4 * Citadel "system dependent" stuff.
5 * See COPYING for copyright information.
7 * Here's where we have the Citadel thread implimentation
14 #include <sys/types.h>
16 #include <sys/socket.h>
21 #if TIME_WITH_SYS_TIME
22 # include <sys/time.h>
26 # include <sys/time.h>
32 #include <libcitadel.h>
35 #include "ctdl_module.h"
36 #include "modules_init.h"
37 #include "housekeeping.h"
39 #include "citserver.h"
40 #include "sysdep_decls.h"
44 * define this to use the new worker_thread method of handling connections
49 * New thread interface.
50 * To create a thread you must call one of the create thread functions.
51 * You must pass it the address of (a pointer to a CtdlThreadNode initialised to NULL) like this
52 * struct CtdlThreadNode *node = NULL;
54 * If the thread is created *node will point to the thread control structure for the created thread.
55 * If the thread creation fails *node remains NULL
56 * Do not free the memory pointed to by *node, it doesn't belong to you.
57 * This new interface duplicates much of the eCrash stuff. We should go for closer integration since that would
58 * remove the need for the calls to eCrashRegisterThread and friends
61 static int num_threads = 0; /* Current number of threads */
62 static int num_workers = 0; /* Current number of worker threads */
63 long statcount = 0; /* are we doing a stats check? */
64 static long stats_done = 0;
66 CtdlThreadNode *CtdlThreadList = NULL;
67 CtdlThreadNode *CtdlThreadSchedList = NULL;
69 static CtdlThreadNode *GC_thread = NULL;
70 static char *CtdlThreadStates[CTDL_THREAD_LAST_STATE];
71 double CtdlThreadLoadAvg = 0;
72 double CtdlThreadWorkerAvg = 0;
73 citthread_key_t ThreadKey;
75 citthread_mutex_t Critters[MAX_SEMAPHORES]; /* Things needing locking */
79 void InitialiseSemaphores(void)
83 /* Set up a bunch of semaphores to be used for critical sections */
84 for (i=0; i<MAX_SEMAPHORES; ++i) {
85 citthread_mutex_init(&Critters[i], NULL);
93 * Obtain a semaphore lock to begin a critical section.
94 * but only if no one else has one
96 int try_critical_section(int which_one)
98 /* For all types of critical sections except those listed here,
99 * ensure nobody ever tries to do a critical section within a
100 * transaction; this could lead to deadlock.
102 if ( (which_one != S_FLOORCACHE)
103 #ifdef DEBUG_MEMORY_LEAKS
104 && (which_one != S_DEBUGMEMLEAKS)
106 && (which_one != S_RPLIST)
110 return (citthread_mutex_trylock(&Critters[which_one]));
115 * Obtain a semaphore lock to begin a critical section.
117 void begin_critical_section(int which_one)
119 /* CtdlLogPrintf(CTDL_DEBUG, "begin_critical_section(%d)\n", which_one); */
121 /* For all types of critical sections except those listed here,
122 * ensure nobody ever tries to do a critical section within a
123 * transaction; this could lead to deadlock.
125 if ( (which_one != S_FLOORCACHE)
126 #ifdef DEBUG_MEMORY_LEAKS
127 && (which_one != S_DEBUGMEMLEAKS)
129 && (which_one != S_RPLIST)
133 citthread_mutex_lock(&Critters[which_one]);
137 * Release a semaphore lock to end a critical section.
139 void end_critical_section(int which_one)
141 citthread_mutex_unlock(&Critters[which_one]);
146 * A function to destroy the TSD
148 static void ctdl_thread_internal_dest_tsd(void *arg)
158 * A function to initialise the thread TSD
160 void ctdl_thread_internal_init_tsd(void)
164 if ((ret = citthread_key_create(&ThreadKey, ctdl_thread_internal_dest_tsd))) {
165 CtdlLogPrintf(CTDL_EMERG, "citthread_key_create: %s\n", strerror(ret));
171 * Ensure that we have a key for thread-specific data.
173 * This should be called immediately after startup by any thread
176 void CtdlThreadAllocTSD(void)
180 if (citthread_getspecific(ThreadKey) != NULL)
183 tsd = malloc(sizeof(ThreadTSD));
187 memset(tsd->cursors, 0, sizeof tsd->cursors);
190 citthread_setspecific(ThreadKey, tsd);
194 void ctdl_thread_internal_free_tsd(void)
196 ctdl_thread_internal_dest_tsd(citthread_getspecific(ThreadKey));
197 citthread_setspecific(ThreadKey, NULL);
201 void ctdl_thread_internal_cleanup(void)
204 CtdlThreadNode *this_thread, *that_thread;
206 for (i=0; i<CTDL_THREAD_LAST_STATE; i++)
208 free (CtdlThreadStates[i]);
211 /* Clean up the scheduled thread list */
212 this_thread = CtdlThreadSchedList;
215 that_thread = this_thread;
216 this_thread = this_thread->next;
217 citthread_mutex_destroy(&that_thread->ThreadMutex);
218 citthread_cond_destroy(&that_thread->ThreadCond);
219 citthread_mutex_destroy(&that_thread->SleepMutex);
220 citthread_cond_destroy(&that_thread->SleepCond);
221 citthread_attr_destroy(&that_thread->attr);
224 ctdl_thread_internal_free_tsd();
227 void ctdl_thread_internal_init(void)
229 CtdlThreadNode *this_thread;
232 CtdlThreadStates[CTDL_THREAD_INVALID] = strdup ("Invalid Thread");
233 CtdlThreadStates[CTDL_THREAD_VALID] = strdup("Valid Thread");
234 CtdlThreadStates[CTDL_THREAD_CREATE] = strdup("Thread being Created");
235 CtdlThreadStates[CTDL_THREAD_CANCELLED] = strdup("Thread Cancelled");
236 CtdlThreadStates[CTDL_THREAD_EXITED] = strdup("Thread Exited");
237 CtdlThreadStates[CTDL_THREAD_STOPPING] = strdup("Thread Stopping");
238 CtdlThreadStates[CTDL_THREAD_STOP_REQ] = strdup("Thread Stop Requested");
239 CtdlThreadStates[CTDL_THREAD_SLEEPING] = strdup("Thread Sleeping");
240 CtdlThreadStates[CTDL_THREAD_RUNNING] = strdup("Thread Running");
241 CtdlThreadStates[CTDL_THREAD_BLOCKED] = strdup("Thread Blocked");
243 /* Get ourself a thread entry */
244 this_thread = malloc(sizeof(CtdlThreadNode));
245 if (this_thread == NULL) {
246 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
249 // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
250 memset (this_thread, 0, sizeof(CtdlThreadNode));
252 citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
253 citthread_cond_init (&(this_thread->ThreadCond), NULL);
254 citthread_mutex_init (&(this_thread->SleepMutex), NULL);
255 citthread_cond_init (&(this_thread->SleepCond), NULL);
257 /* We are garbage collector so create us as running */
258 this_thread->state = CTDL_THREAD_RUNNING;
260 if ((ret = citthread_attr_init(&this_thread->attr))) {
261 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
266 this_thread->name = "Garbage Collection Thread";
268 this_thread->tid = citthread_self();
269 GC_thread = this_thread;
272 num_threads++; // Increase the count of threads in the system.
