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 long statcount = 0;             /* are we doing a stats check? */
  84 static long stats_done = 0;
  85
  86 CtdlThreadNode *CtdlThreadList = NULL;
  87 CtdlThreadNode *CtdlThreadSchedList = NULL;
  88
  89 static CtdlThreadNode *GC_thread = NULL;
  90 static char *CtdlThreadStates[CTDL_THREAD_LAST_STATE];
  91 double CtdlThreadLoadAvg = 0;
  92 double CtdlThreadWorkerAvg = 0;
  93 citthread_key_t ThreadKey;
  94
  95 citthread_mutex_t Critters[MAX_SEMAPHORES];     /* Things needing locking */
  96
  97
  98
  99 void InitialiseSemaphores(void)
 100 {
 101         int i;
 102
 103         /* Set up a bunch of semaphores to be used for critical sections */
 104         for (i=0; i<MAX_SEMAPHORES; ++i) {
 105                 citthread_mutex_init(&Critters[i], NULL);
 106         }
 107 }
 108
 109
 110
 111
 112 /*
 113  * Obtain a semaphore lock to begin a critical section.
 114  * but only if no one else has one
 115  */
 116 int try_critical_section(int which_one)
 117 {
 118         /* For all types of critical sections except those listed here,
 119          * ensure nobody ever tries to do a critical section within a
 120          * transaction; this could lead to deadlock.
 121          */
 122         if (    (which_one != S_FLOORCACHE)
 123 #ifdef DEBUG_MEMORY_LEAKS
 124                 && (which_one != S_DEBUGMEMLEAKS)
 125 #endif
 126                 && (which_one != S_RPLIST)
 127         ) {
 128                 cdb_check_handles();
 129         }
 130         return (citthread_mutex_trylock(&Critters[which_one]));
 131 }
 132
 133
 134 /*
 135  * Obtain a semaphore lock to begin a critical section.
 136  */
 137 void begin_critical_section(int which_one)
 138 {
 139         /* syslog(LOG_DEBUG, "begin_critical_section(%d)\n", which_one); */
 140
 141         /* For all types of critical sections except those listed here,
 142          * ensure nobody ever tries to do a critical section within a
 143          * transaction; this could lead to deadlock.
 144          */
 145         if (    (which_one != S_FLOORCACHE)
 146 #ifdef DEBUG_MEMORY_LEAKS
 147                 && (which_one != S_DEBUGMEMLEAKS)
 148 #endif
 149                 && (which_one != S_RPLIST)
 150         ) {
 151                 cdb_check_handles();
 152         }
 153         citthread_mutex_lock(&Critters[which_one]);
 154 }
 155
 156 /*
 157  * Release a semaphore lock to end a critical section.
 158  */
 159 void end_critical_section(int which_one)
 160 {
 161         citthread_mutex_unlock(&Critters[which_one]);
 162 }
 163
 164
 165 /*
 166  * A function to destroy the TSD
 167  */
 168 static void ctdl_thread_internal_dest_tsd(void *arg)
 169 {
 170         if (arg != NULL) {
 171                 check_handles(arg);
 172                 free(arg);
 173         }
 174 }
 175
 176
 177 /*
 178  * A function to initialise the thread TSD
 179  */
 180 void ctdl_thread_internal_init_tsd(void)
 181 {
 182         int ret;
 183
 184         if ((ret = citthread_key_create(&ThreadKey, ctdl_thread_internal_dest_tsd))) {
 185                 syslog(LOG_EMERG, "citthread_key_create: %s\n", strerror(ret));
 186                 exit(CTDLEXIT_DB);
 187         }
 188 }
 189
 190 /*
 191  * Ensure that we have a key for thread-specific data.
 192  *
 193  * This should be called immediately after startup by any thread
 194  *
 195  */
 196 void CtdlThreadAllocTSD(void)
 197 {
 198         ThreadTSD *tsd;
 199
 200         if (citthread_getspecific(ThreadKey) != NULL)
 201                 return;
 202
 203         tsd = malloc(sizeof(ThreadTSD));
 204
 205         tsd->tid = NULL;
 206
 207         memset(tsd->cursors, 0, sizeof tsd->cursors);
 208         tsd->self = NULL;
 209
 210         citthread_setspecific(ThreadKey, tsd);
 211 }
 212
 213
 214 void ctdl_thread_internal_free_tsd(void)
 215 {
 216         ctdl_thread_internal_dest_tsd(citthread_getspecific(ThreadKey));
 217         citthread_setspecific(ThreadKey, NULL);
 218 }
 219
 220
 221 void ctdl_thread_internal_cleanup(void)
 222 {
 223         int i;
 224         CtdlThreadNode *this_thread, *that_thread;
 225
 226         for (i=0; i<CTDL_THREAD_LAST_STATE; i++)
 227         {
 228                 free (CtdlThreadStates[i]);
 229         }
 230
 231         /* Clean up the scheduled thread list */
 232         this_thread = CtdlThreadSchedList;
 233         while (this_thread)
 234         {
 235                 that_thread = this_thread;
 236                 this_thread = this_thread->next;
 237                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 238                 citthread_cond_destroy(&that_thread->ThreadCond);
 239                 citthread_mutex_destroy(&that_thread->SleepMutex);
 240                 citthread_cond_destroy(&that_thread->SleepCond);
 241                 citthread_attr_destroy(&that_thread->attr);
 242                 free(that_thread);
 243         }
 244         ctdl_thread_internal_free_tsd();
 245 }
 246
 247 void ctdl_thread_internal_init(void)
 248 {
 249         CtdlThreadNode *this_thread;
 250         int ret = 0;
 251
 252         CtdlThreadStates[CTDL_THREAD_INVALID] = strdup ("Invalid Thread");
 253         CtdlThreadStates[CTDL_THREAD_VALID] = strdup("Valid Thread");
 254         CtdlThreadStates[CTDL_THREAD_CREATE] = strdup("Thread being Created");
 255         CtdlThreadStates[CTDL_THREAD_CANCELLED] = strdup("Thread Cancelled");
 256         CtdlThreadStates[CTDL_THREAD_EXITED] = strdup("Thread Exited");
 257         CtdlThreadStates[CTDL_THREAD_STOPPING] = strdup("Thread Stopping");
 258         CtdlThreadStates[CTDL_THREAD_STOP_REQ] = strdup("Thread Stop Requested");
 259         CtdlThreadStates[CTDL_THREAD_SLEEPING] = strdup("Thread Sleeping");
 260         CtdlThreadStates[CTDL_THREAD_RUNNING] = strdup("Thread Running");
 261         CtdlThreadStates[CTDL_THREAD_BLOCKED] = strdup("Thread Blocked");
 262
 263         /* Get ourself a thread entry */
 264         this_thread = malloc(sizeof(CtdlThreadNode));
 265         if (this_thread == NULL) {
 266                 syslog(LOG_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 267                 return;
 268         }
 269         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 270         memset (this_thread, 0, sizeof(CtdlThreadNode));
 271
 272         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 273         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 274         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 275         citthread_cond_init (&(this_thread->SleepCond), NULL);
 276
 277         /* We are garbage collector so create us as running */
 278         this_thread->state = CTDL_THREAD_RUNNING;
 279
 280         if ((ret = citthread_attr_init(&this_thread->attr))) {
 281                 syslog(LOG_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 282                 free(this_thread);
 283                 return;
 284         }
 285
 286         this_thread->name = "Garbage Collection Thread";
 287
 288         this_thread->tid = citthread_self();
 289         GC_thread = this_thread;
 290         CT = this_thread;
 291
 292         num_threads++;  // Increase the count of threads in the system.
