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 #include "event_client.h"
  63
  64 /*
  65  * define this to use the new worker_thread method of handling connections
  66  */
  67 //#define NEW_WORKER
  68
  69 /*
  70  * New thread interface.
  71  * To create a thread you must call one of the create thread functions.
  72  * You must pass it the address of (a pointer to a CtdlThreadNode initialised to NULL) like this
  73  * struct CtdlThreadNode *node = NULL;
  74  * pass in &node
  75  * If the thread is created *node will point to the thread control structure for the created thread.
  76  * If the thread creation fails *node remains NULL
  77  * Do not free the memory pointed to by *node, it doesn't belong to you.
  78  * This new interface duplicates much of the eCrash stuff. We should go for closer integration since that would
  79  * remove the need for the calls to eCrashRegisterThread and friends
  80  */
  81
  82 static int num_threads = 0;                     /* Current number of threads */
  83 static int num_workers = 0;                     /* Current number of worker threads */
  84 long statcount = 0;             /* are we doing a stats check? */
  85 static long stats_done = 0;
  86
  87 CtdlThreadNode *CtdlThreadList = NULL;
  88 CtdlThreadNode *CtdlThreadSchedList = NULL;
  89
  90 static CtdlThreadNode *GC_thread = NULL;
  91 static char *CtdlThreadStates[CTDL_THREAD_LAST_STATE];
  92 double CtdlThreadLoadAvg = 0;
  93 double CtdlThreadWorkerAvg = 0;
  94 citthread_key_t ThreadKey;
  95
  96 citthread_mutex_t Critters[MAX_SEMAPHORES];     /* Things needing locking */
  97
  98
  99
 100 void InitialiseSemaphores(void)
 101 {
 102         int i;
 103
 104         /* Set up a bunch of semaphores to be used for critical sections */
 105         for (i=0; i<MAX_SEMAPHORES; ++i) {
 106                 citthread_mutex_init(&Critters[i], NULL);
 107         }
 108 }
 109
 110
 111
 112
 113 /*
 114  * Obtain a semaphore lock to begin a critical section.
 115  * but only if no one else has one
 116  */
 117 int try_critical_section(int which_one)
 118 {
 119         /* For all types of critical sections except those listed here,
 120          * ensure nobody ever tries to do a critical section within a
 121          * transaction; this could lead to deadlock.
 122          */
 123         if (    (which_one != S_FLOORCACHE)
 124 #ifdef DEBUG_MEMORY_LEAKS
 125                 && (which_one != S_DEBUGMEMLEAKS)
 126 #endif
 127                 && (which_one != S_RPLIST)
 128         ) {
 129                 cdb_check_handles();
 130         }
 131         return (citthread_mutex_trylock(&Critters[which_one]));
 132 }
 133
 134
 135 /*
 136  * Obtain a semaphore lock to begin a critical section.
 137  */
 138 void begin_critical_section(int which_one)
 139 {
 140         /* syslog(LOG_DEBUG, "begin_critical_section(%d)\n", which_one); */
 141
 142         /* For all types of critical sections except those listed here,
 143          * ensure nobody ever tries to do a critical section within a
 144          * transaction; this could lead to deadlock.
 145          */
 146         if (    (which_one != S_FLOORCACHE)
 147 #ifdef DEBUG_MEMORY_LEAKS
 148                 && (which_one != S_DEBUGMEMLEAKS)
 149 #endif
 150                 && (which_one != S_RPLIST)
 151         ) {
 152                 cdb_check_handles();
 153         }
 154         citthread_mutex_lock(&Critters[which_one]);
 155 }
 156
 157 /*
 158  * Release a semaphore lock to end a critical section.
 159  */
 160 void end_critical_section(int which_one)
 161 {
 162         citthread_mutex_unlock(&Critters[which_one]);
 163 }
 164
 165
 166 /*
 167  * A function to destroy the TSD
 168  */
 169 static void ctdl_thread_internal_dest_tsd(void *arg)
 170 {
 171         if (arg != NULL) {
 172                 check_handles(arg);
 173                 free(arg);
 174         }
 175 }
 176
 177
 178 /*
 179  * A function to initialise the thread TSD
 180  */
 181 void ctdl_thread_internal_init_tsd(void)
 182 {
 183         int ret;
 184
 185         if ((ret = citthread_key_create(&ThreadKey, ctdl_thread_internal_dest_tsd))) {
 186                 syslog(LOG_EMERG, "citthread_key_create: %s\n", strerror(ret));
 187                 exit(CTDLEXIT_DB);
 188         }
 189 }
 190
 191 /*
 192  * Ensure that we have a key for thread-specific data.
