Javascript Semaphore - Revision history

Marian at 10:39, 9 September 2024

2024-09-09T10:39:40Z

Marian: /* General */

2024-09-06T12:26:54Z

‎General

Marian: /* General */

2024-09-06T12:26:25Z

‎General

Marian: /* General */

2024-09-06T12:26:04Z

‎General

Marian: /* Constructor */

2024-09-06T12:25:17Z

‎Constructor

Marian: /* Constructor */

2024-09-06T12:24:47Z

‎Constructor

Marian: /* General */

2024-09-06T12:23:44Z

‎General

Marian: /* Usage */

2024-09-06T12:14:51Z

‎Usage

Marian: /* Usage */

2024-09-06T12:14:42Z

‎Usage

Marian at 12:12, 6 September 2024

2024-09-06T12:12:50Z

← Older revision		Revision as of 10:39, 9 September 2024
Line 101:		Line 101:
	Return:<br/>		Return:<br/>
	True on success, false otherwise (no failure reason is known)		True on success, false otherwise (no failure reason is known)
		+
		+
		+	[[Category:Javascript]]

@@ Line 10: / Line 10: @@
 For more information on Semaphore see
-* [en.wikipedia.org/wiki/Semaphore_(programming) Wikipedia]
+* Wikipedia: en.wikipedia.org/wiki/Semaphore_(programming)
 * Linux man pages for sem_wait(), sem_post(), sem_init()

@@ Line 10: / Line 10: @@
 For more information on Semaphore see
-* '''en.wikipedia.org/wiki/Semaphore_(programming)'''
+* [en.wikipedia.org/wiki/Semaphore_(programming) Wikipedia]
 * Linux man pages for sem_wait(), sem_post(), sem_init()

@@ Line 10: / Line 10: @@
 For more information on Semaphore see
-* asdfhttps://en.wikipedia.org/wiki/Semaphore_(programming)
+* '''en.wikipedia.org/wiki/Semaphore_(programming)'''
 * Linux man pages for sem_wait(), sem_post(), sem_init()

@@ Line 85: / Line 85: @@
 A debug message (including semaphore name) will be put in log if wait is called with ''null'' (wait forever) but failed to lock semaphore for a globally (internal) period.<br/>
-Yate '''maxCount''' is not standard operating system implementation of semaphore. It's a protection used to avoid too many semaphore signal (unlock) operations
+'''maxCount''' is not standard operating system implementation of semaphore. It's a Yate protection used to avoid too many semaphore signal (unlock) operations
 == Methods ==

← Older revision		Revision as of 12:24, 6 September 2024
Line 85:		Line 85:
	A debug message (including semaphore name) will be put in log if wait is called with ''null'' (wait forever) but failed to lock semaphore for a globally (internal) period.<br/>		A debug message (including semaphore name) will be put in log if wait is called with ''null'' (wait forever) but failed to lock semaphore for a globally (internal) period.<br/>

		+	Yate '''maxCount''' is not standard operating system implementation of semaphore. It's a protection used to avoid too many semaphore signal (unlock) operations

	== Methods ==		== Methods ==

@@ Line 3: / Line 3: @@
 Semaphores use an internal counter used for waiting/signal operations.<br/>
 Wait (lock) decrements the counter if possible (greater than 0). If possible, returns immediately. If not, the calling thread is will wait until possible.<br/>
-Signal (unlock) increments the counter. One of the waiting thread will continue processing. Yate '''maxCount''' is a protection used to avoid too many semaphore signal (unlock) operations.<br/>
+Signal (unlock) increments the counter. One of the waiting thread will continue processing.<br/>
 All semaphores created by a script are signaled (unlocked) when the script is unloaded.
 == Usage ==

@@ Line 11: / Line 11: @@
 == Usage ==
-In the following example we are handling some message, send a request to create a GTP session and wait for the response (asynchrnously sent by the gtp module).<br/>
+In the following example we are handling some message, send a request to create a GTP session and wait for the response (asynchronously sent by the gtp module).<br/>
 Using a semaphore allows us to wait a long period of time for the result without returning in script context to check if result was received.