 293
 294         this_thread->next = CtdlThreadList;
 295         CtdlThreadList = this_thread;
 296         if (this_thread->next)
 297                 this_thread->next->prev = this_thread;
 298         /* Set up start times */
 299         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 300         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 301 }
 302
 303
 304 /*
 305  * A function to update a threads load averages
 306  */
 307  void ctdl_thread_internal_update_avgs(CtdlThreadNode *this_thread)
 308  {
 309         struct timeval now, result;
 310         double last_duration;
 311
 312         gettimeofday(&now, NULL);
 313         timersub(&now, &(this_thread->last_state_change), &result);
 314         /* I don't think these mutex's are needed here */
 315         citthread_mutex_lock(&this_thread->ThreadMutex);
 316         // result now has a timeval for the time we spent in the last state since we last updated
 317         last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
 318         if (this_thread->state == CTDL_THREAD_SLEEPING)
 319                 this_thread->avg_sleeping += last_duration;
 320         if (this_thread->state == CTDL_THREAD_RUNNING)
 321                 this_thread->avg_running += last_duration;
 322         if (this_thread->state == CTDL_THREAD_BLOCKED)
 323                 this_thread->avg_blocked += last_duration;
 324         memcpy (&this_thread->last_state_change, &now, sizeof (struct timeval));
 325         citthread_mutex_unlock(&this_thread->ThreadMutex);
 326 }
 327
 328 /*
 329  * A function to chenge the state of a thread
 330  */
 331 void ctdl_thread_internal_change_state (CtdlThreadNode *this_thread, enum CtdlThreadState new_state)
 332 {
 333         /*
 334          * Wether we change state or not we need update the load values
 335          */
 336         ctdl_thread_internal_update_avgs(this_thread);
 337         /* This mutex not needed here? */
 338         citthread_mutex_lock(&this_thread->ThreadMutex); /* To prevent race condition of a sleeping thread */
 339         if ((new_state == CTDL_THREAD_STOP_REQ) && (this_thread->state > CTDL_THREAD_STOP_REQ))
 340                 this_thread->state = new_state;
 341         if (((new_state == CTDL_THREAD_SLEEPING) || (new_state == CTDL_THREAD_BLOCKED)) && (this_thread->state == CTDL_THREAD_RUNNING))
 342                 this_thread->state = new_state;
 343         if ((new_state == CTDL_THREAD_RUNNING) && ((this_thread->state == CTDL_THREAD_SLEEPING) || (this_thread->state == CTDL_THREAD_BLOCKED)))
 344                 this_thread->state = new_state;
 345         citthread_mutex_unlock(&this_thread->ThreadMutex);
 346 }
 347
 348
 349 /*
 350  * A function to tell all threads to exit
 351  */
 352 void CtdlThreadStopAll(void)
 353 {
 354         /* First run any registered shutdown hooks.  This probably doesn't belong here. */
 355         PerformSessionHooks(EVT_SHUTDOWN);
 356
 357         /* then close all tcp ports so nobody else can talk to us anymore. */
 358         CtdlShutdownServiceHooks();
 359         //FIXME: The signalling of the condition should not be in the critical_section
 360         // We need to build a list of threads we are going to signal and then signal them afterwards
 361
 362         CtdlThreadNode *this_thread;
 363
 364         begin_critical_section(S_THREAD_LIST);
 365         this_thread = CtdlThreadList;
 366         // Ask the GC thread to stop first so everything knows we are shutting down.