 193  *
 194  * This should be called immediately after startup by any thread
 195  *
 196  */
 197 void CtdlThreadAllocTSD(void)
 198 {
 199         ThreadTSD *tsd;
 200
 201         if (citthread_getspecific(ThreadKey) != NULL)
 202                 return;
 203
 204         tsd = malloc(sizeof(ThreadTSD));
 205
 206         tsd->tid = NULL;
 207
 208         memset(tsd->cursors, 0, sizeof tsd->cursors);
 209         tsd->self = NULL;
 210
 211         citthread_setspecific(ThreadKey, tsd);
 212 }
 213
 214
 215 void ctdl_thread_internal_free_tsd(void)
 216 {
 217         ctdl_thread_internal_dest_tsd(citthread_getspecific(ThreadKey));
 218         citthread_setspecific(ThreadKey, NULL);
 219 }
 220
 221
 222 void ctdl_thread_internal_cleanup(void)
 223 {
 224         int i;
 225         CtdlThreadNode *this_thread, *that_thread;
 226
 227         for (i=0; i<CTDL_THREAD_LAST_STATE; i++)
 228         {
 229                 free (CtdlThreadStates[i]);
 230         }
 231
 232         /* Clean up the scheduled thread list */
 233         this_thread = CtdlThreadSchedList;
 234         while (this_thread)
 235         {
 236                 that_thread = this_thread;
 237                 this_thread = this_thread->next;
 238                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 239                 citthread_cond_destroy(&that_thread->ThreadCond);
 240                 citthread_mutex_destroy(&that_thread->SleepMutex);
 241                 citthread_cond_destroy(&that_thread->SleepCond);
 242                 citthread_attr_destroy(&that_thread->attr);
 243                 free(that_thread);
 244         }
 245         ctdl_thread_internal_free_tsd();
 246 }
 247
 248 void ctdl_thread_internal_init(void)
 249 {
 250         CtdlThreadNode *this_thread;
 251         int ret = 0;
 252
 253         CtdlThreadStates[CTDL_THREAD_INVALID] = strdup ("Invalid Thread");
 254         CtdlThreadStates[CTDL_THREAD_VALID] = strdup("Valid Thread");
 255         CtdlThreadStates[CTDL_THREAD_CREATE] = strdup("Thread being Created");
 256         CtdlThreadStates[CTDL_THREAD_CANCELLED] = strdup("Thread Cancelled");
 257         CtdlThreadStates[CTDL_THREAD_EXITED] = strdup("Thread Exited");
 258         CtdlThreadStates[CTDL_THREAD_STOPPING] = strdup("Thread Stopping");
 259         CtdlThreadStates[CTDL_THREAD_STOP_REQ] = strdup("Thread Stop Requested");
 260         CtdlThreadStates[CTDL_THREAD_SLEEPING] = strdup("Thread Sleeping");
 261         CtdlThreadStates[CTDL_THREAD_RUNNING] = strdup("Thread Running");
 262         CtdlThreadStates[CTDL_THREAD_BLOCKED] = strdup("Thread Blocked");
 263
 264         /* Get ourself a thread entry */
 265         this_thread = malloc(sizeof(CtdlThreadNode));
 266         if (this_thread == NULL) {
 267                 syslog(LOG_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 268                 return;
 269         }
 270         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 271         memset (this_thread, 0, sizeof(CtdlThreadNode));
 272
 273         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 274         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 275         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 276         citthread_cond_init (&(this_thread->SleepCond), NULL);
 277
 278         /* We are garbage collector so create us as running */
 279         this_thread->state = CTDL_THREAD_RUNNING;
 280
 281         if ((ret = citthread_attr_init(&this_thread->attr))) {
 282                 syslog(LOG_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 283                 free(this_thread);
 284                 return;
 285         }
 286
 287         this_thread->name = "Garbage Collection Thread";
 288
 289         this_thread->tid = citthread_self();
 290         GC_thread = this_thread;
 291         CT = this_thread;
 292
 293         num_threads++;  // Increase the count of threads in the system.
 294
 295         this_thread->next = CtdlThreadList;
 296         CtdlThreadList = this_thread;
 297         if (this_thread->next)
 298                 this_thread->next->prev = this_thread;
 299         /* Set up start times */
 300         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 301         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 302 }
 303
 304
 305 /*
 306  * A function to update a threads load averages
 307  */
 308  void ctdl_thread_internal_update_avgs(CtdlThreadNode *this_thread)
 309  {
 310         struct timeval now, result;
 311         double last_duration;
 312
 313         gettimeofday(&now, NULL);
 314         timersub(&now, &(this_thread->last_state_change), &result);
 315         /* I don't think these mutex's are needed here */
 316         citthread_mutex_lock(&this_thread->ThreadMutex);
 317         // result now has a timeval for the time we spent in the last state since we last updated
 318         last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
 319         if (this_thread->state == CTDL_THREAD_SLEEPING)
 320                 this_thread->avg_sleeping += last_duration;
 321         if (this_thread->state == CTDL_THREAD_RUNNING)
 322                 this_thread->avg_running += last_duration;
 323         if (this_thread->state == CTDL_THREAD_BLOCKED)
 324                 this_thread->avg_blocked += last_duration;
 325         memcpy (&this_thread->last_state_change, &now, sizeof (struct timeval));
 326         citthread_mutex_unlock(&this_thread->ThreadMutex);
 327 }
 328
 329 /*
 330  * A function to chenge the state of a thread
 331  */
 332 void ctdl_thread_internal_change_state (CtdlThreadNode *this_thread, enum CtdlThreadState new_state)
 333 {
 334         /*
 335          * Wether we change state or not we need update the load values
 336          */
 337         ctdl_thread_internal_update_avgs(this_thread);
 338         /* This mutex not needed here? */
 339         citthread_mutex_lock(&this_thread->ThreadMutex); /* To prevent race condition of a sleeping thread */
 340         if ((new_state == CTDL_THREAD_STOP_REQ) && (this_thread->state > CTDL_THREAD_STOP_REQ))
 341                 this_thread->state = new_state;
 342         if (((new_state == CTDL_THREAD_SLEEPING) || (new_state == CTDL_THREAD_BLOCKED)) && (this_thread->state == CTDL_THREAD_RUNNING))
 343                 this_thread->state = new_state;
 344         if ((new_state == CTDL_THREAD_RUNNING) && ((this_thread->state == CTDL_THREAD_SLEEPING) || (this_thread->state == CTDL_THREAD_BLOCKED)))
 345                 this_thread->state = new_state;
 346         citthread_mutex_unlock(&this_thread->ThreadMutex);
 347 }
 348
 349
 350 /*
 351  * A function to tell all threads to exit
 352  */
 353 void CtdlThreadStopAll(void)
 354 {
 355         /* First run any registered shutdown hooks.  This probably doesn't belong here. */
 356         PerformSessionHooks(EVT_SHUTDOWN);
 357
 358         /* then close all tcp ports so nobody else can talk to us anymore. */
 359         CtdlShutdownServiceHooks();
 360         //FIXME: The signalling of the condition should not be in the critical_section
 361         // We need to build a list of threads we are going to signal and then signal them afterwards
 362
 363         ShutDownEventQueue();
 364
 365         CtdlThreadNode *this_thread;
 366
 367         begin_critical_section(S_THREAD_LIST);
 368         this_thread = CtdlThreadList;
 369         // Ask the GC thread to stop first so everything knows we are shutting down.
