@ -7,11 +7,16 @@
// 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 "util/thread_posix .h"
# include "util/threadpool .h"
# include <atomic>
# include <unistd.h>
# include <algorithm>
# ifndef OS_WIN
# include <unistd.h>
# endif
# ifdef OS_LINUX
# include <sys/syscall.h>
# include <sys / syscall.h>
# endif
namespace rocksdb {
@ -23,29 +28,128 @@ void ThreadPool::PthreadCall(const char* label, int result) {
}
}
namespace {
# ifdef ROCKSDB_STD_THREADPOOL
struct Lock {
std : : unique_lock < std : : mutex > ul_ ;
Lock ( std : : mutex & m ) : ul_ ( m , std : : defer_lock ) { }
} ;
using Condition = std : : condition_variable ;
inline
int MutexLock ( Lock & mutex ) {
mutex . ul_ . lock ( ) ;
return 0 ;
}
inline
int ConditionWait ( Condition & condition , Lock & lock ) {
condition . wait ( lock . ul_ ) ;
return 0 ;
}
inline
int ConditionSignalAll ( Condition & condition ) {
condition . notify_all ( ) ;
return 0 ;
}
inline
int ConditionSignal ( Condition & condition ) {
condition . notify_one ( ) ;
return 0 ;
}
inline
int MutexUnlock ( Lock & mutex ) {
mutex . ul_ . unlock ( ) ;
return 0 ;
}
inline
void ThreadJoin ( std : : thread & thread ) {
thread . join ( ) ;
}
inline
int ThreadDetach ( std : : thread & thread ) {
thread . detach ( ) ;
return 0 ;
}
# else
using Lock = pthread_mutex_t & ;
using Condition = pthread_cond_t & ;
inline
int MutexLock ( Lock mutex ) {
return pthread_mutex_lock ( & mutex ) ;
}
inline
int ConditionWait ( Condition condition , Lock lock ) {
return pthread_cond_wait ( & condition , & lock ) ;
}
inline
int ConditionSignalAll ( Condition condition ) {
return pthread_cond_broadcast ( & condition ) ;
}
inline
int ConditionSignal ( Condition condition ) {
return pthread_cond_signal ( & condition ) ;
}
inline
int MutexUnlock ( Lock mutex ) {
return pthread_mutex_unlock ( & mutex ) ;
}
inline
void ThreadJoin ( pthread_t & thread ) {
pthread_join ( thread , nullptr ) ;
}
inline
int ThreadDetach ( pthread_t & thread ) {
return pthread_detach ( thread ) ;
}
# endif
}
ThreadPool : : ThreadPool ( )
: total_threads_limit_ ( 1 ) ,
bgthreads_ ( 0 ) ,
queue_ ( ) ,
queue_len_ ( 0 ) ,
queue_len_ ( ) ,
exit_all_threads_ ( false ) ,
low_io_priority_ ( false ) ,
env_ ( nullptr ) {
# ifndef ROCKSDB_STD_THREADPOOL
PthreadCall ( " mutex_init " , pthread_mutex_init ( & mu_ , nullptr ) ) ;
PthreadCall ( " cvar_init " , pthread_cond_init ( & bgsignal_ , nullptr ) ) ;
# endif
}
ThreadPool : : ~ ThreadPool ( ) { assert ( bgthreads_ . size ( ) = = 0U ) ; }
void ThreadPool : : JoinAllThreads ( ) {
PthreadCall ( " lock " , pthread_mutex_lock ( & mu_ ) ) ;
Lock lock ( mu_ ) ;
PthreadCall ( " lock " , MutexLock ( lock ) ) ;
assert ( ! exit_all_threads_ ) ;
exit_all_threads_ = true ;
PthreadCall ( " signalall " , pthread_cond_broadcast ( & bgsignal_ ) ) ;
PthreadCall ( " unlock " , pthread_mutex_unlock ( & mu_ ) ) ;
for ( const auto tid : bgthreads_ ) {
pthread_join ( tid , nullptr ) ;
PthreadCall ( " signalall " , ConditionSignalAll ( bgsignal_ ) ) ;
PthreadCall ( " unlock " , MutexUnlock ( lock ) ) ;
for ( auto & th : bgthreads_ ) {
ThreadJoin ( th ) ;
}
bgthreads_ . clear ( ) ;
}
@ -60,31 +164,35 @@ void ThreadPool::LowerIOPriority() {
void ThreadPool : : BGThread ( size_t thread_id ) {
bool low_io_priority = false ;
while ( true ) {
// Wait until there is an item that is ready to run
PthreadCall ( " lock " , pthread_mutex_lock ( & mu_ ) ) ;
// Wait until there is an item that is ready to run
Lock uniqueLock ( mu_ ) ;
PthreadCall ( " lock " , MutexLock ( uniqueLock ) ) ;
// Stop waiting if the thread needs to do work or needs to terminate.
