citadel/threads.c

   1 /*
   2  * $Id$
   3  *
   4  * Citadel "system dependent" stuff.
   5  * See COPYING for copyright information.
   6  *
   7  * Here's where we have the Citadel thread implimentation
   8  *
   9  */
  10
  11 #include <stdlib.h>
  12 #include <unistd.h>
  13 #include <stdio.h>
  14 #include <sys/types.h>
  15 #include <errno.h>
  16 #include <sys/socket.h>
  17 #include <unistd.h>
  18 #include <fcntl.h>
  19 #include <signal.h>
  20
  21 #if TIME_WITH_SYS_TIME
  22 # include <sys/time.h>
  23 # include <time.h>
  24 #else
  25 # if HAVE_SYS_TIME_H
  26 #  include <sys/time.h>
  27 # else
  28 #  include <time.h>
  29 # endif
  30 #endif
  31
  32 #include <libcitadel.h>
  33
  34 #include "threads.h"
  35 #include "ctdl_module.h"
  36 #include "modules_init.h"
  37 #include "housekeeping.h"
  38 #include "config.h"
  39 #include "citserver.h"
  40 #include "sysdep_decls.h"
  41 #include "context.h"
  42
  43 /*
  44  * define this to use the new worker_thread method of handling connections
  45  */
  46 //#define NEW_WORKER
  47
  48 /*
  49  * New thread interface.
  50  * To create a thread you must call one of the create thread functions.
  51  * You must pass it the address of (a pointer to a CtdlThreadNode initialised to NULL) like this
  52  * struct CtdlThreadNode *node = NULL;
  53  * pass in &node
  54  * If the thread is created *node will point to the thread control structure for the created thread.
  55  * If the thread creation fails *node remains NULL
  56  * Do not free the memory pointed to by *node, it doesn't belong to you.
  57  * This new interface duplicates much of the eCrash stuff. We should go for closer integration since that would
  58  * remove the need for the calls to eCrashRegisterThread and friends
  59  */
  60
  61 static int num_threads = 0;                     /* Current number of threads */
  62 static int num_workers = 0;                     /* Current number of worker threads */
  63 long statcount = 0;             /* are we doing a stats check? */
  64 static long stats_done = 0;
  65
  66 CtdlThreadNode *CtdlThreadList = NULL;
  67 CtdlThreadNode *CtdlThreadSchedList = NULL;
  68
  69 static CtdlThreadNode *GC_thread = NULL;
  70 static char *CtdlThreadStates[CTDL_THREAD_LAST_STATE];
  71 double CtdlThreadLoadAvg = 0;
  72 double CtdlThreadWorkerAvg = 0;
  73 citthread_key_t ThreadKey;
  74
  75 citthread_mutex_t Critters[MAX_SEMAPHORES];     /* Things needing locking */
  76
  77
  78
  79 void InitialiseSemaphores(void)
  80 {
  81         int i;
  82
  83         /* Set up a bunch of semaphores to be used for critical sections */
  84         for (i=0; i<MAX_SEMAPHORES; ++i) {
  85                 citthread_mutex_init(&Critters[i], NULL);
  86         }
  87 }
  88
  89
  90
  91
  92 /*
  93  * Obtain a semaphore lock to begin a critical section.
  94  * but only if no one else has one
  95  */
  96 int try_critical_section(int which_one)
  97 {
  98         /* For all types of critical sections except those listed here,
  99          * ensure nobody ever tries to do a critical section within a
 100          * transaction; this could lead to deadlock.
 101          */
 102         if (    (which_one != S_FLOORCACHE)
 103 #ifdef DEBUG_MEMORY_LEAKS
 104                 && (which_one != S_DEBUGMEMLEAKS)
 105 #endif
 106                 && (which_one != S_RPLIST)
 107         ) {
 108                 cdb_check_handles();
 109         }
 110         return (citthread_mutex_trylock(&Critters[which_one]));
 111 }
 112
 113
 114 /*
 115  * Obtain a semaphore lock to begin a critical section.
 116  */
 117 void begin_critical_section(int which_one)
 118 {
 119         /* CtdlLogPrintf(CTDL_DEBUG, "begin_critical_section(%d)\n", which_one); */
 120
 121         /* For all types of critical sections except those listed here,
 122          * ensure nobody ever tries to do a critical section within a
 123          * transaction; this could lead to deadlock.
 124          */
 125         if (    (which_one != S_FLOORCACHE)
 126 #ifdef DEBUG_MEMORY_LEAKS
 127                 && (which_one != S_DEBUGMEMLEAKS)
 128 #endif
 129                 && (which_one != S_RPLIST)
 130         ) {
 131                 cdb_check_handles();
 132         }
 133         citthread_mutex_lock(&Critters[which_one]);
 134 }
 135
 136 /*
 137  * Release a semaphore lock to end a critical section.
 138  */
 139 void end_critical_section(int which_one)
 140 {
 141         citthread_mutex_unlock(&Critters[which_one]);
 142 }
 143
 144
 145 /*
 146  * A function to destroy the TSD
 147  */
 148 static void ctdl_thread_internal_dest_tsd(void *arg)
 149 {
 150         if (arg != NULL) {
 151                 check_handles(arg);
 152                 free(arg);
 153         }
 154 }
 155
 156
 157 /*
 158  * A function to initialise the thread TSD
 159  */
 160 void ctdl_thread_internal_init_tsd(void)
 161 {
 162         int ret;
 163
 164         if ((ret = citthread_key_create(&ThreadKey, ctdl_thread_internal_dest_tsd))) {
 165                 CtdlLogPrintf(CTDL_EMERG, "citthread_key_create: %s\n", strerror(ret));
 166                 exit(CTDLEXIT_DB);
 167         }
 168 }
 169
 170 /*
 171  * Ensure that we have a key for thread-specific data.