 370         GC_thread->state = CTDL_THREAD_STOP_REQ;
 371         while(this_thread)
 372         {
 373                 if (!citthread_equal(this_thread->tid, GC_thread->tid))
 374                         citthread_kill(this_thread->tid, SIGHUP);
 375
 376                 ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 377                 citthread_cond_signal(&this_thread->ThreadCond);
 378                 citthread_cond_signal(&this_thread->SleepCond);
 379                 this_thread->stop_ticker = time(NULL);
 380                 syslog(LOG_DEBUG, "Thread system stopping thread \"%s\" (0x%08lx).\n",
 381                         this_thread->name, this_thread->tid);
 382                 this_thread = this_thread->next;
 383         }
 384         end_critical_section(S_THREAD_LIST);
 385 }
 386
 387
 388 /*
 389  * A function to wake up all sleeping threads
 390  */
 391 void CtdlThreadWakeAll(void)
 392 {
 393         CtdlThreadNode *this_thread;
 394
 395         syslog(LOG_DEBUG, "Thread system waking all threads.\n");
 396
 397         begin_critical_section(S_THREAD_LIST);
 398         this_thread = CtdlThreadList;
 399         while(this_thread)
 400         {
 401                 if (!this_thread->thread_func)
 402                 {
 403                         citthread_cond_signal(&this_thread->ThreadCond);
 404                         citthread_cond_signal(&this_thread->SleepCond);
 405                 }
 406                 this_thread = this_thread->next;
 407         }
 408         end_critical_section(S_THREAD_LIST);
 409 }
 410
 411
 412 /*
 413  * A function to return the number of threads running in the system
 414  */
 415 int CtdlThreadGetCount(void)
 416 {
 417         return  num_threads;
 418 }
 419
 420 int CtdlThreadGetWorkers(void)
 421 {
 422         return  num_workers;
 423 }
 424
 425 double CtdlThreadGetWorkerAvg(void)
 426 {
 427         double ret;
 428
 429         begin_critical_section(S_THREAD_LIST);
 430         ret =  CtdlThreadWorkerAvg;
 431         end_critical_section(S_THREAD_LIST);
 432         return ret;
 433 }
 434
 435 double CtdlThreadGetLoadAvg(void)
 436 {
 437         double load_avg[3] = {0.0, 0.0, 0.0};
 438
 439         int ret = 0;
 440         int smp_num_cpus;
 441
 442         /* Borrowed this straight from procps */
 443         smp_num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 444         if(smp_num_cpus<1) smp_num_cpus=1; /* SPARC glibc is buggy */
 445
 446 #ifdef HAVE_GETLOADAVG
 447         ret = getloadavg(load_avg, 3);
 448 #endif
 449         if (ret < 0)
 450                 return 0;
 451         return load_avg[0] / smp_num_cpus;
 452 /*
 453  * This old chunk of code return a value that indicated the load on citserver
 454  * This value could easily reach 100 % even when citserver was doing very little and
 455  * hence the machine has much more spare capacity.
 456  * Because this value was used to determine if the machine was under heavy load conditions
 457  * from other processes in the system then citserver could be strangled un-necesarily
 458  * What we are actually trying to achieve is to strangle citserver if the machine is heavily loaded.
 459  * So we have changed this.
 460
 461         begin_critical_section(S_THREAD_LIST);
 462         ret =  CtdlThreadLoadAvg;
 463         end_critical_section(S_THREAD_LIST);
 464         return ret;
 465 */
 466 }
 467
 468
 469
 470
 471 /*
 472  * A function to rename a thread
 473  * Returns a const char *
 474  */
 475 const char *CtdlThreadName(const char *name)
 476 {
 477         const char *old_name;
 478
 479         if (!CT)
 480         {
 481                 syslog(LOG_WARNING, "Thread system WARNING. Attempt to CtdlThreadRename() a non thread. %s\n", name);
 482                 return NULL;
 483         }
 484         old_name = CT->name;
 485         if (name)
 486                 CT->name = name;
 487         return (old_name);
 488 }
 489
 490
 491 /*
 492  * A function to force a thread to exit
 493  */
 494 void CtdlThreadCancel(CtdlThreadNode *thread)
 495 {
 496         CtdlThreadNode *this_thread;
 497
 498         if (!thread)
 499                 this_thread = CT;
 500         else
 501                 this_thread = thread;
 502         if (!this_thread)
 503         {
 504                 syslog(LOG_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() a non thread.\n");
 505                 CtdlThreadStopAll();
 506                 return;
 507         }
 508
 509         if (!this_thread->thread_func)
 510         {
 511                 syslog(LOG_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() the garbage collector.\n");
 512                 CtdlThreadStopAll();
 513                 return;
 514         }
 515
 516         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_CANCELLED);
 517         citthread_cancel(this_thread->tid);
 518 }
 519
 520
 521 /*
 522  * A function for a thread to check if it has been asked to stop
 523  */
 524 int CtdlThreadCheckStop(void)
 525 {
 526         int state;
 527
 528         if (!CT)
 529         {
 530                 syslog(LOG_EMERG, "Thread system PANIC, CtdlThreadCheckStop() called by a non thread.\n");
 531                 CtdlThreadStopAll();
 532                 return -1;
 533         }
 534
 535         state = CT->state;
 536
 537         if (CT->signal)
 538         {
 539                 syslog(LOG_DEBUG, "Thread \"%s\" caught signal %d.\n", CT->name, CT->signal);
 540                 if (CT->signal == SIGHUP)
 541                         CT->state = CTDL_THREAD_STOP_REQ;
 542                 CT->signal = 0;
 543         }
 544         if(state == CTDL_THREAD_STOP_REQ)
 545         {
 546                 CT->state = CTDL_THREAD_STOPPING;
 547                 return -1;
 548         }
 549         else if((state < CTDL_THREAD_STOP_REQ) && (state > CTDL_THREAD_CREATE))
 550         {
 551                 return -1;
 552         }
 553         return 0;
 554 }
 555
 556
 557 /*
 558  * A function to ask a thread to exit
 559  * The thread must call CtdlThreadCheckStop() periodically to determine if it should exit
 560  */
 561 void CtdlThreadStop(CtdlThreadNode *thread)
 562 {
 563         CtdlThreadNode *this_thread;
 564
 565         if (!thread)
 566                 this_thread = CT;
