Merged revisions 184339 via svnmerge from

https://origsvn.digium.com/svn/asterisk/trunk

........
r184339 | russell | 2009-03-25 16:57:19 -0500 (Wed, 25 Mar 2009) | 35 lines

Improve performance of the ast_event cache functionality.

This code comes from svn/asterisk/team/russell/event_performance/.

Here is a summary of the changes that have been made, in order of both
invasiveness and performance impact, from smallest to largest.

1) Asterisk 1.6.1 introduces some additional logic to be able to handle
   distributed device state.  This functionality comes at a cost.
   One relatively minor change in this patch is that the extra processing
   required for distributed device state is now completely bypassed if
   it's not needed.

2) One of the things that I noticed when profiling this code was that a
   _lot_ of time was spent doing string comparisons.  I changed the way
   strings are represented in an event to include a hash value at the front.
   So, before doing a string comparison, we do an integer comparison on the
   hash.

3) Finally, the code that handles the event cache has been re-written.
   I tried to do this in a such a way that it had minimal impact on the API.
   I did have to change one API call, though - ast_event_queue_and_cache().
   However, the way it works now is nicer, IMO.  Each type of event that
   can be cached (MWI, device state) has its own hash table and rules for
   hashing and comparing objects.  This by far made the biggest impact on
   performance.

For additional details regarding this code and how it was tested, please see the
review request.

(closes issue #14738)
Reported by: russell

Review: http://reviewboard.digium.com/r/205/

........


git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.6.2@184343 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 42 insertions, 27 deletions

diff --git a/main/devicestate.c b/main/devicestate.c
index 8410b9592..4572c6604 100644
--- a/main/devicestate.c
+++ b/main/devicestate.c
@@ -196,8 +196,10 @@ struct {
 	ast_cond_t cond;
 	ast_mutex_t lock;
 	AST_LIST_HEAD_NOLOCK(, devstate_change) devstate_change_q;
+	unsigned int enabled:1;
 } devstate_collector = {
 	.thread = AST_PTHREADT_NULL,
+	.enabled = 0,
 };
 
 /* Forward declarations */
@@ -428,22 +430,26 @@ static int getproviderstate(const char *provider, const char *address)
 static void devstate_event(const char *device, enum ast_device_state state)
 {
 	struct ast_event *event;
+	enum ast_event_type event_type;
+
+	if (devstate_collector.enabled) {
+		/* Distributed device state is enabled, so this state change is a change
+		 * for a single server, not the real state. */
+		event_type = AST_EVENT_DEVICE_STATE_CHANGE;
+	} else {
+		event_type = AST_EVENT_DEVICE_STATE;
+	}
 
 	ast_debug(3, "device '%s' state '%d'\n", device, state);
 
-	if (!(event = ast_event_new(AST_EVENT_DEVICE_STATE_CHANGE,
+	if (!(event = ast_event_new(event_type,
 			AST_EVENT_IE_DEVICE, AST_EVENT_IE_PLTYPE_STR, device,
 			AST_EVENT_IE_STATE, AST_EVENT_IE_PLTYPE_UINT, state,
 			AST_EVENT_IE_END))) {
 		return;
 	}
 
-	/* Cache this event, replacing an event in the cache with the same
-	 * device name if it exists. */
-	ast_event_queue_and_cache(event,
-		AST_EVENT_IE_DEVICE, AST_EVENT_IE_PLTYPE_STR,
-		AST_EVENT_IE_EID, AST_EVENT_IE_PLTYPE_RAW, sizeof(struct ast_eid),
-		AST_EVENT_IE_END);
+	ast_event_queue_and_cache(event);
 }
 
 /*! Called by the state change thread to find out what the state is, and then
@@ -632,13 +638,12 @@ static void process_collection(const char *device, struct change_collection *col
 		AST_EVENT_IE_DEVICE, AST_EVENT_IE_PLTYPE_STR, device,
 		AST_EVENT_IE_STATE, AST_EVENT_IE_PLTYPE_UINT, state,
 		AST_EVENT_IE_END);
-	
-	if (!event)
+
+	if (!event) {
 		return;
+	}
 
-	ast_event_queue_and_cache(event,
-		AST_EVENT_IE_DEVICE, AST_EVENT_IE_PLTYPE_STR,
-		AST_EVENT_IE_END);
+	ast_event_queue_and_cache(event);
 }
 
 static void handle_devstate_change(struct devstate_change *sc)
@@ -719,21 +724,6 @@ static void devstate_change_collector_cb(const struct ast_event *event, void *da
 /*! \brief Initialize the device state engine in separate thread */
 int ast_device_state_engine_init(void)
 {
-	devstate_collector.event_sub = ast_event_subscribe(AST_EVENT_DEVICE_STATE_CHANGE,
-		devstate_change_collector_cb, NULL, AST_EVENT_IE_END);
-
-	if (!devstate_collector.event_sub) {
-		ast_log(LOG_ERROR, "Failed to create subscription for the device state change collector\n");
-		return -1;
-	}
-
-	ast_mutex_init(&devstate_collector.lock);
-	ast_cond_init(&devstate_collector.cond, NULL);
-	if (ast_pthread_create_background(&devstate_collector.thread, NULL, run_devstate_collector, NULL) < 0) {
-		ast_log(LOG_ERROR, "Unable to start device state collector thread.\n");
-		return -1;
-	}
-
 	ast_cond_init(&change_pending, NULL);
 	if (ast_pthread_create_background(&change_thread, NULL, do_devstate_changes, NULL) < 0) {
 		ast_log(LOG_ERROR, "Unable to start device state change thread.\n");
@@ -830,3 +820,28 @@ enum ast_device_state ast_devstate_aggregate_result(struct ast_devstate_aggregat
 	return AST_DEVICE_NOT_INUSE;
 }
 
+int ast_enable_distributed_devstate(void)
+{
+	if (devstate_collector.enabled) {
+		return 0;
+	}
+
+	devstate_collector.event_sub = ast_event_subscribe(AST_EVENT_DEVICE_STATE_CHANGE,
+		devstate_change_collector_cb, NULL, AST_EVENT_IE_END);
+
+	if (!devstate_collector.event_sub) {
+		ast_log(LOG_ERROR, "Failed to create subscription for the device state change collector\n");
+		return -1;
+	}
+
+	ast_mutex_init(&devstate_collector.lock);
+	ast_cond_init(&devstate_collector.cond, NULL);
+	if (ast_pthread_create_background(&devstate_collector.thread, NULL, run_devstate_collector, NULL) < 0) {
+		ast_log(LOG_ERROR, "Unable to start device state collector thread.\n");
+		return -1;
+	}
+
+	devstate_collector.enabled = 1;
+
+	return 0;
+}