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 next_tid = 3;                        /* offset LWPID to PID */
  62 static int num_threads = 0;                     /* Current number of threads */
  63 static int num_workers = 0;                     /* Current number of worker threads */
  64 long statcount = 0;             /* are we doing a stats check? */
  65 static long stats_done = 0;
  66
  67 CtdlThreadNode *CtdlThreadList = NULL;
  68 CtdlThreadNode *CtdlThreadSchedList = NULL;
  69
  70 static CtdlThreadNode *GC_thread = NULL;
  71 static char *CtdlThreadStates[CTDL_THREAD_LAST_STATE];
  72 double CtdlThreadLoadAvg = 0;
  73 double CtdlThreadWorkerAvg = 0;
  74 citthread_key_t ThreadKey;
  75
  76 citthread_mutex_t Critters[MAX_SEMAPHORES];     /* Things needing locking */
  77
  78
  79
  80 void InitialiseSemaphores(void)
  81 {
  82         int i;
  83
  84         /* Set up a bunch of semaphores to be used for critical sections */
  85         for (i=0; i<MAX_SEMAPHORES; ++i) {
  86                 citthread_mutex_init(&Critters[i], NULL);
  87         }
  88 }
  89
  90
  91
  92
  93 /*
  94  * Obtain a semaphore lock to begin a critical section.
  95  * but only if no one else has one
  96  */
  97 int try_critical_section(int which_one)
  98 {
  99         /* For all types of critical sections except those listed here,
 100          * ensure nobody ever tries to do a critical section within a
 101          * transaction; this could lead to deadlock.
 102          */
 103         if (    (which_one != S_FLOORCACHE)
 104 #ifdef DEBUG_MEMORY_LEAKS
 105                 && (which_one != S_DEBUGMEMLEAKS)
 106 #endif
 107                 && (which_one != S_RPLIST)
 108         ) {
 109                 cdb_check_handles();
 110         }
 111         return (citthread_mutex_trylock(&Critters[which_one]));
 112 }
 113
 114
 115 /*
 116  * Obtain a semaphore lock to begin a critical section.
 117  */
 118 void begin_critical_section(int which_one)
 119 {
 120         /* CtdlLogPrintf(CTDL_DEBUG, "begin_critical_section(%d)\n", which_one); */
 121
 122         /* For all types of critical sections except those listed here,
 123          * ensure nobody ever tries to do a critical section within a
 124          * transaction; this could lead to deadlock.
 125          */
 126         if (    (which_one != S_FLOORCACHE)
 127 #ifdef DEBUG_MEMORY_LEAKS
 128                 && (which_one != S_DEBUGMEMLEAKS)
 129 #endif
 130                 && (which_one != S_RPLIST)
 131         ) {
 132                 cdb_check_handles();
 133         }
 134         citthread_mutex_lock(&Critters[which_one]);
 135 }
 136
 137 /*
 138  * Release a semaphore lock to end a critical section.
 139  */
 140 void end_critical_section(int which_one)
 141 {
 142         citthread_mutex_unlock(&Critters[which_one]);
 143 }
 144
 145
 146 /*
 147  * A function to destroy the TSD
 148  */
 149 static void ctdl_thread_internal_dest_tsd(void *arg)
 150 {
 151         if (arg != NULL) {
 152                 check_handles(arg);
 153                 free(arg);
 154         }
 155 }
 156
 157
 158 /*
 159  * A function to initialise the thread TSD
 160  */
 161 void ctdl_thread_internal_init_tsd(void)
 162 {
 163         int ret;
 164
 165         if ((ret = citthread_key_create(&ThreadKey, ctdl_thread_internal_dest_tsd))) {
 166                 CtdlLogPrintf(CTDL_EMERG, "citthread_key_create: %s\n", strerror(ret));
 167                 exit(CTDLEXIT_DB);
 168         }
 169 }
 170
 171 /*
 172  * Ensure that we have a key for thread-specific data.
 173  *
 174  * This should be called immediately after startup by any thread
 175  *
 176  */
 177 void CtdlThreadAllocTSD(void)
 178 {
 179         ThreadTSD *tsd;
 180
 181         if (citthread_getspecific(ThreadKey) != NULL)
 182                 return;
 183
 184         tsd = malloc(sizeof(ThreadTSD));
 185
 186         tsd->tid = NULL;
 187
 188         memset(tsd->cursors, 0, sizeof tsd->cursors);
 189         tsd->self = NULL;
 190
 191         citthread_setspecific(ThreadKey, tsd);
 192 }
 193
 194
 195 void ctdl_thread_internal_free_tsd(void)
 196 {
 197         ctdl_thread_internal_dest_tsd(citthread_getspecific(ThreadKey));
 198         citthread_setspecific(ThreadKey, NULL);
 199 }
 200
 201
 202 void ctdl_thread_internal_cleanup(void)
 203 {
 204         int i;
 205         CtdlThreadNode *this_thread, *that_thread;
 206
 207         for (i=0; i<CTDL_THREAD_LAST_STATE; i++)
 208         {
 209                 free (CtdlThreadStates[i]);
 210         }
 211
 212         /* Clean up the scheduled thread list */
 213         this_thread = CtdlThreadSchedList;
 214         while (this_thread)
 215         {
 216                 that_thread = this_thread;
 217                 this_thread = this_thread->next;
 218                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 219                 citthread_cond_destroy(&that_thread->ThreadCond);
 220                 citthread_mutex_destroy(&that_thread->SleepMutex);
 221                 citthread_cond_destroy(&that_thread->SleepCond);
 222                 citthread_attr_destroy(&that_thread->attr);
 223                 free(that_thread);
 224         }
 225         ctdl_thread_internal_free_tsd();
 226 }
 227
 228 void ctdl_thread_internal_init(void)
 229 {
 230         CtdlThreadNode *this_thread;
 231         int ret = 0;
 232
 233         CtdlThreadStates[CTDL_THREAD_INVALID] = strdup ("Invalid Thread");
 234         CtdlThreadStates[CTDL_THREAD_VALID] = strdup("Valid Thread");
 235         CtdlThreadStates[CTDL_THREAD_CREATE] = strdup("Thread being Created");
 236         CtdlThreadStates[CTDL_THREAD_CANCELLED] = strdup("Thread Cancelled");
 237         CtdlThreadStates[CTDL_THREAD_EXITED] = strdup("Thread Exited");
 238         CtdlThreadStates[CTDL_THREAD_STOPPING] = strdup("Thread Stopping");
 239         CtdlThreadStates[CTDL_THREAD_STOP_REQ] = strdup("Thread Stop Requested");
 240         CtdlThreadStates[CTDL_THREAD_SLEEPING] = strdup("Thread Sleeping");
 241         CtdlThreadStates[CTDL_THREAD_RUNNING] = strdup("Thread Running");
 242         CtdlThreadStates[CTDL_THREAD_BLOCKED] = strdup("Thread Blocked");
 243
 244         /* Get ourself a thread entry */
 245         this_thread = malloc(sizeof(CtdlThreadNode));
 246         if (this_thread == NULL) {
 247                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 248                 return;
 249         }
 250         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 251         memset (this_thread, 0, sizeof(CtdlThreadNode));
 252
 253         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 254         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 255         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 256         citthread_cond_init (&(this_thread->SleepCond), NULL);
 257
 258         /* We are garbage collector so create us as running */
 259         this_thread->state = CTDL_THREAD_RUNNING;
 260
 261         if ((ret = citthread_attr_init(&this_thread->attr))) {
 262                 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 263                 free(this_thread);
 264                 return;
 265         }
 266
 267         this_thread->name = "Garbage Collection Thread";
 268
 269         this_thread->tid = citthread_self();
 270         GC_thread = this_thread;
 271         CT = this_thread;
 272
 273         num_threads++;  // Increase the count of threads in the system.