274 this_thread->next = CtdlThreadList;
275 CtdlThreadList = this_thread;
276 if (this_thread->next)
277 this_thread->next->prev = this_thread;
278 /* Set up start times */
279 gettimeofday(&this_thread->start_time, NULL); /* Time this thread started */
280 memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval)); /* Changed state so mark it. */
285 * A function to update a threads load averages
287 void ctdl_thread_internal_update_avgs(CtdlThreadNode *this_thread)
289 struct timeval now, result;
290 double last_duration;
292 gettimeofday(&now, NULL);
293 timersub(&now, &(this_thread->last_state_change), &result);
294 /* I don't think these mutex's are needed here */
295 citthread_mutex_lock(&this_thread->ThreadMutex);
296 // result now has a timeval for the time we spent in the last state since we last updated
297 last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
298 if (this_thread->state == CTDL_THREAD_SLEEPING)
299 this_thread->avg_sleeping += last_duration;
300 if (this_thread->state == CTDL_THREAD_RUNNING)
301 this_thread->avg_running += last_duration;
302 if (this_thread->state == CTDL_THREAD_BLOCKED)
303 this_thread->avg_blocked += last_duration;
304 memcpy (&this_thread->last_state_change, &now, sizeof (struct timeval));
305 citthread_mutex_unlock(&this_thread->ThreadMutex);
309 * A function to chenge the state of a thread
311 void ctdl_thread_internal_change_state (CtdlThreadNode *this_thread, enum CtdlThreadState new_state)
314 * Wether we change state or not we need update the load values
316 ctdl_thread_internal_update_avgs(this_thread);
317 /* This mutex not needed here? */
318 citthread_mutex_lock(&this_thread->ThreadMutex); /* To prevent race condition of a sleeping thread */
319 if ((new_state == CTDL_THREAD_STOP_REQ) && (this_thread->state > CTDL_THREAD_STOP_REQ))
320 this_thread->state = new_state;
321 if (((new_state == CTDL_THREAD_SLEEPING) || (new_state == CTDL_THREAD_BLOCKED)) && (this_thread->state == CTDL_THREAD_RUNNING))
322 this_thread->state = new_state;
323 if ((new_state == CTDL_THREAD_RUNNING) && ((this_thread->state == CTDL_THREAD_SLEEPING) || (this_thread->state == CTDL_THREAD_BLOCKED)))
324 this_thread->state = new_state;
325 citthread_mutex_unlock(&this_thread->ThreadMutex);
330 * A function to tell all threads to exit
332 void CtdlThreadStopAll(void)
334 /* First run any registered shutdown hooks. This probably doesn't belong here. */
335 PerformSessionHooks(EVT_SHUTDOWN);
337 //FIXME: The signalling of the condition should not be in the critical_section
338 // We need to build a list of threads we are going to signal and then signal them afterwards
340 CtdlThreadNode *this_thread;
342 begin_critical_section(S_THREAD_LIST);
343 this_thread = CtdlThreadList;
344 // Ask the GC thread to stop first so everything knows we are shutting down.
345 GC_thread->state = CTDL_THREAD_STOP_REQ;
348 #ifdef THREADS_USESIGNALS
349 if (!citthread_equal(this_thread->tid, GC_thread->tid))
350 citthread_kill(this_thread->tid, SIGHUP);
352 ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
353 citthread_cond_signal(&this_thread->ThreadCond);
354 citthread_cond_signal(&this_thread->SleepCond);
355 this_thread->stop_ticker = time(NULL);
356 CtdlLogPrintf(CTDL_DEBUG, "Thread system stopping thread \"%s\" (0x%08lx).\n",
357 this_thread->name, this_thread->tid);
358 this_thread = this_thread->next;
360 end_critical_section(S_THREAD_LIST);
365 * A function to wake up all sleeping threads
367 void CtdlThreadWakeAll(void)
369 CtdlThreadNode *this_thread;
371 CtdlLogPrintf(CTDL_DEBUG, "Thread system waking all threads.\n");
373 begin_critical_section(S_THREAD_LIST);
374 this_thread = CtdlThreadList;
377 if (!this_thread->thread_func)
379 citthread_cond_signal(&this_thread->ThreadCond);
380 citthread_cond_signal(&this_thread->SleepCond);
382 this_thread = this_thread->next;
384 end_critical_section(S_THREAD_LIST);
389 * A function to return the number of threads running in the system
391 int CtdlThreadGetCount(void)
396 int CtdlThreadGetWorkers(void)
401 double CtdlThreadGetWorkerAvg(void)
405 begin_critical_section(S_THREAD_LIST);
406 ret = CtdlThreadWorkerAvg;
407 end_critical_section(S_THREAD_LIST);
411 double CtdlThreadGetLoadAvg(void)
418 /* Borrowed this straight from procps */
419 smp_num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
420 if(smp_num_cpus<1) smp_num_cpus=1; /* SPARC glibc is buggy */
422 ret = getloadavg(load_avg, 3);
425 return load_avg[0] / smp_num_cpus;
427 * This old chunk of code return a value that indicated the load on citserver
428 * This value could easily reach 100 % even when citserver was doing very little and
429 * hence the machine has much more spare capacity.
