diff options
Diffstat (limited to 'innobase/sync/sync0rw.c')
| -rw-r--r-- | innobase/sync/sync0rw.c | 906 |
1 files changed, 906 insertions, 0 deletions
diff --git a/innobase/sync/sync0rw.c b/innobase/sync/sync0rw.c new file mode 100644 index 00000000000..77589587065 --- /dev/null +++ b/innobase/sync/sync0rw.c @@ -0,0 +1,906 @@ +/****************************************************** +The read-write lock (for thread synchronization) + +(c) 1995 Innobase Oy + +Created 9/11/1995 Heikki Tuuri +*******************************************************/ + +#include "sync0rw.h" +#ifdef UNIV_NONINL +#include "sync0rw.ic" +#endif + +#include "os0thread.h" +#include "mem0mem.h" +#include "srv0srv.h" + +ulint rw_s_system_call_count = 0; +ulint rw_s_spin_wait_count = 0; + +ulint rw_s_exit_count = 0; + +ulint rw_x_system_call_count = 0; +ulint rw_x_spin_wait_count = 0; + +ulint rw_x_exit_count = 0; + +/* The global list of rw-locks */ +rw_lock_list_t rw_lock_list; +mutex_t rw_lock_list_mutex; + +/* The global mutex which protects debug info lists of all rw-locks. +To modify the debug info list of an rw-lock, this mutex has to be +acquired in addition to the mutex protecting the lock. */ + +mutex_t rw_lock_debug_mutex; +os_event_t rw_lock_debug_event; /* If deadlock detection does not + get immediately the mutex, it may + wait for this event */ +ibool rw_lock_debug_waiters; /* This is set to TRUE, if there may + be waiters for the event */ + +/********************************************************************** +Creates a debug info struct. */ +static +rw_lock_debug_t* +rw_lock_debug_create(void); +/*======================*/ +/********************************************************************** +Frees a debug info struct. */ +static +void +rw_lock_debug_free( +/*===============*/ + rw_lock_debug_t* info); + +/********************************************************************** +Creates a debug info struct. */ +static +rw_lock_debug_t* +rw_lock_debug_create(void) +/*======================*/ +{ + return((rw_lock_debug_t*) mem_alloc(sizeof(rw_lock_debug_t))); +} + +/********************************************************************** +Frees a debug info struct. */ +static +void +rw_lock_debug_free( +/*===============*/ + rw_lock_debug_t* info) +{ + mem_free(info); +} + +/********************************************************************** +Creates, or rather, initializes an rw-lock object in a specified memory +location (which must be appropriately aligned). The rw-lock is initialized +to the non-locked state. Explicit freeing of the rw-lock with rw_lock_free +is necessary only if the memory block containing it is freed. */ + +void +rw_lock_create_func( +/*================*/ + rw_lock_t* lock, /* in: pointer to memory */ + char* cfile_name, /* in: file name where created */ + ulint cline) /* in: file line where created */ +{ + /* If this is the very first time a synchronization + object is created, then the following call initializes + the sync system. */ + + mutex_create(rw_lock_get_mutex(lock)); + mutex_set_level(rw_lock_get_mutex(lock), SYNC_NO_ORDER_CHECK); + + ut_memcpy(&(lock->mutex.cfile_name), cfile_name, + ut_min(RW_CNAME_LEN - 1, ut_strlen(cfile_name))); + lock->mutex.cline = cline; + + rw_lock_set_waiters(lock, 0); + rw_lock_set_writer(lock, RW_LOCK_NOT_LOCKED); + lock->writer_count = 0; + rw_lock_set_reader_count(lock, 0); + + lock->writer_is_wait_ex = FALSE; + + UT_LIST_INIT(lock->debug_list); + + lock->magic_n = RW_LOCK_MAGIC_N; + lock->level = SYNC_LEVEL_NONE; + + ut_memcpy(&(lock->cfile_name), cfile_name, + ut_min(RW_CNAME_LEN - 1, ut_strlen(cfile_name))); + lock->cfile_name[RW_CNAME_LEN - 1] = '\0'; + lock->cline = cline; + + mutex_enter(&rw_lock_list_mutex); + + UT_LIST_ADD_FIRST(list, rw_lock_list, lock); + + mutex_exit(&rw_lock_list_mutex); +} + +/********************************************************************** +Calling this function is obligatory only if the memory buffer containing +the rw-lock is freed. Removes an rw-lock object from the global list. The +rw-lock is checked to be in the non-locked state. */ + +void +rw_lock_free( +/*=========*/ + rw_lock_t* lock) /* in: rw-lock */ +{ + ut_ad(rw_lock_validate(lock)); + ut_a(rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED); + ut_a(rw_lock_get_waiters(lock) == 0); + ut_a(rw_lock_get_reader_count(lock) == 0); + + lock->magic_n = 0; + + mutex_free(rw_lock_get_mutex(lock)); + + mutex_enter(&rw_lock_list_mutex); + + UT_LIST_REMOVE(list, rw_lock_list, lock); + + mutex_exit(&rw_lock_list_mutex); +} + +/********************************************************************** +Checks that the rw-lock has been initialized and that there are no +simultaneous shared and exclusive locks. */ + +ibool +rw_lock_validate( +/*=============*/ + rw_lock_t* lock) +{ + ut_a(lock); + + mutex_enter(rw_lock_get_mutex(lock)); + + ut_a(lock->magic_n == RW_LOCK_MAGIC_N); + ut_a((rw_lock_get_reader_count(lock) == 0) + || (rw_lock_get_writer(lock) != RW_LOCK_EX)); + ut_a(rw_lock_get_reader_count(lock) >= 0); + ut_a((rw_lock_get_writer(lock) == RW_LOCK_EX) + || (rw_lock_get_writer(lock) == RW_LOCK_WAIT_EX) + || (rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED)); + ut_a((rw_lock_get_waiters(lock) == 0) + || (rw_lock_get_waiters(lock) == 1)); + ut_a((lock->writer != RW_LOCK_EX) || (lock->writer_count > 0)); + + mutex_exit(rw_lock_get_mutex(lock)); + + return(TRUE); +} + +/********************************************************************** +Lock an rw-lock in shared mode for the current thread. If the rw-lock is +locked in exclusive mode, or there is an exclusive lock request waiting, +the function spins a preset time (controlled by SYNC_SPIN_ROUNDS), waiting +for the lock, before suspending the thread. */ + +void +rw_lock_s_lock_spin( +/*================*/ + rw_lock_t* lock /* in: pointer to rw-lock */ + #ifdef UNIV_SYNC_DEBUG + ,ulint pass, /* in: pass value; != 0, if the lock + will be passed to another thread to unlock */ + char* file_name, /* in: file name where lock requested */ + ulint line /* in: line where requested */ + #endif +) +{ + ulint index; /* index of the reserved wait cell */ + ulint i; /* spin round count */ + + ut_ad(rw_lock_validate(lock)); + +lock_loop: + rw_s_spin_wait_count++; + + /* Spin waiting for the writer field to become free */ + i = 0; + + while (rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED + && i < SYNC_SPIN_ROUNDS) { + if (srv_spin_wait_delay) { + ut_delay(ut_rnd_interval(0, srv_spin_wait_delay)); + } + + i++; + } + + if (i == SYNC_SPIN_ROUNDS) { + os_thread_yield(); + } + + if (srv_print_latch_waits) { + printf( + "Thread %lu spin wait rw-s-lock at %lx cfile %s cline %lu rnds %lu\n", + os_thread_get_curr_id(), (ulint)lock, + &(lock->cfile_name), lock->cline, i); + } + + mutex_enter(rw_lock_get_mutex(lock)); + + /* We try once again to obtain the lock */ + + if (TRUE == rw_lock_s_lock_low(lock + #ifdef UNIV_SYNC_DEBUG + , pass, file_name, + line + #endif + )) { + mutex_exit(rw_lock_get_mutex(lock)); + + return; /* Success */ + } else { + /* If we get here, locking did not succeed, we may + suspend the thread to wait in the wait array */ + + rw_s_system_call_count++; + + sync_array_reserve_cell(sync_primary_wait_array, + lock, RW_LOCK_SHARED, + #ifdef UNIV_SYNC_DEBUG + file_name, line, + #endif + &index); + + rw_lock_set_waiters(lock, 1); + + mutex_exit(rw_lock_get_mutex(lock)); + + if (srv_print_latch_waits) { + printf( + "Thread %lu OS wait rw-s-lock at %lx cfile %s cline %lu\n", + os_thread_get_curr_id(), (ulint)lock, + &(lock->cfile_name), lock->cline); + } + + rw_s_system_call_count++; + + sync_array_wait_event(sync_primary_wait_array, index); + + goto lock_loop; + } +} + +/********************************************************************** +This function is used in the insert buffer to move the ownership of an +x-latch on a buffer frame to the current thread. The x-latch was set by +the buffer read operation and it protected the buffer frame while the +read was done. The ownership is moved because we want that the current +thread is able to acquire a second x-latch which is stored in an mtr. +This, in turn, is needed to pass the debug checks of index page +operations. */ + +void +rw_lock_x_lock_move_ownership( +/*==========================*/ + rw_lock_t* lock) /* in: lock which was x-locked in the + buffer read */ +{ + ut_ad(rw_lock_is_locked(lock, RW_LOCK_EX)); + + mutex_enter(&(lock->mutex)); + + lock->writer_thread = os_thread_get_curr_id(); + + lock->pass = 0; + + mutex_exit(&(lock->mutex)); +} + +/********************************************************************** +Low-level function for acquiring an exclusive lock. */ +UNIV_INLINE +ulint +rw_lock_x_lock_low( +/*===============*/ + /* out: RW_LOCK_NOT_LOCKED if did + not succeed, RW_LOCK_EX if success, + RW_LOCK_WAIT_EX, if got wait reservation */ + rw_lock_t* lock, /* in: pointer to rw-lock */ + ulint pass /* in: pass value; != 0, if the lock will + be passed to another thread to unlock */ + #ifdef UNIV_SYNC_DEBUG + ,char* file_name, /* in: file name where lock requested */ + ulint line /* in: line where requested */ + #endif +) +{ + ut_ad(mutex_own(rw_lock_get_mutex(lock))); + + if (rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED) { + + if (rw_lock_get_reader_count(lock) == 0) { + + rw_lock_set_writer(lock, RW_LOCK_EX); + lock->writer_thread = os_thread_get_curr_id(); + lock->writer_count++; + lock->pass = pass; + + #ifdef UNIV_SYNC_DEBUG + rw_lock_add_debug_info(lock, pass, RW_LOCK_EX, + file_name, line); + #endif + + /* Locking succeeded, we may return */ + return(RW_LOCK_EX); + } else { + /* There are readers, we have to wait */ + rw_lock_set_writer(lock, RW_LOCK_WAIT_EX); + lock->writer_thread = os_thread_get_curr_id(); + lock->pass = pass; + lock->writer_is_wait_ex = TRUE; + + #ifdef UNIV_SYNC_DEBUG + rw_lock_add_debug_info(lock, pass, RW_LOCK_WAIT_EX, + file_name, line); + #endif + + return(RW_LOCK_WAIT_EX); + } + + } else if ((rw_lock_get_writer(lock) == RW_LOCK_WAIT_EX) + && (lock->writer_thread == os_thread_get_curr_id())) { + + if (rw_lock_get_reader_count(lock) == 0) { + + rw_lock_set_writer(lock, RW_LOCK_EX); + lock->writer_count++; + lock->pass = pass; + lock->writer_is_wait_ex = FALSE; + + #ifdef UNIV_SYNC_DEBUG + rw_lock_remove_debug_info(lock, pass, RW_LOCK_WAIT_EX); + rw_lock_add_debug_info(lock, pass, RW_LOCK_EX, + file_name, line); + #endif + + /* Locking succeeded, we may return */ + return(RW_LOCK_EX); + } + + return(RW_LOCK_WAIT_EX); + + } else if ((rw_lock_get_writer(lock) == RW_LOCK_EX) + && (lock->writer_thread == os_thread_get_curr_id()) + && (lock->pass == 0) + && (pass == 0)) { + + lock->writer_count++; + + #ifdef UNIV_SYNC_DEBUG + rw_lock_add_debug_info(lock, pass, RW_LOCK_EX, file_name, + line); + #endif + + /* Locking succeeded, we may return */ + return(RW_LOCK_EX); + } + + /* Locking did not succeed */ + return(RW_LOCK_NOT_LOCKED); +} + +/********************************************************************** +NOTE! Use the corresponding macro, not directly this function! Lock an +rw-lock in exclusive mode for the current thread. If the rw-lock is locked +in shared or exclusive mode, or there is an exclusive lock request waiting, +the