citadel/threads.c

   1 /*
   2  * Thread handling stuff for Citadel server
   3  *
   4  * Copyright (c) 1987-2011 by the citadel.org team
   5  *
   6  * This program is open source software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <stdlib.h>
  22 #include <unistd.h>
  23 #include <stdio.h>
  24 #include <sys/types.h>
  25 #include <errno.h>
  26 #include <sys/socket.h>
  27 #include <unistd.h>
  28 #include <fcntl.h>
  29 #include <signal.h>
  30 #include <syslog.h>
  31
  32 #include "sysdep.h"
  33 #if TIME_WITH_SYS_TIME
  34 # include <sys/time.h>
  35 # include <time.h>
  36 #else
  37 # if HAVE_SYS_TIME_H
  38 #  include <sys/time.h>
  39 # else
  40 #  include <time.h>
  41 # endif
  42 #endif
  43
  44 #ifdef HAVE_SYSCALL_H
  45 # include <syscall.h>
  46 #else
  47 # if HAVE_SYS_SYSCALL_H
  48 #  include <sys/syscall.h>
  49 # endif
  50 #endif
  51
  52 #include <libcitadel.h>
  53
  54 #include "threads.h"
  55 #include "ctdl_module.h"
  56 #include "modules_init.h"
  57 #include "housekeeping.h"
  58 #include "config.h"
  59 #include "citserver.h"
  60 #include "sysdep_decls.h"
  61 #include "context.h"
  62
  63 /*
  64  * define this to use the new worker_thread method of handling connections
  65  */
  66 //#define NEW_WORKER
  67
  68 /*
  69  * New thread interface.
  70  * To create a thread you must call one of the create thread functions.
  71  * You must pass it the address of (a pointer to a CtdlThreadNode initialised to NULL) like this
  72  * struct CtdlThreadNode *node = NULL;
  73  * pass in &node
  74  * If the thread is created *node will point to the thread control structure for the created thread.
  75  * If the thread creation fails *node remains NULL
  76  * Do not free the memory pointed to by *node, it doesn't belong to you.
  77  * This new interface duplicates much of the eCrash stuff. We should go for closer integration since that would
  78  * remove the need for the calls to eCrashRegisterThread and friends
  79  */
  80
  81 static int num_threads = 0;                     /* Current number of threads */
  82 static int num_workers = 0;                     /* Current number of worker threads */
  83
  84 CtdlThreadNode *CtdlThreadList = NULL;
  85 CtdlThreadNode *CtdlThreadSchedList = NULL;
  86
  87 static CtdlThreadNode *GC_thread = NULL;
  88 static char *CtdlThreadStates[CTDL_THREAD_LAST_STATE];
  89 double CtdlThreadLoadAvg = 0;
  90 double CtdlThreadWorkerAvg = 0;
  91 citthread_key_t ThreadKey;
  92
  93 citthread_mutex_t Critters[MAX_SEMAPHORES];     /* Things needing locking */
  94
  95
  96
  97 void InitialiseSemaphores(void)
  98 {
  99         int i;
 100
 101         /* Set up a bunch of semaphores to be used for critical sections */
 102         for (i=0; i<MAX_SEMAPHORES; ++i) {
 103                 citthread_mutex_init(&Critters[i], NULL);
 104         }
 105 }
 106
 107
 108
 109
 110 /*
 111  * Obtain a semaphore lock to begin a critical section.
 112  * but only if no one else has one
 113  */
 114 int try_critical_section(int which_one)
 115 {
 116         /* For all types of critical sections except those listed here,
 117          * ensure nobody ever tries to do a critical section within a
 118          * transaction; this could lead to deadlock.
 119          */
 120         if (    (which_one != S_FLOORCACHE)
 121 #ifdef DEBUG_MEMORY_LEAKS
 122                 && (which_one != S_DEBUGMEMLEAKS)
 123 #endif
 124                 && (which_one != S_RPLIST)
 125         ) {
 126                 cdb_check_handles();
 127         }
 128         return (citthread_mutex_trylock(&Critters[which_one]));
 129 }
 130
 131
 132 /*
 133  * Obtain a semaphore lock to begin a critical section.
 134  */
 135 void begin_critical_section(int which_one)
 136 {
 137         /* syslog(LOG_DEBUG, "begin_critical_section(%d)\n", which_one); */
 138
 139         /* For all types of critical sections except those listed here,
 140          * ensure nobody ever tries to do a critical section within a
 141          * transaction; this could lead to deadlock.
 142          */
 143         if (    (which_one != S_FLOORCACHE)
 144 #ifdef DEBUG_MEMORY_LEAKS
 145                 && (which_one != S_DEBUGMEMLEAKS)
 146 #endif
 147                 && (which_one != S_RPLIST)
 148         ) {
 149                 cdb_check_handles();
 150         }
 151         citthread_mutex_lock(&Critters[which_one]);
 152 }
 153
 154 /*
 155  * Release a semaphore lock to end a critical section.
 156  */
 157 void end_critical_section(int which_one)
 158 {
 159         citthread_mutex_unlock(&Critters[which_one]);
 160 }
 161
 162
 163 /*
 164  * A function to destroy the TSD
 165  */
 166 static void ctdl_thread_internal_dest_tsd(void *arg)
 167 {
 168         if (arg != NULL) {
 169                 check_handles(arg);
 170                 free(arg);
 171         }
 172 }
 173
 174
 175 /*
 176  * A function to initialise the thread TSD
 177  */
 178 void ctdl_thread_internal_init_tsd(void)
 179 {
 180         int ret;
 181
 182         if ((ret = citthread_key_create(&ThreadKey, ctdl_thread_internal_dest_tsd))) {
 183                 syslog(LOG_EMERG, "citthread_key_create: %s\n", strerror(ret));
 184                 exit(CTDLEXIT_DB);
 185         }
 186 }
 187
 188 /*
 189  * Ensure that we have a key for thread-specific data.