 567         else
 568                 this_thread = thread;
 569         if (!this_thread)
 570                 return;
 571         if (!(this_thread->thread_func))
 572                 return;         // Don't stop garbage collector
 573
 574         if (!citthread_equal(this_thread->tid, GC_thread->tid))
 575                 citthread_kill(this_thread->tid, SIGHUP);
 576
 577         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 578         citthread_cond_signal(&this_thread->ThreadCond);
 579         citthread_cond_signal(&this_thread->SleepCond);
 580         this_thread->stop_ticker = time(NULL);
 581 }
 582
 583 /*
 584  * So we now have a sleep command that works with threads but it is in seconds
 585  */
 586 void CtdlThreadSleep(int secs)
 587 {
 588         struct timespec wake_time;
 589         struct timeval time_now;
 590
 591
 592         if (!CT)
 593         {
 594                 syslog(LOG_WARNING, "CtdlThreadSleep() called by something that is not a thread. Should we die?\n");
 595                 return;
 596         }
 597
 598         memset (&wake_time, 0, sizeof(struct timespec));
 599         gettimeofday(&time_now, NULL);
 600         wake_time.tv_sec = time_now.tv_sec + secs;
 601         wake_time.tv_nsec = time_now.tv_usec * 10;
 602
 603         ctdl_thread_internal_change_state (CT, CTDL_THREAD_SLEEPING);
 604
 605         citthread_mutex_lock(&CT->ThreadMutex); /* Prevent something asking us to awaken before we've gone to sleep */
 606         citthread_cond_timedwait(&CT->SleepCond, &CT->ThreadMutex, &wake_time);
 607         citthread_mutex_unlock(&CT->ThreadMutex);
 608
 609         ctdl_thread_internal_change_state (CT, CTDL_THREAD_RUNNING);
 610 }
 611
 612
 613 /*
 614  * Routine to clean up our thread function on exit
 615  */
 616 static void ctdl_internal_thread_cleanup(void *arg)
 617 {
 618         /*
 619          * In here we were called by the current thread because it is exiting
 620          * NB. WE ARE THE CURRENT THREAD
 621          */
 622         if (CT)
 623         {
 624                 const char *name = CT->name;
 625                 const pid_t tid = CT->tid;
 626
 627                 syslog(LOG_NOTICE, "Thread \"%s\" (0x%08lx) exited.\n", name, (unsigned long) tid);
 628         }
 629         else
 630         {
 631                 syslog(LOG_NOTICE, "some ((unknown ? ? ?) Thread exited.\n");
 632         }
 633
 634         #ifdef HAVE_BACKTRACE
 635 ///     eCrash_UnregisterThread();
 636         #endif
 637
 638         citthread_mutex_lock(&CT->ThreadMutex);
 639         CT->state = CTDL_THREAD_EXITED; // needs to be last thing else house keeping will unlink us too early
 640         citthread_mutex_unlock(&CT->ThreadMutex);
 641 }
 642
 643 /*
 644  * A quick function to show the load averages
 645  */
 646 void ctdl_thread_internal_calc_loadavg(void)
 647 {
 648         CtdlThreadNode *that_thread;
 649         double load_avg, worker_avg;
 650         int workers = 0;
 651
 652         that_thread = CtdlThreadList;
 653         load_avg = 0;
 654         worker_avg = 0;
 655         while(that_thread)
 656         {
 657                 /* Update load averages */
 658                 ctdl_thread_internal_update_avgs(that_thread);
 659                 citthread_mutex_lock(&that_thread->ThreadMutex);
 660                 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;
 661                 that_thread->avg_sleeping /= 2;
 662                 that_thread->avg_running /= 2;
 663                 that_thread->avg_blocked /= 2;
 664                 load_avg += that_thread->load_avg;
 665                 if (that_thread->flags & CTDLTHREAD_WORKER)
 666                 {
 667                         worker_avg += that_thread->load_avg;
 668                         workers++;
 669                 }
 670 #ifdef WITH_THREADLOG
 671                 syslog(LOG_DEBUG, "CtdlThread, \"%s\" (%lu) \"%s\" %.2f %.2f %.2f %.2f\n",
 672                         that_thread->name,
 673                         that_thread->tid,
 674                         CtdlThreadStates[that_thread->state],
 675                         that_thread->avg_sleeping,
 676                         that_thread->avg_running,
 677                         that_thread->avg_blocked,
 678                         that_thread->load_avg);
 679 #endif
 680                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 681                 that_thread = that_thread->next;
 682         }
 683         CtdlThreadLoadAvg = load_avg/num_threads;
 684         CtdlThreadWorkerAvg = worker_avg/workers;
 685 #ifdef WITH_THREADLOG
 686         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);
 687 #endif
 688 }
 689
 690
 691 /*
 692  * Garbage collection routine.
 693  * Gets called by main() in a loop to clean up the thread list periodically.
 694  */
 695 void CtdlThreadGC (void)
 696 {
 697         CtdlThreadNode *this_thread, *that_thread;
 698         int workers = 0, sys_workers;
 699         int ret=0;
 700
 701         begin_critical_section(S_THREAD_LIST);
 702
 703         /* Handle exiting of garbage collector thread */
 704         if(num_threads == 1)
 705                 CtdlThreadList->state = CTDL_THREAD_EXITED;
 706
 707 #ifdef WITH_THREADLOG
 708         syslog(LOG_DEBUG, "Thread system running garbage collection.\n");
 709 #endif
 710         /*
 711          * Woke up to do garbage collection
 712          */
 713         this_thread = CtdlThreadList;
 714         while(this_thread)
 715         {
 716                 that_thread = this_thread;
 717                 this_thread = this_thread->next;
 718
 719                 if ((that_thread->state == CTDL_THREAD_STOP_REQ || that_thread->state == CTDL_THREAD_STOPPING)
 720                         && (!citthread_equal(that_thread->tid, citthread_self())))
 721                 {
 722                         syslog(LOG_DEBUG, "Waiting for thread %s (0x%08lx) to exit.\n", that_thread->name, that_thread->tid);
 723                         terminate_stuck_sessions();
 724                 }
 725                 else
 726                 {
 727                         /**
 728                          * Catch the situation where a worker was asked to stop but couldn't and we are not
 729                          * shutting down.