 172  *
 173  * This should be called immediately after startup by any thread
 174  *
 175  */
 176 void CtdlThreadAllocTSD(void)
 177 {
 178         ThreadTSD *tsd;
 179
 180         if (citthread_getspecific(ThreadKey) != NULL)
 181                 return;
 182
 183         tsd = malloc(sizeof(ThreadTSD));
 184
 185         tsd->tid = NULL;
 186
 187         memset(tsd->cursors, 0, sizeof tsd->cursors);
 188         tsd->self = NULL;
 189
 190         citthread_setspecific(ThreadKey, tsd);
 191 }
 192
 193
 194 void ctdl_thread_internal_free_tsd(void)
 195 {
 196         ctdl_thread_internal_dest_tsd(citthread_getspecific(ThreadKey));
 197         citthread_setspecific(ThreadKey, NULL);
 198 }
 199
 200
 201 void ctdl_thread_internal_cleanup(void)
 202 {
 203         int i;
 204         CtdlThreadNode *this_thread, *that_thread;
 205
 206         for (i=0; i<CTDL_THREAD_LAST_STATE; i++)
 207         {
 208                 free (CtdlThreadStates[i]);
 209         }
 210
 211         /* Clean up the scheduled thread list */
 212         this_thread = CtdlThreadSchedList;
 213         while (this_thread)
 214         {
 215                 that_thread = this_thread;
 216                 this_thread = this_thread->next;
 217                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 218                 citthread_cond_destroy(&that_thread->ThreadCond);
 219                 citthread_mutex_destroy(&that_thread->SleepMutex);
 220                 citthread_cond_destroy(&that_thread->SleepCond);
 221                 citthread_attr_destroy(&that_thread->attr);
 222                 free(that_thread);
 223         }
 224         ctdl_thread_internal_free_tsd();
 225 }
 226
 227 void ctdl_thread_internal_init(void)
 228 {
 229         CtdlThreadNode *this_thread;
 230         int ret = 0;
 231
 232         CtdlThreadStates[CTDL_THREAD_INVALID] = strdup ("Invalid Thread");
 233         CtdlThreadStates[CTDL_THREAD_VALID] = strdup("Valid Thread");
 234         CtdlThreadStates[CTDL_THREAD_CREATE] = strdup("Thread being Created");
 235         CtdlThreadStates[CTDL_THREAD_CANCELLED] = strdup("Thread Cancelled");
 236         CtdlThreadStates[CTDL_THREAD_EXITED] = strdup("Thread Exited");
 237         CtdlThreadStates[CTDL_THREAD_STOPPING] = strdup("Thread Stopping");
 238         CtdlThreadStates[CTDL_THREAD_STOP_REQ] = strdup("Thread Stop Requested");
 239         CtdlThreadStates[CTDL_THREAD_SLEEPING] = strdup("Thread Sleeping");
 240         CtdlThreadStates[CTDL_THREAD_RUNNING] = strdup("Thread Running");
 241         CtdlThreadStates[CTDL_THREAD_BLOCKED] = strdup("Thread Blocked");
 242
 243         /* Get ourself a thread entry */
 244         this_thread = malloc(sizeof(CtdlThreadNode));
 245         if (this_thread == NULL) {
 246                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 247                 return;
 248         }
 249         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 250         memset (this_thread, 0, sizeof(CtdlThreadNode));
 251
 252         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 253         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 254         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 255         citthread_cond_init (&(this_thread->SleepCond), NULL);
 256
 257         /* We are garbage collector so create us as running */
 258         this_thread->state = CTDL_THREAD_RUNNING;
 259
 260         if ((ret = citthread_attr_init(&this_thread->attr))) {
 261                 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 262                 free(this_thread);
 263                 return;
 264         }
 265
 266         this_thread->name = "Garbage Collection Thread";
 267
 268         this_thread->tid = citthread_self();
 269         GC_thread = this_thread;
 270         CT = this_thread;
 271
 272         num_threads++;  // Increase the count of threads in the system.
 273
 274         this_thread->next = CtdlThreadList;
 275         CtdlThreadList = this_thread;
 276         if (this_thread->next)
 277                 this_thread->next->prev = this_thread;
 278         /* Set up start times */
 279         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 280         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 281 }
 282
 283
 284 /*
 285  * A function to update a threads load averages
 286  */
 287  void ctdl_thread_internal_update_avgs(CtdlThreadNode *this_thread)
 288  {
 289         struct timeval now, result;
 290         double last_duration;
 291
 292         gettimeofday(&now, NULL);
 293         timersub(&now, &(this_thread->last_state_change), &result);
 294         /* I don't think these mutex's are needed here */
 295         citthread_mutex_lock(&this_thread->ThreadMutex);
 296         // result now has a timeval for the time we spent in the last state since we last updated
 297         last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
 298         if (this_thread->state == CTDL_THREAD_SLEEPING)
 299                 this_thread->avg_sleeping += last_duration;
 300         if (this_thread->state == CTDL_THREAD_RUNNING)
 301                 this_thread->avg_running += last_duration;
 302         if (this_thread->state == CTDL_THREAD_BLOCKED)
 303                 this_thread->avg_blocked += last_duration;
 304         memcpy (&this_thread->last_state_change, &now, sizeof (struct timeval));
 305         citthread_mutex_unlock(&this_thread->ThreadMutex);
 306 }
 307
 308 /*
 309  * A function to chenge the state of a thread
 310  */
 311 void ctdl_thread_internal_change_state (CtdlThreadNode *this_thread, enum CtdlThreadState new_state)
 312 {
 313         /*
 314          * Wether we change state or not we need update the load values
 315          */
 316         ctdl_thread_internal_update_avgs(this_thread);
 317         /* This mutex not needed here? */
 318         citthread_mutex_lock(&this_thread->ThreadMutex); /* To prevent race condition of a sleeping thread */
 319         if ((new_state == CTDL_THREAD_STOP_REQ) && (this_thread->state > CTDL_THREAD_STOP_REQ))
 320                 this_thread->state = new_state;
 321         if (((new_state == CTDL_THREAD_SLEEPING) || (new_state == CTDL_THREAD_BLOCKED)) && (this_thread->state == CTDL_THREAD_RUNNING))
 322                 this_thread->state = new_state;
 323         if ((new_state == CTDL_THREAD_RUNNING) && ((this_thread->state == CTDL_THREAD_SLEEPING) || (this_thread->state == CTDL_THREAD_BLOCKED)))
 324                 this_thread->state = new_state;
 325         citthread_mutex_unlock(&this_thread->ThreadMutex);
 326 }
 327
 328
 329 /*
 330  * A function to tell all threads to exit
 331  */
 332 void CtdlThreadStopAll(void)
 333 {
 334         /* First run any registered shutdown hooks.  This probably doesn't belong here. */
 335         PerformSessionHooks(EVT_SHUTDOWN);
 336
 337         //FIXME: The signalling of the condition should not be in the critical_section
 338         // We need to build a list of threads we are going to signal and then signal them afterwards
 339
 340         CtdlThreadNode *this_thread;
 341
 342         begin_critical_section(S_THREAD_LIST);
 343         this_thread = CtdlThreadList;
 344         // Ask the GC thread to stop first so everything knows we are shutting down.