 190  *
 191  * This should be called immediately after startup by any thread
 192  *
 193  */
 194 void CtdlThreadAllocTSD(void)
 195 {
 196         ThreadTSD *tsd;
 197
 198         if (citthread_getspecific(ThreadKey) != NULL)
 199                 return;
 200
 201         tsd = malloc(sizeof(ThreadTSD));
 202
 203         tsd->tid = NULL;
 204
 205         memset(tsd->cursors, 0, sizeof tsd->cursors);
 206         tsd->self = NULL;
 207
 208         citthread_setspecific(ThreadKey, tsd);
 209 }
 210
 211
 212 void ctdl_thread_internal_free_tsd(void)
 213 {
 214         ctdl_thread_internal_dest_tsd(citthread_getspecific(ThreadKey));
 215         citthread_setspecific(ThreadKey, NULL);
 216 }
 217
 218
 219 void ctdl_thread_internal_cleanup(void)
 220 {
 221         int i;
 222         CtdlThreadNode *this_thread, *that_thread;
 223
 224         for (i=0; i<CTDL_THREAD_LAST_STATE; i++)
 225         {
 226                 free (CtdlThreadStates[i]);
 227         }
 228
 229         /* Clean up the scheduled thread list */
 230         this_thread = CtdlThreadSchedList;
 231         while (this_thread)
 232         {
 233                 that_thread = this_thread;
 234                 this_thread = this_thread->next;
 235                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 236                 citthread_cond_destroy(&that_thread->ThreadCond);
 237                 citthread_mutex_destroy(&that_thread->SleepMutex);
 238                 citthread_cond_destroy(&that_thread->SleepCond);
 239                 citthread_attr_destroy(&that_thread->attr);
 240                 free(that_thread);
 241         }
 242         ctdl_thread_internal_free_tsd();
 243 }
 244
 245 void ctdl_thread_internal_init(void)
 246 {
 247         CtdlThreadNode *this_thread;
 248         int ret = 0;
 249
 250         CtdlThreadStates[CTDL_THREAD_INVALID] = strdup ("Invalid Thread");
 251         CtdlThreadStates[CTDL_THREAD_VALID] = strdup("Valid Thread");
 252         CtdlThreadStates[CTDL_THREAD_CREATE] = strdup("Thread being Created");
 253         CtdlThreadStates[CTDL_THREAD_CANCELLED] = strdup("Thread Cancelled");
 254         CtdlThreadStates[CTDL_THREAD_EXITED] = strdup("Thread Exited");
 255         CtdlThreadStates[CTDL_THREAD_STOPPING] = strdup("Thread Stopping");
 256         CtdlThreadStates[CTDL_THREAD_STOP_REQ] = strdup("Thread Stop Requested");
 257         CtdlThreadStates[CTDL_THREAD_SLEEPING] = strdup("Thread Sleeping");
 258         CtdlThreadStates[CTDL_THREAD_RUNNING] = strdup("Thread Running");
 259         CtdlThreadStates[CTDL_THREAD_BLOCKED] = strdup("Thread Blocked");
 260
 261         /* Get ourself a thread entry */
 262         this_thread = malloc(sizeof(CtdlThreadNode));
 263         if (this_thread == NULL) {
 264                 syslog(LOG_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 265                 return;
 266         }
 267         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 268         memset (this_thread, 0, sizeof(CtdlThreadNode));
 269
 270         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 271         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 272         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 273         citthread_cond_init (&(this_thread->SleepCond), NULL);
 274
 275         /* We are garbage collector so create us as running */
 276         this_thread->state = CTDL_THREAD_RUNNING;
 277
 278         if ((ret = citthread_attr_init(&this_thread->attr))) {
 279                 syslog(LOG_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 280                 free(this_thread);
 281                 return;
 282         }
 283
 284         this_thread->name = "Garbage Collection Thread";
 285
 286         this_thread->tid = citthread_self();
 287         GC_thread = this_thread;
 288         CT = this_thread;
 289
 290         num_threads++;  // Increase the count of threads in the system.
 291
 292         this_thread->next = CtdlThreadList;
 293         CtdlThreadList = this_thread;
 294         if (this_thread->next)
 295                 this_thread->next->prev = this_thread;
 296         /* Set up start times */
 297         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 298         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 299 }
 300
 301
 302 /*
 303  * A function to update a threads load averages
 304  */
 305  void ctdl_thread_internal_update_avgs(CtdlThreadNode *this_thread)
 306  {
 307         struct timeval now, result;
 308         double last_duration;
 309
 310         gettimeofday(&now, NULL);
 311         timersub(&now, &(this_thread->last_state_change), &result);
 312         /* I don't think these mutex's are needed here */
 313         citthread_mutex_lock(&this_thread->ThreadMutex);
 314         // result now has a timeval for the time we spent in the last state since we last updated
 315         last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
 316         if (this_thread->state == CTDL_THREAD_SLEEPING)
 317                 this_thread->avg_sleeping += last_duration;
 318         if (this_thread->state == CTDL_THREAD_RUNNING)
 319                 this_thread->avg_running += last_duration;
 320         if (this_thread->state == CTDL_THREAD_BLOCKED)
 321                 this_thread->avg_blocked += last_duration;
 322         memcpy (&this_thread->last_state_change, &now, sizeof (struct timeval));
 323         citthread_mutex_unlock(&this_thread->ThreadMutex);
 324 }
 325
 326 /*
 327  * A function to chenge the state of a thread
 328  */
 329 void ctdl_thread_internal_change_state (CtdlThreadNode *this_thread, enum CtdlThreadState new_state)
 330 {
 331         /*
 332          * Wether we change state or not we need update the load values
 333          */
 334         ctdl_thread_internal_update_avgs(this_thread);
 335         /* This mutex not needed here? */
 336         citthread_mutex_lock(&this_thread->ThreadMutex); /* To prevent race condition of a sleeping thread */
 337         if ((new_state == CTDL_THREAD_STOP_REQ) && (this_thread->state > CTDL_THREAD_STOP_REQ))
 338                 this_thread->state = new_state;
 339         if (((new_state == CTDL_THREAD_SLEEPING) || (new_state == CTDL_THREAD_BLOCKED)) && (this_thread->state == CTDL_THREAD_RUNNING))
 340                 this_thread->state = new_state;
 341         if ((new_state == CTDL_THREAD_RUNNING) && ((this_thread->state == CTDL_THREAD_SLEEPING) || (this_thread->state == CTDL_THREAD_BLOCKED)))
 342                 this_thread->state = new_state;
 343         citthread_mutex_unlock(&this_thread->ThreadMutex);
 344 }
 345
 346
 347 /*
 348  * A function to tell all threads to exit
 349  */
 350 void CtdlThreadStopAll(void)
 351 {
 352         /* First run any registered shutdown hooks.  This probably doesn't belong here. */
 353         PerformSessionHooks(EVT_SHUTDOWN);
 354
 355         /* then close all tcp ports so nobody else can talk to us anymore. */
 356         CtdlShutdownServiceHooks();
 357         //FIXME: The signalling of the condition should not be in the critical_section
 358         // We need to build a list of threads we are going to signal and then signal them afterwards
 359
 360         CtdlThreadNode *this_thread;
 361
 362         begin_critical_section(S_THREAD_LIST);
 363         this_thread = CtdlThreadList;
 364         // Ask the GC thread to stop first so everything knows we are shutting down.