430 * Because this value was used to determine if the machine was under heavy load conditions
431 * from other processes in the system then citserver could be strangled un-necesarily
432 * What we are actually trying to achieve is to strangle citserver if the machine is heavily loaded.
433 * So we have changed this.
435 begin_critical_section(S_THREAD_LIST);
436 ret = CtdlThreadLoadAvg;
437 end_critical_section(S_THREAD_LIST);
446 * A function to rename a thread
447 * Returns a const char *
449 const char *CtdlThreadName(const char *name)
451 const char *old_name;
455 CtdlLogPrintf(CTDL_WARNING, "Thread system WARNING. Attempt to CtdlThreadRename() a non thread. %s\n", name);
466 * A function to force a thread to exit
468 void CtdlThreadCancel(CtdlThreadNode *thread)
470 CtdlThreadNode *this_thread;
475 this_thread = thread;
478 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() a non thread.\n");
483 if (!this_thread->thread_func)
485 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() the garbage collector.\n");
490 ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_CANCELLED);
491 citthread_cancel(this_thread->tid);
496 * A function for a thread to check if it has been asked to stop
498 int CtdlThreadCheckStop(void)
504 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, CtdlThreadCheckStop() called by a non thread.\n");
511 #ifdef THREADS_USESIGNALS
514 CtdlLogPrintf(CTDL_DEBUG, "Thread \"%s\" caught signal %d.\n", CT->name, CT->signal);
518 if(state == CTDL_THREAD_STOP_REQ)
520 CT->state = CTDL_THREAD_STOPPING;
523 else if((state < CTDL_THREAD_STOP_REQ) && (state > CTDL_THREAD_CREATE))
532 * A function to ask a thread to exit
533 * The thread must call CtdlThreadCheckStop() periodically to determine if it should exit
535 void CtdlThreadStop(CtdlThreadNode *thread)
537 CtdlThreadNode *this_thread;
542 this_thread = thread;
545 if (!(this_thread->thread_func))
546 return; // Don't stop garbage collector
547 #ifdef THREADS_USESIGNALS
548 if (!citthread_equal(this_thread->tid, GC_thread->tid))
549 citthread_kill(this_thread->tid, SIGHUP);
551 ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
552 citthread_cond_signal(&this_thread->ThreadCond);
553 citthread_cond_signal(&this_thread->SleepCond);
554 this_thread->stop_ticker = time(NULL);
558 * So we now have a sleep command that works with threads but it is in seconds
560 void CtdlThreadSleep(int secs)
562 struct timespec wake_time;
563 struct timeval time_now;
568 CtdlLogPrintf(CTDL_WARNING, "CtdlThreadSleep() called by something that is not a thread. Should we die?\n");
572 memset (&wake_time, 0, sizeof(struct timespec));
573 gettimeofday(&time_now, NULL);
574 wake_time.tv_sec = time_now.tv_sec + secs;
575 wake_time.tv_nsec = time_now.tv_usec * 10;
577 ctdl_thread_internal_change_state (CT, CTDL_THREAD_SLEEPING);
579 citthread_mutex_lock(&CT->ThreadMutex); /* Prevent something asking us to awaken before we've gone to sleep */
580 citthread_cond_timedwait(&CT->SleepCond, &CT->ThreadMutex, &wake_time);
581 citthread_mutex_unlock(&CT->ThreadMutex);
583 ctdl_thread_internal_change_state (CT, CTDL_THREAD_RUNNING);
588 * Routine to clean up our thread function on exit
590 static void ctdl_internal_thread_cleanup(void *arg)
593 * In here we were called by the current thread because it is exiting
594 * NB. WE ARE THE CURRENT THREAD
596 CtdlLogPrintf(CTDL_NOTICE, "Thread \"%s\" (0x%08lx) exited.\n", CT->name, CT->tid);
598 #ifdef HAVE_BACKTRACE
599 eCrash_UnregisterThread();
602 citthread_mutex_lock(&CT->ThreadMutex);
603 CT->state = CTDL_THREAD_EXITED; // needs to be last thing else house keeping will unlink us too early
604 citthread_mutex_unlock(&CT->ThreadMutex);
608 * A quick function to show the load averages
610 void ctdl_thread_internal_calc_loadavg(void)
612 CtdlThreadNode *that_thread;
613 double load_avg, worker_avg;
616 that_thread = CtdlThreadList;
621 /* Update load averages */
622 ctdl_thread_internal_update_avgs(that_thread);
623 citthread_mutex_lock(&that_thread->ThreadMutex);
624 that_thread->load_avg = (that_thread->avg_sleeping + that_thread->avg_running) / (that_thread->avg_sleeping + that_thread->avg_running + that_thread->avg_blocked) * 100;
625 that_thread->avg_sleeping /= 2;
626 that_thread->avg_running /= 2;
627 that_thread->avg_blocked /= 2;
628 load_avg += that_thread->load_avg;
629 if (that_thread->flags & CTDLTHREAD_WORKER)
631 worker_avg += that_thread->load_avg;
634 #ifdef WITH_THREADLOG
635 CtdlLogPrintf(CTDL_DEBUG, "CtdlThread, \"%s\" (%lu) \"%s\" %.2f %.2f %.2f %.2f\n",
638 CtdlThreadStates[that_thread->state],
639 that_thread->avg_sleeping,
640 that_thread->avg_running,
641 that_thread->avg_blocked,
642 that_thread->load_avg);
644 citthread_mutex_unlock(&that_thread->ThreadMutex);
645 that_thread = that_thread->next;
647 CtdlThreadLoadAvg = load_avg/num_threads;
648 CtdlThreadWorkerAvg = worker_avg/workers;
649 #ifdef WITH_THREADLOG
650 CtdlLogPrintf(CTDL_INFO, "System load average %.2f, workers averag %.2f, threads %d, workers %d, sessions %d\n", CtdlThreadGetLoadAvg(), CtdlThreadWorkerAvg, num_threads, num_workers, num_sessions);
656 * Garbage collection routine.
