reference_list;
+ {
+ MutexLock l(&mutex_);
+ capacity_ = capacity;
+ high_pri_pool_capacity_ = capacity_ * high_pri_pool_ratio_;
+ EvictFromLRU(0, &last_reference_list);
+ }
+
+ // Free the entries outside of mutex for performance reasons
+ for (auto entry : last_reference_list) {
+ entry->Free();
+ }
+}
+
+void LRUCacheShard::SetStrictCapacityLimit(bool strict_capacity_limit) {
+ MutexLock l(&mutex_);
+ strict_capacity_limit_ = strict_capacity_limit;
+}
+
+Cache::Handle* LRUCacheShard::Lookup(const Slice& key, uint32_t hash) {
+ MutexLock l(&mutex_);
+ LRUHandle* e = table_.Lookup(key, hash);
+ if (e != nullptr) {
+ assert(e->InCache());
+ if (!e->HasRefs()) {
+ // The entry is in LRU since it's in hash and has no external references
+ LRU_Remove(e);
+ }
+ e->Ref();
+ e->SetHit();
+ }
+ return reinterpret_cast<Cache::Handle*>(e);
+}
+
+bool LRUCacheShard::Ref(Cache::Handle* h) {
+ LRUHandle* e = reinterpret_cast<LRUHandle*>(h);
+ MutexLock l(&mutex_);
+ // To create another reference - entry must be already externally referenced
+ assert(e->HasRefs());
+ e->Ref();
+ return true;
+}
+
+void LRUCacheShard::SetHighPriorityPoolRatio(double high_pri_pool_ratio) {
+ MutexLock l(&mutex_);
+ high_pri_pool_ratio_ = high_pri_pool_ratio;
+ high_pri_pool_capacity_ = capacity_ * high_pri_pool_ratio_;
+ MaintainPoolSize();
+}
+
+bool LRUCacheShard::Release(Cache::Handle* handle, bool force_erase) {
+ if (handle == nullptr) {
+ return false;
+ }
+ LRUHandle* e = reinterpret_cast<LRUHandle*>(handle);
+ bool last_reference = false;
+ {
+ MutexLock l(&mutex_);
+ last_reference = e->Unref();
+ if (last_reference && e->InCache()) {
+ // The item is still in cache, and nobody else holds a reference to it
+ if (usage_ > capacity_ || force_erase) {
+ // The LRU list must be empty since the cache is full
+ assert(lru_.next == &lru_ || force_erase);
+ // Take this opportunity and remove the item
+ table_.Remove(e->key(), e->hash);
+ e->SetInCache(false);
+ } else {
+ // Put the item back on the LRU list, and don't free it
+ LRU_Insert(e);
+ last_reference = false;
+ }
+ }
+ if (last_reference) {
+ size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
+ assert(usage_ >= total_charge);
+ usage_ -= total_charge;
+ }
+ }
+
+ // Free the entry here outside of mutex for performance reasons
+ if (last_reference) {
+ e->Free();
+ }
+ return last_reference;
+}
+
+Status LRUCacheShard::Insert(const Slice& key, uint32_t hash, void* value,
+ size_t charge,
+ void (*deleter)(const Slice& key, void* value),
+ Cache::Handle** handle, Cache::Priority priority) {
+ // Allocate the memory here outside of the mutex
+ // If the cache is full, we'll have to release it
+ // It shouldn't happen very often though.
+ LRUHandle* e = reinterpret_cast<LRUHandle*>(
+ new char[sizeof(LRUHandle) - 1 + key.size()]);
+ Status s = Status::OK();
+ autovector<LRUHandle*> last_reference_list;
+
+ e->value = value;
+ e->deleter = deleter;
+ e->charge = charge;
+ e->key_length = key.size();
+ e->flags = 0;
+ e->hash = hash;
+ e->refs = 0;
+ e->next = e->prev = nullptr;
+ e->SetInCache(true);
+ e->SetPriority(priority);
+ memcpy(e->key_data, key.data(), key.size());
+ size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
+
+ {
+ MutexLock l(&mutex_);
+
+ // Free the space following strict LRU policy until enough space
+ // is freed or the lru list is empty
+ EvictFromLRU(total_charge, &last_reference_list);
+
+ if ((usage_ + total_charge) > capacity_ &&
+ (strict_capacity_limit_ || handle == nullptr)) {
+ if (handle == nullptr) {
+ // Don't insert the entry but still return ok, as if the entry inserted
+ // into cache and get evicted immediately.
+ e->SetInCache(false);
+ last_reference_list.push_back(e);
+ } else {
+ delete[] reinterpret_cast<char*>(e);
+ *handle = nullptr;
+ s = Status::Incomplete("Insert failed due to LRU cache being full.");
+ }
+ } else {
+ // Insert into the cache. Note that the cache might get larger than its
+ // capacity if not enough space was freed up.