 367         GC_thread->state = CTDL_THREAD_STOP_REQ;
 368         while(this_thread)
 369         {
 370                 if (!citthread_equal(this_thread->tid, GC_thread->tid))
 371                         citthread_kill(this_thread->tid, SIGHUP);
 372
 373                 ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 374                 citthread_cond_signal(&this_thread->ThreadCond);
 375                 citthread_cond_signal(&this_thread->SleepCond);
 376                 this_thread->stop_ticker = time(NULL);
 377                 syslog(LOG_DEBUG, "Thread system stopping thread \"%s\" (0x%08lx).\n",
 378                         this_thread->name, this_thread->tid);
 379                 this_thread = this_thread->next;
 380         }
 381         end_critical_section(S_THREAD_LIST);
 382 }
 383
 384
 385 /*
 386  * A function to wake up all sleeping threads
 387  */
 388 void CtdlThreadWakeAll(void)
 389 {
 390         CtdlThreadNode *this_thread;
 391
 392         syslog(LOG_DEBUG, "Thread system waking all threads.\n");
 393
 394         begin_critical_section(S_THREAD_LIST);
 395         this_thread = CtdlThreadList;
 396         while(this_thread)
 397         {
 398                 if (!this_thread->thread_func)
 399                 {
 400                         citthread_cond_signal(&this_thread->ThreadCond);
 401                         citthread_cond_signal(&this_thread->SleepCond);
 402                 }
 403                 this_thread = this_thread->next;
 404         }
 405         end_critical_section(S_THREAD_LIST);
 406 }
 407
 408
 409 /*
 410  * A function to return the number of threads running in the system
 411  */
 412 int CtdlThreadGetCount(void)
 413 {
 414         return  num_threads;
 415 }
 416
 417 int CtdlThreadGetWorkers(void)
 418 {
 419         return  num_workers;
 420 }
 421
 422 double CtdlThreadGetWorkerAvg(void)
 423 {
 424         double ret;
 425
 426         begin_critical_section(S_THREAD_LIST);
 427         ret =  CtdlThreadWorkerAvg;
 428         end_critical_section(S_THREAD_LIST);
 429         return ret;
 430 }
 431
 432 double CtdlThreadGetLoadAvg(void)
 433 {
 434         double load_avg[3] = {0.0, 0.0, 0.0};
 435
 436         int ret = 0;
 437         int smp_num_cpus;
 438
 439         /* Borrowed this straight from procps */
 440         smp_num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 441         if(smp_num_cpus<1) smp_num_cpus=1; /* SPARC glibc is buggy */
 442
 443 #ifdef HAVE_GETLOADAVG
 444         ret = getloadavg(load_avg, 3);
 445 #endif
 446         if (ret < 0)
 447                 return 0;
 448         return load_avg[0] / smp_num_cpus;
 449 /*
 450  * This old chunk of code return a value that indicated the load on citserver
 451  * This value could easily reach 100 % even when citserver was doing very little and
 452  * hence the machine has much more spare capacity.
 453  * Because this value was used to determine if the machine was under heavy load conditions
 454  * from other processes in the system then citserver could be strangled un-necesarily
 455  * What we are actually trying to achieve is to strangle citserver if the machine is heavily loaded.
 456  * So we have changed this.
 457
 458         begin_critical_section(S_THREAD_LIST);
 459         ret =  CtdlThreadLoadAvg;
 460         end_critical_section(S_THREAD_LIST);
 461         return ret;
 462 */
 463 }
 464
 465
 466
 467
 468 /*
 469  * A function to rename a thread
 470  * Returns a const char *
 471  */
 472 const char *CtdlThreadName(const char *name)
 473 {
 474         const char *old_name;
 475
 476         if (!CT)
 477         {
 478                 syslog(LOG_WARNING, "Thread system WARNING. Attempt to CtdlThreadRename() a non thread. %s\n", name);
 479                 return NULL;
 480         }
 481         old_name = CT->name;
 482         if (name)
 483                 CT->name = name;
 484         return (old_name);
 485 }
 486
 487
 488 /*
 489  * A function to force a thread to exit
 490  */
 491 void CtdlThreadCancel(CtdlThreadNode *thread)
 492 {
 493         CtdlThreadNode *this_thread;
 494
 495         if (!thread)
 496                 this_thread = CT;
 497         else
 498                 this_thread = thread;
 499         if (!this_thread)
 500         {
 501                 syslog(LOG_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() a non thread.\n");
 502                 CtdlThreadStopAll();
 503                 return;
 504         }
 505
 506         if (!this_thread->thread_func)
 507         {
 508                 syslog(LOG_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() the garbage collector.\n");
 509                 CtdlThreadStopAll();
 510                 return;
 511         }
 512
 513         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_CANCELLED);
 514         citthread_cancel(this_thread->tid);
 515 }
 516
 517
 518 /*
 519  * A function for a thread to check if it has been asked to stop
 520  */
 521 int CtdlThreadCheckStop(void)
 522 {
 523         int state;
 524
 525         if (!CT)
 526         {
 527                 syslog(LOG_EMERG, "Thread system PANIC, CtdlThreadCheckStop() called by a non thread.\n");
 528                 CtdlThreadStopAll();
 529                 return -1;
 530         }
 531
 532         state = CT->state;
 533
 534         if (CT->signal)
 535         {
 536                 syslog(LOG_DEBUG, "Thread \"%s\" caught signal %d.\n", CT->name, CT->signal);
 537                 if (CT->signal == SIGHUP)
 538                         CT->state = CTDL_THREAD_STOP_REQ;
 539                 CT->signal = 0;
 540         }
 541         if(state == CTDL_THREAD_STOP_REQ)
 542         {
 543                 CT->state = CTDL_THREAD_STOPPING;
 544                 return -1;
 545         }
 546         else if((state < CTDL_THREAD_STOP_REQ) && (state > CTDL_THREAD_CREATE))
 547         {
 548                 return -1;
 549         }
 550         return 0;
 551 }
 552
 553
 554 /*
 555  * A function to ask a thread to exit
 556  * The thread must call CtdlThreadCheckStop() periodically to determine if it should exit
 557  */
 558 void CtdlThreadStop(CtdlThreadNode *thread)
 559 {
 560         CtdlThreadNode *this_thread;
 561
 562         if (!thread)
 563                 this_thread = CT;