 730                          */
 731                         that_thread->stop_ticker = 0;
 732                 }
 733
 734                 if (that_thread->stop_ticker + 5 == time(NULL))
 735                 {
 736                         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);
 737                         if ((that_thread->flags & CTDLTHREAD_WORKER) == 0)
 738                                 syslog(LOG_INFO, "Thread System: A non worker thread would have been canceled this may cause message loss.\n");
 739 //                      that_thread->state = CTDL_THREAD_CANCELLED;
 740                         that_thread->stop_ticker++;
 741 //                      citthread_cancel(that_thread->tid);
 742 //                      continue;
 743                 }
 744
 745                 /* Do we need to clean up this thread? */
 746                 if ((that_thread->state != CTDL_THREAD_EXITED) && (that_thread->state != CTDL_THREAD_CANCELLED))
 747                 {
 748                         if(that_thread->flags & CTDLTHREAD_WORKER)
 749                                 workers++;      /* Sanity check on number of worker threads */
 750                         continue;
 751                 }
 752
 753                 if (citthread_equal(that_thread->tid, citthread_self()) && that_thread->thread_func)
 754                 {       /* Sanity check */
 755                         end_critical_section(S_THREAD_LIST);
 756                         syslog(LOG_EMERG, "Thread system PANIC, a thread is trying to clean up after itself.\n");
 757                         abort();
 758                         return;
 759                 }
 760
 761                 if (num_threads <= 0)
 762                 {       /* Sanity check */
 763                         end_critical_section(S_THREAD_LIST);
 764                         syslog(LOG_EMERG, "Thread system PANIC, num_threads <= 0 and trying to do Garbage Collection.\n");
 765                         abort();
 766                         return;
 767                 }
 768
 769                 if(that_thread->flags & CTDLTHREAD_WORKER)
 770                         num_workers--;  /* This is a wroker thread so reduce the count. */
 771                 num_threads--;
 772                 /* If we are unlinking the list head then the next becomes the list head */
 773                 if(that_thread->prev)
 774                         that_thread->prev->next = that_thread->next;
 775                 else
 776                         CtdlThreadList = that_thread->next;
 777                 if(that_thread->next)
 778                         that_thread->next->prev = that_thread->prev;
 779
 780                 citthread_cond_signal(&that_thread->ThreadCond);
 781                 citthread_cond_signal(&that_thread->SleepCond); // Make sure this thread is awake
 782                 citthread_mutex_lock(&that_thread->ThreadMutex);        // Make sure it has done what its doing
 783                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 784                 /*
 785                  * Join on the thread to do clean up and prevent memory leaks
 786                  * Also makes sure the thread has cleaned up after itself before we remove it from the list
 787                  * We can join on the garbage collector thread the join should just return EDEADLCK
 788                  */
 789                 ret = citthread_join (that_thread->tid, NULL);
 790                 if (ret == EDEADLK)
 791                         syslog(LOG_DEBUG, "Garbage collection on own thread.\n");
 792                 else if (ret == EINVAL)
 793                         syslog(LOG_DEBUG, "Garbage collection, that thread already joined on.\n");
 794                 else if (ret == ESRCH)
 795                         syslog(LOG_DEBUG, "Garbage collection, no thread to join on.\n");
 796                 else if (ret != 0)
 797                         syslog(LOG_DEBUG, "Garbage collection, citthread_join returned an unknown error(%d).\n", ret);
 798                 /*
 799                  * Now we own that thread entry
 800                  */
 801                 syslog(LOG_INFO, "Garbage Collection for thread \"%s\" (0x%08lx).\n",
 802                         that_thread->name, that_thread->tid);
 803                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 804                 citthread_cond_destroy(&that_thread->ThreadCond);
 805                 citthread_mutex_destroy(&that_thread->SleepMutex);
 806                 citthread_cond_destroy(&that_thread->SleepCond);
 807                 citthread_attr_destroy(&that_thread->attr);
 808                 free(that_thread);
 809         }
 810         sys_workers = num_workers;
 811         end_critical_section(S_THREAD_LIST);
 812
 813         /* Sanity check number of worker threads */
 814         if (workers != sys_workers)
 815         {
 816                 syslog(LOG_EMERG,
 817                         "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n",
 818                         workers, sys_workers
 819                         );
 820                 abort();
 821         }
 822 }
 823
 824
 825
 826
 827 /*
 828  * Runtime function for a Citadel Thread.
 829  * This initialises the threads environment and then calls the user supplied thread function
 830  * Note that this is the REAL thread function and wraps the users thread function.
 831  */
 832 static void *ctdl_internal_thread_func (void *arg)
 833 {
 834         CtdlThreadNode *this_thread;
 835         void *ret = NULL;
 836
 837         /* lock and unlock the thread list.
 838          * This causes this thread to wait until all its creation stuff has finished before it
 839          * can continue its execution.
 840          */
 841         begin_critical_section(S_THREAD_LIST);
 842         this_thread = (CtdlThreadNode *) arg;
 843         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 844
 845         // Register the cleanup function to take care of when we exit.
 846         citthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
 847         // Get our thread data structure
 848         CtdlThreadAllocTSD();
 849         CT = this_thread;
 850         this_thread->pid = getpid();
 851         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 852         /* Only change to running state if we weren't asked to stop during the create cycle
 853          * Other wise there is a window to allow this threads creation to continue to full grown and
 854          * therby prevent a shutdown of the server.