 365         GC_thread->state = CTDL_THREAD_STOP_REQ;
 366         while(this_thread)
 367         {
 368                 if (!citthread_equal(this_thread->tid, GC_thread->tid))
 369                         citthread_kill(this_thread->tid, SIGHUP);
 370
 371                 ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 372                 citthread_cond_signal(&this_thread->ThreadCond);
 373                 citthread_cond_signal(&this_thread->SleepCond);
 374                 this_thread->stop_ticker = time(NULL);
 375                 syslog(LOG_DEBUG, "Thread system stopping thread \"%s\" (0x%08lx).\n",
 376                         this_thread->name, this_thread->tid);
 377                 this_thread = this_thread->next;
 378         }
 379         end_critical_section(S_THREAD_LIST);
 380 }
 381
 382
 383 /*
 384  * A function to wake up all sleeping threads
 385  */
 386 void CtdlThreadWakeAll(void)
 387 {
 388         CtdlThreadNode *this_thread;
 389
 390         syslog(LOG_DEBUG, "Thread system waking all threads.\n");
 391
 392         begin_critical_section(S_THREAD_LIST);
 393         this_thread = CtdlThreadList;
 394         while(this_thread)
 395         {
 396                 if (!this_thread->thread_func)
 397                 {
 398                         citthread_cond_signal(&this_thread->ThreadCond);
 399                         citthread_cond_signal(&this_thread->SleepCond);
 400                 }
 401                 this_thread = this_thread->next;
 402         }
 403         end_critical_section(S_THREAD_LIST);
 404 }
 405
 406
 407 /*
 408  * A function to return the number of threads running in the system
 409  */
 410 int CtdlThreadGetCount(void)
 411 {
 412         return  num_threads;
 413 }
 414
 415 int CtdlThreadGetWorkers(void)
 416 {
 417         return  num_workers;
 418 }
 419
 420 double CtdlThreadGetWorkerAvg(void)
 421 {
 422         double ret;
 423
 424         begin_critical_section(S_THREAD_LIST);
 425         ret =  CtdlThreadWorkerAvg;
 426         end_critical_section(S_THREAD_LIST);
 427         return ret;
 428 }
 429
 430 double CtdlThreadGetLoadAvg(void)
 431 {
 432         double load_avg[3] = {0.0, 0.0, 0.0};
 433
 434         int ret = 0;
 435         int smp_num_cpus;
 436
 437         /* Borrowed this straight from procps */
 438         smp_num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 439         if(smp_num_cpus<1) smp_num_cpus=1; /* SPARC glibc is buggy */
 440
 441 #ifdef HAVE_GETLOADAVG
 442         ret = getloadavg(load_avg, 3);
 443 #endif
 444         if (ret < 0)
 445                 return 0;
 446         return load_avg[0] / smp_num_cpus;
 447 /*
 448  * This old chunk of code return a value that indicated the load on citserver
 449  * This value could easily reach 100 % even when citserver was doing very little and
 450  * hence the machine has much more spare capacity.
 451  * Because this value was used to determine if the machine was under heavy load conditions
 452  * from other processes in the system then citserver could be strangled un-necesarily
 453  * What we are actually trying to achieve is to strangle citserver if the machine is heavily loaded.
 454  * So we have changed this.
 455
 456         begin_critical_section(S_THREAD_LIST);
 457         ret =  CtdlThreadLoadAvg;
 458         end_critical_section(S_THREAD_LIST);
 459         return ret;
 460 */
 461 }
 462
 463
 464
 465
 466 /*
 467  * A function to rename a thread
 468  * Returns a const char *
 469  */
 470 const char *CtdlThreadName(const char *name)
 471 {
 472         const char *old_name;
 473
 474         if (!CT)
 475         {
 476                 syslog(LOG_WARNING, "Thread system WARNING. Attempt to CtdlThreadRename() a non thread. %s\n", name);
 477                 return NULL;
 478         }
 479         old_name = CT->name;
 480         if (name)
 481                 CT->name = name;
 482         return (old_name);
 483 }
 484
 485
 486 /*
 487  * A function to force a thread to exit
 488  */
 489 void CtdlThreadCancel(CtdlThreadNode *thread)
 490 {
 491         CtdlThreadNode *this_thread;
 492
 493         if (!thread)
 494                 this_thread = CT;
 495         else
 496                 this_thread = thread;
 497         if (!this_thread)
 498         {
 499                 syslog(LOG_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() a non thread.\n");
 500                 CtdlThreadStopAll();
 501                 return;
 502         }
 503
 504         if (!this_thread->thread_func)
 505         {
 506                 syslog(LOG_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() the garbage collector.\n");
 507                 CtdlThreadStopAll();
 508                 return;
 509         }
 510
 511         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_CANCELLED);
 512         citthread_cancel(this_thread->tid);
 513 }
 514
 515
 516 /*
 517  * A function for a thread to check if it has been asked to stop
 518  */
 519 int CtdlThreadCheckStop(void)
 520 {
 521         int state;
 522
 523         if (!CT)
 524         {
 525                 syslog(LOG_EMERG, "Thread system PANIC, CtdlThreadCheckStop() called by a non thread.\n");
 526                 CtdlThreadStopAll();
 527                 return -1;
 528         }
 529
 530         state = CT->state;
 531
 532         if (CT->signal)
 533         {
 534                 syslog(LOG_DEBUG, "Thread \"%s\" caught signal %d.\n", CT->name, CT->signal);
 535                 if (CT->signal == SIGHUP)
 536                         CT->state = CTDL_THREAD_STOP_REQ;
 537                 CT->signal = 0;
 538         }