 564         else
 565                 this_thread = thread;
 566         if (!this_thread)
 567                 return;
 568         if (!(this_thread->thread_func))
 569                 return;         // Don't stop garbage collector
 570
 571         if (!citthread_equal(this_thread->tid, GC_thread->tid))
 572                 citthread_kill(this_thread->tid, SIGHUP);
 573
 574         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 575         citthread_cond_signal(&this_thread->ThreadCond);
 576         citthread_cond_signal(&this_thread->SleepCond);
 577         this_thread->stop_ticker = time(NULL);
 578 }
 579
 580 /*
 581  * So we now have a sleep command that works with threads but it is in seconds
 582  */
 583 void CtdlThreadSleep(int secs)
 584 {
 585         struct timespec wake_time;
 586         struct timeval time_now;
 587
 588
 589         if (!CT)
 590         {
 591                 syslog(LOG_WARNING, "CtdlThreadSleep() called by something that is not a thread. Should we die?\n");
 592                 return;
 593         }
 594
 595         memset (&wake_time, 0, sizeof(struct timespec));
 596         gettimeofday(&time_now, NULL);
 597         wake_time.tv_sec = time_now.tv_sec + secs;
 598         wake_time.tv_nsec = time_now.tv_usec * 10;
 599
 600         ctdl_thread_internal_change_state (CT, CTDL_THREAD_SLEEPING);
 601
 602         citthread_mutex_lock(&CT->ThreadMutex); /* Prevent something asking us to awaken before we've gone to sleep */
 603         citthread_cond_timedwait(&CT->SleepCond, &CT->ThreadMutex, &wake_time);
 604         citthread_mutex_unlock(&CT->ThreadMutex);
 605
 606         ctdl_thread_internal_change_state (CT, CTDL_THREAD_RUNNING);
 607 }
 608
 609
 610 /*
 611  * Routine to clean up our thread function on exit
 612  */
 613 static void ctdl_internal_thread_cleanup(void *arg)
 614 {
 615         /*
 616          * In here we were called by the current thread because it is exiting
 617          * NB. WE ARE THE CURRENT THREAD
 618          */
 619         if (CT)
 620         {
 621                 const char *name = CT->name;
 622                 const pid_t tid = CT->tid;
 623
 624                 syslog(LOG_NOTICE, "Thread \"%s\" (0x%08lx) exited.\n", name, (unsigned long) tid);
 625         }
 626         else
 627         {
 628                 syslog(LOG_NOTICE, "some ((unknown ? ? ?) Thread exited.\n");
 629         }
 630
 631         #ifdef HAVE_BACKTRACE
 632 ///     eCrash_UnregisterThread();
 633         #endif
 634
 635         citthread_mutex_lock(&CT->ThreadMutex);
 636         CT->state = CTDL_THREAD_EXITED; // needs to be last thing else house keeping will unlink us too early
 637         citthread_mutex_unlock(&CT->ThreadMutex);
 638 }
 639
 640 /*
 641  * A quick function to show the load averages
 642  */
 643 void ctdl_thread_internal_calc_loadavg(void)
 644 {
 645         CtdlThreadNode *that_thread;
 646         double load_avg, worker_avg;
 647         int workers = 0;
 648
 649         that_thread = CtdlThreadList;
 650         load_avg = 0;
 651         worker_avg = 0;
 652         while(that_thread)
 653         {
 654                 /* Update load averages */
 655                 ctdl_thread_internal_update_avgs(that_thread);
 656                 citthread_mutex_lock(&that_thread->ThreadMutex);
 657                 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;
 658                 that_thread->avg_sleeping /= 2;
 659                 that_thread->avg_running /= 2;
 660                 that_thread->avg_blocked /= 2;
 661                 load_avg += that_thread->load_avg;
 662                 if (that_thread->flags & CTDLTHREAD_WORKER)
 663                 {
 664                         worker_avg += that_thread->load_avg;
 665                         workers++;
 666                 }
 667 #ifdef WITH_THREADLOG
 668                 syslog(LOG_DEBUG, "CtdlThread, \"%s\" (%lu) \"%s\" %.2f %.2f %.2f %.2f\n",
 669                         that_thread->name,
 670                         that_thread->tid,
 671                         CtdlThreadStates[that_thread->state],
 672                         that_thread->avg_sleeping,
 673                         that_thread->avg_running,
 674                         that_thread->avg_blocked,
 675                         that_thread->load_avg);
 676 #endif
 677                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 678                 that_thread = that_thread->next;
 679         }
 680         CtdlThreadLoadAvg = load_avg/num_threads;
 681         CtdlThreadWorkerAvg = worker_avg/workers;
 682 #ifdef WITH_THREADLOG
 683         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);
 684 #endif
 685 }
 686
 687
 688 /*
 689  * Garbage collection routine.
 690  * Gets called by main() in a loop to clean up the thread list periodically.
 691  */
 692 void CtdlThreadGC (void)
 693 {
 694         CtdlThreadNode *this_thread, *that_thread;
 695         int workers = 0, sys_workers;
 696         int ret=0;
 697
 698         begin_critical_section(S_THREAD_LIST);
 699
 700         /* Handle exiting of garbage collector thread */
 701         if(num_threads == 1)
 702                 CtdlThreadList->state = CTDL_THREAD_EXITED;
 703
 704 #ifdef WITH_THREADLOG
 705         syslog(LOG_DEBUG, "Thread system running garbage collection.\n");
 706 #endif
 707         /*
 708          * Woke up to do garbage collection
 709          */
 710         this_thread = CtdlThreadList;
 711         while(this_thread)
 712         {
 713                 that_thread = this_thread;
 714                 this_thread = this_thread->next;
 715
 716                 if ((that_thread->state == CTDL_THREAD_STOP_REQ || that_thread->state == CTDL_THREAD_STOPPING)
 717                         && (!citthread_equal(that_thread->tid, citthread_self())))
 718                 {
 719                         syslog(LOG_DEBUG, "Waiting for thread %s (0x%08lx) to exit.\n", that_thread->name, that_thread->tid);
 720                         terminate_stuck_sessions();
 721                 }
 722                 else
 723                 {
 724                         /**
 725                          * Catch the situation where a worker was asked to stop but couldn't and we are not
 726                          * shutting down.