 274
 275         this_thread->next = CtdlThreadList;
 276         CtdlThreadList = this_thread;
 277         if (this_thread->next)
 278                 this_thread->next->prev = this_thread;
 279         /* Set up start times */
 280         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 281         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 282 }
 283
 284
 285 /*
 286  * A function to update a threads load averages
 287  */
 288  void ctdl_thread_internal_update_avgs(CtdlThreadNode *this_thread)
 289  {
 290         struct timeval now, result;
 291         double last_duration;
 292
 293         gettimeofday(&now, NULL);
 294         timersub(&now, &(this_thread->last_state_change), &result);
 295         /* I don't think these mutex's are needed here */
 296         citthread_mutex_lock(&this_thread->ThreadMutex);
 297         // result now has a timeval for the time we spent in the last state since we last updated
 298         last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
 299         if (this_thread->state == CTDL_THREAD_SLEEPING)
 300                 this_thread->avg_sleeping += last_duration;
 301         if (this_thread->state == CTDL_THREAD_RUNNING)
 302                 this_thread->avg_running += last_duration;
 303         if (this_thread->state == CTDL_THREAD_BLOCKED)
 304                 this_thread->avg_blocked += last_duration;
 305         memcpy (&this_thread->last_state_change, &now, sizeof (struct timeval));
 306         citthread_mutex_unlock(&this_thread->ThreadMutex);
 307 }
 308
 309 /*
 310  * A function to chenge the state of a thread
 311  */
 312 void ctdl_thread_internal_change_state (CtdlThreadNode *this_thread, enum CtdlThreadState new_state)
 313 {
 314         /*
 315          * Wether we change state or not we need update the load values
 316          */
 317         ctdl_thread_internal_update_avgs(this_thread);
 318         /* This mutex not needed here? */
 319         citthread_mutex_lock(&this_thread->ThreadMutex); /* To prevent race condition of a sleeping thread */
 320         if ((new_state == CTDL_THREAD_STOP_REQ) && (this_thread->state > CTDL_THREAD_STOP_REQ))
 321                 this_thread->state = new_state;
 322         if (((new_state == CTDL_THREAD_SLEEPING) || (new_state == CTDL_THREAD_BLOCKED)) && (this_thread->state == CTDL_THREAD_RUNNING))
 323                 this_thread->state = new_state;
 324         if ((new_state == CTDL_THREAD_RUNNING) && ((this_thread->state == CTDL_THREAD_SLEEPING) || (this_thread->state == CTDL_THREAD_BLOCKED)))
 325                 this_thread->state = new_state;
 326         citthread_mutex_unlock(&this_thread->ThreadMutex);
 327 }
 328
 329
 330 /*
 331  * A function to tell all threads to exit
 332  */
 333 void CtdlThreadStopAll(void)
 334 {
 335         /* First run any registered shutdown hooks.  This probably doesn't belong here. */
 336         PerformSessionHooks(EVT_SHUTDOWN);
 337
 338         //FIXME: The signalling of the condition should not be in the critical_section
 339         // We need to build a list of threads we are going to signal and then signal them afterwards
 340
 341         CtdlThreadNode *this_thread;
 342
 343         begin_critical_section(S_THREAD_LIST);
 344         this_thread = CtdlThreadList;
 345         // Ask the GC thread to stop first so everything knows we are shutting down.
