pjsip: Move from threadpool to taskpool

This change moves the PJSIP module from the threadpool API
to the taskpool API. PJSIP-specific implementations for
task usage have been removed and replaced with calls to
the optimized taskpool implementations instead. The need
for a pool of serializers has also been removed as
taskpool inherently provides this. The default settings
have also been changed to be more realistic for common
usage.

UpgradeNote: The threadpool_* options in pjsip.conf have now
been deprecated though they continue to be read and used.
They have been replaced with taskpool options that give greater
control over the underlying taskpool used for PJSIP. An alembic
upgrade script has been added to add these options to realtime
as well.

include/asterisk/res_pjsip.h

@@ -1921,7 +1921,7 @@ struct ast_sip_endpoint *ast_sip_get_artificial_endpoint(void);
  * There are three major types of threads that SIP will have to deal with:
  * \li Asterisk threads
  * \li PJSIP threads
- * \li SIP threadpool threads (a.k.a. "servants")
+ * \li SIP taskpool threads (a.k.a. "servants")
  *
  * \par Asterisk Threads
  *
@@ -1963,7 +1963,7 @@ struct ast_sip_endpoint *ast_sip_get_artificial_endpoint(void);
  * is NULL, then the work will be handed off to whatever servant can currently handle
  * the task. If this pointer is non-NULL, then the task will not be executed until
  * previous tasks pushed with the same serializer have completed. For more information
- * on serializers and the benefits they provide, see \ref ast_threadpool_serializer
+ * on serializers and the benefits they provide, see \ref ast_taskpool_serializer
  *
  * \par Scheduler
  *
@@ -1992,7 +1992,7 @@ typedef int (*ast_sip_task)(void *user_data);
  * \brief Create a new serializer for SIP tasks
  * \since 13.8.0
  *
- * See \ref ast_threadpool_serializer for more information on serializers.
+ * See \ref ast_taskpool_serializer for more information on serializers.
  * SIP creates serializers so that tasks operating on similar data will run
  * in sequence.
  *
@@ -2009,7 +2009,7 @@ struct ast_serializer_shutdown_group;
  * \brief Create a new serializer for SIP tasks
  * \since 13.8.0
  *
- * See \ref ast_threadpool_serializer for more information on serializers.
+ * See \ref ast_taskpool_serializer for more information on serializers.
  * SIP creates serializers so that tasks operating on similar data will run
  * in sequence.
  *
@@ -2251,7 +2251,7 @@ enum ast_sip_scheduler_task_flags {
 struct ast_sip_sched_task;
 
 /*!
- * \brief Schedule a task to run in the res_pjsip thread pool
+ * \brief Schedule a task to run in the res_pjsip taskpool
  * \since 13.9.0
  *
  * \param serializer The serializer to use.  If NULL, don't use a serializer (see note below)
@@ -2266,7 +2266,7 @@ struct ast_sip_sched_task;
  * \par Serialization
  *
  * Specifying a serializer guarantees serialized execution but NOT specifying a serializer
- * may still result in tasks being effectively serialized if the thread pool is busy.
+ * may still result in tasks being effectively serialized if the taskpool is busy.
  * The point of the serializer BTW is not to prevent parallel executions of the SAME task.
  * That happens automatically (see below).  It's to prevent the task from running at the same
  * time as other work using the same serializer, whether or not it's being run by the scheduler.
@@ -3662,15 +3662,15 @@ int ast_sip_get_host_ip(int af, pj_sockaddr *addr);
 const char *ast_sip_get_host_ip_string(int af);
 
 /*!
- * \brief Return the size of the SIP threadpool's task queue
+ * \brief Return the size of the SIP taskpool's task queue
  * \since 13.7.0
  */
-long ast_sip_threadpool_queue_size(void);
+long ast_sip_taskpool_queue_size(void);
 
 /*!
- * \brief Retrieve the SIP threadpool object
+ * \brief Retrieve the SIP taskpool object
  */
-struct ast_threadpool *ast_sip_threadpool(void);
+struct ast_taskpool *ast_sip_taskpool(void);
 
 /*!
  * \brief Retrieve transport state

include/asterisk/res_pjsip_session.h

@@ -195,7 +195,7 @@ struct ast_sip_session {
 	struct ao2_container *datastores;
 	/*! Serializer for tasks relating to this SIP session */
 	struct ast_taskprocessor *serializer;
-	/*! Non-null if the session serializer is suspended or being suspended. */
+	/*! \deprecated Non-null if the session serializer is suspended or being suspended. */
 	struct ast_sip_session_suspender *suspended;
 	/*! Requests that could not be sent due to current inv_session state */
 	AST_LIST_HEAD_NOLOCK(, ast_sip_session_delayed_request) delayed_requests;

include/asterisk/taskpool.h

@@ -318,4 +318,24 @@ struct ast_taskprocessor *ast_taskpool_serializer_group(const char *name,
  */
 int ast_taskpool_serializer_push_wait(struct ast_taskprocessor *serializer, int (*task)(void *data), void *data);
 
+/*!
+ * \brief Suspend a serializer, causing tasks to be queued until unsuspended
+ * \since 23.1.0
+ * \since 22.7.0
+ * \since 20.17.0
+ *
+ * \param serializer The serializer to suspend
+ */
+void ast_taskpool_serializer_suspend(struct ast_taskprocessor *serializer);
+
+/*!
+ * \brief Unsuspend a serializer, causing tasks to be executed
+ * \since 23.1.0
+ * \since 22.7.0
+ * \since 20.17.0
+ *
+ * \param serializer The serializer to unsuspend
+ */
+void ast_taskpool_serializer_unsuspend(struct ast_taskprocessor *serializer);
+
 #endif /* ASTERISK_TASKPOOL_H */