while ( ! exit_all_threads_ & & ! IsLastExcessiveThread ( thread_id ) & &
( queue_ . empty ( ) | | IsExcessiveThread ( thread_id ) ) ) {
PthreadCall ( " wait " , pthread_cond_wait ( & bgsignal_ , & mu_ ) ) ;
PthreadCall ( " wait " , ConditionWait ( bgsignal_ , uniqueLock ) ) ;
}
if ( exit_all_threads_ ) { // mechanism to let BG threads exit safely
PthreadCall ( " unlock " , pthread_mutex_unlock ( & mu_ ) ) ;
PthreadCall ( " unlock " , MutexUnlock ( uniqueLock ) ) ;
break ;
}
if ( IsLastExcessiveThread ( thread_id ) ) {
// Current thread is the last generated one and is excessive.
// We always terminate excessive thread in the reverse order of
// generation time.
auto terminating_thread = bgthreads_ . back ( ) ;
pthread_detach ( terminating_thread ) ;
auto & terminating_thread = bgthreads_ . back ( ) ;
PthreadCall ( " detach " , ThreadDetach ( terminating_thread ) ) ;
bgthreads_ . pop_back ( ) ;
if ( HasExcessiveThread ( ) ) {
// There is still at least more excessive thread to terminate.
WakeUpAllThreads ( ) ;
}
PthreadCall ( " unlock " , pthread_mutex_unlock ( & mu_ ) ) ;
PthreadCall ( " unlock " , MutexUnlock ( uniqueLock ) ) ;
break ;
}
void ( * function ) ( void * ) = queue_ . front ( ) . function ;
void * arg = queue_ . front ( ) . arg ;
queue_ . pop_front ( ) ;
@ -92,7 +200,7 @@ void ThreadPool::BGThread(size_t thread_id) {
std : : memory_order_relaxed ) ;
bool decrease_io_priority = ( low_io_priority ! = low_io_priority_ ) ;
PthreadCall ( " unlock " , pthread_mutex_unlock ( & mu_ ) ) ;
PthreadCall ( " unlock " , MutexUnlock ( uniqueLock ) ) ;
# ifdef OS_LINUX
if ( decrease_io_priority ) {
@ -124,7 +232,7 @@ void ThreadPool::BGThread(size_t thread_id) {
struct BGThreadMetadata {
ThreadPool * thread_pool_ ;
size_t thread_id_ ; // Thread count in the thread.
