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// bthread - A M:N threading library to make applications more concurrent.
// Copyright (c) 2014 Baidu, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Author: Ge,Jun (gejun@baidu.com)
// Date: Sun Jul 13 15:04:18 CST 2014
#ifndef BUTIL_RESOURCE_POOL_INL_H
#define BUTIL_RESOURCE_POOL_INL_H
#include <iostream> // std::ostream
#include <pthread.h> // pthread_mutex_t
#include <algorithm> // std::max, std::min
#include "butil/atomicops.h" // butil::atomic
#include "butil/macros.h" // BAIDU_CACHELINE_ALIGNMENT
#include "butil/scoped_lock.h" // BAIDU_SCOPED_LOCK
#include "butil/thread_local.h" // thread_atexit
#include <vector>
#ifdef BUTIL_RESOURCE_POOL_NEED_FREE_ITEM_NUM
#define BAIDU_RESOURCE_POOL_FREE_ITEM_NUM_ADD1 \
(_global_nfree.fetch_add(1, butil::memory_order_relaxed))
#define BAIDU_RESOURCE_POOL_FREE_ITEM_NUM_SUB1 \
(_global_nfree.fetch_sub(1, butil::memory_order_relaxed))
#else
#define BAIDU_RESOURCE_POOL_FREE_ITEM_NUM_ADD1
#define BAIDU_RESOURCE_POOL_FREE_ITEM_NUM_SUB1
#endif
namespace butil {
template <typename T>
struct ResourceId {
uint64_t value;
operator uint64_t() const {
return value;
}
template <typename T2>
ResourceId<T2> cast() const {
ResourceId<T2> id = { value };
return id;
}
};
template <typename T, size_t NITEM>
struct ResourcePoolFreeChunk {
size_t nfree;
ResourceId<T> ids[NITEM];
};
// for gcc 3.4.5
template <typename T>
struct ResourcePoolFreeChunk<T, 0> {
size_t nfree;
ResourceId<T> ids[0];
};
struct ResourcePoolInfo {
size_t local_pool_num;
size_t block_group_num;
size_t block_num;
size_t item_num;
size_t block_item_num;
size_t free_chunk_item_num;
size_t total_size;
#ifdef BUTIL_RESOURCE_POOL_NEED_FREE_ITEM_NUM
size_t free_item_num;
#endif
};
static const size_t RP_MAX_BLOCK_NGROUP = 65536;
static const size_t RP_GROUP_NBLOCK_NBIT = 16;
static const size_t RP_GROUP_NBLOCK = (1UL << RP_GROUP_NBLOCK_NBIT);
static const size_t RP_INITIAL_FREE_LIST_SIZE = 1024;
template <typename T>
class ResourcePoolBlockItemNum {
static const size_t N1 = ResourcePoolBlockMaxSize<T>::value / sizeof(T);
static const size_t N2 = (N1 < 1 ? 1 : N1);
public:
static const size_t value = (N2 > ResourcePoolBlockMaxItem<T>::value ?
ResourcePoolBlockMaxItem<T>::value : N2);
};
template <typename T>
class BAIDU_CACHELINE_ALIGNMENT ResourcePool {
public:
static const size_t BLOCK_NITEM = ResourcePoolBlockItemNum<T>::value;
static const size_t FREE_CHUNK_NITEM = BLOCK_NITEM;
// Free identifiers are batched in a FreeChunk before they're added to
// global list(_free_chunks).
typedef ResourcePoolFreeChunk<T, FREE_CHUNK_NITEM> FreeChunk;
typedef ResourcePoolFreeChunk<T, 0> DynamicFreeChunk;
// When a thread needs memory, it allocates a Block. To improve locality,
// items in the Block are only used by the thread.
// To support cache-aligned objects, align Block.items by cacheline.
struct BAIDU_CACHELINE_ALIGNMENT Block {
char items[sizeof(T) * BLOCK_NITEM];
size_t nitem;
Block() : nitem(0) {}
};
// A Resource addresses at most RP_MAX_BLOCK_NGROUP BlockGroups,
// each BlockGroup addresses at most RP_GROUP_NBLOCK blocks. So a
// resource addresses at most RP_MAX_BLOCK_NGROUP * RP_GROUP_NBLOCK Blocks.
struct BlockGroup {
butil::atomic<size_t> nblock;
butil::atomic<Block*> blocks[RP_GROUP_NBLOCK];
BlockGroup() : nblock(0) {
// We fetch_add nblock in add_block() before setting the entry,
// thus address_resource() may sees the unset entry. Initialize
// all entries to NULL makes such address_resource() return NULL.