657 * Gets called by main() in a loop to clean up the thread list periodically.
659 void CtdlThreadGC (void)
661 CtdlThreadNode *this_thread, *that_thread;
662 int workers = 0, sys_workers;
665 begin_critical_section(S_THREAD_LIST);
667 /* Handle exiting of garbage collector thread */
669 CtdlThreadList->state = CTDL_THREAD_EXITED;
671 #ifdef WITH_THREADLOG
672 CtdlLogPrintf(CTDL_DEBUG, "Thread system running garbage collection.\n");
675 * Woke up to do garbage collection
677 this_thread = CtdlThreadList;
680 that_thread = this_thread;
681 this_thread = this_thread->next;
683 if ((that_thread->state == CTDL_THREAD_STOP_REQ || that_thread->state == CTDL_THREAD_STOPPING)
684 && (!citthread_equal(that_thread->tid, citthread_self())))
685 CtdlLogPrintf(CTDL_DEBUG, "Waiting for thread %s (0x%08lx) to exit.\n", that_thread->name, that_thread->tid);
689 * Catch the situation where a worker was asked to stop but couldn't and we are not
692 that_thread->stop_ticker = 0;
695 if (that_thread->stop_ticker + 5 == time(NULL))
697 CtdlLogPrintf(CTDL_DEBUG, "Thread System: The thread \"%s\" (0x%08lx) failed to self terminate within 5 ticks. It would be cancelled now.\n", that_thread->name, that_thread->tid);
698 if ((that_thread->flags & CTDLTHREAD_WORKER) == 0)
699 CtdlLogPrintf(CTDL_INFO, "Thread System: A non worker thread would have been canceled this may cause message loss.\n");
700 // that_thread->state = CTDL_THREAD_CANCELLED;
701 that_thread->stop_ticker++;
702 // citthread_cancel(that_thread->tid);
706 /* Do we need to clean up this thread? */
707 if ((that_thread->state != CTDL_THREAD_EXITED) && (that_thread->state != CTDL_THREAD_CANCELLED))
709 if(that_thread->flags & CTDLTHREAD_WORKER)
710 workers++; /* Sanity check on number of worker threads */
714 if (citthread_equal(that_thread->tid, citthread_self()) && that_thread->thread_func)
716 end_critical_section(S_THREAD_LIST);
717 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, a thread is trying to clean up after itself.\n");
722 if (num_threads <= 0)
724 end_critical_section(S_THREAD_LIST);
725 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, num_threads <= 0 and trying to do Garbage Collection.\n");
730 if(that_thread->flags & CTDLTHREAD_WORKER)
731 num_workers--; /* This is a wroker thread so reduce the count. */
733 /* If we are unlinking the list head then the next becomes the list head */
734 if(that_thread->prev)
735 that_thread->prev->next = that_thread->next;
737 CtdlThreadList = that_thread->next;
738 if(that_thread->next)
739 that_thread->next->prev = that_thread->prev;
741 citthread_cond_signal(&that_thread->ThreadCond);
742 citthread_cond_signal(&that_thread->SleepCond); // Make sure this thread is awake
743 citthread_mutex_lock(&that_thread->ThreadMutex); // Make sure it has done what its doing
744 citthread_mutex_unlock(&that_thread->ThreadMutex);
746 * Join on the thread to do clean up and prevent memory leaks
747 * Also makes sure the thread has cleaned up after itself before we remove it from the list
748 * We can join on the garbage collector thread the join should just return EDEADLCK
750 ret = citthread_join (that_thread->tid, NULL);
752 CtdlLogPrintf(CTDL_DEBUG, "Garbage collection on own thread.\n");
753 else if (ret == EINVAL)
754 CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, that thread already joined on.\n");
755 else if (ret == ESRCH)
756 CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, no thread to join on.\n");
758 CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, citthread_join returned an unknown error(%d).\n", ret);
760 * Now we own that thread entry
762 CtdlLogPrintf(CTDL_INFO, "Garbage Collection for thread \"%s\" (0x%08lx).\n",
763 that_thread->name, that_thread->tid);
764 citthread_mutex_destroy(&that_thread->ThreadMutex);
765 citthread_cond_destroy(&that_thread->ThreadCond);
766 citthread_mutex_destroy(&that_thread->SleepMutex);
767 citthread_cond_destroy(&that_thread->SleepCond);
768 citthread_attr_destroy(&that_thread->attr);
771 sys_workers = num_workers;
772 end_critical_section(S_THREAD_LIST);
774 /* Sanity check number of worker threads */
775 if (workers != sys_workers)
777 CtdlLogPrintf(CTDL_EMERG,
778 "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n",
789 * Runtime function for a Citadel Thread.
790 * This initialises the threads environment and then calls the user supplied thread function
791 * Note that this is the REAL thread function and wraps the users thread function.
793 static void *ctdl_internal_thread_func (void *arg)
795 CtdlThreadNode *this_thread;
798 /* lock and unlock the thread list.
799 * This causes this thread to wait until all its creation stuff has finished before it
800 * can continue its execution.
802 begin_critical_section(S_THREAD_LIST);
803 this_thread = (CtdlThreadNode *) arg;
804 gettimeofday(&this_thread->start_time, NULL); /* Time this thread started */
805 // citthread_mutex_lock(&this_thread->ThreadMutex);
807 // Register the cleanup function to take care of when we exit.
808 citthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
809 // Get our thread data structure
810 CtdlThreadAllocTSD();
812 this_thread->pid = getpid();
813 memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval)); /* Changed state so mark it. */
814 /* Only change to running state if we weren't asked to stop during the create cycle
815 * Other wise there is a window to allow this threads creation to continue to full grown and
816 * therby prevent a shutdown of the server.