 855          */
 856         if (!CtdlThreadCheckStop())
 857         {
 858                 citthread_mutex_lock(&this_thread->ThreadMutex);
 859                 this_thread->state = CTDL_THREAD_RUNNING;
 860                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 861         }
 862         end_critical_section(S_THREAD_LIST);
 863
 864         // Register for tracing
 865         #ifdef HAVE_BACKTRACE
 866 ///     eCrash_RegisterThread(this_thread->name, 0);
 867         #endif
 868
 869         // Tell the world we are here
 870 #if defined(HAVE_SYSCALL_H) && defined (SYS_gettid)
 871         this_thread->reltid = syscall(SYS_gettid);
 872 #endif
 873         syslog(LOG_NOTICE, "Created a new thread \"%s\" (0x%08lx).\n",
 874                 this_thread->name, this_thread->tid);
 875
 876         /*
 877          * run the thread to do the work but only if we haven't been asked to stop
 878          */
 879         if (!CtdlThreadCheckStop())
 880                 ret = (this_thread->thread_func)(this_thread->user_args);
 881
 882         /*
 883          * Our thread is exiting either because it wanted to end or because the server is stopping
 884          * We need to clean up
 885          */
 886         citthread_cleanup_pop(1);       // Execute our cleanup routine and remove it
 887
 888         return(ret);
 889 }
 890
 891
 892
 893
 894 /*
 895  * Function to initialise an empty thread structure
 896  */
 897 CtdlThreadNode *ctdl_internal_init_thread_struct(CtdlThreadNode *this_thread, long flags)
 898 {
 899         int ret = 0;
 900
 901         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 902         memset (this_thread, 0, sizeof(CtdlThreadNode));
 903
 904         /* Create the mutex's early so we can use them */
 905         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 906         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 907         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 908         citthread_cond_init (&(this_thread->SleepCond), NULL);
 909
 910         this_thread->state = CTDL_THREAD_CREATE;
 911
 912         if ((ret = citthread_attr_init(&this_thread->attr))) {
 913                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 914                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 915                 citthread_cond_destroy(&(this_thread->ThreadCond));
 916                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 917                 citthread_cond_destroy(&(this_thread->SleepCond));
 918                 syslog(LOG_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 919                 free(this_thread);
 920                 return NULL;
 921         }
 922
 923         /* Our per-thread stacks need to be bigger than the default size,
 924          * otherwise the MIME parser crashes on FreeBSD, and the IMAP service
 925          * crashes on 64-bit Linux.
 926          */
 927         if (flags & CTDLTHREAD_BIGSTACK)
 928         {
 929 #ifdef WITH_THREADLOG
 930                 syslog(LOG_INFO, "Thread system. Creating BIG STACK thread.\n");
 931 #endif
 932                 if ((ret = citthread_attr_setstacksize(&this_thread->attr, THREADSTACKSIZE))) {
 933                         citthread_mutex_unlock(&this_thread->ThreadMutex);
 934                         citthread_mutex_destroy(&(this_thread->ThreadMutex));
 935                         citthread_cond_destroy(&(this_thread->ThreadCond));
 936                         citthread_mutex_destroy(&(this_thread->SleepMutex));
 937                         citthread_cond_destroy(&(this_thread->SleepCond));
 938                         citthread_attr_destroy(&this_thread->attr);
 939                         syslog(LOG_EMERG, "Thread system, citthread_attr_setstacksize: %s\n",
 940                                 strerror(ret));
 941                         free(this_thread);
 942                         return NULL;
 943                 }
 944         }
 945
 946         /* Set this new thread with an avg_blocked of 2. We do this so that its creation affects the
 947          * load average for the system. If we don't do this then we create a mass of threads at the same time
 948          * because the creation didn't affect the load average.
 949          */
 950         this_thread->avg_blocked = 2;
 951
 952         return (this_thread);
 953 }
 954
 955
 956
 957
 958 /*
 959  * Internal function to create a thread.
 960  */
 961 CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void *(*thread_func) (void *arg), void *args)
 962 {
 963         int ret = 0;
 964         CtdlThreadNode *this_thread;
 965
 966         if (num_threads >= 32767)
 967         {
 968                 syslog(LOG_EMERG, "Thread system. Thread list full.\n");
 969                 return NULL;
 970         }
 971
 972         this_thread = malloc(sizeof(CtdlThreadNode));
 973         if (this_thread == NULL) {
 974                 syslog(LOG_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 975                 return NULL;
 976         }
 977
 978         /* Initialise the thread structure */
 979         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
 980         {
 981                 free(this_thread);
 982                 syslog(LOG_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
 983                 return NULL;
 984         }
 985         /*
 986          * If we got here we are going to create the thread so we must initilise the structure
 987          * first because most implimentations of threading can't create it in a stopped state
 988          * and it might want to do things with its structure that aren't initialised otherwise.
 989          */
 990         if(name)
 991         {
 992                 this_thread->name = name;
 993         }
 994         else
 995         {
 996                 this_thread->name = "Un-named Thread";
 997         }
 998
 999         this_thread->flags = flags;
1000         this_thread->thread_func = thread_func;
1001         this_thread->user_args = args;
1002
1003         begin_critical_section(S_THREAD_LIST);
1004         /*
1005          * We pass this_thread into the thread as its args so that it can find out information
1006          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1007          * thread function needs to finish off the setup of the structure
1008          */
1009         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1010         {
1011                 end_critical_section(S_THREAD_LIST);
1012                 syslog(LOG_ALERT, "Thread system, Can't create thread: %s\n",
1013                         strerror(ret));
1014                 citthread_mutex_unlock(&this_thread->ThreadMutex);
1015                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1016                 citthread_cond_destroy(&(this_thread->ThreadCond));
1017                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1018                 citthread_cond_destroy(&(this_thread->SleepCond));
1019                 citthread_attr_destroy(&this_thread->attr);
1020                 free(this_thread);
1021                 return NULL;
1022         }
1023         num_threads++;  // Increase the count of threads in the system.
1024         if(this_thread->flags & CTDLTHREAD_WORKER)
1025                 num_workers++;
1026
1027         this_thread->next = CtdlThreadList;
1028         CtdlThreadList = this_thread;
1029         if (this_thread->next)
1030                 this_thread->next->prev = this_thread;
1031         ctdl_thread_internal_calc_loadavg();
1032
1033         end_critical_section(S_THREAD_LIST);
1034
1035         return this_thread;
1036 }
1037
1038 /*
1039  * Wrapper function to create a thread
1040  * ensures the critical section and other protections are in place.