 346         GC_thread->state = CTDL_THREAD_STOP_REQ;
 347         while(this_thread)
 348         {
 349                 if (!citthread_equal(this_thread->tid, GC_thread->tid))
 350                         citthread_kill(this_thread->tid, SIGHUP);
 351
 352                 ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 353                 citthread_cond_signal(&this_thread->ThreadCond);
 354                 citthread_cond_signal(&this_thread->SleepCond);
 355                 this_thread->stop_ticker = time(NULL);
 356                 CtdlLogPrintf(CTDL_DEBUG, "Thread system stopping thread \"%s\" (0x%08lx).\n",
 357                         this_thread->name, this_thread->tid);
 358                 this_thread = this_thread->next;
 359         }
 360         end_critical_section(S_THREAD_LIST);
 361 }
 362
 363
 364 /*
 365  * A function to wake up all sleeping threads
 366  */
 367 void CtdlThreadWakeAll(void)
 368 {
 369         CtdlThreadNode *this_thread;
 370
 371         CtdlLogPrintf(CTDL_DEBUG, "Thread system waking all threads.\n");
 372
 373         begin_critical_section(S_THREAD_LIST);
 374         this_thread = CtdlThreadList;
 375         while(this_thread)
 376         {
 377                 if (!this_thread->thread_func)
 378                 {
 379                         citthread_cond_signal(&this_thread->ThreadCond);
 380                         citthread_cond_signal(&this_thread->SleepCond);
 381                 }
 382                 this_thread = this_thread->next;
 383         }
 384         end_critical_section(S_THREAD_LIST);
 385 }
 386
 387
 388 /*
 389  * A function to return the number of threads running in the system
 390  */
 391 int CtdlThreadGetCount(void)
 392 {
 393         return  num_threads;
 394 }
 395
 396 int CtdlThreadGetWorkers(void)
 397 {
 398         return  num_workers;
 399 }
 400
 401 double CtdlThreadGetWorkerAvg(void)
 402 {
 403         double ret;
 404
 405         begin_critical_section(S_THREAD_LIST);
 406         ret =  CtdlThreadWorkerAvg;
 407         end_critical_section(S_THREAD_LIST);
 408         return ret;
 409 }
 410
 411 double CtdlThreadGetLoadAvg(void)
 412 {
 413         double load_avg[3] = {0.0, 0.0, 0.0};
 414
 415         int ret = 0;
 416         int smp_num_cpus;
 417
 418         /* Borrowed this straight from procps */
 419         smp_num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 420         if(smp_num_cpus<1) smp_num_cpus=1; /* SPARC glibc is buggy */
 421
 422 #ifdef HAVE_GETLOADAVG
 423         ret = getloadavg(load_avg, 3);
 424 #endif
 425         if (ret < 0)
 426                 return 0;
 427         return load_avg[0] / smp_num_cpus;
 428 /*
 429  * This old chunk of code return a value that indicated the load on citserver
 430  * This value could easily reach 100 % even when citserver was doing very little and
 431  * hence the machine has much more spare capacity.
 432  * Because this value was used to determine if the machine was under heavy load conditions
 433  * from other processes in the system then citserver could be strangled un-necesarily
 434  * What we are actually trying to achieve is to strangle citserver if the machine is heavily loaded.
 435  * So we have changed this.
 436
 437         begin_critical_section(S_THREAD_LIST);
 438         ret =  CtdlThreadLoadAvg;
 439         end_critical_section(S_THREAD_LIST);
 440         return ret;
 441 */
 442 }
 443
 444
 445
 446
 447 /*
 448  * A function to rename a thread
 449  * Returns a const char *
 450  */
 451 const char *CtdlThreadName(const char *name)
 452 {
 453         const char *old_name;
 454
 455         if (!CT)
 456         {
 457                 CtdlLogPrintf(CTDL_WARNING, "Thread system WARNING. Attempt to CtdlThreadRename() a non thread. %s\n", name);
 458                 return NULL;
 459         }
 460         old_name = CT->name;
 461         if (name)
 462                 CT->name = name;
 463         return (old_name);
 464 }
 465
 466
 467 /*
 468  * A function to force a thread to exit
 469  */
 470 void CtdlThreadCancel(CtdlThreadNode *thread)
 471 {
 472         CtdlThreadNode *this_thread;
 473
 474         if (!thread)
 475                 this_thread = CT;
 476         else
 477                 this_thread = thread;
 478         if (!this_thread)
 479         {
 480                 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() a non thread.\n");
 481                 CtdlThreadStopAll();
 482                 return;
 483         }
 484
 485         if (!this_thread->thread_func)
 486         {
 487                 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() the garbage collector.\n");
 488                 CtdlThreadStopAll();
 489                 return;
 490         }
 491
 492         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_CANCELLED);
 493         citthread_cancel(this_thread->tid);
 494 }
 495
 496
 497 /*
 498  * A function for a thread to check if it has been asked to stop
 499  */
 500 int CtdlThreadCheckStop(void)
 501 {
 502         int state;
 503
 504         if (!CT)
 505         {
 506                 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, CtdlThreadCheckStop() called by a non thread.\n");
 507                 CtdlThreadStopAll();
 508                 return -1;
 509         }
 510
 511         state = CT->state;
 512
 513         if (CT->signal)
 514         {
 515                 CtdlLogPrintf(CTDL_DEBUG, "Thread \"%s\" caught signal %d.\n", CT->name, CT->signal);
 516                 if (CT->signal == SIGHUP)
 517                         CT->state = CTDL_THREAD_STOP_REQ;
 518                 CT->signal = 0;
 519         }
 520         if(state == CTDL_THREAD_STOP_REQ)
 521         {
 522                 CT->state = CTDL_THREAD_STOPPING;
 523                 return -1;
 524         }
 525         else if((state < CTDL_THREAD_STOP_REQ) && (state > CTDL_THREAD_CREATE))
 526         {
 527                 return -1;
 528         }
 529         return 0;
 530 }
 531
 532
 533 /*
 534  * A function to ask a thread to exit
 535  * The thread must call CtdlThreadCheckStop() periodically to determine if it should exit
 536  */
 537 void CtdlThreadStop(CtdlThreadNode *thread)
 538 {
 539         CtdlThreadNode *this_thread;
 540
 541         if (!thread)