 727                          */
 728                         that_thread->stop_ticker = 0;
 729                 }
 730
 731                 if (that_thread->stop_ticker + 5 == time(NULL))
 732                 {
 733                         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);
 734                         if ((that_thread->flags & CTDLTHREAD_WORKER) == 0)
 735                                 syslog(LOG_INFO, "Thread System: A non worker thread would have been canceled this may cause message loss.\n");
 736 //                      that_thread->state = CTDL_THREAD_CANCELLED;
 737                         that_thread->stop_ticker++;
 738 //                      citthread_cancel(that_thread->tid);
 739 //                      continue;
 740                 }
 741
 742                 /* Do we need to clean up this thread? */
 743                 if ((that_thread->state != CTDL_THREAD_EXITED) && (that_thread->state != CTDL_THREAD_CANCELLED))
 744                 {
 745                         if(that_thread->flags & CTDLTHREAD_WORKER)
 746                                 workers++;      /* Sanity check on number of worker threads */
 747                         continue;
 748                 }
 749
 750                 if (citthread_equal(that_thread->tid, citthread_self()) && that_thread->thread_func)
 751                 {       /* Sanity check */
 752                         end_critical_section(S_THREAD_LIST);
 753                         syslog(LOG_EMERG, "Thread system PANIC, a thread is trying to clean up after itself.\n");
 754                         abort();
 755                         return;
 756                 }
 757
 758                 if (num_threads <= 0)
 759                 {       /* Sanity check */
 760                         end_critical_section(S_THREAD_LIST);
 761                         syslog(LOG_EMERG, "Thread system PANIC, num_threads <= 0 and trying to do Garbage Collection.\n");
 762                         abort();
 763                         return;
 764                 }
 765
 766                 if(that_thread->flags & CTDLTHREAD_WORKER)
 767                         num_workers--;  /* This is a wroker thread so reduce the count. */
 768                 num_threads--;
 769                 /* If we are unlinking the list head then the next becomes the list head */
 770                 if(that_thread->prev)
 771                         that_thread->prev->next = that_thread->next;
 772                 else
 773                         CtdlThreadList = that_thread->next;
 774                 if(that_thread->next)
 775                         that_thread->next->prev = that_thread->prev;
 776
 777                 citthread_cond_signal(&that_thread->ThreadCond);
 778                 citthread_cond_signal(&that_thread->SleepCond); // Make sure this thread is awake
 779                 citthread_mutex_lock(&that_thread->ThreadMutex);        // Make sure it has done what its doing
 780                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 781                 /*
 782                  * Join on the thread to do clean up and prevent memory leaks
 783                  * Also makes sure the thread has cleaned up after itself before we remove it from the list
 784                  * We can join on the garbage collector thread the join should just return EDEADLCK
 785                  */
 786                 ret = citthread_join (that_thread->tid, NULL);
 787                 if (ret == EDEADLK)
 788                         syslog(LOG_DEBUG, "Garbage collection on own thread.\n");
 789                 else if (ret == EINVAL)
 790                         syslog(LOG_DEBUG, "Garbage collection, that thread already joined on.\n");
 791                 else if (ret == ESRCH)
 792                         syslog(LOG_DEBUG, "Garbage collection, no thread to join on.\n");
 793                 else if (ret != 0)
 794                         syslog(LOG_DEBUG, "Garbage collection, citthread_join returned an unknown error(%d).\n", ret);
 795                 /*
 796                  * Now we own that thread entry
 797                  */
 798                 syslog(LOG_INFO, "Garbage Collection for thread \"%s\" (0x%08lx).\n",
 799                         that_thread->name, that_thread->tid);
 800                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 801                 citthread_cond_destroy(&that_thread->ThreadCond);
 802                 citthread_mutex_destroy(&that_thread->SleepMutex);
 803                 citthread_cond_destroy(&that_thread->SleepCond);
 804                 citthread_attr_destroy(&that_thread->attr);
 805                 free(that_thread);
 806         }
 807         sys_workers = num_workers;
 808         end_critical_section(S_THREAD_LIST);
 809
 810         /* Sanity check number of worker threads */
 811         if (workers != sys_workers)
 812         {
 813                 syslog(LOG_EMERG,
 814                         "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n",
 815                         workers, sys_workers
 816                         );
 817                 abort();
 818         }
 819 }
 820
 821
 822
 823
 824 /*
 825  * Runtime function for a Citadel Thread.
 826  * This initialises the threads environment and then calls the user supplied thread function
 827  * Note that this is the REAL thread function and wraps the users thread function.
 828  */
 829 static void *ctdl_internal_thread_func (void *arg)
 830 {
 831         CtdlThreadNode *this_thread;
 832         void *ret = NULL;
 833
 834         /* lock and unlock the thread list.
 835          * This causes this thread to wait until all its creation stuff has finished before it
 836          * can continue its execution.
 837          */
 838         begin_critical_section(S_THREAD_LIST);
 839         this_thread = (CtdlThreadNode *) arg;
 840         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 841
 842         // Register the cleanup function to take care of when we exit.
 843         citthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
 844         // Get our thread data structure
 845         CtdlThreadAllocTSD();
 846         CT = this_thread;
 847         this_thread->pid = getpid();
 848         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 849         /* Only change to running state if we weren't asked to stop during the create cycle
 850          * Other wise there is a window to allow this threads creation to continue to full grown and
 851          * therby prevent a shutdown of the server.
 852          */
 853         if (!CtdlThreadCheckStop())
 854         {
 855                 citthread_mutex_lock(&this_thread->ThreadMutex);
 856                 this_thread->state = CTDL_THREAD_RUNNING;
 857                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 858         }
 859         end_critical_section(S_THREAD_LIST);
 860
 861         // Register for tracing
 862         #ifdef HAVE_BACKTRACE
 863 ///     eCrash_RegisterThread(this_thread->name, 0);
 864         #endif
 865
 866         // Tell the world we are here
 867 #if defined(HAVE_SYSCALL_H) && defined (SYS_gettid)
 868         this_thread->reltid = syscall(SYS_gettid);
 869 #endif
 870         syslog(LOG_NOTICE, "Created a new thread \"%s\" (0x%08lx).\n",
 871                 this_thread->name, this_thread->tid);
 872
 873         /*
 874          * run the thread to do the work but only if we haven't been asked to stop
 875          */
 876         if (!CtdlThreadCheckStop())
 877                 ret = (this_thread->thread_func)(this_thread->user_args);
 878
 879         /*
 880          * Our thread is exiting either because it wanted to end or because the server is stopping
 881          * We need to clean up
 882          */
 883         citthread_cleanup_pop(1);       // Execute our cleanup routine and remove it
 884
 885         return(ret);
 886 }
 887
 888
 889
 890
 891 /*
 892  * Function to initialise an empty thread structure
 893  */
 894 CtdlThreadNode *ctdl_internal_init_thread_struct(CtdlThreadNode *this_thread, long flags)
 895 {
 896         int ret = 0;
 897
 898         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 899         memset (this_thread, 0, sizeof(CtdlThreadNode));
 900
 901         /* Create the mutex's early so we can use them */
 902         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 903         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 904         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 905         citthread_cond_init (&(this_thread->SleepCond), NULL);
 906
 907         this_thread->state = CTDL_THREAD_CREATE;
 908
 909         if ((ret = citthread_attr_init(&this_thread->attr))) {
 910                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 911                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 912                 citthread_cond_destroy(&(this_thread->ThreadCond));
 913                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 914                 citthread_cond_destroy(&(this_thread->SleepCond));
 915                 syslog(LOG_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 916                 free(this_thread);
 917                 return NULL;
 918         }
 919
 920         /* Our per-thread stacks need to be bigger than the default size,
 921          * otherwise the MIME parser crashes on FreeBSD, and the IMAP service
 922          * crashes on 64-bit Linux.