function spins a preset time (controlled by SYNC_SPIN_ROUNDS), waiting +for the lock before suspending the thread. If the same thread has an x-lock +on the rw-lock, locking succeed, with the following exception: if pass != 0, +only a single x-lock may be taken on the lock. NOTE: If the same thread has +an s-lock, locking does not succeed! */ + +void +rw_lock_x_lock_func( +/*================*/ + rw_lock_t* lock, /* in: pointer to rw-lock */ + ulint pass /* in: pass value; != 0, if the lock will + be passed to another thread to unlock */ + #ifdef UNIV_SYNC_DEBUG + ,char* file_name, /* in: file name where lock requested */ + ulint line /* in: line where requested */ + #endif +) +{ + ulint index; /* index of the reserved wait cell */ + ulint state; /* lock state acquired */ + ulint i; /* spin round count */ + + ut_ad(rw_lock_validate(lock)); + +lock_loop: + /* Acquire the mutex protecting the rw-lock fields */ + mutex_enter_fast(&(lock->mutex)); + + state = rw_lock_x_lock_low(lock, pass + #ifdef UNIV_SYNC_DEBUG + ,file_name, line + #endif + ); + + mutex_exit(&(lock->mutex)); + + if (state == RW_LOCK_EX) { + + return; /* Locking succeeded */ + + } else if (state == RW_LOCK_NOT_LOCKED) { + + /* Spin waiting for the writer field to become free */ + i = 0; + + while (rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED + && i < SYNC_SPIN_ROUNDS) { + if (srv_spin_wait_delay) { + ut_delay(ut_rnd_interval(0, + srv_spin_wait_delay)); + } + + i++; + } + if (i == SYNC_SPIN_ROUNDS) { + os_thread_yield(); + } + } else if (state == RW_LOCK_WAIT_EX) { + + /* Spin waiting for the reader count field to become zero */ + i = 0; + + while (rw_lock_get_reader_count(lock) != 0 + && i < SYNC_SPIN_ROUNDS) { + if (srv_spin_wait_delay) { + ut_delay(ut_rnd_interval(0, + srv_spin_wait_delay)); + } + + i++; + } + if (i == SYNC_SPIN_ROUNDS) { + os_thread_yield(); + } + } else { + ut_error; + } + + if (srv_print_latch_waits) { + printf( + "Thread %lu spin wait rw-x-lock at %lx cfile %s cline %lu rnds %lu\n", + os_thread_get_curr_id(), (ulint)lock, + &(lock->cfile_name), lock->cline, i); + } + + rw_x_spin_wait_count++; + + /* We try once again to obtain the lock. Acquire the mutex protecting + the rw-lock fields */ + + mutex_enter(rw_lock_get_mutex(lock)); + + state = rw_lock_x_lock_low(lock, pass + #ifdef UNIV_SYNC_DEBUG + ,file_name, line + #endif + ); + + if (state == RW_LOCK_EX) { + mutex_exit(rw_lock_get_mutex(lock)); + + return; /* Locking succeeded */ + } + + rw_x_system_call_count++; + + sync_array_reserve_cell(sync_primary_wait_array, + lock, RW_LOCK_EX, + #ifdef UNIV_SYNC_DEBUG + file_name, line, + #endif + &index); + + rw_lock_set_waiters(lock, 1); + + mutex_exit(rw_lock_get_mutex(lock)); + + if (srv_print_latch_waits) { + printf( + "Thread %lu OS wait for rw-x-lock at %lx cfile %s cline %lu\n", + os_thread_get_curr_id(), (ulint)lock, &(lock->cfile_name), + lock->cline); + } + + rw_x_system_call_count++; + + sync_array_wait_event(sync_primary_wait_array, index); + + goto lock_loop; +} + +/********************************************************************** +Acquires the debug mutex. We cannot use the mutex defined in sync0sync, +because the debug mutex is also acquired in sync0arr while holding the OS +mutex protecting the sync array, and the ordinary mutex_enter might +recursively call routines in sync0arr, leading to a deadlock on the OS +mutex. */ + +void +rw_lock_debug_mutex_enter(void) +/*==========================*/ +{ +loop: + if (0 == mutex_enter_nowait(&rw_lock_debug_mutex)) { + + return; + } + + os_event_reset(rw_lock_debug_event); + + rw_lock_debug_waiters = TRUE; + + if (0 == mutex_enter_nowait(&rw_lock_debug_mutex)) { + + return; + } + + os_event_wait(rw_lock_debug_event); + + goto