 542                 this_thread = CT;
 543         else
 544                 this_thread = thread;
 545         if (!this_thread)
 546                 return;
 547         if (!(this_thread->thread_func))
 548                 return;         // Don't stop garbage collector
 549
 550         if (!citthread_equal(this_thread->tid, GC_thread->tid))
 551                 citthread_kill(this_thread->tid, SIGHUP);
 552
 553         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 554         citthread_cond_signal(&this_thread->ThreadCond);
 555         citthread_cond_signal(&this_thread->SleepCond);
 556         this_thread->stop_ticker = time(NULL);
 557 }
 558
 559 /*
 560  * So we now have a sleep command that works with threads but it is in seconds
 561  */
 562 void CtdlThreadSleep(int secs)
 563 {
 564         struct timespec wake_time;
 565         struct timeval time_now;
 566
 567
 568         if (!CT)
 569         {
 570                 CtdlLogPrintf(CTDL_WARNING, "CtdlThreadSleep() called by something that is not a thread. Should we die?\n");
 571                 return;
 572         }
 573
 574         memset (&wake_time, 0, sizeof(struct timespec));
 575         gettimeofday(&time_now, NULL);
 576         wake_time.tv_sec = time_now.tv_sec + secs;
 577         wake_time.tv_nsec = time_now.tv_usec * 10;
 578
 579         ctdl_thread_internal_change_state (CT, CTDL_THREAD_SLEEPING);
 580
 581         citthread_mutex_lock(&CT->ThreadMutex); /* Prevent something asking us to awaken before we've gone to sleep */
 582         citthread_cond_timedwait(&CT->SleepCond, &CT->ThreadMutex, &wake_time);
 583         citthread_mutex_unlock(&CT->ThreadMutex);
 584
 585         ctdl_thread_internal_change_state (CT, CTDL_THREAD_RUNNING);
 586 }
 587
 588
 589 /*
 590  * Routine to clean up our thread function on exit
 591  */
 592 static void ctdl_internal_thread_cleanup(void *arg)
 593 {
 594         /*
 595          * In here we were called by the current thread because it is exiting
 596          * NB. WE ARE THE CURRENT THREAD
 597          */
 598         if (CT)
 599         {
 600                 const char *name = CT->name;
 601                 const pid_t tid = CT->tid;
 602
 603                 CtdlLogPrintf(CTDL_NOTICE, "Thread \"%s\" (0x%08lx) exited.\n", name, tid);
 604         }
 605         else
 606         {
 607                 CtdlLogPrintf(CTDL_NOTICE, "some ((unknown ? ? ?) Thread exited.\n");
 608         }
 609
 610         #ifdef HAVE_BACKTRACE
 611 ///     eCrash_UnregisterThread();
 612         #endif
 613
 614         citthread_mutex_lock(&CT->ThreadMutex);
 615         CT->state = CTDL_THREAD_EXITED; // needs to be last thing else house keeping will unlink us too early
 616         citthread_mutex_unlock(&CT->ThreadMutex);
 617 }
 618
 619 /*
 620  * A quick function to show the load averages
 621  */
 622 void ctdl_thread_internal_calc_loadavg(void)
 623 {
 624         CtdlThreadNode *that_thread;
 625         double load_avg, worker_avg;
 626         int workers = 0;
 627
 628         that_thread = CtdlThreadList;
 629         load_avg = 0;
 630         worker_avg = 0;
 631         while(that_thread)
 632         {
 633                 /* Update load averages */
 634                 ctdl_thread_internal_update_avgs(that_thread);
 635                 citthread_mutex_lock(&that_thread->ThreadMutex);
 636                 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;
 637                 that_thread->avg_sleeping /= 2;
 638                 that_thread->avg_running /= 2;
 639                 that_thread->avg_blocked /= 2;
 640                 load_avg += that_thread->load_avg;
 641                 if (that_thread->flags & CTDLTHREAD_WORKER)
 642                 {
 643                         worker_avg += that_thread->load_avg;
 644                         workers++;
 645                 }
 646 #ifdef WITH_THREADLOG
 647                 CtdlLogPrintf(CTDL_DEBUG, "CtdlThread, \"%s\" (%lu) \"%s\" %.2f %.2f %.2f %.2f\n",
 648                         that_thread->name,
 649                         that_thread->tid,
 650                         CtdlThreadStates[that_thread->state],
 651                         that_thread->avg_sleeping,
 652                         that_thread->avg_running,
 653                         that_thread->avg_blocked,
 654                         that_thread->load_avg);
 655 #endif
 656                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 657                 that_thread = that_thread->next;
 658         }
 659         CtdlThreadLoadAvg = load_avg/num_threads;
 660         CtdlThreadWorkerAvg = worker_avg/workers;
 661 #ifdef WITH_THREADLOG
 662         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);
 663 #endif
 664 }
 665
 666
 667 /*
 668  * Garbage collection routine.
 669  * Gets called by main() in a loop to clean up the thread list periodically.
 670  */
 671 void CtdlThreadGC (void)
 672 {
 673         CtdlThreadNode *this_thread, *that_thread;
 674         int workers = 0, sys_workers;
 675         int ret=0;
 676
 677         begin_critical_section(S_THREAD_LIST);
 678
 679         /* Handle exiting of garbage collector thread */
 680         if(num_threads == 1)
 681                 CtdlThreadList->state = CTDL_THREAD_EXITED;
 682
 683 #ifdef WITH_THREADLOG
 684         CtdlLogPrintf(CTDL_DEBUG, "Thread system running garbage collection.\n");
 685 #endif
 686         /*
 687          * Woke up to do garbage collection
 688          */
 689         this_thread = CtdlThreadList;
 690         while(this_thread)
 691         {
 692                 that_thread = this_thread;
 693                 this_thread = this_thread->next;
 694
 695                 if ((that_thread->state == CTDL_THREAD_STOP_REQ || that_thread->state == CTDL_THREAD_STOPPING)
 696                         && (!citthread_equal(that_thread->tid, citthread_self())))
 697                                 CtdlLogPrintf(CTDL_DEBUG, "Waiting for thread %s (0x%08lx) to exit.\n", that_thread->name, that_thread->tid);
 698                 else
 699                 {
 700                         /**
 701                          * Catch the situation where a worker was asked to stop but couldn't and we are not
 702                          * shutting down.