818 // citthread_mutex_unlock(&this_thread->ThreadMutex);
820 if (!CtdlThreadCheckStop())
822 citthread_mutex_lock(&this_thread->ThreadMutex);
823 this_thread->state = CTDL_THREAD_RUNNING;
824 citthread_mutex_unlock(&this_thread->ThreadMutex);
826 end_critical_section(S_THREAD_LIST);
828 // Register for tracing
829 #ifdef HAVE_BACKTRACE
830 eCrash_RegisterThread(this_thread->name, 0);
833 // Tell the world we are here
834 CtdlLogPrintf(CTDL_NOTICE, "Created a new thread \"%s\" (0x%08lx).\n",
835 this_thread->name, this_thread->tid);
838 * run the thread to do the work but only if we haven't been asked to stop
840 if (!CtdlThreadCheckStop())
841 ret = (this_thread->thread_func)(this_thread->user_args);
844 * Our thread is exiting either because it wanted to end or because the server is stopping
845 * We need to clean up
847 citthread_cleanup_pop(1); // Execute our cleanup routine and remove it
856 * Function to initialise an empty thread structure
858 CtdlThreadNode *ctdl_internal_init_thread_struct(CtdlThreadNode *this_thread, long flags)
862 // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
863 memset (this_thread, 0, sizeof(CtdlThreadNode));
865 /* Create the mutex's early so we can use them */
866 citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
867 citthread_cond_init (&(this_thread->ThreadCond), NULL);
868 citthread_mutex_init (&(this_thread->SleepMutex), NULL);
869 citthread_cond_init (&(this_thread->SleepCond), NULL);
871 this_thread->state = CTDL_THREAD_CREATE;
873 if ((ret = citthread_attr_init(&this_thread->attr))) {
874 citthread_mutex_unlock(&this_thread->ThreadMutex);
875 citthread_mutex_destroy(&(this_thread->ThreadMutex));
876 citthread_cond_destroy(&(this_thread->ThreadCond));
877 citthread_mutex_destroy(&(this_thread->SleepMutex));
878 citthread_cond_destroy(&(this_thread->SleepCond));
879 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
884 /* Our per-thread stacks need to be bigger than the default size,
885 * otherwise the MIME parser crashes on FreeBSD, and the IMAP service
886 * crashes on 64-bit Linux.
888 if (flags & CTDLTHREAD_BIGSTACK)
890 #ifdef WITH_THREADLOG
891 CtdlLogPrintf(CTDL_INFO, "Thread system. Creating BIG STACK thread.\n");
893 if ((ret = citthread_attr_setstacksize(&this_thread->attr, THREADSTACKSIZE))) {
894 citthread_mutex_unlock(&this_thread->ThreadMutex);
895 citthread_mutex_destroy(&(this_thread->ThreadMutex));
896 citthread_cond_destroy(&(this_thread->ThreadCond));
897 citthread_mutex_destroy(&(this_thread->SleepMutex));
898 citthread_cond_destroy(&(this_thread->SleepCond));
899 citthread_attr_destroy(&this_thread->attr);
900 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_setstacksize: %s\n",
907 /* Set this new thread with an avg_blocked of 2. We do this so that its creation affects the
908 * load average for the system. If we don't do this then we create a mass of threads at the same time
909 * because the creation didn't affect the load average.
911 this_thread->avg_blocked = 2;
913 return (this_thread);
920 * Internal function to create a thread.
922 CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void *(*thread_func) (void *arg), void *args)
925 CtdlThreadNode *this_thread;
927 if (num_threads >= 32767)
929 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
933 this_thread = malloc(sizeof(CtdlThreadNode));
934 if (this_thread == NULL) {
935 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
939 /* Initialise the thread structure */
940 if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
943 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
947 * If we got here we are going to create the thread so we must initilise the structure
948 * first because most implimentations of threading can't create it in a stopped state
949 * and it might want to do things with its structure that aren't initialised otherwise.
953 this_thread->name = name;
957 this_thread->name = "Un-named Thread";
960 this_thread->flags = flags;
961 this_thread->thread_func = thread_func;
962 this_thread->user_args = args;
964 // citthread_mutex_lock(&this_thread->ThreadMutex);
966 begin_critical_section(S_THREAD_LIST);
968 * We pass this_thread into the thread as its args so that it can find out information
969 * about itself and it has a bit of storage space for itself, not to mention that the REAL
970 * thread function needs to finish off the setup of the structure
972 if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
974 end_critical_section(S_THREAD_LIST);
975 CtdlLogPrintf(CTDL_ALERT, "Thread system, Can't create thread: %s\n",
977 citthread_mutex_unlock(&this_thread->ThreadMutex);
978 citthread_mutex_destroy(&(this_thread->ThreadMutex));
979 citthread_cond_destroy(&(this_thread->ThreadCond));
980 citthread_mutex_destroy(&(this_thread->SleepMutex));
981 citthread_cond_destroy(&(this_thread->SleepCond));
982 citthread_attr_destroy(&this_thread->attr);
987 num_threads++; // Increase the count of threads in the system.
988 if(this_thread->flags & CTDLTHREAD_WORKER)
991 this_thread->next = CtdlThreadList;
992 CtdlThreadList = this_thread;
993 if (this_thread->next)
994 this_thread->next->prev = this_thread;
995 ctdl_thread_internal_calc_loadavg();
997 // citthread_mutex_unlock(&this_thread->ThreadMutex);
998 end_critical_section(S_THREAD_LIST);
1004 * Wrapper function to create a thread
1005 * ensures the critical section and other protections are in place.
1006 * char *name = name to give to thread, if NULL, use generic name
1007 * int flags = flags to determine type of thread and standard facilities
1009 CtdlThreadNode *CtdlThreadCreate(char *name, long flags, void *(*thread_func) (void *arg), void *args)
1011 CtdlThreadNode *ret = NULL;
1013 ret = ctdl_internal_create_thread(name, flags, thread_func, args);
1020 * Internal function to schedule a thread.