memset(blocks, 0, sizeof(butil::atomic<Block*>) * RP_GROUP_NBLOCK);
}
};
// Each thread has an instance of this class.
class BAIDU_CACHELINE_ALIGNMENT LocalPool {
public:
explicit LocalPool(ResourcePool* pool)
: _pool(pool)
, _cur_block(NULL)
, _cur_block_index(0) {
_cur_free.nfree = 0;
}
~LocalPool() {
// Add to global _free_chunks if there're some free resources
if (_cur_free.nfree) {
_pool->push_free_chunk(_cur_free);
}
_pool->clear_from_destructor_of_local_pool();
}
static void delete_local_pool(void* arg) {
delete(LocalPool*)arg;
}
// We need following macro to construct T with different CTOR_ARGS
// which may include parenthesis because when T is POD, "new T()"
// and "new T" are different: former one sets all fields to 0 which
// we don't want.
#define BAIDU_RESOURCE_POOL_GET(CTOR_ARGS) \
/* Fetch local free id */ \
if (_cur_free.nfree) { \
const ResourceId<T> free_id = _cur_free.ids[--_cur_free.nfree]; \
*id = free_id; \
BAIDU_RESOURCE_POOL_FREE_ITEM_NUM_SUB1; \
return unsafe_address_resource(free_id); \
} \
/* Fetch a FreeChunk from global. \
TODO: Popping from _free needs to copy a FreeChunk which is \
costly, but hardly impacts amortized performance. */ \
if (_pool->pop_free_chunk(_cur_free)) { \
--_cur_free.nfree; \
const ResourceId<T> free_id = _cur_free.ids[_cur_free.nfree]; \
*id = free_id; \
BAIDU_RESOURCE_POOL_FREE_ITEM_NUM_SUB1; \
return unsafe_address_resource(free_id); \
} \
/* Fetch memory from local block */ \
if (_cur_block && _cur_block->nitem < BLOCK_NITEM) { \
id->value = _cur_block_index * BLOCK_NITEM + _cur_block->nitem; \
T* p = new ((T*)_cur_block->items + _cur_block->nitem) T CTOR_ARGS; \
if (!ResourcePoolValidator<T>::validate(p)) { \
p->~T(); \
return NULL; \
} \
++_cur_block->nitem; \
return p; \
} \
/* Fetch a Block from global */ \
_cur_block = add_block(&_cur_block_index); \
if (_cur_block != NULL) { \
id->value = _cur_block_index * BLOCK_NITEM + _cur_block->nitem; \
T* p = new ((T*)_cur_block->items + _cur_block->nitem) T CTOR_ARGS; \
if (!ResourcePoolValidator<T>::validate(p)) { \
p->~T(); \
return NULL; \
} \
++_cur_block->nitem; \
return p; \
} \
return NULL; \
inline T* get(ResourceId<T>* id) {
BAIDU_RESOURCE_POOL_GET();
}
template <typename A1>
inline T* get(ResourceId<T>* id, const A1& a1) {
BAIDU_RESOURCE_POOL_GET((a1));
}
template <typename A1, typename A2>
inline T* get(ResourceId<T>* id, const A1& a1, const A2& a2) {
BAIDU_RESOURCE_POOL_GET((a1, a2));
}
#undef BAIDU_RESOURCE_POOL_GET
inline int return_resource(ResourceId<T> id) {
// Return to local free list
if (_cur_free.nfree < ResourcePool::free_chunk_nitem()) {
_cur_free.ids[_cur_free.nfree++] = id;
BAIDU_RESOURCE_POOL_FREE_ITEM_NUM_ADD1;
return 0;
}
// Local free list is full, return it to global.