 703                          */
 704                         that_thread->stop_ticker = 0;
 705                 }
 706
 707                 if (that_thread->stop_ticker + 5 == time(NULL))
 708                 {
 709                         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);
 710                         if ((that_thread->flags & CTDLTHREAD_WORKER) == 0)
 711                                 CtdlLogPrintf(CTDL_INFO, "Thread System: A non worker thread would have been canceled this may cause message loss.\n");
 712 //                      that_thread->state = CTDL_THREAD_CANCELLED;
 713                         that_thread->stop_ticker++;
 714 //                      citthread_cancel(that_thread->tid);
 715 //                      continue;
 716                 }
 717
 718                 /* Do we need to clean up this thread? */
 719                 if ((that_thread->state != CTDL_THREAD_EXITED) && (that_thread->state != CTDL_THREAD_CANCELLED))
 720                 {
 721                         if(that_thread->flags & CTDLTHREAD_WORKER)
 722                                 workers++;      /* Sanity check on number of worker threads */
 723                         continue;
 724                 }
 725
 726                 if (citthread_equal(that_thread->tid, citthread_self()) && that_thread->thread_func)
 727                 {       /* Sanity check */
 728                         end_critical_section(S_THREAD_LIST);
 729                         CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, a thread is trying to clean up after itself.\n");
 730                         abort();
 731                         return;
 732                 }
 733
 734                 if (num_threads <= 0)
 735                 {       /* Sanity check */
 736                         end_critical_section(S_THREAD_LIST);
 737                         CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, num_threads <= 0 and trying to do Garbage Collection.\n");
 738                         abort();
 739                         return;
 740                 }
 741
 742                 if(that_thread->flags & CTDLTHREAD_WORKER)
 743                         num_workers--;  /* This is a wroker thread so reduce the count. */
 744                 num_threads--;
 745                 /* If we are unlinking the list head then the next becomes the list head */
 746                 if(that_thread->prev)
 747                         that_thread->prev->next = that_thread->next;
 748                 else
 749                         CtdlThreadList = that_thread->next;
 750                 if(that_thread->next)
 751                         that_thread->next->prev = that_thread->prev;
 752
 753                 citthread_cond_signal(&that_thread->ThreadCond);
 754                 citthread_cond_signal(&that_thread->SleepCond); // Make sure this thread is awake
 755                 citthread_mutex_lock(&that_thread->ThreadMutex);        // Make sure it has done what its doing
 756                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 757                 /*
 758                  * Join on the thread to do clean up and prevent memory leaks
 759                  * Also makes sure the thread has cleaned up after itself before we remove it from the list
 760                  * We can join on the garbage collector thread the join should just return EDEADLCK
 761                  */
 762                 ret = citthread_join (that_thread->tid, NULL);
 763                 if (ret == EDEADLK)
 764                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection on own thread.\n");
 765                 else if (ret == EINVAL)
 766                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, that thread already joined on.\n");
 767                 else if (ret == ESRCH)
 768                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, no thread to join on.\n");
 769                 else if (ret != 0)
 770                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, citthread_join returned an unknown error(%d).\n", ret);
 771                 /*
 772                  * Now we own that thread entry
 773                  */
 774                 CtdlLogPrintf(CTDL_INFO, "Garbage Collection for thread \"%s\" (0x%08lx).\n",
 775                         that_thread->name, that_thread->tid);
 776                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 777                 citthread_cond_destroy(&that_thread->ThreadCond);
 778                 citthread_mutex_destroy(&that_thread->SleepMutex);
 779                 citthread_cond_destroy(&that_thread->SleepCond);
 780                 citthread_attr_destroy(&that_thread->attr);
 781                 free(that_thread);
 782         }
 783         sys_workers = num_workers;
 784         end_critical_section(S_THREAD_LIST);
 785
 786         /* Sanity check number of worker threads */
 787         if (workers != sys_workers)
 788         {
 789                 CtdlLogPrintf(CTDL_EMERG,
 790                         "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n",
 791                         workers, sys_workers
 792                         );
 793                 abort();
 794         }
 795 }
 796
 797
 798
 799
 800 /*
 801  * Runtime function for a Citadel Thread.
 802  * This initialises the threads environment and then calls the user supplied thread function
 803  * Note that this is the REAL thread function and wraps the users thread function.
 804  */
 805 static void *ctdl_internal_thread_func (void *arg)
 806 {
 807         CtdlThreadNode *this_thread;
 808         void *ret = NULL;
 809
 810         /* lock and unlock the thread list.
 811          * This causes this thread to wait until all its creation stuff has finished before it
 812          * can continue its execution.
 813          */
 814         begin_critical_section(S_THREAD_LIST);
 815         this_thread = (CtdlThreadNode *) arg;
 816         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 817
 818         // Register the cleanup function to take care of when we exit.
 819         citthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
 820         // Get our thread data structure
 821         CtdlThreadAllocTSD();
 822         CT = this_thread;
 823         this_thread->pid = getpid();
 824         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 825         /* Only change to running state if we weren't asked to stop during the create cycle
 826          * Other wise there is a window to allow this threads creation to continue to full grown and
 827          * therby prevent a shutdown of the server.
 828          */
 829         if (!CtdlThreadCheckStop())
 830         {
 831                 citthread_mutex_lock(&this_thread->ThreadMutex);
 832                 this_thread->state = CTDL_THREAD_RUNNING;
 833                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 834         }
 835         end_critical_section(S_THREAD_LIST);
 836
 837         // Register for tracing
 838         #ifdef HAVE_BACKTRACE
 839 ///     eCrash_RegisterThread(this_thread->name, 0);
 840         #endif
 841
 842         // Tell the world we are here
 843         CtdlLogPrintf(CTDL_NOTICE, "Created a new thread \"%s\" (0x%08lx).\n",
 844                 this_thread->name, this_thread->tid);
 845
 846         /*
 847          * run the thread to do the work but only if we haven't been asked to stop
 848          */
 849         if (!CtdlThreadCheckStop())
 850                 ret = (this_thread->thread_func)(this_thread->user_args);
 851
 852         /*
 853          * Our thread is exiting either because it wanted to end or because the server is stopping
 854          * We need to clean up
 855          */
 856         citthread_cleanup_pop(1);       // Execute our cleanup routine and remove it
 857
 858         return(ret);
 859 }
 860
 861
 862
 863
 864 /*
 865  * Function to initialise an empty thread structure
 866  */
 867 CtdlThreadNode *ctdl_internal_init_thread_struct(CtdlThreadNode *this_thread, long flags)
 868 {
 869         int ret = 0;
 870
 871         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 872         memset (this_thread, 0, sizeof(CtdlThreadNode));
 873
 874         /* Create the mutex's early so we can use them */
 875         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 876         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 877         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 878         citthread_cond_init (&(this_thread->SleepCond), NULL);
 879
 880         this_thread->state = CTDL_THREAD_CREATE;
 881
 882         if ((ret = citthread_attr_init(&this_thread->attr))) {
 883                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 884                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 885                 citthread_cond_destroy(&(this_thread->ThreadCond));
 886                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 887                 citthread_cond_destroy(&(this_thread->SleepCond));
 888                 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 889                 free(this_thread);
 890                 return NULL;
 891         }
 892
 893         /* Our per-thread stacks need to be bigger than the default size,
 894          * otherwise the MIME parser crashes on FreeBSD, and the IMAP service
 895          * crashes on 64-bit Linux.