 345         GC_thread->state = CTDL_THREAD_STOP_REQ;
 346         while(this_thread)
 347         {
 348                 if (!citthread_equal(this_thread->tid, GC_thread->tid))
 349                         citthread_kill(this_thread->tid, SIGHUP);
 350
 351                 ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 352                 citthread_cond_signal(&this_thread->ThreadCond);
 353                 citthread_cond_signal(&this_thread->SleepCond);
 354                 this_thread->stop_ticker = time(NULL);
 355                 CtdlLogPrintf(CTDL_DEBUG, "Thread system stopping thread \"%s\" (0x%08lx).\n",
 356                         this_thread->name, this_thread->tid);
 357                 this_thread = this_thread->next;
 358         }
 359         end_critical_section(S_THREAD_LIST);
 360 }
 361
 362
 363 /*
 364  * A function to wake up all sleeping threads
 365  */
 366 void CtdlThreadWakeAll(void)
 367 {
 368         CtdlThreadNode *this_thread;
 369
 370         CtdlLogPrintf(CTDL_DEBUG, "Thread system waking all threads.\n");
 371
 372         begin_critical_section(S_THREAD_LIST);
 373         this_thread = CtdlThreadList;
 374         while(this_thread)
 375         {
 376                 if (!this_thread->thread_func)
 377                 {
 378                         citthread_cond_signal(&this_thread->ThreadCond);
 379                         citthread_cond_signal(&this_thread->SleepCond);
 380                 }
 381                 this_thread = this_thread->next;
 382         }
 383         end_critical_section(S_THREAD_LIST);
 384 }
 385
 386
 387 /*
 388  * A function to return the number of threads running in the system
 389  */
 390 int CtdlThreadGetCount(void)
 391 {
 392         return  num_threads;
 393 }
 394
 395 int CtdlThreadGetWorkers(void)
 396 {
 397         return  num_workers;
 398 }
 399
 400 double CtdlThreadGetWorkerAvg(void)
 401 {
 402         double ret;
 403
 404         begin_critical_section(S_THREAD_LIST);
 405         ret =  CtdlThreadWorkerAvg;
 406         end_critical_section(S_THREAD_LIST);
 407         return ret;
 408 }
 409
 410 double CtdlThreadGetLoadAvg(void)
 411 {
 412         double load_avg[3] = {0.0, 0.0, 0.0};
 413
 414         int ret = 0;
 415         int smp_num_cpus;
 416
 417         /* Borrowed this straight from procps */
 418         smp_num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 419         if(smp_num_cpus<1) smp_num_cpus=1; /* SPARC glibc is buggy */
 420
 421 #ifdef HAVE_GETLOADAVG
 422         ret = getloadavg(load_avg, 3);
 423 #endif
 424         if (ret < 0)
 425                 return 0;
 426         return load_avg[0] / smp_num_cpus;
 427 /*
 428  * This old chunk of code return a value that indicated the load on citserver
 429  * This value could easily reach 100 % even when citserver was doing very little and
 430  * hence the machine has much more spare capacity.
 431  * Because this value was used to determine if the machine was under heavy load conditions
 432  * from other processes in the system then citserver could be strangled un-necesarily
 433  * What we are actually trying to achieve is to strangle citserver if the machine is heavily loaded.
 434  * So we have changed this.
 435
 436         begin_critical_section(S_THREAD_LIST);
 437         ret =  CtdlThreadLoadAvg;
 438         end_critical_section(S_THREAD_LIST);
 439         return ret;
 440 */
 441 }
 442
 443
 444
 445
 446 /*
 447  * A function to rename a thread
 448  * Returns a const char *
 449  */
 450 const char *CtdlThreadName(const char *name)
 451 {
 452         const char *old_name;
 453
 454         if (!CT)
 455         {
 456                 CtdlLogPrintf(CTDL_WARNING, "Thread system WARNING. Attempt to CtdlThreadRename() a non thread. %s\n", name);
 457                 return NULL;
 458         }
 459         old_name = CT->name;
 460         if (name)
 461                 CT->name = name;
 462         return (old_name);
 463 }
 464
 465
 466 /*
 467  * A function to force a thread to exit
 468  */
 469 void CtdlThreadCancel(CtdlThreadNode *thread)
 470 {
 471         CtdlThreadNode *this_thread;
 472
 473         if (!thread)
 474                 this_thread = CT;
 475         else
 476                 this_thread = thread;
 477         if (!this_thread)
 478         {
 479                 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() a non thread.\n");
 480                 CtdlThreadStopAll();
 481                 return;
 482         }
 483
 484         if (!this_thread->thread_func)
 485         {
 486                 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() the garbage collector.\n");
 487                 CtdlThreadStopAll();
 488                 return;
 489         }
 490
 491         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_CANCELLED);
 492         citthread_cancel(this_thread->tid);
 493 }
 494
 495
 496 /*
 497  * A function for a thread to check if it has been asked to stop
 498  */
 499 int CtdlThreadCheckStop(void)
 500 {
 501         int state;
 502
 503         if (!CT)
 504         {
 505                 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, CtdlThreadCheckStop() called by a non thread.\n");
 506                 CtdlThreadStopAll();
 507                 return -1;
 508         }
 509
 510         state = CT->state;
 511
 512         if (CT->signal)
 513         {
 514                 CtdlLogPrintf(CTDL_DEBUG, "Thread \"%s\" caught signal %d.\n", CT->name, CT->signal);
 515                 if (CT->signal == SIGHUP)
 516                         CT->state = CTDL_THREAD_STOP_REQ;
 517                 CT->signal = 0;
 518         }
 519         if(state == CTDL_THREAD_STOP_REQ)
 520         {
 521                 CT->state = CTDL_THREAD_STOPPING;
 522                 return -1;
 523         }
 524         else if((state < CTDL_THREAD_STOP_REQ) && (state > CTDL_THREAD_CREATE))
 525         {
 526                 return -1;
 527         }
 528         return 0;
 529 }
 530
 531
 532 /*
 533  * A function to ask a thread to exit
 534  * The thread must call CtdlThreadCheckStop() periodically to determine if it should exit
 535  */
 536 void CtdlThreadStop(CtdlThreadNode *thread)
 537 {
 538         CtdlThreadNode *this_thread;
 539
 540         if (!thread)
 541                 this_thread = CT;
 542         else