1021 * Must be called from within a S_THREAD_LIST critical section
1023 CtdlThreadNode *CtdlThreadSchedule(char *name, long flags, void *(*thread_func) (void *arg), void *args, time_t when)
1025 CtdlThreadNode *this_thread;
1027 if (num_threads >= 32767)
1029 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
1033 this_thread = malloc(sizeof(CtdlThreadNode));
1034 if (this_thread == NULL) {
1035 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
1038 /* Initialise the thread structure */
1039 if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
1042 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
1047 * If we got here we are going to create the thread so we must initilise the structure
1048 * first because most implimentations of threading can't create it in a stopped state
1049 * and it might want to do things with its structure that aren't initialised otherwise.
1053 this_thread->name = name;
1057 this_thread->name = "Un-named Thread";
1060 this_thread->flags = flags;
1061 this_thread->thread_func = thread_func;
1062 this_thread->user_args = args;
1065 * When to start this thread
1067 this_thread->when = when;
1069 begin_critical_section(S_SCHEDULE_LIST);
1070 this_thread->next = CtdlThreadSchedList;
1071 CtdlThreadSchedList = this_thread;
1072 if (this_thread->next)
1073 this_thread->next->prev = this_thread;
1074 end_critical_section(S_SCHEDULE_LIST);
1081 CtdlThreadNode *ctdl_thread_internal_start_scheduled (CtdlThreadNode *this_thread)
1085 // citthread_mutex_lock(&that_thread->ThreadMutex);
1086 begin_critical_section(S_THREAD_LIST);
1088 * We pass this_thread into the thread as its args so that it can find out information
1089 * about itself and it has a bit of storage space for itself, not to mention that the REAL
1090 * thread function needs to finish off the setup of the structure
1092 if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1094 end_critical_section(S_THREAD_LIST);
1095 CtdlLogPrintf(CTDL_DEBUG, "Failed to start scheduled thread \"%s\": %s\n", this_thread->name, strerror(ret));
1096 // citthread_mutex_unlock(&this_thread->ThreadMutex);
1097 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1098 citthread_cond_destroy(&(this_thread->ThreadCond));
1099 citthread_mutex_destroy(&(this_thread->SleepMutex));
1100 citthread_cond_destroy(&(this_thread->SleepCond));
1101 citthread_attr_destroy(&this_thread->attr);
1107 num_threads++; // Increase the count of threads in the system.
1108 if(this_thread->flags & CTDLTHREAD_WORKER)
1111 this_thread->next = CtdlThreadList;
1112 CtdlThreadList = this_thread;
1113 if (this_thread->next)
1114 this_thread->next->prev = this_thread;
1115 // citthread_mutex_unlock(&that_thread->ThreadMutex);
1117 ctdl_thread_internal_calc_loadavg();
1118 end_critical_section(S_THREAD_LIST);
1126 void ctdl_thread_internal_check_scheduled(void)
1128 CtdlThreadNode *this_thread, *that_thread;
1131 /* Don't start scheduled threads if the system wants single user mode */
1132 if (CtdlWantSingleUser())
1135 if (try_critical_section(S_SCHEDULE_LIST))
1136 return; /* If this list is locked we wait till the next chance */
1140 #ifdef WITH_THREADLOG
1141 CtdlLogPrintf(CTDL_DEBUG, "Checking for scheduled threads to start.\n");
1144 this_thread = CtdlThreadSchedList;
1147 that_thread = this_thread;
1148 this_thread = this_thread->next;
1150 if (now > that_thread->when)
1152 /* Unlink from schedule list */
1153 if (that_thread->prev)
1154 that_thread->prev->next = that_thread->next;
1156 CtdlThreadSchedList = that_thread->next;
1157 if (that_thread->next)
1158 that_thread->next->prev = that_thread->prev;
1160 that_thread->next = that_thread->prev = NULL;
1161 #ifdef WITH_THREADLOG
1162 CtdlLogPrintf(CTDL_DEBUG, "About to start scheduled thread \"%s\".\n", that_thread->name);
1164 if (CT->state > CTDL_THREAD_STOP_REQ)
1165 { /* Only start it if the system is not stopping */
1166 if (ctdl_thread_internal_start_scheduled (that_thread))
1168 #ifdef WITH_THREADLOG
1169 CtdlLogPrintf(CTDL_INFO, "Thread system, Started a scheduled thread \"%s\" (0x%08lx).\n",
1170 that_thread->name, that_thread->tid);
1175 #ifdef WITH_THREADLOG
1178 CtdlLogPrintf(CTDL_DEBUG, "Thread \"%s\" will start in %ld seconds.\n",
1179 that_thread->name, that_thread->when - time(NULL));
1183 end_critical_section(S_SCHEDULE_LIST);
1188 * A warapper function for select so we can show a thread as blocked
1190 int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
1194 ctdl_thread_internal_change_state(CT, CTDL_THREAD_BLOCKED);
1195 if (!CtdlThreadCheckStop())
1196 ret = select(n, readfds, writefds, exceptfds, timeout);
1198 * If the select returned <= 0 then it failed due to an error
1199 * or timeout so this thread could stop if asked to do so.
1200 * Anything else means it needs to continue unless the system is shutting down
1205 * The select says this thread needs to do something useful.
1206 * This thread was in an idle state so it may have been asked to stop
1207 * but if the system isn't shutting down this thread is no longer
1208 * idle and select has given it a task to do so it must not stop
1209 * In this condition we need to force it into the running state.
1210 * CtdlThreadGC will clear its ticker for us.
1212 * FIXME: there is still a small hole here. It is possible for the sequence of locking
1213 * to allow the state to get changed to STOP_REQ just after this code if the other thread
1214 * has decided to change the state before this lock, it there fore has to wait till the lock
1215 * completes but it will continue to change the state. We need something a bit better here.