+ LRUHandle* old = table_.Insert(e);
+ usage_ += total_charge;
+ if (old != nullptr) {
+ assert(old->InCache());
+ old->SetInCache(false);
+ if (!old->HasRefs()) {
+ // old is on LRU because it's in cache and its reference count is 0
+ LRU_Remove(old);
+ size_t old_total_charge =
+ old->CalcTotalCharge(metadata_charge_policy_);
+ assert(usage_ >= old_total_charge);
+ usage_ -= old_total_charge;
+ last_reference_list.push_back(old);
+ }
+ }
+ if (handle == nullptr) {
+ LRU_Insert(e);
+ } else {
+ e->Ref();
+ *handle = reinterpret_cast<Cache::Handle*>(e);
+ }
+ }
+ }
+
+ // Free the entries here outside of mutex for performance reasons
+ for (auto entry : last_reference_list) {
+ entry->Free();
+ }
+
+ return s;
+}
+
+void LRUCacheShard::Erase(const Slice& key, uint32_t hash) {
+ LRUHandle* e;
+ bool last_reference = false;
+ {
+ MutexLock l(&mutex_);
+ e = table_.Remove(key, hash);
+ if (e != nullptr) {
+ assert(e->InCache());
+ e->SetInCache(false);
+ if (!e->HasRefs()) {
+ // The entry is in LRU since it's in hash and has no external references
+ LRU_Remove(e);
+ size_t total_charge = e->CalcTotalCharge(metadata_charge_policy_);
+ assert(usage_ >= total_charge);
+ usage_ -= total_charge;
+ last_reference = true;
+ }
+ }
+ }
+
+ // Free the entry here outside of mutex for performance reasons
+ // last_reference will only be true if e != nullptr
+ if (last_reference) {
+ e->Free();
+ }
+}
+
+size_t LRUCacheShard::GetUsage() const {
+ MutexLock l(&mutex_);
+ return usage_;
+}
+
+size_t LRUCacheShard::GetPinnedUsage() const {
+ MutexLock l(&mutex_);
+ assert(usage_ >= lru_usage_);
+ return usage_ - lru_usage_;
+}
+
+std::string LRUCacheShard::GetPrintableOptions() const {
+ const int kBufferSize = 200;
+ char buffer[kBufferSize];
+ {
+ MutexLock l(&mutex_);
+ snprintf(buffer, kBufferSize, " high_pri_pool_ratio: %.3lf\n",
+ high_pri_pool_ratio_);
+ }
+ return std::string(buffer);
+}
+
+LRUCache::LRUCache(size_t capacity, int num_shard_bits,
+ bool strict_capacity_limit, double high_pri_pool_ratio,
+ std::shared_ptr<MemoryAllocator> allocator,
+ bool use_adaptive_mutex,
+ CacheMetadataChargePolicy metadata_charge_policy)
+ : ShardedCache(capacity, num_shard_bits, strict_capacity_limit,
+ std::move(allocator)) {
+ num_shards_ = 1 << num_shard_bits;
+ shards_ = reinterpret_cast<LRUCacheShard*>(
+ port::cacheline_aligned_alloc(sizeof(LRUCacheShard) * num_shards_));
+ size_t per_shard = (capacity + (num_shards_ - 1)) / num_shards_;
+ for (int i = 0; i < num_shards_; i++) {
+ new (&shards_[i])
+ LRUCacheShard(per_shard, strict_capacity_limit, high_pri_pool_ratio,
+ use_adaptive_mutex, metadata_charge_policy);
+ }
+}
+
+LRUCache::~LRUCache() {
+ if (shards_ != nullptr) {
+ assert(num_shards_ > 0);
+ for (int i = 0; i < num_shards_; i++) {
+ shards_[i].~LRUCacheShard();
+ }
+ port::cacheline_aligned_free(shards_);
+ }
+}
+
+CacheShard* LRUCache::GetShard(int shard) {
+ return reinterpret_cast<CacheShard*>(&shards_[shard]);
+}
+
+const CacheShard* LRUCache::GetShard(int shard) const {
+ return reinterpret_cast<CacheShard*>(&shards_[shard]);
+}
+
+void* LRUCache::Value(Handle* handle) {
+ return reinterpret_cast<const LRUHandle*>(handle)->value;
+}
+
+size_t LRUCache::GetCharge(Handle* handle) const {
+ return reinterpret_cast<const LRUHandle*>(handle)->charge;
+}
+
+uint32_t LRUCache::GetHash(Handle* handle) const {
+ return reinterpret_cast<const LRUHandle*>(handle)->hash;
+}
+
+void LRUCache::DisownData() {
+// Do not drop data if compile with ASAN to suppress leak warning.
+#if defined(__clang__)
+#if !defined(__has_feature) || !__has_feature(address_sanitizer)
+ shards_ = nullptr;
+ num_shards_ = 0;
+#endif
+#else // __clang__
+#ifndef __SANITIZE_ADDRESS__
+ shards_ = nullptr;
+ num_shards_ = 0;
+#endif // !__SANITIZE_ADDRESS__
+#endif // __clang__
+}
+
+size_t LRUCache::TEST_GetLRUSize() {
+ size_t lru_size_of_all_shards = 0;
+ for (int i = 0; i < num_shards_; i++) {
+ 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