loop; +} + +/********************************************************************** +Releases the debug mutex. */ + +void +rw_lock_debug_mutex_exit(void) +/*==========================*/ +{ + mutex_exit(&rw_lock_debug_mutex); + + if (rw_lock_debug_waiters) { + rw_lock_debug_waiters = FALSE; + os_event_set(rw_lock_debug_event); + } +} + +/********************************************************************** +Inserts the debug information for an rw-lock. */ + +void +rw_lock_add_debug_info( +/*===================*/ + rw_lock_t* lock, /* in: rw-lock */ + ulint pass, /* in: pass value */ + ulint lock_type, /* in: lock type */ + char* file_name, /* in: file where requested */ + ulint line) /* in: line where requested */ +{ + rw_lock_debug_t* info; + + ut_ad(lock); + ut_ad(file_name); + + info = rw_lock_debug_create(); + + rw_lock_debug_mutex_enter(); + + info->file_name = file_name; + info->line = line; + info->lock_type = lock_type; + info->thread_id = os_thread_get_curr_id(); + info->pass = pass; + + UT_LIST_ADD_FIRST(list, lock->debug_list, info); + + rw_lock_debug_mutex_exit(); + + if ((pass == 0) && (lock_type != RW_LOCK_WAIT_EX)) { + sync_thread_add_level(lock, lock->level); + } +} + +/********************************************************************** +Removes a debug information struct for an rw-lock. */ + +void +rw_lock_remove_debug_info( +/*======================*/ + rw_lock_t* lock, /* in: rw-lock */ + ulint pass, /* in: pass value */ + ulint lock_type) /* in: lock type */ +{ + rw_lock_debug_t* info; + + ut_ad(lock); + + if ((pass == 0) && (lock_type != RW_LOCK_WAIT_EX)) { + sync_thread_reset_level(lock); + } + + rw_lock_debug_mutex_enter(); + + info = UT_LIST_GET_FIRST(lock->debug_list); + + while (info != NULL) { + if ((pass == info->pass) + && ((pass != 0) + || (info->thread_id == os_thread_get_curr_id())) + && (info->lock_type == lock_type)) { + + /* Found! */ + UT_LIST_REMOVE(list, lock->debug_list, info); + rw_lock_debug_mutex_exit(); + + rw_lock_debug_free(info); + + return; + } + + info = UT_LIST_GET_NEXT(list, info); + } + + ut_error; +} + +/********************************************************************** +Sets the rw-lock latching level field. */ + +void +rw_lock_set_level( +/*==============*/ + rw_lock_t* lock, /* in: rw-lock */ + ulint level) /* in: level */ +{ + lock->level = level; +} + +/********************************************************************** +Checks if the thread has locked the rw-lock in the specified mode, with +the pass value == 0. */ + +ibool +rw_lock_own( +/*========*/ + /* out: TRUE if locked */ + rw_lock_t* lock, /* in: rw-lock */ + ulint lock_type) /* in: lock type */ +{ + rw_lock_debug_t* info; + + ut_ad(lock); + ut_ad(rw_lock_validate(lock)); + +#ifndef UNIV_SYNC_DEBUG + ut_error; +#endif + mutex_enter(&(lock->mutex)); + + info = UT_LIST_GET_FIRST(lock->debug_list); + + while (info != NULL) { + + if ((info->thread_id == os_thread_get_curr_id()) + && (info->pass == 0) + && (info->lock_type == lock_type)) { + + mutex_exit(&(lock->mutex)); + /* Found! */ + + return(TRUE); + } + + info = UT_LIST_GET_NEXT(list, info); + } + mutex_exit(&(lock->mutex)); + + return(FALSE); +} + +/********************************************************************** +Checks if somebody has locked the rw-lock in the specified mode. */ + +ibool +rw_lock_is_locked( +/*==============*/ + /* out: TRUE if locked */ + rw_lock_t* lock, /* in: rw-lock */ + ulint lock_type) /* in: lock type: RW_LOCK_SHARED, + RW_LOCK_EX */ +{ + ibool ret = FALSE; + + ut_ad(lock); + ut_ad(rw_lock_validate(lock)); + + mutex_enter(&(lock->mutex)); + + if (lock_type == RW_LOCK_SHARED) { + if (lock->reader_count > 0) { + ret = TRUE; + } + } else if (lock_type == RW_LOCK_EX) { + if (lock->writer == RW_LOCK_EX) { + ret = TRUE; + } + } else { + ut_error; + } + + mutex_exit(&(lock->mutex)); + + return(ret); +} + +/******************************************************************* +Prints debug info of currently locked rw-locks. */ + +void +rw_lock_list_print_info(void) +/*=========================*/ +{ +#ifndef UNIV_SYNC_DEBUG + printf( + "Sorry, cannot give rw-lock list info in non-debug version!