 539         if(state == CTDL_THREAD_STOP_REQ)
 540         {
 541                 CT->state = CTDL_THREAD_STOPPING;
 542                 return -1;
 543         }
 544         else if((state < CTDL_THREAD_STOP_REQ) && (state > CTDL_THREAD_CREATE))
 545         {
 546                 return -1;
 547         }
 548         return 0;
 549 }
 550
 551
 552 /*
 553  * A function to ask a thread to exit
 554  * The thread must call CtdlThreadCheckStop() periodically to determine if it should exit
 555  */
 556 void CtdlThreadStop(CtdlThreadNode *thread)
 557 {
 558         CtdlThreadNode *this_thread;
 559
 560         if (!thread)
 561                 this_thread = CT;
 562         else
 563                 this_thread = thread;
 564         if (!this_thread)
 565                 return;
 566         if (!(this_thread->thread_func))
 567                 return;         // Don't stop garbage collector
 568
 569         if (!citthread_equal(this_thread->tid, GC_thread->tid))
 570                 citthread_kill(this_thread->tid, SIGHUP);
 571
 572         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 573         citthread_cond_signal(&this_thread->ThreadCond);
 574         citthread_cond_signal(&this_thread->SleepCond);
 575         this_thread->stop_ticker = time(NULL);
 576 }
 577
 578 /*
 579  * So we now have a sleep command that works with threads but it is in seconds
 580  */
 581 void CtdlThreadSleep(int secs)
 582 {
 583         struct timespec wake_time;
 584         struct timeval time_now;
 585
 586
 587         if (!CT)
 588         {
 589                 syslog(LOG_WARNING, "CtdlThreadSleep() called by something that is not a thread. Should we die?\n");
 590                 return;
 591         }
 592
 593         memset (&wake_time, 0, sizeof(struct timespec));
 594         gettimeofday(&time_now, NULL);
 595         wake_time.tv_sec = time_now.tv_sec + secs;
 596         wake_time.tv_nsec = time_now.tv_usec * 10;
 597
 598         ctdl_thread_internal_change_state (CT, CTDL_THREAD_SLEEPING);
 599
 600         citthread_mutex_lock(&CT->ThreadMutex); /* Prevent something asking us to awaken before we've gone to sleep */
 601         citthread_cond_timedwait(&CT->SleepCond, &CT->ThreadMutex, &wake_time);
 602         citthread_mutex_unlock(&CT->ThreadMutex);
 603
 604         ctdl_thread_internal_change_state (CT, CTDL_THREAD_RUNNING);
 605 }
 606
 607
 608 /*
 609  * Routine to clean up our thread function on exit
 610  */
 611 static void ctdl_internal_thread_cleanup(void *arg)
 612 {
 613         /*
 614          * In here we were called by the current thread because it is exiting
 615          * NB. WE ARE THE CURRENT THREAD
 616          */
 617         if (CT)
 618         {
 619                 const char *name = CT->name;
 620                 const pid_t tid = CT->tid;
 621
 622                 syslog(LOG_NOTICE, "Thread \"%s\" (0x%08lx) exited.\n", name, (unsigned long) tid);
 623         }
 624         else
 625         {
 626                 syslog(LOG_NOTICE, "some ((unknown ? ? ?) Thread exited.\n");
 627         }
 628
 629         #ifdef HAVE_BACKTRACE
 630 ///     eCrash_UnregisterThread();
 631         #endif
 632
 633         citthread_mutex_lock(&CT->ThreadMutex);
 634         CT->state = CTDL_THREAD_EXITED; // needs to be last thing else house keeping will unlink us too early
 635         citthread_mutex_unlock(&CT->ThreadMutex);
 636 }
 637
 638 /*
 639  * A quick function to show the load averages
 640  */
 641 void ctdl_thread_internal_calc_loadavg(void)
 642 {
 643         CtdlThreadNode *that_thread;
 644         double load_avg, worker_avg;
 645         int workers = 0;
 646
 647         that_thread = CtdlThreadList;
 648         load_avg = 0;
 649         worker_avg = 0;
 650         while(that_thread)
 651         {
 652                 /* Update load averages */
 653                 ctdl_thread_internal_update_avgs(that_thread);
 654                 citthread_mutex_lock(&that_thread->ThreadMutex);
 655                 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;
 656                 that_thread->avg_sleeping /= 2;
 657                 that_thread->avg_running /= 2;
 658                 that_thread->avg_blocked /= 2;
 659                 load_avg += that_thread->load_avg;
 660                 if (that_thread->flags & CTDLTHREAD_WORKER)
 661                 {
 662                         worker_avg += that_thread->load_avg;
 663                         workers++;
 664                 }
 665 #ifdef WITH_THREADLOG
 666                 syslog(LOG_DEBUG, "CtdlThread, \"%s\" (%lu) \"%s\" %.2f %.2f %.2f %.2f\n",
 667                         that_thread->name,
 668                         that_thread->tid,
 669                         CtdlThreadStates[that_thread->state],
 670                         that_thread->avg_sleeping,
 671                         that_thread->avg_running,
 672                         that_thread->avg_blocked,
 673                         that_thread->load_avg);
 674 #endif
 675                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 676                 that_thread = that_thread->next;
 677         }
 678         CtdlThreadLoadAvg = load_avg/num_threads;
 679         CtdlThreadWorkerAvg = worker_avg/workers;
 680 #ifdef WITH_THREADLOG
 681         syslog(LOG_INFO, "System load average %.2f, workers averag %.2f, threads %d, workers %d, sessions %d\n", CtdlThreadGetLoadAvg(), CtdlThreadWorkerAvg, num_threads, num_workers, num_sessions);
 682 #endif
 683 }
 684
 685
 686 /*
 687  * Garbage collection routine.
 688  * Gets called by main() in a loop to clean up the thread list periodically.