 896          */
 897         if (flags & CTDLTHREAD_BIGSTACK)
 898         {
 899 #ifdef WITH_THREADLOG
 900                 CtdlLogPrintf(CTDL_INFO, "Thread system. Creating BIG STACK thread.\n");
 901 #endif
 902                 if ((ret = citthread_attr_setstacksize(&this_thread->attr, THREADSTACKSIZE))) {
 903                         citthread_mutex_unlock(&this_thread->ThreadMutex);
 904                         citthread_mutex_destroy(&(this_thread->ThreadMutex));
 905                         citthread_cond_destroy(&(this_thread->ThreadCond));
 906                         citthread_mutex_destroy(&(this_thread->SleepMutex));
 907                         citthread_cond_destroy(&(this_thread->SleepCond));
 908                         citthread_attr_destroy(&this_thread->attr);
 909                         CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_setstacksize: %s\n",
 910                                 strerror(ret));
 911                         free(this_thread);
 912                         return NULL;
 913                 }
 914         }
 915
 916         /* Set this new thread with an avg_blocked of 2. We do this so that its creation affects the
 917          * load average for the system. If we don't do this then we create a mass of threads at the same time
 918          * because the creation didn't affect the load average.
 919          */
 920         this_thread->avg_blocked = 2;
 921
 922         return (this_thread);
 923 }
 924
 925
 926
 927
 928 /*
 929  * Internal function to create a thread.
 930  */
 931 CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void *(*thread_func) (void *arg), void *args)
 932 {
 933         int ret = 0;
 934         CtdlThreadNode *this_thread;
 935
 936         if (num_threads >= 32767)
 937         {
 938                 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
 939                 return NULL;
 940         }
 941
 942         this_thread = malloc(sizeof(CtdlThreadNode));
 943         if (this_thread == NULL) {
 944                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 945                 return NULL;
 946         }
 947
 948         /* Initialise the thread structure */
 949         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
 950         {
 951                 free(this_thread);
 952                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
 953                 return NULL;
 954         }
 955         /*
 956          * If we got here we are going to create the thread so we must initilise the structure
 957          * first because most implimentations of threading can't create it in a stopped state
 958          * and it might want to do things with its structure that aren't initialised otherwise.
 959          */
 960         if(name)
 961         {
 962                 this_thread->name = name;
 963         }
 964         else
 965         {
 966                 this_thread->name = "Un-named Thread";
 967         }
 968
 969         this_thread->flags = flags;
 970         this_thread->thread_func = thread_func;
 971         this_thread->user_args = args;
 972
 973         begin_critical_section(S_THREAD_LIST);
 974         /*
 975          * We pass this_thread into the thread as its args so that it can find out information
 976          * about itself and it has a bit of storage space for itself, not to mention that the REAL
 977          * thread function needs to finish off the setup of the structure
 978          */
 979         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
 980         {
 981                 end_critical_section(S_THREAD_LIST);
 982                 CtdlLogPrintf(CTDL_ALERT, "Thread system, Can't create thread: %s\n",
 983                         strerror(ret));
 984                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 985                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 986                 citthread_cond_destroy(&(this_thread->ThreadCond));
 987                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 988                 citthread_cond_destroy(&(this_thread->SleepCond));
 989                 citthread_attr_destroy(&this_thread->attr);
 990                 free(this_thread);
 991                 return NULL;
 992         }
 993         this_thread->reltid = next_tid;
 994         next_tid++;
 995         num_threads++;  // Increase the count of threads in the system.
 996         if(this_thread->flags & CTDLTHREAD_WORKER)
 997                 num_workers++;
 998
 999         this_thread->next = CtdlThreadList;
1000         CtdlThreadList = this_thread;
1001         if (this_thread->next)
1002                 this_thread->next->prev = this_thread;
1003         ctdl_thread_internal_calc_loadavg();
1004
1005         end_critical_section(S_THREAD_LIST);
1006
1007         return this_thread;
1008 }
1009
1010 /*
1011  * Wrapper function to create a thread
1012  * ensures the critical section and other protections are in place.
1013  * char *name = name to give to thread, if NULL, use generic name
1014  * int flags = flags to determine type of thread and standard facilities
1015  */
1016 CtdlThreadNode *CtdlThreadCreate(char *name, long flags, void *(*thread_func) (void *arg), void *args)
1017 {
1018         CtdlThreadNode *ret = NULL;
1019
1020         ret = ctdl_internal_create_thread(name, flags, thread_func, args);
1021         return ret;
1022 }
1023
1024
1025
1026 /*
1027  * Internal function to schedule a thread.
1028  * Must be called from within a S_THREAD_LIST critical section
1029  */
1030 CtdlThreadNode *CtdlThreadSchedule(char *name, long flags, void *(*thread_func) (void *arg), void *args, time_t when)
1031 {
1032         CtdlThreadNode *this_thread;
1033
1034         if (num_threads >= 32767)
1035         {
1036                 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
1037                 return NULL;
1038         }
1039
1040         this_thread = malloc(sizeof(CtdlThreadNode));
1041         if (this_thread == NULL) {
1042                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
1043                 return NULL;
1044         }
1045         /* Initialise the thread structure */
1046         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
1047         {
1048                 free(this_thread);
1049                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
1050                 return NULL;
1051         }
1052
1053         /*
1054          * If we got here we are going to create the thread so we must initilise the structure
1055          * first because most implimentations of threading can't create it in a stopped state
1056          * and it might want to do things with its structure that aren't initialised otherwise.
1057          */
1058         if(name)
1059         {
1060                 this_thread->name = name;
1061         }
1062         else
1063         {
1064                 this_thread->name = "Un-named Thread";
1065         }
1066
1067         this_thread->flags = flags;
1068         this_thread->thread_func = thread_func;
1069         this_thread->user_args = args;
1070
1071         /*
1072          * When to start this thread
1073          */
1074         this_thread->when = when;
1075
1076         begin_critical_section(S_SCHEDULE_LIST);
1077         this_thread->next = CtdlThreadSchedList;
1078         CtdlThreadSchedList = this_thread;
1079         if (this_thread->next)
1080                 this_thread->next->prev = this_thread;
1081         end_critical_section(S_SCHEDULE_LIST);
1082
1083         return this_thread;
1084 }
1085
1086
1087
1088 CtdlThreadNode *ctdl_thread_internal_start_scheduled (CtdlThreadNode *this_thread)
1089 {
1090         int ret = 0;
1091
1092         begin_critical_section(S_THREAD_LIST);
1093         /*
1094          * We pass this_thread into the thread as its args so that it can find out information
1095          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1096          * thread function needs to finish off the setup of the structure
1097          */
1098         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1099         {
1100                 end_critical_section(S_THREAD_LIST);
1101                 CtdlLogPrintf(CTDL_DEBUG, "Failed to start scheduled thread \"%s\": %s\n", this_thread->name, strerror(ret));
1102                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1103                 citthread_cond_destroy(&(this_thread->ThreadCond));
1104                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1105                 citthread_cond_destroy(&(this_thread->SleepCond));
1106                 citthread_attr_destroy(&this_thread->attr);
1107                 free(this_thread);
1108                 return NULL;
1109         }
1110
1111
1112         num_threads++;  // Increase the count of threads in the system.