 543                 this_thread = thread;
 544         if (!this_thread)
 545                 return;
 546         if (!(this_thread->thread_func))
 547                 return;         // Don't stop garbage collector
 548
 549         if (!citthread_equal(this_thread->tid, GC_thread->tid))
 550                 citthread_kill(this_thread->tid, SIGHUP);
 551
 552         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 553         citthread_cond_signal(&this_thread->ThreadCond);
 554         citthread_cond_signal(&this_thread->SleepCond);
 555         this_thread->stop_ticker = time(NULL);
 556 }
 557
 558 /*
 559  * So we now have a sleep command that works with threads but it is in seconds
 560  */
 561 void CtdlThreadSleep(int secs)
 562 {
 563         struct timespec wake_time;
 564         struct timeval time_now;
 565
 566
 567         if (!CT)
 568         {
 569                 CtdlLogPrintf(CTDL_WARNING, "CtdlThreadSleep() called by something that is not a thread. Should we die?\n");
 570                 return;
 571         }
 572
 573         memset (&wake_time, 0, sizeof(struct timespec));
 574         gettimeofday(&time_now, NULL);
 575         wake_time.tv_sec = time_now.tv_sec + secs;
 576         wake_time.tv_nsec = time_now.tv_usec * 10;
 577
 578         ctdl_thread_internal_change_state (CT, CTDL_THREAD_SLEEPING);
 579
 580         citthread_mutex_lock(&CT->ThreadMutex); /* Prevent something asking us to awaken before we've gone to sleep */
 581         citthread_cond_timedwait(&CT->SleepCond, &CT->ThreadMutex, &wake_time);
 582         citthread_mutex_unlock(&CT->ThreadMutex);
 583
 584         ctdl_thread_internal_change_state (CT, CTDL_THREAD_RUNNING);
 585 }
 586
 587
 588 /*
 589  * Routine to clean up our thread function on exit
 590  */
 591 static void ctdl_internal_thread_cleanup(void *arg)
 592 {
 593         /*
 594          * In here we were called by the current thread because it is exiting
 595          * NB. WE ARE THE CURRENT THREAD
 596          */
 597         if (CT)
 598         {
 599                 const char *name = CT->name;
 600                 const pid_t tid = CT->tid;
 601
 602                 CtdlLogPrintf(CTDL_NOTICE, "Thread \"%s\" (0x%08lx) exited.\n", name, tid);
 603         }
 604         else
 605         {
 606                 CtdlLogPrintf(CTDL_NOTICE, "some ((unknown ? ? ?) Thread exited.\n");
 607         }
 608
 609         #ifdef HAVE_BACKTRACE
 610 ///     eCrash_UnregisterThread();
 611         #endif
 612
 613         citthread_mutex_lock(&CT->ThreadMutex);
 614         CT->state = CTDL_THREAD_EXITED; // needs to be last thing else house keeping will unlink us too early
 615         citthread_mutex_unlock(&CT->ThreadMutex);
 616 }
 617
 618 /*
 619  * A quick function to show the load averages
 620  */
 621 void ctdl_thread_internal_calc_loadavg(void)
 622 {
 623         CtdlThreadNode *that_thread;
 624         double load_avg, worker_avg;
 625         int workers = 0;
 626
 627         that_thread = CtdlThreadList;
 628         load_avg = 0;
 629         worker_avg = 0;
 630         while(that_thread)
 631         {
 632                 /* Update load averages */
 633                 ctdl_thread_internal_update_avgs(that_thread);
 634                 citthread_mutex_lock(&that_thread->ThreadMutex);
 635                 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;
 636                 that_thread->avg_sleeping /= 2;
 637                 that_thread->avg_running /= 2;
 638                 that_thread->avg_blocked /= 2;
 639                 load_avg += that_thread->load_avg;
 640                 if (that_thread->flags & CTDLTHREAD_WORKER)
 641                 {
 642                         worker_avg += that_thread->load_avg;
 643                         workers++;
 644                 }
 645 #ifdef WITH_THREADLOG
 646                 CtdlLogPrintf(CTDL_DEBUG, "CtdlThread, \"%s\" (%lu) \"%s\" %.2f %.2f %.2f %.2f\n",
 647                         that_thread->name,
 648                         that_thread->tid,
 649                         CtdlThreadStates[that_thread->state],
 650                         that_thread->avg_sleeping,
 651                         that_thread->avg_running,
 652                         that_thread->avg_blocked,
 653                         that_thread->load_avg);
 654 #endif
 655                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 656                 that_thread = that_thread->next;
 657         }
 658         CtdlThreadLoadAvg = load_avg/num_threads;
 659         CtdlThreadWorkerAvg = worker_avg/workers;
 660 #ifdef WITH_THREADLOG
 661         CtdlLogPrintf(CTDL_INFO, "System load average %.2f, workers averag %.2f, threads %d, workers %d, sessions %d\n", CtdlThreadGetLoadAvg(), CtdlThreadWorkerAvg, num_threads, num_workers, num_sessions);
 662 #endif
 663 }
 664
 665
 666 /*
 667  * Garbage collection routine.
 668  * Gets called by main() in a loop to clean up the thread list periodically.
 669  */
 670 void CtdlThreadGC (void)
 671 {
 672         CtdlThreadNode *this_thread, *that_thread;
 673         int workers = 0, sys_workers;
 674         int ret=0;
 675
 676         begin_critical_section(S_THREAD_LIST);
 677
 678         /* Handle exiting of garbage collector thread */
 679         if(num_threads == 1)
 680                 CtdlThreadList->state = CTDL_THREAD_EXITED;
 681
 682 #ifdef WITH_THREADLOG
 683         CtdlLogPrintf(CTDL_DEBUG, "Thread system running garbage collection.\n");
 684 #endif
 685         /*
 686          * Woke up to do garbage collection
 687          */
 688         this_thread = CtdlThreadList;
 689         while(this_thread)
 690         {
 691                 that_thread = this_thread;
 692                 this_thread = this_thread->next;
 693
 694                 if ((that_thread->state == CTDL_THREAD_STOP_REQ || that_thread->state == CTDL_THREAD_STOPPING)
 695                         && (!citthread_equal(that_thread->tid, citthread_self())))
 696                                 CtdlLogPrintf(CTDL_DEBUG, "Waiting for thread %s (0x%08lx) to exit.\n", that_thread->name, that_thread->tid);
 697                 else
 698                 {
 699                         /**
 700                          * Catch the situation where a worker was asked to stop but couldn't and we are not
 701                          * shutting down.