\n"); +#else + rw_lock_t* lock; + ulint count = 0; + rw_lock_debug_t* info; + + mutex_enter(&rw_lock_list_mutex); + + printf("----------------------------------------------\n"); + printf("RW-LOCK INFO\n"); + + lock = UT_LIST_GET_FIRST(rw_lock_list); + + while (lock != NULL) { + + count++; + + mutex_enter(&(lock->mutex)); + + if ((rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED) + || (rw_lock_get_reader_count(lock) != 0) + || (rw_lock_get_waiters(lock) != 0)) { + + printf("RW-LOCK: %lx ", (ulint)lock); + + if (rw_lock_get_waiters(lock)) { + printf(" Waiters for the lock exist\n"); + } else { + printf("\n"); + } + + info = UT_LIST_GET_FIRST(lock->debug_list); + while (info != NULL) { + rw_lock_debug_print(info); + info = UT_LIST_GET_NEXT(list, info); + } + } + + mutex_exit(&(lock->mutex)); + lock = UT_LIST_GET_NEXT(list, lock); + } + + printf("Total number of rw-locks %ld\n", count); + mutex_exit(&rw_lock_list_mutex); +#endif +} + +/******************************************************************* +Prints debug info of an rw-lock. */ + +void +rw_lock_print( +/*==========*/ + rw_lock_t* lock) /* in: rw-lock */ +{ +#ifndef UNIV_SYNC_DEBUG + printf( + "Sorry, cannot give rw-lock info in non-debug version!\n"); +#else + ulint count = 0; + rw_lock_debug_t* info; + + printf("----------------------------------------------\n"); + printf("RW-LOCK INFO\n"); + printf("RW-LOCK: %lx ", (ulint)lock); + + mutex_enter(&(lock->mutex)); + if ((rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED) + || (rw_lock_get_reader_count(lock) != 0) + || (rw_lock_get_waiters(lock) != 0)) { + + if (rw_lock_get_waiters(lock)) { + printf(" Waiters for the lock exist\n"); + } else { + printf("\n"); + } + + info = UT_LIST_GET_FIRST(lock->debug_list); + while (info != NULL) { + rw_lock_debug_print(info); + info = UT_LIST_GET_NEXT(list, info); + } + } + + mutex_exit(&(lock->mutex)); +#endif +} + +/************************************************************************* +Prints info of a debug struct. */ + +void +rw_lock_debug_print( +/*================*/ + rw_lock_debug_t* info) /* in: debug struct */ +{ + ulint rwt; + + rwt = info->lock_type; + + printf("Locked: thread %ld file %s line %ld ", + info->thread_id, info->file_name, info->line); + if (rwt == RW_LOCK_SHARED) { + printf("S-LOCK"); + } else if (rwt == RW_LOCK_EX) { + printf("X-LOCK"); + } else if (rwt == RW_LOCK_WAIT_EX) { + printf("WAIT X-LOCK"); + } else { + ut_error; + } + if (info->pass != 0) { + printf(" pass value %lu", info->pass); + } + printf("\n"); +} + +/******************************************************************* +Returns the number of currently locked rw-locks. Works only in the debug +version. */ + +ulint +rw_lock_n_locked(void) +/*==================*/ +{ +#ifndef UNIV_SYNC_DEBUG + printf( + "Sorry, cannot give rw-lock info in non-debug version!\n"); + ut_error; + return(0); +#else + rw_lock_t* lock; + ulint count = 0; + + mutex_enter(&rw_lock_list_mutex); + + lock = UT_LIST_GET_FIRST(rw_lock_list); + + while (lock != NULL) { + mutex_enter(rw_lock_get_mutex(lock)); + + if ((rw_lock_get_writer(lock) != RW_LOCK_NOT_LOCKED) + || (rw_lock_get_reader_count(lock) != 0)) { + count++; + } + + mutex_exit(rw_lock_get_mutex(lock)); + lock = UT_LIST_GET_NEXT(list, lock); + } + + mutex_exit(&rw_lock_list_mutex); + + return(count); +#endif +} |