diff --git a/devicestate.c b/devicestate.c index 621e8f1fd01d8e51cdd17c449c97bbce58aded9b..0474f5de1cd5608c46fc1c58372ae0fba2890015 100755 --- a/devicestate.c +++ b/devicestate.c @@ -44,7 +44,6 @@ struct state_change { static AST_LIST_HEAD_STATIC(state_changes, state_change); static pthread_t change_thread = AST_PTHREADT_NULL; -AST_MUTEX_DEFINE_STATIC(change_pending_lock); static pthread_cond_t change_pending; int ast_parse_device_state(const char *device) @@ -138,6 +137,7 @@ void ast_devstate_del(ast_devstate_cb_type callback, void *data) AST_LIST_UNLOCK(&devstate_cbs); } +/*--- do_state_change: Notify callback watchers of change, and notify PBX core for hint updates */ static void do_state_change(const char *device) { int state; @@ -155,7 +155,6 @@ static void do_state_change(const char *device) ast_hint_state_changed(device); } -/*--- ast_device_state_changed: Notify callback watchers of change, and notify PBX core for hint updates */ int ast_device_state_changed(const char *fmt, ...) { char buf[AST_MAX_EXTENSION]; @@ -183,15 +182,10 @@ int ast_device_state_changed(const char *fmt, ...) strcpy(change->device, device); AST_LIST_LOCK(&state_changes); AST_LIST_INSERT_TAIL(&state_changes, change, list); - if (AST_LIST_FIRST(&state_changes) == change) { - AST_LIST_UNLOCK(&state_changes); + if (AST_LIST_FIRST(&state_changes) == change) /* the list was empty, signal the thread */ - ast_mutex_lock(&change_pending_lock); pthread_cond_signal(&change_pending); - ast_mutex_unlock(&change_pending_lock); - } else { - AST_LIST_UNLOCK(&state_changes); - } + AST_LIST_UNLOCK(&state_changes); } return 1; @@ -201,20 +195,21 @@ static void *do_changes(void *data) { struct state_change *cur; + AST_LIST_LOCK(&state_changes); for(;;) { - ast_mutex_lock(&change_pending_lock); - pthread_cond_wait(&change_pending, &change_pending_lock); - for (;;) { - AST_LIST_LOCK(&state_changes); - cur = AST_LIST_REMOVE_HEAD(&state_changes, list); + /* the list lock will _always_ be held at this point in the loop */ + cur = AST_LIST_REMOVE_HEAD(&state_changes, list); + if (cur) { + /* we got an entry, so unlock the list while we process it */ AST_LIST_UNLOCK(&state_changes); - if (!cur) - break; - do_state_change(cur->device); free(cur); + AST_LIST_LOCK(&state_changes); + } else { + /* there was no entry, so atomically unlock the list and wait for + the condition to be signalled (returns with the lock held) */ + pthread_cond_wait(&change_pending, &state_changes.lock); } - ast_mutex_unlock(&change_pending_lock); } return NULL;