1217 citthread_mutex_lock(&CT->ThreadMutex); /* To prevent race condition of a sleeping thread */
1218 if (GC_thread->state > CTDL_THREAD_STOP_REQ && CT->state <= CTDL_THREAD_STOP_REQ)
1220 CtdlLogPrintf(CTDL_DEBUG, "Thread %s (0x%08lx) refused stop request.\n", CT->name, CT->tid);
1221 CT->state = CTDL_THREAD_RUNNING;
1223 citthread_mutex_unlock(&CT->ThreadMutex);
1226 ctdl_thread_internal_change_state(CT, CTDL_THREAD_RUNNING);
1233 void *new_worker_thread(void *arg);
1234 extern void close_masters (void);
1237 void *simulation_worker (void*arg) {
1238 struct CitContext *this;
1240 this = CreateNewContext();
1242 this->state = CON_IDLE;
1243 dead_session_purge(1);
1244 begin_critical_section(S_SESSION_TABLE);
1246 end_critical_section(S_SESSION_TABLE);
1251 void *simulation_thread (void *arg)
1253 long stats = statcount;
1256 CtdlThreadCreate("Connection simulation worker", CTDLTHREAD_BIGSTACK, simulation_worker, NULL);
1259 CtdlThreadStopAll();
1263 void go_threading(void)
1266 CtdlThreadNode *last_worker;
1267 struct timeval start, now, result;
1268 double last_duration;
1271 * Initialise the thread system
1273 ctdl_thread_internal_init();
1275 /* Second call to module init functions now that threading is up */
1277 initialise_modules(1);
1279 CtdlLogPrintf(CTDL_EMERG, "Running connection simulation stats\n");
1280 gettimeofday(&start, NULL);
1281 CtdlThreadCreate("Connection simulation master", CTDLTHREAD_BIGSTACK, simulation_thread, NULL);
1286 * This thread is now used for garbage collection of other threads in the thread list
1288 CtdlLogPrintf(CTDL_INFO, "Startup thread %d becoming garbage collector,\n", citthread_self());
1291 * We do a lot of locking and unlocking of the thread list in here.
1292 * We do this so that we can repeatedly release time for other threads
1293 * that may be waiting on the thread list.
1294 * We are a low priority thread so we can afford to do this
1297 while (CtdlThreadGetCount())
1300 exit_signal = CT->signal;
1303 CtdlThreadStopAll();
1306 check_sched_shutdown();
1307 if (CT->state > CTDL_THREAD_STOP_REQ)
1309 begin_critical_section(S_THREAD_LIST);
1310 ctdl_thread_internal_calc_loadavg();
1311 end_critical_section(S_THREAD_LIST);
1313 ctdl_thread_internal_check_scheduled(); /* start scheduled threads */
1316 /* Reduce the size of the worker thread pool if necessary. */
1317 if ((CtdlThreadGetWorkers() > config.c_min_workers + 1) && (CtdlThreadWorkerAvg < 20) && (CT->state > CTDL_THREAD_STOP_REQ))
1319 /* Ask a worker thread to stop as we no longer need it */
1320 begin_critical_section(S_THREAD_LIST);
1321 last_worker = CtdlThreadList;
1324 citthread_mutex_lock(&last_worker->ThreadMutex);
1325 if (last_worker->flags & CTDLTHREAD_WORKER && (last_worker->state > CTDL_THREAD_STOPPING) && (last_worker->Context == NULL))
1327 citthread_mutex_unlock(&last_worker->ThreadMutex);
1330 citthread_mutex_unlock(&last_worker->ThreadMutex);
1331 last_worker = last_worker->next;
1333 end_critical_section(S_THREAD_LIST);
1336 #ifdef WITH_THREADLOG
1337 CtdlLogPrintf(CTDL_DEBUG, "Thread system, stopping excess worker thread \"%s\" (0x%08lx).\n",
1342 CtdlThreadStop(last_worker);
1347 * If all our workers are working hard, start some more to help out
1350 /* FIXME: come up with a better way to dynamically alter the number of threads
1351 * based on the system load
1355 if ((((CtdlThreadGetWorkers() < config.c_max_workers) && (CtdlThreadGetWorkers() <= num_sessions) ) || CtdlThreadGetWorkers() < config.c_min_workers) && (CT->state > CTDL_THREAD_STOP_REQ))
1357 if ((((CtdlThreadGetWorkers() < config.c_max_workers) && (CtdlThreadGetWorkerAvg() > 60)) || CtdlThreadGetWorkers() < config.c_min_workers) && (CT->state > CTDL_THREAD_STOP_REQ))
1358 #endif /* NEW_WORKER */
1360 /* Only start new threads if we are not going to overload the machine */
1361 if (CtdlThreadGetLoadAvg() < ((double)1.00)) {
1362 for (i=0; i<5 ; i++) {
1364 CtdlThreadCreate("Worker Thread (new)",
1365 CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER,
1370 CtdlThreadCreate("Worker Thread",
1371 CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER,
1375 #endif /* NEW_WORKER */
1379 CtdlLogPrintf (CTDL_WARNING, "Server strangled due to machine load average too high.\n");
1385 if (CtdlThreadGetCount() <= 1) // Shutting down clean up the garbage collector
1390 #ifdef THREADS_USESIGNALS
1391 if (CtdlThreadGetCount() && CT->state > CTDL_THREAD_STOP_REQ)
1393 if (CtdlThreadGetCount() && !statcount)
1398 * If the above loop exits we must be shutting down since we obviously have no threads
1400 ctdl_thread_internal_cleanup();
1403 gettimeofday(&now, NULL);
1404 timersub(&now, &start, &result);
1405 last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
1406 CtdlLogPrintf(CTDL_EMERG, "Simulated %ld connections in %f seconds\n", stats_done, last_duration);
1414 * Starting a new implimentation of a worker thread.
1415 * This new implimentation will be faster and do more work per thread.
1419 * Select on master socket.
1420 * First worker thread in here acquires the lock and builds an FDSET of master sockets.
1421 * then it goes into a loop selecting on the master sockets timing out every few milliseconds.