 702                          */
 703                         that_thread->stop_ticker = 0;
 704                 }
 705
 706                 if (that_thread->stop_ticker + 5 == time(NULL))
 707                 {
 708                         CtdlLogPrintf(CTDL_DEBUG, "Thread System: The thread \"%s\" (0x%08lx) failed to self terminate within 5 ticks. It would be cancelled now.\n", that_thread->name, that_thread->tid);
 709                         if ((that_thread->flags & CTDLTHREAD_WORKER) == 0)
 710                                 CtdlLogPrintf(CTDL_INFO, "Thread System: A non worker thread would have been canceled this may cause message loss.\n");
 711 //                      that_thread->state = CTDL_THREAD_CANCELLED;
 712                         that_thread->stop_ticker++;
 713 //                      citthread_cancel(that_thread->tid);
 714 //                      continue;
 715                 }
 716
 717                 /* Do we need to clean up this thread? */
 718                 if ((that_thread->state != CTDL_THREAD_EXITED) && (that_thread->state != CTDL_THREAD_CANCELLED))
 719                 {
 720                         if(that_thread->flags & CTDLTHREAD_WORKER)
 721                                 workers++;      /* Sanity check on number of worker threads */
 722                         continue;
 723                 }
 724
 725                 if (citthread_equal(that_thread->tid, citthread_self()) && that_thread->thread_func)
 726                 {       /* Sanity check */
 727                         end_critical_section(S_THREAD_LIST);
 728                         CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, a thread is trying to clean up after itself.\n");
 729                         abort();
 730                         return;
 731                 }
 732
 733                 if (num_threads <= 0)
 734                 {       /* Sanity check */
 735                         end_critical_section(S_THREAD_LIST);
 736                         CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, num_threads <= 0 and trying to do Garbage Collection.\n");
 737                         abort();
 738                         return;
 739                 }
 740
 741                 if(that_thread->flags & CTDLTHREAD_WORKER)
 742                         num_workers--;  /* This is a wroker thread so reduce the count. */
 743                 num_threads--;
 744                 /* If we are unlinking the list head then the next becomes the list head */
 745                 if(that_thread->prev)
 746                         that_thread->prev->next = that_thread->next;
 747                 else
 748                         CtdlThreadList = that_thread->next;
 749                 if(that_thread->next)
 750                         that_thread->next->prev = that_thread->prev;
 751
 752                 citthread_cond_signal(&that_thread->ThreadCond);
 753                 citthread_cond_signal(&that_thread->SleepCond); // Make sure this thread is awake
 754                 citthread_mutex_lock(&that_thread->ThreadMutex);        // Make sure it has done what its doing
 755                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 756                 /*
 757                  * Join on the thread to do clean up and prevent memory leaks
 758                  * Also makes sure the thread has cleaned up after itself before we remove it from the list
 759                  * We can join on the garbage collector thread the join should just return EDEADLCK
 760                  */
 761                 ret = citthread_join (that_thread->tid, NULL);
 762                 if (ret == EDEADLK)
 763                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection on own thread.\n");
 764                 else if (ret == EINVAL)
 765                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, that thread already joined on.\n");
 766                 else if (ret == ESRCH)
 767                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, no thread to join on.\n");
 768                 else if (ret != 0)
 769                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, citthread_join returned an unknown error(%d).\n", ret);
 770                 /*
 771                  * Now we own that thread entry
 772                  */
 773                 CtdlLogPrintf(CTDL_INFO, "Garbage Collection for thread \"%s\" (0x%08lx).\n",
 774                         that_thread->name, that_thread->tid);
 775                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 776                 citthread_cond_destroy(&that_thread->ThreadCond);
 777                 citthread_mutex_destroy(&that_thread->SleepMutex);
 778                 citthread_cond_destroy(&that_thread->SleepCond);
 779                 citthread_attr_destroy(&that_thread->attr);
 780                 free(that_thread);
 781         }
 782         sys_workers = num_workers;
 783         end_critical_section(S_THREAD_LIST);
 784
 785         /* Sanity check number of worker threads */
 786         if (workers != sys_workers)
 787         {
 788                 CtdlLogPrintf(CTDL_EMERG,
 789                         "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n",
 790                         workers, sys_workers
 791                         );
 792                 abort();
 793         }
 794 }
 795
 796
 797
 798
 799 /*
 800  * Runtime function for a Citadel Thread.
 801  * This initialises the threads environment and then calls the user supplied thread function
 802  * Note that this is the REAL thread function and wraps the users thread function.
 803  */
 804 static void *ctdl_internal_thread_func (void *arg)
 805 {
 806         CtdlThreadNode *this_thread;
 807         void *ret = NULL;
 808
 809         /* lock and unlock the thread list.
 810          * This causes this thread to wait until all its creation stuff has finished before it
 811          * can continue its execution.
 812          */
 813         begin_critical_section(S_THREAD_LIST);
 814         this_thread = (CtdlThreadNode *) arg;
 815         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 816
 817         // Register the cleanup function to take care of when we exit.
 818         citthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
 819         // Get our thread data structure
 820         CtdlThreadAllocTSD();
 821         CT = this_thread;
 822         this_thread->pid = getpid();
 823         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 824         /* Only change to running state if we weren't asked to stop during the create cycle
 825          * Other wise there is a window to allow this threads creation to continue to full grown and
 826          * therby prevent a shutdown of the server.
 827          */
 828         if (!CtdlThreadCheckStop())
 829         {
 830                 citthread_mutex_lock(&this_thread->ThreadMutex);
 831                 this_thread->state = CTDL_THREAD_RUNNING;
 832                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 833         }
 834         end_critical_section(S_THREAD_LIST);
 835
 836         // Register for tracing
 837         #ifdef HAVE_BACKTRACE
 838 ///     eCrash_RegisterThread(this_thread->name, 0);
 839         #endif
 840
 841         // Tell the world we are here
 842         CtdlLogPrintf(CTDL_NOTICE, "Created a new thread \"%s\" (0x%08lx).\n",
 843                 this_thread->name, this_thread->tid);
 844
 845         /*
 846          * run the thread to do the work but only if we haven't been asked to stop
 847          */
 848         if (!CtdlThreadCheckStop())
 849                 ret = (this_thread->thread_func)(this_thread->user_args);
 850
 851         /*
 852          * Our thread is exiting either because it wanted to end or because the server is stopping
 853          * We need to clean up
 854          */
 855         citthread_cleanup_pop(1);       // Execute our cleanup routine and remove it
 856
 857         return(ret);
 858 }
 859
 860
 861
 862
 863 /*
 864  * Function to initialise an empty thread structure
 865  */
 866 CtdlThreadNode *ctdl_internal_init_thread_struct(CtdlThreadNode *this_thread, long flags)
 867 {
 868         int ret = 0;
 869
 870         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 871         memset (this_thread, 0, sizeof(CtdlThreadNode));
 872
 873         /* Create the mutex's early so we can use them */
 874         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 875         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 876         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 877         citthread_cond_init (&(this_thread->SleepCond), NULL);
 878
 879         this_thread->state = CTDL_THREAD_CREATE;
 880
 881         if ((ret = citthread_attr_init(&this_thread->attr))) {
 882                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 883                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 884                 citthread_cond_destroy(&(this_thread->ThreadCond));
 885                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 886                 citthread_cond_destroy(&(this_thread->SleepCond));
 887                 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 888                 free(this_thread);
 889                 return NULL;
 890         }
 891
 892         /* Our per-thread stacks need to be bigger than the default size,
 893          * otherwise the MIME parser crashes on FreeBSD, and the IMAP service
 894          * crashes on 64-bit Linux.