 923          */
 924         if (flags & CTDLTHREAD_BIGSTACK)
 925         {
 926 #ifdef WITH_THREADLOG
 927                 syslog(LOG_INFO, "Thread system. Creating BIG STACK thread.\n");
 928 #endif
 929                 if ((ret = citthread_attr_setstacksize(&this_thread->attr, THREADSTACKSIZE))) {
 930                         citthread_mutex_unlock(&this_thread->ThreadMutex);
 931                         citthread_mutex_destroy(&(this_thread->ThreadMutex));
 932                         citthread_cond_destroy(&(this_thread->ThreadCond));
 933                         citthread_mutex_destroy(&(this_thread->SleepMutex));
 934                         citthread_cond_destroy(&(this_thread->SleepCond));
 935                         citthread_attr_destroy(&this_thread->attr);
 936                         syslog(LOG_EMERG, "Thread system, citthread_attr_setstacksize: %s\n",
 937                                 strerror(ret));
 938                         free(this_thread);
 939                         return NULL;
 940                 }
 941         }
 942
 943         /* Set this new thread with an avg_blocked of 2. We do this so that its creation affects the
 944          * load average for the system. If we don't do this then we create a mass of threads at the same time
 945          * because the creation didn't affect the load average.
 946          */
 947         this_thread->avg_blocked = 2;
 948
 949         return (this_thread);
 950 }
 951
 952
 953
 954
 955 /*
 956  * Internal function to create a thread.
 957  */
 958 CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void *(*thread_func) (void *arg), void *args)
 959 {
 960         int ret = 0;
 961         CtdlThreadNode *this_thread;
 962
 963         if (num_threads >= 32767)
 964         {
 965                 syslog(LOG_EMERG, "Thread system. Thread list full.\n");
 966                 return NULL;
 967         }
 968
 969         this_thread = malloc(sizeof(CtdlThreadNode));
 970         if (this_thread == NULL) {
 971                 syslog(LOG_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 972                 return NULL;
 973         }
 974
 975         /* Initialise the thread structure */
 976         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
 977         {
 978                 free(this_thread);
 979                 syslog(LOG_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
 980                 return NULL;
 981         }
 982         /*
 983          * If we got here we are going to create the thread so we must initilise the structure
 984          * first because most implimentations of threading can't create it in a stopped state
 985          * and it might want to do things with its structure that aren't initialised otherwise.
 986          */
 987         if(name)
 988         {
 989                 this_thread->name = name;
 990         }
 991         else
 992         {
 993                 this_thread->name = "Un-named Thread";
 994         }
 995
 996         this_thread->flags = flags;
 997         this_thread->thread_func = thread_func;
 998         this_thread->user_args = args;
 999
1000         begin_critical_section(S_THREAD_LIST);
1001         /*
1002          * We pass this_thread into the thread as its args so that it can find out information
1003          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1004          * thread function needs to finish off the setup of the structure
1005          */
1006         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1007         {
1008                 end_critical_section(S_THREAD_LIST);
1009                 syslog(LOG_ALERT, "Thread system, Can't create thread: %s\n",
1010                         strerror(ret));
1011                 citthread_mutex_unlock(&this_thread->ThreadMutex);
1012                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1013                 citthread_cond_destroy(&(this_thread->ThreadCond));
1014                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1015                 citthread_cond_destroy(&(this_thread->SleepCond));
1016                 citthread_attr_destroy(&this_thread->attr);
1017                 free(this_thread);
1018                 return NULL;
1019         }
1020         num_threads++;  // Increase the count of threads in the system.
1021         if(this_thread->flags & CTDLTHREAD_WORKER)
1022                 num_workers++;
1023
1024         this_thread->next = CtdlThreadList;
1025         CtdlThreadList = this_thread;
1026         if (this_thread->next)
1027                 this_thread->next->prev = this_thread;
1028         ctdl_thread_internal_calc_loadavg();
1029
1030         end_critical_section(S_THREAD_LIST);
1031
1032         return this_thread;
1033 }
1034
1035 /*
1036  * Wrapper function to create a thread
1037  * ensures the critical section and other protections are in place.
1038  * char *name = name to give to thread, if NULL, use generic name
1039  * int flags = flags to determine type of thread and standard facilities
1040  */
1041 CtdlThreadNode *CtdlThreadCreate(char *name, long flags, void *(*thread_func) (void *arg), void *args)
1042 {
1043         CtdlThreadNode *ret = NULL;
1044
1045         ret = ctdl_internal_create_thread(name, flags, thread_func, args);
1046         return ret;
1047 }
1048
1049
1050
1051 CtdlThreadNode *ctdl_thread_internal_start_scheduled (CtdlThreadNode *this_thread)
1052 {
1053         int ret = 0;
1054
1055         begin_critical_section(S_THREAD_LIST);
1056         /*
1057          * We pass this_thread into the thread as its args so that it can find out information
1058          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1059          * thread function needs to finish off the setup of the structure
1060          */
1061         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1062         {
1063                 end_critical_section(S_THREAD_LIST);
1064                 syslog(LOG_DEBUG, "Failed to start scheduled thread \"%s\": %s\n", this_thread->name, strerror(ret));
1065                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1066                 citthread_cond_destroy(&(this_thread->ThreadCond));
1067                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1068                 citthread_cond_destroy(&(this_thread->SleepCond));
1069                 citthread_attr_destroy(&this_thread->attr);
1070                 free(this_thread);
1071                 return NULL;
1072         }
1073
1074
1075         num_threads++;  // Increase the count of threads in the system.