1113         if(this_thread->flags & CTDLTHREAD_WORKER)
1114                 num_workers++;
1115
1116         this_thread->next = CtdlThreadList;
1117         CtdlThreadList = this_thread;
1118         if (this_thread->next)
1119                 this_thread->next->prev = this_thread;
1120
1121         ctdl_thread_internal_calc_loadavg();
1122         end_critical_section(S_THREAD_LIST);
1123
1124
1125         return this_thread;
1126 }
1127
1128
1129
1130 void ctdl_thread_internal_check_scheduled(void)
1131 {
1132         CtdlThreadNode *this_thread, *that_thread;
1133         time_t now;
1134
1135         /* Don't start scheduled threads if the system wants single user mode */
1136         if (CtdlWantSingleUser())
1137                 return;
1138
1139         if (try_critical_section(S_SCHEDULE_LIST))
1140                 return; /* If this list is locked we wait till the next chance */
1141
1142         now = time(NULL);
1143
1144 #ifdef WITH_THREADLOG
1145         CtdlLogPrintf(CTDL_DEBUG, "Checking for scheduled threads to start.\n");
1146 #endif
1147
1148         this_thread = CtdlThreadSchedList;
1149         while(this_thread)
1150         {
1151                 that_thread = this_thread;
1152                 this_thread = this_thread->next;
1153
1154                 if (now > that_thread->when)
1155                 {
1156                         /* Unlink from schedule list */
1157                         if (that_thread->prev)
1158                                 that_thread->prev->next = that_thread->next;
1159                         else
1160                                 CtdlThreadSchedList = that_thread->next;
1161                         if (that_thread->next)
1162                                 that_thread->next->prev = that_thread->prev;
1163
1164                         that_thread->next = that_thread->prev = NULL;
1165 #ifdef WITH_THREADLOG
1166                         CtdlLogPrintf(CTDL_DEBUG, "About to start scheduled thread \"%s\".\n", that_thread->name);
1167 #endif
1168                         if (CT->state > CTDL_THREAD_STOP_REQ)
1169                         {       /* Only start it if the system is not stopping */
1170                                 if (ctdl_thread_internal_start_scheduled (that_thread))
1171                                 {
1172 #ifdef WITH_THREADLOG
1173                                         CtdlLogPrintf(CTDL_INFO, "Thread system, Started a scheduled thread \"%s\" (0x%08lx).\n",
1174                                                 that_thread->name, that_thread->tid);
1175 #endif
1176                                 }
1177                         }
1178                 }
1179 #ifdef WITH_THREADLOG
1180                 else
1181                 {
1182                         CtdlLogPrintf(CTDL_DEBUG, "Thread \"%s\" will start in %ld seconds.\n",
1183                                 that_thread->name, that_thread->when - time(NULL));
1184                 }
1185 #endif
1186         }
1187         end_critical_section(S_SCHEDULE_LIST);
1188 }
1189
1190
1191 /*
1192  * A warapper function for select so we can show a thread as blocked
1193  */
1194 int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
1195 {
1196         int ret = 0;
1197
1198         ctdl_thread_internal_change_state(CT, CTDL_THREAD_BLOCKED);
1199         if (!CtdlThreadCheckStop())
1200                 ret = select(n, readfds, writefds, exceptfds, timeout);
1201         /**
1202          * If the select returned <= 0 then it failed due to an error
1203          * or timeout so this thread could stop if asked to do so.
1204          * Anything else means it needs to continue unless the system is shutting down
1205          */
1206         if (ret > 0)
1207         {
1208                 /**
1209                  * The select says this thread needs to do something useful.
1210                  * This thread was in an idle state so it may have been asked to stop
1211                  * but if the system isn't shutting down this thread is no longer
1212                  * idle and select has given it a task to do so it must not stop
1213                  * In this condition we need to force it into the running state.
1214                  * CtdlThreadGC will clear its ticker for us.
1215                  *
1216                  * FIXME: there is still a small hole here. It is possible for the sequence of locking
1217                  * to allow the state to get changed to STOP_REQ just after this code if the other thread
1218                  * has decided to change the state before this lock, it there fore has to wait till the lock
1219                  * completes but it will continue to change the state. We need something a bit better here.