 895          */
 896         if (flags & CTDLTHREAD_BIGSTACK)
 897         {
 898 #ifdef WITH_THREADLOG
 899                 CtdlLogPrintf(CTDL_INFO, "Thread system. Creating BIG STACK thread.\n");
 900 #endif
 901                 if ((ret = citthread_attr_setstacksize(&this_thread->attr, THREADSTACKSIZE))) {
 902                         citthread_mutex_unlock(&this_thread->ThreadMutex);
 903                         citthread_mutex_destroy(&(this_thread->ThreadMutex));
 904                         citthread_cond_destroy(&(this_thread->ThreadCond));
 905                         citthread_mutex_destroy(&(this_thread->SleepMutex));
 906                         citthread_cond_destroy(&(this_thread->SleepCond));
 907                         citthread_attr_destroy(&this_thread->attr);
 908                         CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_setstacksize: %s\n",
 909                                 strerror(ret));
 910                         free(this_thread);
 911                         return NULL;
 912                 }
 913         }
 914
 915         /* Set this new thread with an avg_blocked of 2. We do this so that its creation affects the
 916          * load average for the system. If we don't do this then we create a mass of threads at the same time
 917          * because the creation didn't affect the load average.
 918          */
 919         this_thread->avg_blocked = 2;
 920
 921         return (this_thread);
 922 }
 923
 924
 925
 926
 927 /*
 928  * Internal function to create a thread.
 929  */
 930 CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void *(*thread_func) (void *arg), void *args)
 931 {
 932         int ret = 0;
 933         CtdlThreadNode *this_thread;
 934
 935         if (num_threads >= 32767)
 936         {
 937                 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
 938                 return NULL;
 939         }
 940
 941         this_thread = malloc(sizeof(CtdlThreadNode));
 942         if (this_thread == NULL) {
 943                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 944                 return NULL;
 945         }
 946
 947         /* Initialise the thread structure */
 948         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
 949         {
 950                 free(this_thread);
 951                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
 952                 return NULL;
 953         }
 954         /*
 955          * If we got here we are going to create the thread so we must initilise the structure
 956          * first because most implimentations of threading can't create it in a stopped state
 957          * and it might want to do things with its structure that aren't initialised otherwise.
 958          */
 959         if(name)
 960         {
 961                 this_thread->name = name;
 962         }
 963         else
 964         {
 965                 this_thread->name = "Un-named Thread";
 966         }
 967
 968         this_thread->flags = flags;
 969         this_thread->thread_func = thread_func;
 970         this_thread->user_args = args;
 971
 972         begin_critical_section(S_THREAD_LIST);
 973         /*
 974          * We pass this_thread into the thread as its args so that it can find out information
 975          * about itself and it has a bit of storage space for itself, not to mention that the REAL
 976          * thread function needs to finish off the setup of the structure
 977          */
 978         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
 979         {
 980                 end_critical_section(S_THREAD_LIST);
 981                 CtdlLogPrintf(CTDL_ALERT, "Thread system, Can't create thread: %s\n",
 982                         strerror(ret));
 983                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 984                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 985                 citthread_cond_destroy(&(this_thread->ThreadCond));
 986                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 987                 citthread_cond_destroy(&(this_thread->SleepCond));
 988                 citthread_attr_destroy(&this_thread->attr);
 989                 free(this_thread);
 990                 return NULL;
 991         }
 992
 993         num_threads++;  // Increase the count of threads in the system.
 994         if(this_thread->flags & CTDLTHREAD_WORKER)
 995                 num_workers++;
 996
 997         this_thread->next = CtdlThreadList;
 998         CtdlThreadList = this_thread;
 999         if (this_thread->next)
1000                 this_thread->next->prev = this_thread;
1001         ctdl_thread_internal_calc_loadavg();
1002
1003         end_critical_section(S_THREAD_LIST);
1004
1005         return this_thread;
1006 }
1007
1008 /*
1009  * Wrapper function to create a thread
1010  * ensures the critical section and other protections are in place.
1011  * char *name = name to give to thread, if NULL, use generic name
1012  * int flags = flags to determine type of thread and standard facilities
1013  */
1014 CtdlThreadNode *CtdlThreadCreate(char *name, long flags, void *(*thread_func) (void *arg), void *args)
1015 {
1016         CtdlThreadNode *ret = NULL;
1017
1018         ret = ctdl_internal_create_thread(name, flags, thread_func, args);
1019         return ret;
1020 }
1021
1022
1023
1024 /*
1025  * Internal function to schedule a thread.
1026  * Must be called from within a S_THREAD_LIST critical section
1027  */
1028 CtdlThreadNode *CtdlThreadSchedule(char *name, long flags, void *(*thread_func) (void *arg), void *args, time_t when)
1029 {
1030         CtdlThreadNode *this_thread;
1031
1032         if (num_threads >= 32767)
1033         {
1034                 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
1035                 return NULL;
1036         }
1037
1038         this_thread = malloc(sizeof(CtdlThreadNode));
1039         if (this_thread == NULL) {
1040                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
1041                 return NULL;
1042         }
1043         /* Initialise the thread structure */
1044         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
1045         {
1046                 free(this_thread);
1047                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
1048                 return NULL;
1049         }
1050
1051         /*
1052          * If we got here we are going to create the thread so we must initilise the structure
1053          * first because most implimentations of threading can't create it in a stopped state
1054          * and it might want to do things with its structure that aren't initialised otherwise.
