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         CtdlLogPrintf(CTDL_NOTICE, "Thread \"%s\" (0x%08lx) exited.\n", CT->name, CT->tid);
 598
 599         #ifdef HAVE_BACKTRACE
 600         eCrash_UnregisterThread();
 601         #endif
 602
 603         citthread_mutex_lock(&CT->ThreadMutex);
 604         CT->state = CTDL_THREAD_EXITED; // needs to be last thing else house keeping will unlink us too early
 605         citthread_mutex_unlock(&CT->ThreadMutex);
 606 }
 607
 608 /*
 609  * A quick function to show the load averages
 610  */
 611 void ctdl_thread_internal_calc_loadavg(void)
 612 {
 613         CtdlThreadNode *that_thread;
 614         double load_avg, worker_avg;
 615         int workers = 0;
 616
 617         that_thread = CtdlThreadList;
 618         load_avg = 0;
 619         worker_avg = 0;
 620         while(that_thread)
 621         {
 622                 /* Update load averages */
 623                 ctdl_thread_internal_update_avgs(that_thread);
 624                 citthread_mutex_lock(&that_thread->ThreadMutex);
 625                 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;
 626                 that_thread->avg_sleeping /= 2;
 627                 that_thread->avg_running /= 2;
 628                 that_thread->avg_blocked /= 2;
 629                 load_avg += that_thread->load_avg;
 630                 if (that_thread->flags & CTDLTHREAD_WORKER)
 631                 {
 632                         worker_avg += that_thread->load_avg;
 633                         workers++;
 634                 }
 635 #ifdef WITH_THREADLOG
 636                 CtdlLogPrintf(CTDL_DEBUG, "CtdlThread, \"%s\" (%lu) \"%s\" %.2f %.2f %.2f %.2f\n",
 637                         that_thread->name,
 638                         that_thread->tid,
 639                         CtdlThreadStates[that_thread->state],
 640                         that_thread->avg_sleeping,
 641                         that_thread->avg_running,
 642                         that_thread->avg_blocked,
 643                         that_thread->load_avg);
 644 #endif
 645                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 646                 that_thread = that_thread->next;
 647         }
 648         CtdlThreadLoadAvg = load_avg/num_threads;
 649         CtdlThreadWorkerAvg = worker_avg/workers;
 650 #ifdef WITH_THREADLOG
 651         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);
 652 #endif
 653 }
 654
 655
 656 /*
 657  * Garbage collection routine.
 658  * Gets called by main() in a loop to clean up the thread list periodically.
 659  */
 660 void CtdlThreadGC (void)
 661 {
 662         CtdlThreadNode *this_thread, *that_thread;
 663         int workers = 0, sys_workers;
 664         int ret=0;
 665
 666         begin_critical_section(S_THREAD_LIST);
 667
 668         /* Handle exiting of garbage collector thread */
 669         if(num_threads == 1)
 670                 CtdlThreadList->state = CTDL_THREAD_EXITED;
 671
 672 #ifdef WITH_THREADLOG
 673         CtdlLogPrintf(CTDL_DEBUG, "Thread system running garbage collection.\n");
 674 #endif
 675         /*
 676          * Woke up to do garbage collection
 677          */
 678         this_thread = CtdlThreadList;
 679         while(this_thread)
 680         {
 681                 that_thread = this_thread;
 682                 this_thread = this_thread->next;
 683
 684                 if ((that_thread->state == CTDL_THREAD_STOP_REQ || that_thread->state == CTDL_THREAD_STOPPING)
 685                         && (!citthread_equal(that_thread->tid, citthread_self())))
 686                                 CtdlLogPrintf(CTDL_DEBUG, "Waiting for thread %s (0x%08lx) to exit.\n", that_thread->name, that_thread->tid);
 687                 else
 688                 {
 689                         /**
 690                          * Catch the situation where a worker was asked to stop but couldn't and we are not
 691                          * shutting down.
