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td_sync_get_info, td_ta_sync_tracking_enable, td_sync_get_stats, td_sync_setstate, td_sync_waiters - operations on a synchronization object in libc_db

cc [ flag... ] file... -lc_db [ library... ]
#include <proc_service.h>
#include <thread_db.h>

td_err_e td_sync_get_info(const td_synchandle_t *sh_p, td_syncinfo_t *si_p);

td_err_e td_ta_sync_tracking_enable(const td_thragent_t *ta_p, int on_off);

td_err_e td_sync_get_stats(const td_synchandle_t *sh_p, td_syncstats_t *ss_p);

td_err_e td_sync_setstate(const td_synchandle_t *sh_p, int value);

typedef int td_thr_iter_f(const td_thrhandle_t *th_p, void *cb_data_p);

td_err_e td_sync_waiters(const td_synchandle_t *sh_p, td_thr_iter_f *cb,
 void *cb_data_p);

Synchronization objects include mutexes, condition variables, semaphores, and reader-writer locks. In the same way that thread operations use a thread handle of type td_thrhandle_t, operations on synchronization objects use a synchronization object handle of type td_synchandle_t.

The controlling process obtains synchronization object handles either by calling the function td_ta_sync_iter() to obtain handles for all synchronization objects of the target process that are known to the libc_db library of interfaces, or by mapping the address of a synchronization object in the address space of the target process to a handle by calling td_ta_map_addr2sync(3C_DB).

Not all synchronization objects that a process uses can be known to the libc_db library and returned by td_ta_sync_iter(3C_DB). A synchronization object is known to libc_db only if it has been the target of a synchronization primitive in the process (such as mutex_lock(), described on the mutex_init(3C) manual page) after td_ta_new(3C_DB) has been called to attach to the process and td_ta_sync_tracking_enable() has been called to enable synchronization object tracking.

The td_ta_sync_tracking_enable() function turns synchronization object tracking on or off for the process identified by ta_p, depending on whether on_off is 0 (off) or non-zero (on).

The td_sync_get_info() function fills in the td_syncinfo_t structure *si_p with values for the synchronization object identified by sh_p. The td_syncinfo_t structure contains the following fields: td_thragent_t *si_ta_p

psaddr_t si_sv_addr td_sync_type_e si_type int si_shared_type td_sync_flags_t si_flags int si_state.sema_count int si_state.nreaders int si_state.mutex_locked int si_size uint8_t si_has_waiters uint8_t si_is_wlocked uint8_t si_rcount uint8_t si_prioceiling td_thrhandle_t si_owner pid_t si_ownerpid

The td_sync_get_stats() function fills in the td_syncstats_t structure *ss_p with values for the synchronization object identified by sh_p. The td_syncstats_t structure contains an embedded td_syncinfo_t structure that is filled in as described above for td_sync_get_info(). In addition, usage statistics gathered since td_ta_sync_tracking_enable() was called to enable synchronization object tracking are returned in the ss_un.mutex, ss_un.cond, ss_un.rwlock, or ss_un.sema members of the td_syncstats_t structure, depending on the type of the synchronization object.

The td_sync_setstate function modifies the state of synchronization object si_p, depending on the synchronization object type. For mutexes, td_sync_setstate is unlocked if the value is 0. Otherwise it is locked. For semaphores, the semaphore's count is set to the value. For reader-writer locks, the reader count set to the value if value is >0. The count is set to write-locked if value is -1. It is set to unlocked if the value is 0. Setting the state of a synchronization object from a libc_db interface may cause the synchronization object's semantics to be violated from the point of view of the threads in the target process. For example, if a thread holds a mutex, and td_sync_setstate is used to set the mutex to unlocked, then a different thread will also be able to subsequently acquire the same mutex.

The td_sync_waiters function iterates over the set of thread handles of threads blocked on sh_p. The callback function cb is called once for each such thread handle, and is passed the thread handle and cb_data_p. If the callback function returns a non-zero value, iteration is terminated early. See td_ta_thr_iter(3C_DB).

TD_OK TD_BADTH TD_DBERR TD_ERR

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE

MT-Level Safe

libc_db(3LIB), mutex_init(3C), td_ta_map_addr2sync(3C_DB), td_ta_sync_iter(3C_DB), td_ta_thr_iter(3C_DB), attributes(7)