1055          */
1056         if(name)
1057         {
1058                 this_thread->name = name;
1059         }
1060         else
1061         {
1062                 this_thread->name = "Un-named Thread";
1063         }
1064
1065         this_thread->flags = flags;
1066         this_thread->thread_func = thread_func;
1067         this_thread->user_args = args;
1068
1069         /*
1070          * When to start this thread
1071          */
1072         this_thread->when = when;
1073
1074         begin_critical_section(S_SCHEDULE_LIST);
1075         this_thread->next = CtdlThreadSchedList;
1076         CtdlThreadSchedList = this_thread;
1077         if (this_thread->next)
1078                 this_thread->next->prev = this_thread;
1079         end_critical_section(S_SCHEDULE_LIST);
1080
1081         return this_thread;
1082 }
1083
1084
1085
1086 CtdlThreadNode *ctdl_thread_internal_start_scheduled (CtdlThreadNode *this_thread)
1087 {
1088         int ret = 0;
1089
1090         begin_critical_section(S_THREAD_LIST);
1091         /*
1092          * We pass this_thread into the thread as its args so that it can find out information
1093          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1094          * thread function needs to finish off the setup of the structure
1095          */
1096         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1097         {
1098                 end_critical_section(S_THREAD_LIST);
1099                 CtdlLogPrintf(CTDL_DEBUG, "Failed to start scheduled thread \"%s\": %s\n", this_thread->name, strerror(ret));
1100                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1101                 citthread_cond_destroy(&(this_thread->ThreadCond));
1102                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1103                 citthread_cond_destroy(&(this_thread->SleepCond));
1104                 citthread_attr_destroy(&this_thread->attr);
1105                 free(this_thread);
1106                 return NULL;
1107         }
1108
1109
1110         num_threads++;  // Increase the count of threads in the system.
1111         if(this_thread->flags & CTDLTHREAD_WORKER)
1112                 num_workers++;
1113
1114         this_thread->next = CtdlThreadList;
1115         CtdlThreadList = this_thread;
1116         if (this_thread->next)
1117                 this_thread->next->prev = this_thread;
1118
1119         ctdl_thread_internal_calc_loadavg();
1120         end_critical_section(S_THREAD_LIST);
1121
1122
1123         return this_thread;
1124 }
1125
1126
1127
1128 void ctdl_thread_internal_check_scheduled(void)
1129 {
1130         CtdlThreadNode *this_thread, *that_thread;
1131         time_t now;
1132
1133         /* Don't start scheduled threads if the system wants single user mode */
1134         if (CtdlWantSingleUser())
1135                 return;
1136
1137         if (try_critical_section(S_SCHEDULE_LIST))
1138                 return; /* If this list is locked we wait till the next chance */
1139
1140         now = time(NULL);
1141
1142 #ifdef WITH_THREADLOG
1143         CtdlLogPrintf(CTDL_DEBUG, "Checking for scheduled threads to start.\n");
1144 #endif
1145
1146         this_thread = CtdlThreadSchedList;
1147         while(this_thread)
1148         {
1149                 that_thread = this_thread;
1150                 this_thread = this_thread->next;
1151
1152                 if (now > that_thread->when)
1153                 {
1154                         /* Unlink from schedule list */
1155                         if (that_thread->prev)
1156                                 that_thread->prev->next = that_thread->next;
1157                         else
1158                                 CtdlThreadSchedList = that_thread->next;
1159                         if (that_thread->next)
1160                                 that_thread->next->prev = that_thread->prev;
1161
1162                         that_thread->next = that_thread->prev = NULL;
1163 #ifdef WITH_THREADLOG
1164                         CtdlLogPrintf(CTDL_DEBUG, "About to start scheduled thread \"%s\".\n", that_thread->name);
1165 #endif
1166                         if (CT->state > CTDL_THREAD_STOP_REQ)
1167                         {       /* Only start it if the system is not stopping */
1168                                 if (ctdl_thread_internal_start_scheduled (that_thread))
1169                                 {
1170 #ifdef WITH_THREADLOG
1171                                         CtdlLogPrintf(CTDL_INFO, "Thread system, Started a scheduled thread \"%s\" (0x%08lx).\n",
1172                                                 that_thread->name, that_thread->tid);
1173 #endif
1174                                 }
1175                         }
1176                 }
1177 #ifdef WITH_THREADLOG
1178                 else
1179                 {
1180                         CtdlLogPrintf(CTDL_DEBUG, "Thread \"%s\" will start in %ld seconds.\n",
1181                                 that_thread->name, that_thread->when - time(NULL));
1182                 }
1183 #endif
1184         }
1185         end_critical_section(S_SCHEDULE_LIST);
1186 }
1187
1188
1189 /*
1190  * A warapper function for select so we can show a thread as blocked
1191  */
1192 int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
1193 {
1194         int ret = 0;
1195
1196         ctdl_thread_internal_change_state(CT, CTDL_THREAD_BLOCKED);
1197         if (!CtdlThreadCheckStop())
1198                 ret = select(n, readfds, writefds, exceptfds, timeout);
1199         /**
1200          * If the select returned <= 0 then it failed due to an error
1201          * or timeout so this thread could stop if asked to do so.
1202          * Anything else means it needs to continue unless the system is shutting down
1203          */
1204         if (ret > 0)
1205         {
1206                 /**
1207                  * The select says this thread needs to do something useful.
1208                  * This thread was in an idle state so it may have been asked to stop
1209                  * but if the system isn't shutting down this thread is no longer
1210                  * idle and select has given it a task to do so it must not stop
1211                  * In this condition we need to force it into the running state.
1212                  * CtdlThreadGC will clear its ticker for us.
1213                  *
1214                  * FIXME: there is still a small hole here. It is possible for the sequence of locking
1215                  * to allow the state to get changed to STOP_REQ just after this code if the other thread
1216                  * has decided to change the state before this lock, it there fore has to wait till the lock
1217                  * completes but it will continue to change the state. We need something a bit better here.