 689  */
 690 void CtdlThreadGC (void)
 691 {
 692
 693
 694         return;
 695         /* FIXME this is a big deal, but I think it's causing corruption */
 696
 697
 698         CtdlThreadNode *this_thread, *that_thread;
 699         int workers = 0, sys_workers;
 700         int ret=0;
 701
 702         begin_critical_section(S_THREAD_LIST);
 703
 704         /* Handle exiting of garbage collector thread */
 705         if(num_threads == 1)
 706                 CtdlThreadList->state = CTDL_THREAD_EXITED;
 707
 708 #ifdef WITH_THREADLOG
 709         syslog(LOG_DEBUG, "Thread system running garbage collection.\n");
 710 #endif
 711         /*
 712          * Woke up to do garbage collection
 713          */
 714         this_thread = CtdlThreadList;
 715         while(this_thread)
 716         {
 717                 that_thread = this_thread;
 718                 this_thread = this_thread->next;
 719
 720                 if ((that_thread->state == CTDL_THREAD_STOP_REQ || that_thread->state == CTDL_THREAD_STOPPING)
 721                         && (!citthread_equal(that_thread->tid, citthread_self())))
 722                 {
 723                         syslog(LOG_DEBUG, "Waiting for thread %s (0x%08lx) to exit.\n", that_thread->name, that_thread->tid);
 724                         terminate_stuck_sessions();
 725                 }
 726                 else
 727                 {
 728                         /**
 729                          * Catch the situation where a worker was asked to stop but couldn't and we are not
 730                          * shutting down.
 731                          */
 732                         that_thread->stop_ticker = 0;
 733                 }
 734
 735                 if (that_thread->stop_ticker + 5 == time(NULL))
 736                 {
 737                         syslog(LOG_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);
 738                         if ((that_thread->flags & CTDLTHREAD_WORKER) == 0)
 739                                 syslog(LOG_INFO, "Thread System: A non worker thread would have been canceled this may cause message loss.\n");
 740 //                      that_thread->state = CTDL_THREAD_CANCELLED;
 741                         that_thread->stop_ticker++;
 742 //                      citthread_cancel(that_thread->tid);
 743 //                      continue;
 744                 }
 745
 746                 /* Do we need to clean up this thread? */
 747                 if ((that_thread->state != CTDL_THREAD_EXITED) && (that_thread->state != CTDL_THREAD_CANCELLED))
 748                 {
 749                         if(that_thread->flags & CTDLTHREAD_WORKER)
 750                                 workers++;      /* Sanity check on number of worker threads */
 751                         continue;
 752                 }
 753
 754                 if (citthread_equal(that_thread->tid, citthread_self()) && that_thread->thread_func)
 755                 {       /* Sanity check */
 756                         end_critical_section(S_THREAD_LIST);
 757                         syslog(LOG_EMERG, "Thread system PANIC, a thread is trying to clean up after itself.\n");
 758                         abort();
 759                         return;
 760                 }
 761
 762                 if (num_threads <= 0)
 763                 {       /* Sanity check */
 764                         end_critical_section(S_THREAD_LIST);
 765                         syslog(LOG_EMERG, "Thread system PANIC, num_threads <= 0 and trying to do Garbage Collection.\n");
 766                         abort();
 767                         return;
 768                 }
 769
 770                 if(that_thread->flags & CTDLTHREAD_WORKER)
 771                         num_workers--;  /* This is a wroker thread so reduce the count. */
 772                 num_threads--;
 773                 /* If we are unlinking the list head then the next becomes the list head */
 774                 if(that_thread->prev)
 775                         that_thread->prev->next = that_thread->next;
 776                 else
 777                         CtdlThreadList = that_thread->next;
 778                 if(that_thread->next)
 779                         that_thread->next->prev = that_thread->prev;
 780
 781                 citthread_cond_signal(&that_thread->ThreadCond);
 782                 citthread_cond_signal(&that_thread->SleepCond); // Make sure this thread is awake
 783                 citthread_mutex_lock(&that_thread->ThreadMutex);        // Make sure it has done what its doing
 784                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 785                 /*
 786                  * Join on the thread to do clean up and prevent memory leaks
 787                  * Also makes sure the thread has cleaned up after itself before we remove it from the list
 788                  * We can join on the garbage collector thread the join should just return EDEADLCK
 789                  */
 790                 ret = citthread_join (that_thread->tid, NULL);
 791                 if (ret == EDEADLK)
 792                         syslog(LOG_DEBUG, "Garbage collection on own thread.\n");
 793                 else if (ret == EINVAL)
 794                         syslog(LOG_DEBUG, "Garbage collection, that thread already joined on.\n");
 795                 else if (ret == ESRCH)
 796                         syslog(LOG_DEBUG, "Garbage collection, no thread to join on.\n");
 797                 else if (ret != 0)
 798                         syslog(LOG_DEBUG, "Garbage collection, citthread_join returned an unknown error(%d).\n", ret);
 799                 /*
 800                  * Now we own that thread entry
 801                  */
 802                 syslog(LOG_INFO, "Garbage Collection for thread \"%s\" (0x%08lx).\n",
 803                         that_thread->name, that_thread->tid);
 804                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 805                 citthread_cond_destroy(&that_thread->ThreadCond);
 806                 citthread_mutex_destroy(&that_thread->SleepMutex);
 807                 citthread_cond_destroy(&that_thread->SleepCond);
 808                 citthread_attr_destroy(&that_thread->attr);
 809                 free(that_thread);
 810         }
 811         sys_workers = num_workers;
 812         end_critical_section(S_THREAD_LIST);
 813
 814         /* Sanity check number of worker threads */
 815         if (workers != sys_workers)
 816         {
 817                 syslog(LOG_EMERG,
 818                         "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n",
 819                         workers, sys_workers
 820                         );
 821                 abort();
 822         }
 823 }
 824
 825
 826
 827
 828 /*
 829  * Runtime function for a Citadel Thread.
 830  * This initialises the threads environment and then calls the user supplied thread function
 831  * Note that this is the REAL thread function and wraps the users thread function.
 832  */
 833 static void *ctdl_internal_thread_func (void *arg)
 834 {
 835         CtdlThreadNode *this_thread;
 836         void *ret = NULL;
 837
 838         /* lock and unlock the thread list.