1076         if(this_thread->flags & CTDLTHREAD_WORKER)
1077                 num_workers++;
1078
1079         this_thread->next = CtdlThreadList;
1080         CtdlThreadList = this_thread;
1081         if (this_thread->next)
1082                 this_thread->next->prev = this_thread;
1083
1084         ctdl_thread_internal_calc_loadavg();
1085         end_critical_section(S_THREAD_LIST);
1086
1087
1088         return this_thread;
1089 }
1090
1091
1092
1093 void ctdl_thread_internal_check_scheduled(void)
1094 {
1095         CtdlThreadNode *this_thread, *that_thread;
1096         time_t now;
1097
1098         /* Don't start scheduled threads if the system wants single user mode */
1099         if (CtdlWantSingleUser())
1100                 return;
1101
1102         if (try_critical_section(S_SCHEDULE_LIST))
1103                 return; /* If this list is locked we wait till the next chance */
1104
1105         now = time(NULL);
1106
1107 #ifdef WITH_THREADLOG
1108         syslog(LOG_DEBUG, "Checking for scheduled threads to start.\n");
1109 #endif
1110
1111         this_thread = CtdlThreadSchedList;
1112         while(this_thread)
1113         {
1114                 that_thread = this_thread;
1115                 this_thread = this_thread->next;
1116
1117                 if (now > that_thread->when)
1118                 {
1119                         /* Unlink from schedule list */
1120                         if (that_thread->prev)
1121                                 that_thread->prev->next = that_thread->next;
1122                         else
1123                                 CtdlThreadSchedList = that_thread->next;
1124                         if (that_thread->next)
1125                                 that_thread->next->prev = that_thread->prev;
1126
1127                         that_thread->next = that_thread->prev = NULL;
1128 #ifdef WITH_THREADLOG
1129                         syslog(LOG_DEBUG, "About to start scheduled thread \"%s\".\n", that_thread->name);
1130 #endif
1131                         if (CT->state > CTDL_THREAD_STOP_REQ)
1132                         {       /* Only start it if the system is not stopping */
1133                                 if (ctdl_thread_internal_start_scheduled (that_thread))
1134                                 {
1135 #ifdef WITH_THREADLOG
1136                                         syslog(LOG_INFO, "Thread system, Started a scheduled thread \"%s\" (0x%08lx).\n",
1137                                                 that_thread->name, that_thread->tid);
1138 #endif
1139                                 }
1140                         }
1141                 }
1142 #ifdef WITH_THREADLOG
1143                 else
1144                 {
1145                         syslog(LOG_DEBUG, "Thread \"%s\" will start in %ld seconds.\n",
1146                                 that_thread->name, that_thread->when - time(NULL));
1147                 }
1148 #endif
1149         }
1150         end_critical_section(S_SCHEDULE_LIST);
1151 }
1152
1153
1154 /*
1155  * A warapper function for select so we can show a thread as blocked
1156  */
1157 int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
1158 {
1159         int ret = 0;
1160
1161         ctdl_thread_internal_change_state(CT, CTDL_THREAD_BLOCKED);
1162         if (!CtdlThreadCheckStop())
1163                 ret = select(n, readfds, writefds, exceptfds, timeout);
1164         /**
1165          * If the select returned <= 0 then it failed due to an error
1166          * or timeout so this thread could stop if asked to do so.
1167          * Anything else means it needs to continue unless the system is shutting down
1168          */
1169         if (ret > 0)
1170         {
1171                 /**
1172                  * The select says this thread needs to do something useful.
1173                  * This thread was in an idle state so it may have been asked to stop
1174                  * but if the system isn't shutting down this thread is no longer
1175                  * idle and select has given it a task to do so it must not stop
1176                  * In this condition we need to force it into the running state.
1177                  * CtdlThreadGC will clear its ticker for us.
1178                  *
1179                  * FIXME: there is still a small hole here. It is possible for the sequence of locking
1180                  * to allow the state to get changed to STOP_REQ just after this code if the other thread
1181                  * has decided to change the state before this lock, it there fore has to wait till the lock
1182                  * completes but it will continue to change the state. We need something a bit better here.