1041  * char *name = name to give to thread, if NULL, use generic name
1042  * int flags = flags to determine type of thread and standard facilities
1043  */
1044 CtdlThreadNode *CtdlThreadCreate(char *name, long flags, void *(*thread_func) (void *arg), void *args)
1045 {
1046         CtdlThreadNode *ret = NULL;
1047
1048         ret = ctdl_internal_create_thread(name, flags, thread_func, args);
1049         return ret;
1050 }
1051
1052
1053
1054 CtdlThreadNode *ctdl_thread_internal_start_scheduled (CtdlThreadNode *this_thread)
1055 {
1056         int ret = 0;
1057
1058         begin_critical_section(S_THREAD_LIST);
1059         /*
1060          * We pass this_thread into the thread as its args so that it can find out information
1061          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1062          * thread function needs to finish off the setup of the structure
1063          */
1064         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1065         {
1066                 end_critical_section(S_THREAD_LIST);
1067                 syslog(LOG_DEBUG, "Failed to start scheduled thread \"%s\": %s\n", this_thread->name, strerror(ret));
1068                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1069                 citthread_cond_destroy(&(this_thread->ThreadCond));
1070                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1071                 citthread_cond_destroy(&(this_thread->SleepCond));
1072                 citthread_attr_destroy(&this_thread->attr);
1073                 free(this_thread);
1074                 return NULL;
1075         }
1076
1077
1078         num_threads++;  // Increase the count of threads in the system.
1079         if(this_thread->flags & CTDLTHREAD_WORKER)
1080                 num_workers++;
1081
1082         this_thread->next = CtdlThreadList;
1083         CtdlThreadList = this_thread;
1084         if (this_thread->next)
1085                 this_thread->next->prev = this_thread;
1086
1087         ctdl_thread_internal_calc_loadavg();
1088         end_critical_section(S_THREAD_LIST);
1089
1090
1091         return this_thread;
1092 }
1093
1094
1095
1096 void ctdl_thread_internal_check_scheduled(void)
1097 {
1098         CtdlThreadNode *this_thread, *that_thread;
1099         time_t now;
1100
1101         /* Don't start scheduled threads if the system wants single user mode */
1102         if (CtdlWantSingleUser())
1103                 return;
1104
1105         if (try_critical_section(S_SCHEDULE_LIST))
1106                 return; /* If this list is locked we wait till the next chance */
1107
1108         now = time(NULL);
1109
1110 #ifdef WITH_THREADLOG
1111         syslog(LOG_DEBUG, "Checking for scheduled threads to start.\n");
1112 #endif
1113
1114         this_thread = CtdlThreadSchedList;
1115         while(this_thread)
1116         {
1117                 that_thread = this_thread;
1118                 this_thread = this_thread->next;
1119
1120                 if (now > that_thread->when)
1121                 {
1122                         /* Unlink from schedule list */
1123                         if (that_thread->prev)
1124                                 that_thread->prev->next = that_thread->next;
1125                         else
1126                                 CtdlThreadSchedList = that_thread->next;
1127                         if (that_thread->next)
1128                                 that_thread->next->prev = that_thread->prev;
1129
1130                         that_thread->next = that_thread->prev = NULL;
1131 #ifdef WITH_THREADLOG
1132                         syslog(LOG_DEBUG, "About to start scheduled thread \"%s\".\n", that_thread->name);
1133 #endif
1134                         if (CT->state > CTDL_THREAD_STOP_REQ)
1135                         {       /* Only start it if the system is not stopping */
1136                                 if (ctdl_thread_internal_start_scheduled (that_thread))
1137                                 {
1138 #ifdef WITH_THREADLOG
1139                                         syslog(LOG_INFO, "Thread system, Started a scheduled thread \"%s\" (0x%08lx).\n",
1140                                                 that_thread->name, that_thread->tid);
1141 #endif
1142                                 }
1143                         }
1144                 }
1145 #ifdef WITH_THREADLOG
1146                 else
1147                 {
1148                         syslog(LOG_DEBUG, "Thread \"%s\" will start in %ld seconds.\n",
1149                                 that_thread->name, that_thread->when - time(NULL));
1150                 }
1151 #endif
1152         }
1153         end_critical_section(S_SCHEDULE_LIST);
1154 }
1155
1156
1157 /*
1158  * A warapper function for select so we can show a thread as blocked
1159  */
1160 int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
1161 {
1162         int ret = 0;
1163
1164         ctdl_thread_internal_change_state(CT, CTDL_THREAD_BLOCKED);
1165         if (!CtdlThreadCheckStop())
1166                 ret = select(n, readfds, writefds, exceptfds, timeout);
1167         /**
1168          * If the select returned <= 0 then it failed due to an error
1169          * or timeout so this thread could stop if asked to do so.
1170          * Anything else means it needs to continue unless the system is shutting down
1171          */
1172         if (ret > 0)
1173         {
1174                 /**
1175                  * The select says this thread needs to do something useful.
1176                  * This thread was in an idle state so it may have been asked to stop
1177                  * but if the system isn't shutting down this thread is no longer
1178                  * idle and select has given it a task to do so it must not stop
1179                  * In this condition we need to force it into the running state.
1180                  * CtdlThreadGC will clear its ticker for us.
1181                  *
1182                  * FIXME: there is still a small hole here. It is possible for the sequence of locking
1183                  * to allow the state to get changed to STOP_REQ just after this code if the other thread
1184                  * has decided to change the state before this lock, it there fore has to wait till the lock
1185                  * completes but it will continue to change the state. We need something a bit better here.