// For copying issue, check comment in upper get()
if (_pool->push_free_chunk(_cur_free)) {
_cur_free.nfree = 1;
_cur_free.ids[0] = id;
BAIDU_RESOURCE_POOL_FREE_ITEM_NUM_ADD1;
return 0;
}
return -1;
}
private:
ResourcePool* _pool;
Block* _cur_block;
size_t _cur_block_index;
FreeChunk _cur_free;
};
static inline T* unsafe_address_resource(ResourceId<T> id) {
const size_t block_index = id.value / BLOCK_NITEM;
return (T*)(_block_groups[(block_index >> RP_GROUP_NBLOCK_NBIT)]
.load(butil::memory_order_consume)
->blocks[(block_index & (RP_GROUP_NBLOCK - 1))]
.load(butil::memory_order_consume)->items) +
id.value - block_index * BLOCK_NITEM;
}
static inline T* address_resource(ResourceId<T> id) {
const size_t block_index = id.value / BLOCK_NITEM;
const size_t group_index = (block_index >> RP_GROUP_NBLOCK_NBIT);
if (__builtin_expect(group_index < RP_MAX_BLOCK_NGROUP, 1)) {
BlockGroup* bg =
_block_groups[group_index].load(butil::memory_order_consume);
if (__builtin_expect(bg != NULL, 1)) {
Block* b = bg->blocks[block_index & (RP_GROUP_NBLOCK - 1)]
.load(butil::memory_order_consume);
if (__builtin_expect(b != NULL, 1)) {
const size_t offset = id.value - block_index * BLOCK_NITEM;
if (__builtin_expect(offset < b->nitem, 1)) {
return (T*)b->items + offset;
}
}
}
}
return NULL;
}
inline T* get_resource(ResourceId<T>* id) {
LocalPool* lp = get_or_new_local_pool();
if (__builtin_expect(lp != NULL, 1)) {
return lp->get(id);
}
return NULL;
}
template <typename A1>
inline T* get_resource(ResourceId<T>* id, const A1& arg1) {
LocalPool* lp = get_or_new_local_pool();
if (__builtin_expect(lp != NULL, 1)) {
return lp->get(id, arg1);
}
return NULL;
}
template <typename A1, typename A2>
inline T* get_resource(ResourceId<T>* id, const A1& arg1, const A2& arg2) {
LocalPool* lp = get_or_new_local_pool();
if (__builtin_expect(lp != NULL, 1)) {
return lp->get(id, arg1, arg2);
}
return NULL;
}
inline int return_resource(ResourceId<T> id) {
LocalPool* lp = get_or_new_local_pool();
if (__builtin_expect(lp != NULL, 1)) {
return lp->return_resource(id);
}
return -1;
}
void clear_resources() {
LocalPool* lp = _local_pool;
if (lp) {
_local_pool = NULL;
butil::thread_atexit_cancel(LocalPool::delete_local_pool, lp);
delete lp;
}
}
static inline size_t free_chunk_nitem() {
const size_t n = ResourcePoolFreeChunkMaxItem<T>::value();
return n < FREE_CHUNK_NITEM ? n : FREE_CHUNK_NITEM;
}
// Number of all allocated objects, including being used and free.
ResourcePoolInfo describe_resources() const {
ResourcePoolInfo info;
info.local_pool_num = _nlocal.load(butil::memory_order_relaxed);
info.block_group_num = _ngroup.load(butil::memory_order_acquire);
info.block_num = 0;
info.item_num = 0;
info.free_chunk_item_num = free_chunk_nitem();
info.block_item_num = BLOCK_NITEM;
#ifdef BUTIL_RESOURCE_POOL_NEED_FREE_ITEM_NUM
info.free_item_num = _global_nfree.load(butil::memory_order_relaxed);
#endif
for (size_t i = 0; i < info.block_group_num; ++i) {
BlockGroup* bg = _block_groups[i].load(butil::memory_order_consume);
if (NULL == bg) {
break;
}
size_t nblock = std::min(bg->nblock.load(butil::memory_order_relaxed),
RP_GROUP_NBLOCK);
info.block_num += nblock;
for (size_t j = 0; j < nblock; ++j) {
Block* b = bg->blocks[j].load(butil::memory_order_consume);
if (NULL != b) {
info.item_num += b->nitem;
}
}
}
info.total_size = info.block_num * info.block_item_num * sizeof(T);
return info;
}
static inline ResourcePool* singleton() {
ResourcePool* p = _singleton.load(butil::memory_order_consume);
if (p) {
return p;
}
pthread_mutex_lock(&_singleton_mutex);
p = _singleton.load(butil::memory_order_consume);
if (!p) {
p = new ResourcePool();
_singleton.store(p, butil::memory_order_release);
}
pthread_mutex_unlock(&_singleton_mutex);
return p;
}
private:
ResourcePool() {
_free_chunks.reserve(RP_INITIAL_FREE_LIST_SIZE);
pthread_mutex_init(&_free_chunks_mutex, NULL);
}
~ResourcePool() {
pthread_mutex_destroy(&_free_chunks_mutex);
}
// Create a Block and append it to right-most BlockGroup.