1422 * If it times out it rebiulds its list and loops.
1423 * If the select succeeds it creates a new context and returns.
1424 * During this time the other workers are selecting on existing contexts or sleeping.
1426 void select_on_master(void)
1429 struct ServiceFunctionHook *serviceptr;
1430 int ssock; /* Descriptor for client socket */
1435 struct CitContext *con;
1436 const char *old_name;
1440 old_name = CtdlThreadName("select_on_master");
1442 /* Initialize the fdset. */
1446 /* First, add the various master sockets to the fdset. */
1447 for (serviceptr = ServiceHookTable; serviceptr != NULL; serviceptr = serviceptr->next ) {
1448 m = serviceptr->msock;
1449 FD_SET(m, &readfds);
1455 tv.tv_sec = 1; /* wake up every 1 sec if no input */
1457 retval = CtdlThreadSelect(highest + 1, &readfds, NULL, NULL, &tv);
1459 /* Select got an error or we are shutting down so get out */
1460 if (retval == 0 || CtdlThreadCheckStop()) {
1461 CtdlThreadName(old_name);
1465 /* Select says something happened on one of our master sockets so now we handle it */
1466 for (serviceptr = ServiceHookTable; serviceptr != NULL; serviceptr = serviceptr->next ) {
1467 if (FD_ISSET(serviceptr->msock, &readfds)) {
1468 ssock = accept(serviceptr->msock, NULL, 0);
1470 CtdlLogPrintf(CTDL_DEBUG, "New client socket %d\n", ssock);
1471 /* The master socket is non-blocking but the client
1472 * sockets need to be blocking, otherwise certain
1473 * operations barf on FreeBSD. Not a fatal error.
1475 if (fcntl(ssock, F_SETFL, 0) < 0) {
1476 CtdlLogPrintf(CTDL_EMERG,
1477 "citserver: Can't set socket to blocking: %s\n",
1481 /* New context will be created already
1482 * set up in the CON_EXECUTING state.
1484 con = CreateNewContext();
1487 /* Assign our new socket number to it. */
1488 con->client_socket = ssock;
1489 con->h_command_function = serviceptr->h_command_function;
1490 con->h_async_function = serviceptr->h_async_function;
1491 con->ServiceName = serviceptr->ServiceName;
1492 /* Determine whether it's a local socket */
1493 if (serviceptr->sockpath != NULL)
1494 con->is_local_socket = 1;
1496 /* Set the SO_REUSEADDR socket option */
1498 setsockopt(ssock, SOL_SOCKET, SO_REUSEADDR, &i, sizeof(i));
1500 become_session(con);
1502 serviceptr->h_greeting_function();
1503 become_session(NULL);
1504 con->state = CON_IDLE;
1510 CtdlThreadName(old_name);
1514 * Select on client socket.
1515 * First worker thread in here acquires the lock and builds an FDSET of client sockets.
1516 * then it selects on the client sockets timing out after 1 second.
1517 * If it times out the thread goes off to check on housekeeping etc.
1518 * If the select succeeds the thread goes off to handle the client request.
1519 * If the list of client connections is empty the threads all sleep for one second
1521 struct CitContext *select_on_client(void)
1527 const char *old_name;
1530 old_name = CtdlThreadName("select_on_client");
1532 /* Initialise the fdset */
1534 FD_SET(CT->Context->client_socket, &readfds);
1535 highest = CT->Context->client_socket;
1536 /* Now we can select on any connections that are waiting */
1538 if (!CtdlThreadCheckStop())
1540 tv.tv_sec = config.c_sleeping; /* wake up every second if no input */
1542 retval = select(highest + 1, &readfds, NULL, NULL, &tv);
1544 else /* Shutting down? */
1546 CtdlThreadName(old_name);
1551 /* Now figure out who made this select() unblock.
1552 * First, check for an error or exit condition.
1555 if (errno == EBADF) {
1556 CtdlLogPrintf(CTDL_NOTICE, "select() failed: (%s)\n",
1559 if (errno != EINTR) {
1560 CtdlLogPrintf(CTDL_EMERG, "Exiting (%s)\n", strerror(errno));
1561 CtdlThreadStopAll();
1562 } else if (!CtdlThreadCheckStop()) {
1563 CtdlLogPrintf(CTDL_DEBUG, "Un handled select failure.\n");
1565 CtdlThreadName(old_name);
1568 else if(retval == 0)
1570 CtdlThreadName(old_name);
1571 CT->Context->kill_me = 1;
1576 CT->Context->state = CON_EXECUTING;
1577 CT->Context->input_waiting = 1;
1579 CtdlThreadName(old_name);
1580 return (CT->Context);
1586 * Do the worker threads work when needed
1588 int execute_session(struct CitContext *bind_me)
1592 become_session(bind_me);
1594 /* If the client has sent a command, execute it. */
1595 if (CC->input_waiting) {
1596 CC->h_command_function();
1597 CC->input_waiting = 0;
1600 /* If there are asynchronous messages waiting and the
1601 * client supports it, do those now */
1602 if ((CC->is_async) && (CC->async_waiting)
1603 && (CC->h_async_function != NULL)) {
1604 CC->h_async_function();
1605 CC->async_waiting = 0;
1608 force_purge = CC->kill_me;
1611 become_session(NULL);
1612 bind_me->state = CON_IDLE;
1620 * A new worker_thread loop.
1623 void *new_worker_thread(void *arg)
1625 struct CitContext *bind_me;
1628 while (!CtdlThreadCheckStop()) {
1630 /* make doubly sure we're not holding any stale db handles
1631 * which might cause a deadlock.
1633 cdb_check_handles();
1635 bind_me = NULL; /* Which session shall we handle? */
1637 if (CT->Context == NULL)
1639 if (CtdlThreadCheckStop())
1643 bind_me = select_on_client();
1644 if (CtdlThreadCheckStop())
1648 force_purge = execute_session(bind_me);
1650 dead_session_purge(force_purge);
1651 if (CtdlThreadCheckStop())