1220                  */
1221                 citthread_mutex_lock(&CT->ThreadMutex); /* To prevent race condition of a sleeping thread */
1222                 if (GC_thread->state > CTDL_THREAD_STOP_REQ && CT->state <= CTDL_THREAD_STOP_REQ)
1223                 {
1224                         CtdlLogPrintf(CTDL_DEBUG, "Thread %s (0x%08lx) refused stop request.\n", CT->name, CT->tid);
1225                         CT->state = CTDL_THREAD_RUNNING;
1226                 }
1227                 citthread_mutex_unlock(&CT->ThreadMutex);
1228         }
1229
1230         ctdl_thread_internal_change_state(CT, CTDL_THREAD_RUNNING);
1231
1232         return ret;
1233 }
1234
1235
1236
1237 void *new_worker_thread(void *arg);
1238 extern void close_masters (void);
1239
1240
1241 void *simulation_worker (void*arg) {
1242         struct CitContext *this;
1243
1244         this = CreateNewContext();
1245         CtdlThreadSleep(1);
1246         this->kill_me = 1;
1247         this->state = CON_IDLE;
1248         dead_session_purge(1);
1249         begin_critical_section(S_SESSION_TABLE);
1250         stats_done++;
1251         end_critical_section(S_SESSION_TABLE);
1252         return NULL;
1253 }
1254
1255
1256 void *simulation_thread (void *arg)
1257 {
1258         long stats = statcount;
1259
1260         while(stats && !CtdlThreadCheckStop()) {
1261                 CtdlThreadCreate("Connection simulation worker", CTDLTHREAD_BIGSTACK, simulation_worker, NULL);
1262                 stats--;
1263         }
1264         CtdlThreadStopAll();
1265         return NULL;
1266 }
1267
1268 void go_threading(void)
1269 {
1270         int i;
1271         CtdlThreadNode *last_worker;
1272         struct timeval start, now, result;
1273         double last_duration;
1274
1275         /*
1276          * Initialise the thread system
1277          */
1278         ctdl_thread_internal_init();
1279
1280         /* Second call to module init functions now that threading is up */
1281         if (!statcount) {
1282                 initialise_modules(1);
1283                 CtdlThreadCreate("select_on_master", CTDLTHREAD_BIGSTACK, select_on_master, NULL);
1284         }
1285         else {
1286                 CtdlLogPrintf(CTDL_EMERG, "Running connection simulation stats\n");
1287                 gettimeofday(&start, NULL);
1288                 CtdlThreadCreate("Connection simulation master", CTDLTHREAD_BIGSTACK, simulation_thread, NULL);
1289         }
1290
1291
1292         /*
1293          * This thread is now used for garbage collection of other threads in the thread list
1294          */
1295         CtdlLogPrintf(CTDL_INFO, "Startup thread %d becoming garbage collector,\n", citthread_self());
1296
1297         /*
1298          * We do a lot of locking and unlocking of the thread list in here.
1299          * We do this so that we can repeatedly release time for other threads
1300          * that may be waiting on the thread list.
1301          * We are a low priority thread so we can afford to do this
1302          */
1303
1304         while (CtdlThreadGetCount())
1305         {
1306                 if (CT->signal)
1307                         exit_signal = CT->signal;
1308                 if (exit_signal)
1309                 {
1310                         CtdlThreadStopAll();
1311                 }
1312                 check_sched_shutdown();
1313                 if (CT->state > CTDL_THREAD_STOP_REQ)
1314                 {
1315                         begin_critical_section(S_THREAD_LIST);
1316                         ctdl_thread_internal_calc_loadavg();
1317                         end_critical_section(S_THREAD_LIST);
1318
1319                         ctdl_thread_internal_check_scheduled(); /* start scheduled threads */
1320                 }
1321
1322                 /* Reduce the size of the worker thread pool if necessary. */
1323                 if ((CtdlThreadGetWorkers() > config.c_min_workers + 1) && (CtdlThreadWorkerAvg < 20) && (CT->state > CTDL_THREAD_STOP_REQ))
1324                 {
1325                         /* Ask a worker thread to stop as we no longer need it */
1326                         begin_critical_section(S_THREAD_LIST);
1327                         last_worker = CtdlThreadList;
1328                         while (last_worker)
1329                         {
1330                                 citthread_mutex_lock(&last_worker->ThreadMutex);
1331                                 if (last_worker->flags & CTDLTHREAD_WORKER && (last_worker->state > CTDL_THREAD_STOPPING) && (last_worker->Context == NULL))
1332                                 {
1333                                         citthread_mutex_unlock(&last_worker->ThreadMutex);
1334                                         break;
1335                                 }
1336                                 citthread_mutex_unlock(&last_worker->ThreadMutex);
1337                                 last_worker = last_worker->next;
1338                         }
1339                         end_critical_section(S_THREAD_LIST);
1340                         if (last_worker)
1341                         {
1342 #ifdef WITH_THREADLOG
1343                                 CtdlLogPrintf(CTDL_DEBUG, "Thread system, stopping excess worker thread \"%s\" (0x%08lx).\n",
1344                                         last_worker->name,
1345                                         last_worker->tid
1346                                         );
1347 #endif
1348                                 CtdlThreadStop(last_worker);
1349                         }
1350                 }
1351
1352                 /*
1353                  * If all our workers are working hard, start some more to help out
1354                  * with things
1355                  */
1356                 /* FIXME: come up with a better way to dynamically alter the number of threads
1357                  * based on the system load
1358                  */
1359                 if (!statcount) {
1360                 if ((((CtdlThreadGetWorkers() < config.c_max_workers) && (CtdlThreadGetWorkerAvg() > 60)) || CtdlThreadGetWorkers() < config.c_min_workers) && (CT->state > CTDL_THREAD_STOP_REQ))
1361                 {
1362                         /* Only start new threads if we are not going to overload the machine */
1363                         /* Temporarily set to 10 should be enough to make sure we don't stranglew the server
1364                          * at least until we make this a config option */
1365                         if (CtdlThreadGetLoadAvg() < ((double)10.00)) {
1366                                 for (i=0; i<5 ; i++) {
1367                                         CtdlThreadCreate("Worker Thread",
1368                                                 CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER,
1369                                                 worker_thread,
1370                                                 NULL
1371                                                 );
1372                                 }
1373                         }
1374                         else
1375                                 CtdlLogPrintf (CTDL_WARNING, "Server strangled due to machine load average too high.\n");
1376                 }
1377                 }
1378
1379                 CtdlThreadGC();
1380
1381                 if (CtdlThreadGetCount() <= 1) // Shutting down clean up the garbage collector
1382                 {
1383                         CtdlThreadGC();
1384                 }
1385
1386 #ifdef THREADS_USESIGNALS
1387                 if (CtdlThreadGetCount() && CT->state > CTDL_THREAD_STOP_REQ)
1388 #else
1389                 if (CtdlThreadGetCount())
1390 #endif
1391                         CtdlThreadSleep(1);
1392         }
1393         /*
1394          * If the above loop exits we must be shutting down since we obviously have no threads
1395          */
1396         ctdl_thread_internal_cleanup();
1397
1398         if (statcount) {
1399                 gettimeofday(&now, NULL);
1400                 timersub(&now, &start, &result);
1401                 last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
1402                 CtdlLogPrintf(CTDL_EMERG, "Simulated %ld connections in %f seconds\n", stats_done, last_duration);
1403         }
1404 }
1405
1406
1407
1408