static Block* add_block(size_t* index) {
Block* const new_block = new(std::nothrow) Block;
if (NULL == new_block) {
return NULL;
}
size_t ngroup;
do {
ngroup = _ngroup.load(butil::memory_order_acquire);
if (ngroup >= 1) {
BlockGroup* const g =
_block_groups[ngroup - 1].load(butil::memory_order_consume);
const size_t block_index =
g->nblock.fetch_add(1, butil::memory_order_relaxed);
if (block_index < RP_GROUP_NBLOCK) {
g->blocks[block_index].store(
new_block, butil::memory_order_release);
*index = (ngroup - 1) * RP_GROUP_NBLOCK + block_index;
return new_block;
}
g->nblock.fetch_sub(1, butil::memory_order_relaxed);
}
} while (add_block_group(ngroup));
// Fail to add_block_group.
delete new_block;
return NULL;
}
// Create a BlockGroup and append it to _block_groups.
// Shall be called infrequently because a BlockGroup is pretty big.
static bool add_block_group(size_t old_ngroup) {
BlockGroup* bg = NULL;
BAIDU_SCOPED_LOCK(_block_group_mutex);
const size_t ngroup = _ngroup.load(butil::memory_order_acquire);
if (ngroup != old_ngroup) {
// Other thread got lock and added group before this thread.
return true;
}
if (ngroup < RP_MAX_BLOCK_NGROUP) {
bg = new(std::nothrow) BlockGroup;
if (NULL != bg) {
// Release fence is paired with consume fence in address() and
// add_block() to avoid un-constructed bg to be seen by other
// threads.
_block_groups[ngroup].store(bg, butil::memory_order_release);
_ngroup.store(ngroup + 1, butil::memory_order_release);
}
}
return bg != NULL;
}
inline LocalPool* get_or_new_local_pool() {
LocalPool* lp = _local_pool;
if (lp != NULL) {
return lp;
}
lp = new(std::nothrow) LocalPool(this);
if (NULL == lp) {
return NULL;
}
BAIDU_SCOPED_LOCK(_change_thread_mutex); //avoid race with clear()
_local_pool = lp;
butil::thread_atexit(LocalPool::delete_local_pool, lp);
_nlocal.fetch_add(1, butil::memory_order_relaxed);
return lp;
}
void clear_from_destructor_of_local_pool() {
// Remove tls
_local_pool = NULL;
if (_nlocal.fetch_sub(1, butil::memory_order_relaxed) != 1) {
return;
}
// Can't delete global even if all threads(called ResourcePool
// functions) quit because the memory may still be referenced by
// other threads. But we need to validate that all memory can
// be deallocated correctly in tests, so wrap the function with
// a macro which is only defined in unittests.
#ifdef BAIDU_CLEAR_RESOURCE_POOL_AFTER_ALL_THREADS_QUIT
BAIDU_SCOPED_LOCK(_change_thread_mutex); // including acquire fence.
// Do nothing if there're active threads.
if (_nlocal.load(butil::memory_order_relaxed) != 0) {
return;
}
// All threads exited and we're holding _change_thread_mutex to avoid
// racing with new threads calling get_resource().
// Clear global free list.
FreeChunk dummy;
while (pop_free_chunk(dummy));
// Delete all memory
const size_t ngroup = _ngroup.exchange(0, butil::memory_order_relaxed);
for (size_t i = 0; i < ngroup; ++i) {
BlockGroup* bg = _block_groups[i].load(butil::memory_order_relaxed);
if (NULL == bg) {
break;
}
size_t nblock = std::min(bg->nblock.load(butil::memory_order_relaxed),
RP_GROUP_NBLOCK);
for (size_t j = 0; j < nblock; ++j) {
Block* b = bg->blocks[j].load(butil::memory_order_relaxed);
if (NULL == b) {
continue;
}
for (size_t k = 0; k < b->nitem; ++k) {
T* const objs = (T*)b->items;
objs[k].~T();
}
delete b;
}
delete bg;
}
memset(_block_groups, 0, sizeof(BlockGroup*) * RP_MAX_BLOCK_NGROUP);
#endif
}
private:
bool pop_free_chunk(FreeChunk& c) {
// Critical for the case that most return_object are called in
// different threads of get_object.