1218                  */
1219                 citthread_mutex_lock(&CT->ThreadMutex); /* To prevent race condition of a sleeping thread */
1220                 if (GC_thread->state > CTDL_THREAD_STOP_REQ && CT->state <= CTDL_THREAD_STOP_REQ)
1221                 {
1222                         CtdlLogPrintf(CTDL_DEBUG, "Thread %s (0x%08lx) refused stop request.\n", CT->name, CT->tid);
1223                         CT->state = CTDL_THREAD_RUNNING;
1224                 }
1225                 citthread_mutex_unlock(&CT->ThreadMutex);
1226         }
1227
1228         ctdl_thread_internal_change_state(CT, CTDL_THREAD_RUNNING);
1229
1230         return ret;
1231 }
1232
1233
1234
1235 void *new_worker_thread(void *arg);
1236 extern void close_masters (void);
1237
1238
1239 void *simulation_worker (void*arg) {
1240         struct CitContext *this;
1241
1242         this = CreateNewContext();
1243         CtdlThreadSleep(1);
1244         this->kill_me = 1;
1245         this->state = CON_IDLE;
1246         dead_session_purge(1);
1247         begin_critical_section(S_SESSION_TABLE);
1248         stats_done++;
1249         end_critical_section(S_SESSION_TABLE);
1250         return NULL;
1251 }
1252
1253
1254 void *simulation_thread (void *arg)
1255 {
1256         long stats = statcount;
1257
1258         while(stats && !CtdlThreadCheckStop()) {
1259                 CtdlThreadCreate("Connection simulation worker", CTDLTHREAD_BIGSTACK, simulation_worker, NULL);
1260                 stats--;
1261         }
1262         CtdlThreadStopAll();
1263         return NULL;
1264 }
1265
1266 void go_threading(void)
1267 {
1268         int i;
1269         CtdlThreadNode *last_worker;
1270         struct timeval start, now, result;
1271         double last_duration;
1272
1273         /*
1274          * Initialise the thread system
1275          */
1276         ctdl_thread_internal_init();
1277
1278         /* Second call to module init functions now that threading is up */
1279         if (!statcount) {
1280                 initialise_modules(1);
1281                 CtdlThreadCreate("select_on_master", CTDLTHREAD_BIGSTACK, select_on_master, NULL);
1282         }
1283         else {
1284                 CtdlLogPrintf(CTDL_EMERG, "Running connection simulation stats\n");
1285                 gettimeofday(&start, NULL);
1286                 CtdlThreadCreate("Connection simulation master", CTDLTHREAD_BIGSTACK, simulation_thread, NULL);
1287         }
1288
1289
1290         /*
1291          * This thread is now used for garbage collection of other threads in the thread list
1292          */
1293         CtdlLogPrintf(CTDL_INFO, "Startup thread %d becoming garbage collector,\n", citthread_self());
1294
1295         /*
1296          * We do a lot of locking and unlocking of the thread list in here.
1297          * We do this so that we can repeatedly release time for other threads
1298          * that may be waiting on the thread list.
1299          * We are a low priority thread so we can afford to do this
1300          */
1301
1302         while (CtdlThreadGetCount())
1303         {
1304                 if (CT->signal)
1305                         exit_signal = CT->signal;
1306                 if (exit_signal)
1307                 {
1308                         CtdlThreadStopAll();
1309                 }
1310                 check_sched_shutdown();
1311                 if (CT->state > CTDL_THREAD_STOP_REQ)
1312                 {
1313                         begin_critical_section(S_THREAD_LIST);
1314                         ctdl_thread_internal_calc_loadavg();
1315                         end_critical_section(S_THREAD_LIST);
1316
1317                         ctdl_thread_internal_check_scheduled(); /* start scheduled threads */
1318                 }
1319
1320                 /* Reduce the size of the worker thread pool if necessary. */
1321                 if ((CtdlThreadGetWorkers() > config.c_min_workers + 1) && (CtdlThreadWorkerAvg < 20) && (CT->state > CTDL_THREAD_STOP_REQ))
1322                 {
1323                         /* Ask a worker thread to stop as we no longer need it */
1324                         begin_critical_section(S_THREAD_LIST);
1325                         last_worker = CtdlThreadList;
1326                         while (last_worker)
1327                         {
1328                                 citthread_mutex_lock(&last_worker->ThreadMutex);
1329                                 if (last_worker->flags & CTDLTHREAD_WORKER && (last_worker->state > CTDL_THREAD_STOPPING) && (last_worker->Context == NULL))
1330                                 {
1331                                         citthread_mutex_unlock(&last_worker->ThreadMutex);
1332                                         break;
1333                                 }
1334                                 citthread_mutex_unlock(&last_worker->ThreadMutex);
1335                                 last_worker = last_worker->next;
1336                         }
1337                         end_critical_section(S_THREAD_LIST);
1338                         if (last_worker)
1339                         {
1340 #ifdef WITH_THREADLOG
1341                                 CtdlLogPrintf(CTDL_DEBUG, "Thread system, stopping excess worker thread \"%s\" (0x%08lx).\n",
1342                                         last_worker->name,
1343                                         last_worker->tid
1344                                         );
1345 #endif
1346                                 CtdlThreadStop(last_worker);
1347                         }
1348                 }
1349
1350                 /*
1351                  * If all our workers are working hard, start some more to help out
1352                  * with things
1353                  */
1354                 /* FIXME: come up with a better way to dynamically alter the number of threads
1355                  * based on the system load
1356                  */
1357                 if (!statcount) {
1358                 if ((((CtdlThreadGetWorkers() < config.c_max_workers) && (CtdlThreadGetWorkerAvg() > 60)) || CtdlThreadGetWorkers() < config.c_min_workers) && (CT->state > CTDL_THREAD_STOP_REQ))
1359                 {
1360                         /* Only start new threads if we are not going to overload the machine */
1361                         /* Temporarily set to 10 should be enough to make sure we don't stranglew the server
1362                          * at least until we make this a config option */
1363                         if (CtdlThreadGetLoadAvg() < ((double)10.00)) {
1364                                 for (i=0; i<5 ; i++) {
1365                                         CtdlThreadCreate("Worker Thread",
1366                                                 CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER,
1367                                                 worker_thread,
1368                                                 NULL
1369                                                 );
1370                                 }
1371                         }
1372                         else
1373                                 CtdlLogPrintf (CTDL_WARNING, "Server strangled due to machine load average too high.\n");
1374                 }
1375                 }
1376
1377                 CtdlThreadGC();
1378
1379                 if (CtdlThreadGetCount() <= 1) // Shutting down clean up the garbage collector
1380                 {
1381                         CtdlThreadGC();
1382                 }
1383
1384 #ifdef THREADS_USESIGNALS
1385                 if (CtdlThreadGetCount() && CT->state > CTDL_THREAD_STOP_REQ)
1386 #else
1387                 if (CtdlThreadGetCount())
1388 #endif
1389                         CtdlThreadSleep(1);
1390         }
1391         /*
1392          * If the above loop exits we must be shutting down since we obviously have no threads
1393          */
1394         ctdl_thread_internal_cleanup();
1395
1396         if (statcount) {
1397                 gettimeofday(&now, NULL);
1398                 timersub(&now, &start, &result);
1399                 last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
1400                 CtdlLogPrintf(CTDL_EMERG, "Simulated %ld connections in %f seconds\n", stats_done, last_duration);
1401         }
1402 }
1403
1404
1405
1406