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// 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/sharded_cache.h"
#include <string>
#include "util/mutexlock.h"
namespace ROCKSDB_NAMESPACE {
ShardedCache::ShardedCache(size_t capacity, int num_shard_bits,
bool strict_capacity_limit,
std::shared_ptr<MemoryAllocator> allocator)
: Cache(std::move(allocator)),
num_shard_bits_(num_shard_bits),
capacity_(capacity),
strict_capacity_limit_(strict_capacity_limit),
last_id_(1) {}
void ShardedCache::SetCapacity(size_t capacity) {
int num_shards = 1 << num_shard_bits_;
const size_t per_shard = (capacity + (num_shards - 1)) / num_shards;
MutexLock l(&capacity_mutex_);
for (int s = 0; s < num_shards; s++) {
GetShard(s)->SetCapacity(per_shard);
}
capacity_ = capacity;
}
void ShardedCache::SetStrictCapacityLimit(bool strict_capacity_limit) {
int num_shards = 1 << num_shard_bits_;
MutexLock l(&capacity_mutex_);
for (int s = 0; s < num_shards; s++) {
GetShard(s)->SetStrictCapacityLimit(strict_capacity_limit);
}
strict_capacity_limit_ = strict_capacity_limit;
}
Status ShardedCache::Insert(const Slice& key, void* value, size_t charge,
void (*deleter)(const Slice& key, void* value),
Handle** handle, Priority priority) {
uint32_t hash = HashSlice(key);
return GetShard(Shard(hash))
->Insert(key, hash, value, charge, deleter, handle, priority);
}
Cache::Handle* ShardedCache::Lookup(const Slice& key, Statistics* /*stats*/) {
uint32_t hash = HashSlice(key);
return GetShard(Shard(hash))->Lookup(key, hash);
}
bool ShardedCache::Ref(Handle* handle) {
uint32_t hash = GetHash(handle);
return GetShard(Shard(hash))->Ref(handle);
}
bool ShardedCache::Release(Handle* handle, bool force_erase) {
uint32_t hash = GetHash(handle);
return GetShard(Shard(hash))->Release(handle, force_erase);
}
void ShardedCache::Erase(const Slice& key) {
uint32_t hash = HashSlice(key);
GetShard(Shard(hash))->Erase(key, hash);
}
uint64_t ShardedCache::NewId() {
return last_id_.fetch_add(1, std::memory_order_relaxed);
}
size_t ShardedCache::GetCapacity() const {
MutexLock l(&capacity_mutex_);
return capacity_;
}
bool ShardedCache::HasStrictCapacityLimit() const {
MutexLock l(&capacity_mutex_);
return strict_capacity_limit_;
}
size_t ShardedCache::GetUsage() const {
// We will not lock the cache when getting the usage from shards.
int num_shards = 1 << num_shard_bits_;
size_t usage = 0;
for (int s = 0; s < num_shards; s++) {
usage += GetShard(s)->GetUsage();
}
return usage;
}
size_t ShardedCache::GetUsage(Handle* handle) const {
return GetCharge(handle);
}
size_t ShardedCache::GetPinnedUsage() const {
// We will not lock the cache when getting the usage from shards.
int num_shards = 1 << num_shard_bits_;
size_t usage = 0;
for (int s = 0; s < num_shards; s++) {
usage += GetShard(s)->GetPinnedUsage();
}
return usage;
}
void ShardedCache::ApplyToAllCacheEntries(void (*callback)(void*, size_t),
bool thread_safe) {
int num_shards = 1 << num_shard_bits_;
for (int s = 0; s < num_shards; s++) {
GetShard(s)->ApplyToAllCacheEntries(callback, thread_safe);
}
}
void ShardedCache::EraseUnRefEntries() {
int num_shards = 1 << num_shard_bits_;
for (int s = 0; s < num_shards; s++) {
GetShard(s)->EraseUnRefEntries();
}
}
std::string ShardedCache::GetPrintableOptions() const {
std::string ret;
ret.reserve(20000);
const int kBufferSize = 200;
char buffer[kBufferSize];
{
MutexLock l(&capacity_mutex_);
snprintf(buffer, kBufferSize, " capacity : %" ROCKSDB_PRIszt "\n",
capacity_);
ret.append(buffer);
snprintf(buffer, kBufferSize, " num_shard_bits : %d\n", num_shard_bits_);
ret.append(buffer);
snprintf(buffer, kBufferSize, " strict_capacity_limit : %d\n",
strict_capacity_limit_);
ret.append(buffer);
}
snprintf(buffer, kBufferSize, " memory_allocator : %s\n",
memory_allocator() ? memory_allocator()->Name() : "None");
ret.append(buffer);
ret.append(GetShard(0)->GetPrintableOptions());
return ret;
}
int GetDefaultCacheShardBits(size_t capacity) {
int num_shard_bits = 0;
size_t min_shard_size = 512L * 1024L; // Every shard is at least 512KB.
size_t num_shards = capacity / min_shard_size;
while (num_shards >>= 1) {
if (++num_shard_bits >= 6) {
// No more than 6.
return num_shard_bits;
}
}
return num_shard_bits;
}
} // namespace ROCKSDB_NAMESPACE
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