 692                          */
 693                         that_thread->stop_ticker = 0;
 694                 }
 695
 696                 if (that_thread->stop_ticker + 5 == time(NULL))
 697                 {
 698                         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);
 699                         if ((that_thread->flags & CTDLTHREAD_WORKER) == 0)
 700                                 CtdlLogPrintf(CTDL_INFO, "Thread System: A non worker thread would have been canceled this may cause message loss.\n");
 701 //                      that_thread->state = CTDL_THREAD_CANCELLED;
 702                         that_thread->stop_ticker++;
 703 //                      citthread_cancel(that_thread->tid);
 704 //                      continue;
 705                 }
 706
 707                 /* Do we need to clean up this thread? */
 708                 if ((that_thread->state != CTDL_THREAD_EXITED) && (that_thread->state != CTDL_THREAD_CANCELLED))
 709                 {
 710                         if(that_thread->flags & CTDLTHREAD_WORKER)
 711                                 workers++;      /* Sanity check on number of worker threads */
 712                         continue;
 713                 }
 714
 715                 if (citthread_equal(that_thread->tid, citthread_self()) && that_thread->thread_func)
 716                 {       /* Sanity check */
 717                         end_critical_section(S_THREAD_LIST);
 718                         CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, a thread is trying to clean up after itself.\n");
 719                         abort();
 720                         return;
 721                 }
 722
 723                 if (num_threads <= 0)
 724                 {       /* Sanity check */
 725                         end_critical_section(S_THREAD_LIST);
 726                         CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, num_threads <= 0 and trying to do Garbage Collection.\n");
 727                         abort();
 728                         return;
 729                 }
 730
 731                 if(that_thread->flags & CTDLTHREAD_WORKER)
 732                         num_workers--;  /* This is a wroker thread so reduce the count. */
 733                 num_threads--;
 734                 /* If we are unlinking the list head then the next becomes the list head */
 735                 if(that_thread->prev)
 736                         that_thread->prev->next = that_thread->next;
 737                 else
 738                         CtdlThreadList = that_thread->next;
 739                 if(that_thread->next)
 740                         that_thread->next->prev = that_thread->prev;
 741
 742                 citthread_cond_signal(&that_thread->ThreadCond);
 743                 citthread_cond_signal(&that_thread->SleepCond); // Make sure this thread is awake
 744                 citthread_mutex_lock(&that_thread->ThreadMutex);        // Make sure it has done what its doing
 745                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 746                 /*
 747                  * Join on the thread to do clean up and prevent memory leaks
 748                  * Also makes sure the thread has cleaned up after itself before we remove it from the list
 749                  * We can join on the garbage collector thread the join should just return EDEADLCK
 750                  */
 751                 ret = citthread_join (that_thread->tid, NULL);
 752                 if (ret == EDEADLK)
 753                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection on own thread.\n");
 754                 else if (ret == EINVAL)
 755                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, that thread already joined on.\n");
 756                 else if (ret == ESRCH)
 757                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, no thread to join on.\n");
 758                 else if (ret != 0)
 759                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, citthread_join returned an unknown error(%d).\n", ret);
 760                 /*
 761                  * Now we own that thread entry
 762                  */
 763                 CtdlLogPrintf(CTDL_INFO, "Garbage Collection for thread \"%s\" (0x%08lx).\n",
 764                         that_thread->name, that_thread->tid);
 765                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 766                 citthread_cond_destroy(&that_thread->ThreadCond);
 767                 citthread_mutex_destroy(&that_thread->SleepMutex);
 768                 citthread_cond_destroy(&that_thread->SleepCond);
 769                 citthread_attr_destroy(&that_thread->attr);
 770                 free(that_thread);
 771         }
 772         sys_workers = num_workers;
 773         end_critical_section(S_THREAD_LIST);
 774
 775         /* Sanity check number of worker threads */
 776         if (workers != sys_workers)
 777         {
 778                 CtdlLogPrintf(CTDL_EMERG,
 779                         "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n",
 780                         workers, sys_workers
 781                         );
 782                 abort();
 783         }
 784 }
 785
 786
 787
 788
 789 /*
 790  * Runtime function for a Citadel Thread.
 791  * This initialises the threads environment and then calls the user supplied thread function
 792  * Note that this is the REAL thread function and wraps the users thread function.
 793  */
 794 static void *ctdl_internal_thread_func (void *arg)
 795 {
 796         CtdlThreadNode *this_thread;
 797         void *ret = NULL;
 798
 799         /* lock and unlock the thread list.
 800          * This causes this thread to wait until all its creation stuff has finished before it
 801          * can continue its execution.
 802          */
 803         begin_critical_section(S_THREAD_LIST);
 804         this_thread = (CtdlThreadNode *) arg;
 805         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 806
 807         // Register the cleanup function to take care of when we exit.
 808         citthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
 809         // Get our thread data structure
 810         CtdlThreadAllocTSD();
 811         CT = this_thread;
 812         this_thread->pid = getpid();
 813         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 814         /* Only change to running state if we weren't asked to stop during the create cycle
 815          * Other wise there is a window to allow this threads creation to continue to full grown and
 816          * therby prevent a shutdown of the server.