@@ Line 24: / Line 24: @@
       track.semaphore = new Engine.Semaphore(id);
       globalList[id] = track;
-      // Build and send the message request
+      // Build and send the request
       var m = new Message("gtp.request");
-      // Fill message parameters ...
+      // Fill request specific parameters ...
       m.context = id;
       if (m.dispatch(true)) {
@@ Line 68: / Line 68: @@
   Message.install(someMessageHandler,"somemessage");
   Message.install(onGtpResponse,"gtp.response");
 == Constructor ==

← Older revision		Revision as of 12:12, 6 September 2024
Line 1:		Line 1:
		+	== General ==
		+
		+	Semaphores use an internal counter used for waiting/signal operations.<br/>
		+	Wait (lock) decrements the counter if possible (greater than 0). If possible, returns immediately. If not, the calling thread is will wait until possible.<br/>
		+	Signal (unlock) increments the counter. One of the waiting thread will continue processing. Yate '''maxCount''' is a protection used to avoid too many semaphore signal (unlock) operations.<br/>
		+
		+
		+	All semaphores created by a script are signaled (unlocked) when the script is unloaded.
		+
		+
		+	== Usage ==
		+
		+	In the following example we are handling some message, send a request to create a GTP session and wait for the response (asynchrnously sent by the gtp module).<br/>
		+	Using a semaphore allows us to wait a long period of time for the result without returning in script context to check if result was received.
		+
		+	globalList = {};
		+	globalList_id = 0;
		+
		+	function startGtpSession()
		+	{
		+	// Prepare response tracking and handling
		+	var id = Engine.debugName() + ++globalList_id;
		+	var track = {};
		+	track.semaphore = new Engine.Semaphore(id);
		+	globalList[id] = track;
		+	// Build and send the message request
		+	var m = new Message("gtp.request");
		+	// Fill message parameters ...
		+	m.context = id;
		+	if (m.dispatch(true)) {
		+	while (!track.response) {
		+	// Remember: Message.dispatch(true) and Semaphore.wait() release script context mutex
		+	// Check Engine object existence: it will not be available if script is unloaded
		+	if (!Engine)
		+	return null;
		+	track.semaphore.wait(1000);
		+	}
		+	}
		+	delete globalList[id];
		+	return track.response;
		+	}
		+
		+	function onGtpResponse(msg)
		+	{
		+	var track = globalList[msg.context];
		+	if (!track)
		+	return false;
		+	delete globalList[msg.context];
		+	// NOTE: Set some data we may need for response processing in 'track'
		+	track.response = {};
		+	// Signal the waiting entity
		+	if (track.semaphore)
		+	track.semaphore.signal();
		+	return true;
		+	}
		+
		+	function someMessageHandler(msg)
		+	{
		+	var res = startGtpSession();
		+	if (!res) {
		+	// Create failed locally
		+	}
		+	else {
		+	// Process result
		+	}
		+	}
		+
		+	Message.install(someMessageHandler,"somemessage");
		+	Message.install(onGtpResponse,"gtp.response");
		+
		+

	== Constructor ==		== Constructor ==
		+
		+	* '''new Engine.Semaphore([name[,initialCount[,maxCount]]])'''
		+	Parameters:<br/>
		+	'''name''' String. Semaphore name<br/>
		+	'''initialCount''' Numeric. Semaphore initial count. Default: 0. Forced to value of ''maxCount'' if greater than it<br/>
		+	'''maxCount''' Numeric. Semaphore maximum count. Default: 1<br/>
		+
		+	Semaphore name should always be set for debug purposes.<br/>
		+	Yate (see command line parameters) may be started with mutex (any lockable) locking debug options.<br/>
		+	A debug message (including semaphore name) will be put in log if wait is called with ''null'' (wait forever) but failed to lock semaphore for a globally (internal) period.<br/>


	== Methods ==		== Methods ==
		+
		+	* '''wait(maxWait)'''
		+	Attempt to get a lock on the semaphore and eventually wait for it.<br/>
		+	Parameters:<br/>
		+	'''maxWait''' Time to wait for locking. ''null'': wait until allowed. Otherwise: interval (in milliseconds) to wait (0: don't wait). Default: 0<br/>
		+	Return:<br/>
		+	True on success, false otherwise (waiting time elapsed without locking the semaphore or script is unloading)
		+
		+
		+	* '''signal()'''
		+	Unlock the semaphore.<br/>
		+	Return:<br/>
		+	True on success, false otherwise (no failure reason is known)