explicit BGThreadMetadata ( ThreadPool * thread_pool , size_t thread_id )
BGThreadMetadata ( ThreadPool * thread_pool , size_t thread_id )
: thread_pool_ ( thread_pool ) , thread_id_ ( thread_id ) { }
} ;
@ -148,13 +256,14 @@ static void* BGThreadWrapper(void* arg) {
}
void ThreadPool : : WakeUpAllThreads ( ) {
PthreadCall ( " signalall " , pthread_cond_broadcast ( & bgsignal_ ) ) ;
PthreadCall ( " signalall " , ConditionSignalAll ( bgsignal_ ) ) ;
}
void ThreadPool : : SetBackgroundThreadsInternal ( int num , bool allow_reduce ) {
PthreadCall ( " lock " , pthread_mutex_lock ( & mu_ ) ) ;
Lock lock ( mu_ ) ;
PthreadCall ( " lock " , MutexLock ( lock ) ) ;
if ( exit_all_threads_ ) {
PthreadCall ( " unlock " , pthread_mutex_unlock ( & mu_ ) ) ;
PthreadCall ( " unlock " , MutexUnlock ( lock ) ) ;
return ;
}
if ( num > total_threads_limit_ | |
@ -163,7 +272,7 @@ void ThreadPool::SetBackgroundThreadsInternal(int num, bool allow_reduce) {
WakeUpAllThreads ( ) ;
StartBGThreads ( ) ;
}
PthreadCall ( " unlock " , pthread_mutex_unlock ( & mu_ ) ) ;
PthreadCall ( " unlock " , MutexUnlock ( lock ) ) ;
}
void ThreadPool : : IncBackgroundThreadsIfNeeded ( int num ) {
@ -177,11 +286,15 @@ void ThreadPool::SetBackgroundThreads(int num) {
void ThreadPool : : StartBGThreads ( ) {
// Start background thread if necessary
while ( ( int ) bgthreads_ . size ( ) < total_threads_limit_ ) {
# ifdef ROCKSDB_STD_THREADPOOL
std : : thread p_t ( & BGThreadWrapper ,
new BGThreadMetadata ( this , bgthreads_ . size ( ) ) ) ;
bgthreads_ . push_back ( std : : move ( p_t ) ) ;
# else
pthread_t t ;
PthreadCall ( " create thread " ,
pthread_create ( & t , nullptr , & BGThreadWrapper ,
new BGThreadMetadata ( this , bgthreads_ . size ( ) ) ) ) ;
// Set the thread name to aid debugging
# if defined(_GNU_SOURCE) && defined(__GLIBC_PREREQ)
# if __GLIBC_PREREQ(2, 12)
@ -192,17 +305,19 @@ void ThreadPool::StartBGThreads() {
pthread_setname_np ( t , name_buf ) ;
# endif
# endif
bgthreads_ . push_back ( t ) ;
# endif
}
}
void ThreadPool : : Schedule ( void ( * function ) ( void * arg1 ) , void * arg , void * tag ,
void ( * unschedFunction ) ( void * arg ) ) {
PthreadCall ( " lock " , pthread_mutex_lock ( & mu_ ) ) ;
Lock lock ( mu_ ) ;
PthreadCall ( " lock " , MutexLock ( lock ) ) ;
if ( exit_all_threads_ ) {
PthreadCall ( " unlock " , pthread_mutex_unlock ( & mu_ ) ) ;
PthreadCall ( " unlock " , MutexUnlock ( lock ) ) ;
return ;
}
@ -219,19 +334,21 @@ void ThreadPool::Schedule(void (*function)(void* arg1), void* arg, void* tag,
if ( ! HasExcessiveThread ( ) ) {
// Wake up at least one waiting thread.
PthreadCall ( " signal " , pthread_cond_signal ( & bgsignal_ ) ) ;
PthreadCall ( " signal " , ConditionSignal ( bgsignal_ ) ) ;
} else {
// Need to wake up all threads to make sure the one woken
// up is not the one to terminate.
WakeUpAllThreads ( ) ;
}
PthreadCall ( " unlock " , pthread_mutex_unlock ( & mu_ ) ) ;
PthreadCall ( " unlock " , MutexUnlock ( lock ) ) ;
}
int ThreadPool : : UnSchedule ( void * arg ) {
int count = 0 ;
PthreadCall ( " lock " , pthread_mutex_lock ( & mu_ ) ) ;
Lock lock ( mu_ ) ;
PthreadCall ( " lock " , MutexLock ( lock ) ) ;
// Remove from priority queue
BGQueue : : iterator it = queue_ . begin ( ) ;
@ -245,12 +362,12 @@ int ThreadPool::UnSchedule(void* arg) {
it = queue_ . erase ( it ) ;
count + + ;
} else {
it + + ;
+ + it ;
}
}
queue_len_ . store ( static_cast < unsigned int > ( queue_ . size ( ) ) ,
std : : memory_order_relaxed ) ;
PthreadCall ( " unlock " , pthread_mutex_unlock ( & mu_ ) ) ;
PthreadCall ( " unlock " , MutexUnlock ( lock ) ) ;
return count ;
}