1183                  */
1184                 citthread_mutex_lock(&CT->ThreadMutex); /* To prevent race condition of a sleeping thread */
1185                 if (GC_thread->state > CTDL_THREAD_STOP_REQ && CT->state <= CTDL_THREAD_STOP_REQ)
1186                 {
1187                         syslog(LOG_DEBUG, "Thread %s (0x%08lx) refused stop request.\n", CT->name, CT->tid);
1188                         CT->state = CTDL_THREAD_RUNNING;
1189                 }
1190                 citthread_mutex_unlock(&CT->ThreadMutex);
1191         }
1192
1193         ctdl_thread_internal_change_state(CT, CTDL_THREAD_RUNNING);
1194
1195         return ret;
1196 }
1197
1198
1199
1200 void *new_worker_thread(void *arg);
1201 extern void close_masters (void);
1202
1203
1204 void *simulation_worker (void*arg) {
1205         struct CitContext *this;
1206
1207         this = CreateNewContext();
1208         CtdlThreadSleep(1);
1209         this->kill_me = 1;
1210         this->state = CON_IDLE;
1211         dead_session_purge(1);
1212         begin_critical_section(S_SESSION_TABLE);
1213         stats_done++;
1214         end_critical_section(S_SESSION_TABLE);
1215         return NULL;
1216 }
1217
1218
1219 void *simulation_thread (void *arg)
1220 {
1221         long stats = statcount;
1222
1223         while(stats && !CtdlThreadCheckStop()) {
1224                 CtdlThreadCreate("Connection simulation worker", CTDLTHREAD_BIGSTACK, simulation_worker, NULL);
1225                 stats--;
1226         }
1227         CtdlThreadStopAll();
1228         return NULL;
1229 }
1230
1231 void go_threading(void)
1232 {
1233         int i;
1234         CtdlThreadNode *last_worker;
1235         struct timeval start, now, result;
1236         double last_duration;
1237
1238         /*
1239          * Initialise the thread system
1240          */
1241         ctdl_thread_internal_init();
1242
1243         /* Second call to module init functions now that threading is up */
1244         if (!statcount) {
1245                 initialise_modules(1);
1246                 CtdlThreadCreate("select_on_master", CTDLTHREAD_BIGSTACK, select_on_master, NULL);
1247         }
1248         else {
1249                 syslog(LOG_EMERG, "Running connection simulation stats\n");
1250                 gettimeofday(&start, NULL);
1251                 CtdlThreadCreate("Connection simulation master", CTDLTHREAD_BIGSTACK, simulation_thread, NULL);
1252         }
1253
1254
1255         /*
1256          * This thread is now used for garbage collection of other threads in the thread list
1257          */
1258         syslog(LOG_INFO, "Startup thread %ld becoming garbage collector,\n", (long) citthread_self());
1259
1260         /*
1261          * We do a lot of locking and unlocking of the thread list in here.
1262          * We do this so that we can repeatedly release time for other threads
1263          * that may be waiting on the thread list.
1264          * We are a low priority thread so we can afford to do this
1265          */
1266
1267         while (CtdlThreadGetCount())
1268         {
1269                 if (CT->signal)
1270                         exit_signal = CT->signal;
1271                 if (exit_signal)
1272                 {
1273                         CtdlThreadStopAll();
1274                 }
1275                 check_sched_shutdown();
1276                 if (CT->state > CTDL_THREAD_STOP_REQ)
1277                 {
1278                         begin_critical_section(S_THREAD_LIST);
1279                         ctdl_thread_internal_calc_loadavg();
1280                         end_critical_section(S_THREAD_LIST);
1281
1282                         ctdl_thread_internal_check_scheduled(); /* start scheduled threads */
1283                 }
1284
1285                 /* Reduce the size of the worker thread pool if necessary. */
1286                 if ((CtdlThreadGetWorkers() > config.c_min_workers + 1) && (CtdlThreadWorkerAvg < 20) && (CT->state > CTDL_THREAD_STOP_REQ))
1287                 {
1288                         /* Ask a worker thread to stop as we no longer need it */
1289                         begin_critical_section(S_THREAD_LIST);
1290                         last_worker = CtdlThreadList;
1291                         while (last_worker)
1292                         {
1293                                 citthread_mutex_lock(&last_worker->ThreadMutex);
1294                                 if (last_worker->flags & CTDLTHREAD_WORKER && (last_worker->state > CTDL_THREAD_STOPPING) && (last_worker->Context == NULL))
1295                                 {
1296                                         citthread_mutex_unlock(&last_worker->ThreadMutex);
1297                                         break;
1298                                 }
1299                                 citthread_mutex_unlock(&last_worker->ThreadMutex);
1300                                 last_worker = last_worker->next;
1301                         }
1302                         end_critical_section(S_THREAD_LIST);
1303                         if (last_worker)
1304                         {
1305 #ifdef WITH_THREADLOG
1306                                 syslog(LOG_DEBUG, "Thread system, stopping excess worker thread \"%s\" (0x%08lx).\n",
1307                                         last_worker->name,
1308                                         last_worker->tid
1309                                         );
1310 #endif
1311                                 CtdlThreadStop(last_worker);
1312                         }
1313                 }
1314
1315                 /*
1316                  * If all our workers are working hard, start some more to help out
1317                  * with things
1318                  */
1319                 /* FIXME: come up with a better way to dynamically alter the number of threads
1320                  * based on the system load
1321                  */
1322                 if (!statcount) {
1323                 if ((((CtdlThreadGetWorkers() < config.c_max_workers) && (CtdlThreadGetWorkerAvg() > 60)) || CtdlThreadGetWorkers() < config.c_min_workers) && (CT->state > CTDL_THREAD_STOP_REQ))
1324                 {
1325                         /* Only start new threads if we are not going to overload the machine */
1326                         /* Temporarily set to 10 should be enough to make sure we don't stranglew the server
1327                          * at least until we make this a config option */
1328                         if (CtdlThreadGetLoadAvg() < ((double)10.00)) {
1329                                 for (i=0; i<5 ; i++) {
1330                                         CtdlThreadCreate("Worker Thread",
1331                                                 CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER,
1332                                                 worker_thread,
1333                                                 NULL
1334                                                 );
1335                                 }
1336                         }
1337                         else
1338                                 syslog(LOG_WARNING, "Server strangled due to machine load average too high.\n");
1339                 }
1340                 }
1341
1342                 CtdlThreadGC();
1343
1344                 if (CtdlThreadGetCount() <= 1) // Shutting down clean up the garbage collector
1345                 {
1346                         CtdlThreadGC();
1347                 }
1348
1349 #ifdef THREADS_USESIGNALS
1350                 if (CtdlThreadGetCount() && CT->state > CTDL_THREAD_STOP_REQ)
1351 #else
1352                 if (CtdlThreadGetCount())
1353 #endif
1354                         CtdlThreadSleep(1);
1355         }
1356         /*
1357          * If the above loop exits we must be shutting down since we obviously have no threads
1358          */
1359         ctdl_thread_internal_cleanup();
1360
1361         if (statcount) {
1362                 gettimeofday(&now, NULL);
1363                 timersub(&now, &start, &result);
1364                 last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
1365                 syslog(LOG_EMERG, "Simulated %ld connections in %f seconds\n", stats_done, last_duration);
1366         }
1367 }
1368
1369
1370
1371