 839          * This causes this thread to wait until all its creation stuff has finished before it
 840          * can continue its execution.
 841          */
 842         begin_critical_section(S_THREAD_LIST);
 843         this_thread = (CtdlThreadNode *) arg;
 844         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 845
 846         // Register the cleanup function to take care of when we exit.
 847         citthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
 848         // Get our thread data structure
 849         CtdlThreadAllocTSD();
 850         CT = this_thread;
 851         this_thread->pid = getpid();
 852         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 853         /* Only change to running state if we weren't asked to stop during the create cycle
 854          * Other wise there is a window to allow this threads creation to continue to full grown and
 855          * therby prevent a shutdown of the server.
 856          */
 857         if (!CtdlThreadCheckStop())
 858         {
 859                 citthread_mutex_lock(&this_thread->ThreadMutex);
 860                 this_thread->state = CTDL_THREAD_RUNNING;
 861                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 862         }
 863         end_critical_section(S_THREAD_LIST);
 864
 865         // Register for tracing
 866         #ifdef HAVE_BACKTRACE
 867 ///     eCrash_RegisterThread(this_thread->name, 0);
 868         #endif
 869
 870         // Tell the world we are here
 871 #if defined(HAVE_SYSCALL_H) && defined (SYS_gettid)
 872         this_thread->reltid = syscall(SYS_gettid);
 873 #endif
 874         syslog(LOG_NOTICE, "Created a new thread \"%s\" (0x%08lx).\n",
 875                 this_thread->name, this_thread->tid);
 876
 877         /*
 878          * run the thread to do the work but only if we haven't been asked to stop
 879          */
 880         if (!CtdlThreadCheckStop())
 881                 ret = (this_thread->thread_func)(this_thread->user_args);
 882
 883         /*
 884          * Our thread is exiting either because it wanted to end or because the server is stopping
 885          * We need to clean up
 886          */
 887         citthread_cleanup_pop(1);       // Execute our cleanup routine and remove it
 888
 889         return(ret);
 890 }
 891
 892
 893
 894
 895 /*
 896  * Function to initialise an empty thread structure
 897  */
 898 CtdlThreadNode *ctdl_internal_init_thread_struct(CtdlThreadNode *this_thread, long flags)
 899 {
 900         int ret = 0;
 901
 902         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 903         memset (this_thread, 0, sizeof(CtdlThreadNode));
 904
 905         /* Create the mutex's early so we can use them */
 906         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 907         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 908         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 909         citthread_cond_init (&(this_thread->SleepCond), NULL);
 910
 911         this_thread->state = CTDL_THREAD_CREATE;
 912
 913         if ((ret = citthread_attr_init(&this_thread->attr))) {
 914                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 915                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 916                 citthread_cond_destroy(&(this_thread->ThreadCond));
 917                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 918                 citthread_cond_destroy(&(this_thread->SleepCond));
 919                 syslog(LOG_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 920                 free(this_thread);
 921                 return NULL;
 922         }
 923
 924         /* Our per-thread stacks need to be bigger than the default size,
 925          * otherwise the MIME parser crashes on FreeBSD, and the IMAP service
 926          * crashes on 64-bit Linux.
 927          */
 928         if (flags & CTDLTHREAD_BIGSTACK)
 929         {
 930 #ifdef WITH_THREADLOG
 931                 syslog(LOG_INFO, "Thread system. Creating BIG STACK thread.\n");
 932 #endif
 933                 if ((ret = citthread_attr_setstacksize(&this_thread->attr, THREADSTACKSIZE))) {
 934                         citthread_mutex_unlock(&this_thread->ThreadMutex);
 935                         citthread_mutex_destroy(&(this_thread->ThreadMutex));
 936                         citthread_cond_destroy(&(this_thread->ThreadCond));
 937                         citthread_mutex_destroy(&(this_thread->SleepMutex));
 938                         citthread_cond_destroy(&(this_thread->SleepCond));
 939                         citthread_attr_destroy(&this_thread->attr);
 940                         syslog(LOG_EMERG, "Thread system, citthread_attr_setstacksize: %s\n",
 941                                 strerror(ret));
 942                         free(this_thread);
 943                         return NULL;
 944                 }
 945         }
 946
 947         /* Set this new thread with an avg_blocked of 2. We do this so that its creation affects the
 948          * load average for the system. If we don't do this then we create a mass of threads at the same time
 949          * because the creation didn't affect the load average.
 950          */
 951         this_thread->avg_blocked = 2;
 952
 953         return (this_thread);
 954 }
 955
 956
 957
 958
 959 /*
 960  * Internal function to create a thread.
 961  */
 962 CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void *(*thread_func) (void *arg), void *args)
 963 {
 964         int ret = 0;
 965         CtdlThreadNode *this_thread;
 966
 967         if (num_threads >= 32767)
 968         {
 969                 syslog(LOG_EMERG, "Thread system. Thread list full.\n");
 970                 return NULL;
 971         }
 972
 973         this_thread = malloc(sizeof(CtdlThreadNode));
 974         if (this_thread == NULL) {
 975                 syslog(LOG_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 976                 return NULL;
 977         }
 978
 979         /* Initialise the thread structure */
 980         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
 981         {
 982                 free(this_thread);
 983                 syslog(LOG_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
 984                 return NULL;
 985         }
 986         /*
 987          * If we got here we are going to create the thread so we must initilise the structure
 988          * first because most implimentations of threading can't create it in a stopped state
 989          * and it might want to do things with its structure that aren't initialised otherwise.
 990          */
 991         if(name)
 992         {
 993                 this_thread->name = name;
 994         }
 995         else
 996         {
 997                 this_thread->name = "Un-named Thread";
 998         }
 999
1000         this_thread->flags = flags;
1001         this_thread->thread_func = thread_func;
1002         this_thread->user_args = args;
1003
1004         begin_critical_section(S_THREAD_LIST);
1005         /*
1006          * We pass this_thread into the thread as its args so that it can find out information
1007          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1008          * thread function needs to finish off the setup of the structure
1009          */
1010         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1011         {
1012                 end_critical_section(S_THREAD_LIST);
1013                 syslog(LOG_ALERT, "Thread system, Can't create thread: %s\n",
1014                         strerror(ret));
1015                 citthread_mutex_unlock(&this_thread->ThreadMutex);
1016                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1017                 citthread_cond_destroy(&(this_thread->ThreadCond));
1018                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1019                 citthread_cond_destroy(&(this_thread->SleepCond));
1020                 citthread_attr_destroy(&this_thread->attr);
1021                 free(this_thread);
1022                 return NULL;
1023         }
1024         num_threads++;  // Increase the count of threads in the system.