if (_free_chunks.empty()) {
return false;
}
pthread_mutex_lock(&_free_chunks_mutex);
if (_free_chunks.empty()) {
pthread_mutex_unlock(&_free_chunks_mutex);
return false;
}
DynamicFreeChunk* p = _free_chunks.back();
_free_chunks.pop_back();
pthread_mutex_unlock(&_free_chunks_mutex);
c.nfree = p->nfree;
memcpy(c.ids, p->ids, sizeof(*p->ids) * p->nfree);
free(p);
return true;
}
bool push_free_chunk(const FreeChunk& c) {
DynamicFreeChunk* p = (DynamicFreeChunk*)malloc(
offsetof(DynamicFreeChunk, ids) + sizeof(*c.ids) * c.nfree);
if (!p) {
return false;
}
p->nfree = c.nfree;
memcpy(p->ids, c.ids, sizeof(*c.ids) * c.nfree);
pthread_mutex_lock(&_free_chunks_mutex);
_free_chunks.push_back(p);
pthread_mutex_unlock(&_free_chunks_mutex);
return true;
}
static butil::static_atomic<ResourcePool*> _singleton;
static pthread_mutex_t _singleton_mutex;
static BAIDU_THREAD_LOCAL LocalPool* _local_pool;
static butil::static_atomic<long> _nlocal;
static butil::static_atomic<size_t> _ngroup;
static pthread_mutex_t _block_group_mutex;
static pthread_mutex_t _change_thread_mutex;
static butil::static_atomic<BlockGroup*> _block_groups[RP_MAX_BLOCK_NGROUP];
std::vector<DynamicFreeChunk*> _free_chunks;
pthread_mutex_t _free_chunks_mutex;
#ifdef BUTIL_RESOURCE_POOL_NEED_FREE_ITEM_NUM
static butil::static_atomic<size_t> _global_nfree;
#endif
};
// Declare template static variables:
template <typename T>
const size_t ResourcePool<T>::FREE_CHUNK_NITEM;
template <typename T>
BAIDU_THREAD_LOCAL typename ResourcePool<T>::LocalPool*
ResourcePool<T>::_local_pool = NULL;
template <typename T>
butil::static_atomic<ResourcePool<T>*> ResourcePool<T>::_singleton =
BUTIL_STATIC_ATOMIC_INIT(NULL);
template <typename T>
pthread_mutex_t ResourcePool<T>::_singleton_mutex = PTHREAD_MUTEX_INITIALIZER;
template <typename T>
butil::static_atomic<long> ResourcePool<T>::_nlocal = BUTIL_STATIC_ATOMIC_INIT(0);
template <typename T>
butil::static_atomic<size_t> ResourcePool<T>::_ngroup = BUTIL_STATIC_ATOMIC_INIT(0);
template <typename T>
pthread_mutex_t ResourcePool<T>::_block_group_mutex = PTHREAD_MUTEX_INITIALIZER;
template <typename T>
pthread_mutex_t ResourcePool<T>::_change_thread_mutex =
PTHREAD_MUTEX_INITIALIZER;
template <typename T>
butil::static_atomic<typename ResourcePool<T>::BlockGroup*>
ResourcePool<T>::_block_groups[RP_MAX_BLOCK_NGROUP] = {};
#ifdef BUTIL_RESOURCE_POOL_NEED_FREE_ITEM_NUM
template <typename T>
butil::static_atomic<size_t> ResourcePool<T>::_global_nfree = BUTIL_STATIC_ATOMIC_INIT(0);
#endif
template <typename T>
inline bool operator==(ResourceId<T> id1, ResourceId<T> id2) {
return id1.value == id2.value;
}
template <typename T>
inline bool operator!=(ResourceId<T> id1, ResourceId<T> id2) {
return id1.value != id2.value;
}
// Disable comparisons between different typed ResourceId
template <typename T1, typename T2>
bool operator==(ResourceId<T1> id1, ResourceId<T2> id2);
template <typename T1, typename T2>
bool operator!=(ResourceId<T1> id1, ResourceId<T2> id2);
inline std::ostream& operator<<(std::ostream& os,
ResourcePoolInfo const& info) {
return os << "local_pool_num: " << info.local_pool_num
<< "\nblock_group_num: " << info.block_group_num
<< "\nblock_num: " << info.block_num
<< "\nitem_num: " << info.item_num
<< "\nblock_item_num: " << info.block_item_num
<< "\nfree_chunk_item_num: " << info.free_chunk_item_num
<< "\ntotal_size: " << info.total_size;
#ifdef BUTIL_RESOURCE_POOL_NEED_FREE_ITEM_NUM
<< "\nfree_num: " << info.free_item_num
#endif
;
}
} // namespace butil
#endif // BUTIL_RESOURCE_POOL_INL_H