1186                  */
1187                 citthread_mutex_lock(&CT->ThreadMutex); /* To prevent race condition of a sleeping thread */
1188                 if (GC_thread->state > CTDL_THREAD_STOP_REQ && CT->state <= CTDL_THREAD_STOP_REQ)
1189                 {
1190                         syslog(LOG_DEBUG, "Thread %s (0x%08lx) refused stop request.\n", CT->name, CT->tid);
1191                         CT->state = CTDL_THREAD_RUNNING;
1192                 }
1193                 citthread_mutex_unlock(&CT->ThreadMutex);
1194         }
1195
1196         ctdl_thread_internal_change_state(CT, CTDL_THREAD_RUNNING);
1197
1198         return ret;
1199 }
1200
1201
1202
1203 void *new_worker_thread(void *arg);
1204 extern void close_masters (void);
1205
1206
1207 void *simulation_worker (void*arg) {
1208         struct CitContext *this;
1209
1210         this = CreateNewContext();
1211         CtdlThreadSleep(1);
1212         this->kill_me = KILLME_SIMULATION_WORKER;
1213         this->state = CON_IDLE;
1214         dead_session_purge(1);
1215         begin_critical_section(S_SESSION_TABLE);
1216         stats_done++;
1217         end_critical_section(S_SESSION_TABLE);
1218         return NULL;
1219 }
1220
1221
1222 void *simulation_thread (void *arg)
1223 {
1224         long stats = statcount;
1225
1226         while(stats && !CtdlThreadCheckStop()) {
1227                 CtdlThreadCreate("Connection simulation worker", CTDLTHREAD_BIGSTACK, simulation_worker, NULL);
1228                 stats--;
1229         }
1230         CtdlThreadStopAll();
1231         return NULL;
1232 }
1233
1234 void go_threading(void)
1235 {
1236         int i;
1237         CtdlThreadNode *last_worker;
1238         struct timeval start, now, result;
1239         double last_duration;
1240
1241         /*
1242          * Initialise the thread system
1243          */
1244         ctdl_thread_internal_init();
1245
1246         /* Second call to module init functions now that threading is up */
1247         if (!statcount) {
1248                 initialise_modules(1);
1249                 CtdlThreadCreate("select_on_master", CTDLTHREAD_BIGSTACK, select_on_master, NULL);
1250         }
1251         else {
1252                 syslog(LOG_EMERG, "Running connection simulation stats\n");
1253                 gettimeofday(&start, NULL);
1254                 CtdlThreadCreate("Connection simulation master", CTDLTHREAD_BIGSTACK, simulation_thread, NULL);
1255         }
1256
1257
1258         /*
1259          * This thread is now used for garbage collection of other threads in the thread list
1260          */
1261         syslog(LOG_INFO, "Startup thread %ld becoming garbage collector,\n", (long) citthread_self());
1262
1263         /*
1264          * We do a lot of locking and unlocking of the thread list in here.
1265          * We do this so that we can repeatedly release time for other threads
1266          * that may be waiting on the thread list.
1267          * We are a low priority thread so we can afford to do this
1268          */
1269
1270         while (CtdlThreadGetCount())
1271         {
1272                 if (CT->signal)
1273                         exit_signal = CT->signal;
1274                 if (exit_signal)
1275                 {
1276                         CtdlThreadStopAll();
1277                 }
1278                 check_sched_shutdown();
1279                 if (CT->state > CTDL_THREAD_STOP_REQ)
1280                 {
1281                         begin_critical_section(S_THREAD_LIST);
1282                         ctdl_thread_internal_calc_loadavg();
1283                         end_critical_section(S_THREAD_LIST);
1284
1285                         ctdl_thread_internal_check_scheduled(); /* start scheduled threads */
1286                 }
1287
1288                 /* Reduce the size of the worker thread pool if necessary. */
1289                 if ((CtdlThreadGetWorkers() > config.c_min_workers + 1) && (CtdlThreadWorkerAvg < 20) && (CT->state > CTDL_THREAD_STOP_REQ))
1290                 {
1291                         /* Ask a worker thread to stop as we no longer need it */
1292                         begin_critical_section(S_THREAD_LIST);
1293                         last_worker = CtdlThreadList;
1294                         while (last_worker)
1295                         {
1296                                 citthread_mutex_lock(&last_worker->ThreadMutex);
1297                                 if (last_worker->flags & CTDLTHREAD_WORKER && (last_worker->state > CTDL_THREAD_STOPPING) && (last_worker->Context == NULL))
1298                                 {
1299                                         citthread_mutex_unlock(&last_worker->ThreadMutex);
1300                                         break;
1301                                 }
1302                                 citthread_mutex_unlock(&last_worker->ThreadMutex);
1303                                 last_worker = last_worker->next;
1304                         }
1305                         end_critical_section(S_THREAD_LIST);
1306                         if (last_worker)
1307                         {
1308 #ifdef WITH_THREADLOG
1309                                 syslog(LOG_DEBUG, "Thread system, stopping excess worker thread \"%s\" (0x%08lx).\n",
1310                                         last_worker->name,
1311                                         last_worker->tid
1312                                         );
1313 #endif
1314                                 CtdlThreadStop(last_worker);
1315                         }
1316                 }
1317
1318                 /*
1319                  * If all our workers are working hard, start some more to help out
1320                  * with things
1321                  */
1322                 /* FIXME: come up with a better way to dynamically alter the number of threads
1323                  * based on the system load
1324                  */
1325                 if (!statcount) {
1326                 if ((((CtdlThreadGetWorkers() < config.c_max_workers) && (CtdlThreadGetWorkerAvg() > 60)) || CtdlThreadGetWorkers() < config.c_min_workers) && (CT->state > CTDL_THREAD_STOP_REQ))
1327                 {
1328                         /* Only start new threads if we are not going to overload the machine */
1329                         /* Temporarily set to 10 should be enough to make sure we don't stranglew the server
1330                          * at least until we make this a config option */
1331                         if (CtdlThreadGetLoadAvg() < ((double)10.00)) {
1332                                 for (i=0; i<5 ; i++) {
1333                                         CtdlThreadCreate("Worker Thread",
1334                                                 CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER,
1335                                                 worker_thread,
1336                                                 NULL
1337                                                 );
1338                                 }
1339                         }
1340                         else
1341                                 syslog(LOG_WARNING, "Server strangled due to machine load average too high.\n");
1342                 }
1343                 }
1344
1345                 CtdlThreadGC();
1346
1347                 if (CtdlThreadGetCount() <= 1) // Shutting down clean up the garbage collector
1348                 {
1349                         CtdlThreadGC();
1350                 }
1351
1352 #ifdef THREADS_USESIGNALS
1353                 if (CtdlThreadGetCount() && CT->state > CTDL_THREAD_STOP_REQ)
1354 #else
1355                 if (CtdlThreadGetCount())
1356 #endif
1357                         CtdlThreadSleep(1);
1358         }
1359         /*
1360          * If the above loop exits we must be shutting down since we obviously have no threads
1361          */
1362         ctdl_thread_internal_cleanup();
1363
1364         if (statcount) {
1365                 gettimeofday(&now, NULL);
1366                 timersub(&now, &start, &result);
1367                 last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
1368                 syslog(LOG_EMERG, "Simulated %ld connections in %f seconds\n", stats_done, last_duration);
1369         }
1370 }
1371
1372
1373
1374