1025         if(this_thread->flags & CTDLTHREAD_WORKER)
1026                 num_workers++;
1027
1028         this_thread->next = CtdlThreadList;
1029         CtdlThreadList = this_thread;
1030         if (this_thread->next)
1031                 this_thread->next->prev = this_thread;
1032         ctdl_thread_internal_calc_loadavg();
1033
1034         end_critical_section(S_THREAD_LIST);
1035
1036         return this_thread;
1037 }
1038
1039 /*
1040  * Wrapper function to create a thread
1041  * ensures the critical section and other protections are in place.
1042  * char *name = name to give to thread, if NULL, use generic name
1043  * int flags = flags to determine type of thread and standard facilities
1044  */
1045 CtdlThreadNode *CtdlThreadCreate(char *name, long flags, void *(*thread_func) (void *arg), void *args)
1046 {
1047         CtdlThreadNode *ret = NULL;
1048
1049         ret = ctdl_internal_create_thread(name, flags, thread_func, args);
1050         return ret;
1051 }
1052
1053
1054
1055 CtdlThreadNode *ctdl_thread_internal_start_scheduled (CtdlThreadNode *this_thread)
1056 {
1057         int ret = 0;
1058
1059         begin_critical_section(S_THREAD_LIST);
1060         /*
1061          * We pass this_thread into the thread as its args so that it can find out information
1062          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1063          * thread function needs to finish off the setup of the structure
1064          */
1065         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1066         {
1067                 end_critical_section(S_THREAD_LIST);
1068                 syslog(LOG_DEBUG, "Failed to start scheduled thread \"%s\": %s\n", this_thread->name, strerror(ret));
1069                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1070                 citthread_cond_destroy(&(this_thread->ThreadCond));
1071                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1072                 citthread_cond_destroy(&(this_thread->SleepCond));
1073                 citthread_attr_destroy(&this_thread->attr);
1074                 free(this_thread);
1075                 return NULL;
1076         }
1077
1078
1079         num_threads++;  // Increase the count of threads in the system.
1080         if(this_thread->flags & CTDLTHREAD_WORKER)
1081                 num_workers++;
1082
1083         this_thread->next = CtdlThreadList;
1084         CtdlThreadList = this_thread;
1085         if (this_thread->next)
1086                 this_thread->next->prev = this_thread;
1087
1088         ctdl_thread_internal_calc_loadavg();
1089         end_critical_section(S_THREAD_LIST);
1090
1091
1092         return this_thread;
1093 }
1094
1095
1096
1097 void ctdl_thread_internal_check_scheduled(void)
1098 {
1099         CtdlThreadNode *this_thread, *that_thread;
1100         time_t now;
1101
1102         /* Don't start scheduled threads if the system wants single user mode */
1103         if (CtdlWantSingleUser())
1104                 return;
1105
1106         if (try_critical_section(S_SCHEDULE_LIST))
1107                 return; /* If this list is locked we wait till the next chance */
1108
1109         now = time(NULL);
1110
1111 #ifdef WITH_THREADLOG
1112         syslog(LOG_DEBUG, "Checking for scheduled threads to start.\n");
1113 #endif
1114
1115         this_thread = CtdlThreadSchedList;
1116         while(this_thread)
1117         {
1118                 that_thread = this_thread;
1119                 this_thread = this_thread->next;
1120
1121                 if (now > that_thread->when)
1122                 {
1123                         /* Unlink from schedule list */
1124                         if (that_thread->prev)
1125                                 that_thread->prev->next = that_thread->next;
1126                         else
1127                                 CtdlThreadSchedList = that_thread->next;
1128                         if (that_thread->next)
1129                                 that_thread->next->prev = that_thread->prev;
1130
1131                         that_thread->next = that_thread->prev = NULL;
1132 #ifdef WITH_THREADLOG
1133                         syslog(LOG_DEBUG, "About to start scheduled thread \"%s\".\n", that_thread->name);
1134 #endif
1135                         if (CT->state > CTDL_THREAD_STOP_REQ)
1136                         {       /* Only start it if the system is not stopping */
1137                                 if (ctdl_thread_internal_start_scheduled (that_thread))
1138                                 {
1139 #ifdef WITH_THREADLOG
1140                                         syslog(LOG_INFO, "Thread system, Started a scheduled thread \"%s\" (0x%08lx).\n",
1141                                                 that_thread->name, that_thread->tid);
1142 #endif
1143                                 }
1144                         }
1145                 }
1146 #ifdef WITH_THREADLOG
1147                 else
1148                 {
1149                         syslog(LOG_DEBUG, "Thread \"%s\" will start in %ld seconds.\n",
1150                                 that_thread->name, that_thread->when - time(NULL));
1151                 }
1152 #endif
1153         }
1154         end_critical_section(S_SCHEDULE_LIST);
1155 }
1156
1157
1158 /*
1159  * A warapper function for select so we can show a thread as blocked
1160  */
1161 int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
1162 {
1163         int ret = 0;
1164
1165         ctdl_thread_internal_change_state(CT, CTDL_THREAD_BLOCKED);
1166         if (!CtdlThreadCheckStop())
1167                 ret = select(n, readfds, writefds, exceptfds, timeout);
1168         /**
1169          * If the select returned <= 0 then it failed due to an error
1170          * or timeout so this thread could stop if asked to do so.
1171          * Anything else means it needs to continue unless the system is shutting down
1172          */
1173         if (ret > 0)
1174         {
1175                 /**
1176                  * The select says this thread needs to do something useful.
1177                  * This thread was in an idle state so it may have been asked to stop
1178                  * but if the system isn't shutting down this thread is no longer
1179                  * idle and select has given it a task to do so it must not stop
1180                  * In this condition we need to force it into the running state.
1181                  * CtdlThreadGC will clear its ticker for us.
1182                  *
1183                  * FIXME: there is still a small hole here. It is possible for the sequence of locking
1184                  * to allow the state to get changed to STOP_REQ just after this code if the other thread
1185                  * has decided to change the state before this lock, it there fore has to wait till the lock
1186                  * completes but it will continue to change the state. We need something a bit better here.
1187                  */
1188                 citthread_mutex_lock(&CT->ThreadMutex); /* To prevent race condition of a sleeping thread */
1189                 if (GC_thread->state > CTDL_THREAD_STOP_REQ && CT->state <= CTDL_THREAD_STOP_REQ)
1190                 {
1191                         syslog(LOG_DEBUG, "Thread %s (0x%08lx) refused stop request.\n", CT->name, CT->tid);
1192                         CT->state = CTDL_THREAD_RUNNING;
1193                 }
1194                 citthread_mutex_unlock(&CT->ThreadMutex);
1195         }
1196
1197         ctdl_thread_internal_change_state(CT, CTDL_THREAD_RUNNING);
1198
1199         return ret;
1200 }
1201
1202
1203
1204 void *new_worker_thread(void *arg);
1205 extern void close_masters (void);
1206
1207
1208
1209 void go_threading(void)
1210 {
1211         int i;
1212         CtdlThreadNode *last_worker;
1213         struct timeval start, now, result;
1214         double last_duration;
1215
1216         /*
1217          * Initialise the thread system
1218          */
1219         ctdl_thread_internal_init();
1220
1221         /* Second call to module init functions now that threading is up */
1222         initialise_modules(1);
1223         CtdlThreadCreate("select_on_master", CTDLTHREAD_BIGSTACK, select_on_master, NULL);
1224
1225         /*
1226          * This thread is now used for garbage collection of other threads in the thread list
1227          */
1228         syslog(LOG_INFO, "Startup thread %ld becoming garbage collector,\n", (long) citthread_self());
1229
1230         /*
1231          * We do a lot of locking and unlocking of the thread list in here.
1232          * We do this so that we can repeatedly release time for other threads
1233          * that may be waiting on the thread list.
1234          * We are a low priority thread so we can afford to do this
1235          */
1236
1237         while (CtdlThreadGetCount())
1238         {
1239                 if (CT->signal)
1240                         exit_signal = CT->signal;
1241                 if (exit_signal)
1242                 {
1243                         CtdlThreadStopAll();
1244                 }
1245                 check_sched_shutdown();
1246                 if (CT->state > CTDL_THREAD_STOP_REQ)
1247                 {
1248                         begin_critical_section(S_THREAD_LIST);
1249                         ctdl_thread_internal_calc_loadavg();
1250                         end_critical_section(S_THREAD_LIST);
1251
1252                         ctdl_thread_internal_check_scheduled(); /* start scheduled threads */
1253                 }
1254
1255                 /* Reduce the size of the worker thread pool if necessary. */
1256                 if ((CtdlThreadGetWorkers() > config.c_min_workers + 1) && (CtdlThreadWorkerAvg < 20) && (CT->state > CTDL_THREAD_STOP_REQ))
1257                 {
1258                         /* Ask a worker thread to stop as we no longer need it */
1259                         begin_critical_section(S_THREAD_LIST);
1260                         last_worker = CtdlThreadList;
1261                         while (last_worker)
1262                         {
1263                                 citthread_mutex_lock(&last_worker->ThreadMutex);
1264                                 if (last_worker->flags & CTDLTHREAD_WORKER && (last_worker->state > CTDL_THREAD_STOPPING) && (last_worker->Context == NULL))
1265                                 {
1266                                         citthread_mutex_unlock(&last_worker->ThreadMutex);
1267                                         break;
1268                                 }
1269                                 citthread_mutex_unlock(&last_worker->ThreadMutex);
1270                                 last_worker = last_worker->next;
1271                         }
1272                         end_critical_section(S_THREAD_LIST);
1273                         if (last_worker)
1274                         {
1275 #ifdef WITH_THREADLOG
1276                                 syslog(LOG_DEBUG, "Thread system, stopping excess worker thread \"%s\" (0x%08lx).\n",
1277                                         last_worker->name,
1278                                         last_worker->tid
1279                                         );
1280 #endif
1281                                 CtdlThreadStop(last_worker);
1282                         }
1283                 }
1284
1285                 /*
1286                  * If all our workers are working hard, start some more to help out
1287                  * with things
1288                  */
1289                 /* FIXME: come up with a better way to dynamically alter the number of threads
1290                  * based on the system load
1291                  */
1292                 if (    (((CtdlThreadGetWorkers() < config.c_max_workers)
1293                         && (CtdlThreadGetWorkerAvg() > 60))
1294                         || CtdlThreadGetWorkers() < config.c_min_workers)
1295                         && (CT->state > CTDL_THREAD_STOP_REQ)
1296                 )
1297                 {
1298                         /* Only start new threads if we are not going to overload the machine */
1299                         /* Temporarily set to 10 should be enough to make sure we don't stranglew the server
1300                          * at least until we make this a config option */
1301                         if (CtdlThreadGetLoadAvg() < ((double)10.00)) {
1302                                 for (i=0; i<5 ; i++) {
1303                                         CtdlThreadCreate("Worker Thread",
1304                                                 CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER,
1305                                                 worker_thread,
1306                                                 NULL
1307                                                 );
1308                                 }
1309                         }
1310                         else
1311                                 syslog(LOG_WARNING, "Server strangled due to machine load average too high.\n");
1312                 }
1313
1314                 CtdlThreadGC();
1315
1316                 if (CtdlThreadGetCount() <= 1) // Shutting down clean up the garbage collector
1317                 {
1318                         CtdlThreadGC();
1319                 }
1320
1321 #ifdef THREADS_USESIGNALS
1322                 if (CtdlThreadGetCount() && CT->state > CTDL_THREAD_STOP_REQ)
1323 #else
1324                 if (CtdlThreadGetCount())
1325 #endif
1326                         CtdlThreadSleep(1);
1327         }
1328         /*
1329          * If the above loop exits we must be shutting down since we obviously have no threads
1330          */
1331         ctdl_thread_internal_cleanup();
1332 }
1333
1334
1335
1336