 817          */
 818         if (!CtdlThreadCheckStop())
 819         {
 820                 citthread_mutex_lock(&this_thread->ThreadMutex);
 821                 this_thread->state = CTDL_THREAD_RUNNING;
 822                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 823         }
 824         end_critical_section(S_THREAD_LIST);
 825
 826         // Register for tracing
 827         #ifdef HAVE_BACKTRACE
 828         eCrash_RegisterThread(this_thread->name, 0);
 829         #endif
 830
 831         // Tell the world we are here
 832         CtdlLogPrintf(CTDL_NOTICE, "Created a new thread \"%s\" (0x%08lx).\n",
 833                 this_thread->name, this_thread->tid);
 834
 835         /*
 836          * run the thread to do the work but only if we haven't been asked to stop
 837          */
 838         if (!CtdlThreadCheckStop())
 839                 ret = (this_thread->thread_func)(this_thread->user_args);
 840
 841         /*
 842          * Our thread is exiting either because it wanted to end or because the server is stopping
 843          * We need to clean up
 844          */
 845         citthread_cleanup_pop(1);       // Execute our cleanup routine and remove it
 846
 847         return(ret);
 848 }
 849
 850
 851
 852
 853 /*
 854  * Function to initialise an empty thread structure
 855  */
 856 CtdlThreadNode *ctdl_internal_init_thread_struct(CtdlThreadNode *this_thread, long flags)
 857 {
 858         int ret = 0;
 859
 860         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 861         memset (this_thread, 0, sizeof(CtdlThreadNode));
 862
 863         /* Create the mutex's early so we can use them */
 864         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 865         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 866         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 867         citthread_cond_init (&(this_thread->SleepCond), NULL);
 868
 869         this_thread->state = CTDL_THREAD_CREATE;
 870
 871         if ((ret = citthread_attr_init(&this_thread->attr))) {
 872                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 873                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 874                 citthread_cond_destroy(&(this_thread->ThreadCond));
 875                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 876                 citthread_cond_destroy(&(this_thread->SleepCond));
 877                 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 878                 free(this_thread);
 879                 return NULL;
 880         }
 881
 882         /* Our per-thread stacks need to be bigger than the default size,
 883          * otherwise the MIME parser crashes on FreeBSD, and the IMAP service
 884          * crashes on 64-bit Linux.
 885          */
 886         if (flags & CTDLTHREAD_BIGSTACK)
 887         {
 888 #ifdef WITH_THREADLOG
 889                 CtdlLogPrintf(CTDL_INFO, "Thread system. Creating BIG STACK thread.\n");
 890 #endif
 891                 if ((ret = citthread_attr_setstacksize(&this_thread->attr, THREADSTACKSIZE))) {
 892                         citthread_mutex_unlock(&this_thread->ThreadMutex);
 893                         citthread_mutex_destroy(&(this_thread->ThreadMutex));
 894                         citthread_cond_destroy(&(this_thread->ThreadCond));
 895                         citthread_mutex_destroy(&(this_thread->SleepMutex));
 896                         citthread_cond_destroy(&(this_thread->SleepCond));
 897                         citthread_attr_destroy(&this_thread->attr);
 898                         CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_setstacksize: %s\n",
 899                                 strerror(ret));
 900                         free(this_thread);
 901                         return NULL;
 902                 }
 903         }
 904
 905         /* Set this new thread with an avg_blocked of 2. We do this so that its creation affects the
 906          * load average for the system. If we don't do this then we create a mass of threads at the same time
 907          * because the creation didn't affect the load average.
 908          */
 909         this_thread->avg_blocked = 2;
 910
 911         return (this_thread);
 912 }
 913
 914
 915
 916
 917 /*
 918  * Internal function to create a thread.
 919  */
 920 CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void *(*thread_func) (void *arg), void *args)
 921 {
 922         int ret = 0;
 923         CtdlThreadNode *this_thread;
 924
 925         if (num_threads >= 32767)
 926         {
 927                 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
 928                 return NULL;
 929         }
 930
 931         this_thread = malloc(sizeof(CtdlThreadNode));
 932         if (this_thread == NULL) {
 933                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 934                 return NULL;
 935         }
 936
 937         /* Initialise the thread structure */
 938         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
 939         {
 940                 free(this_thread);
 941                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
 942                 return NULL;
 943         }
 944         /*
 945          * If we got here we are going to create the thread so we must initilise the structure
 946          * first because most implimentations of threading can't create it in a stopped state
 947          * and it might want to do things with its structure that aren't initialised otherwise.
 948          */
 949         if(name)
 950         {
 951                 this_thread->name = name;
 952         }
 953         else
 954         {
 955                 this_thread->name = "Un-named Thread";
 956         }
 957
 958         this_thread->flags = flags;
 959         this_thread->thread_func = thread_func;
 960         this_thread->user_args = args;
 961
 962         begin_critical_section(S_THREAD_LIST);
 963         /*
 964          * We pass this_thread into the thread as its args so that it can find out information
 965          * about itself and it has a bit of storage space for itself, not to mention that the REAL
 966          * thread function needs to finish off the setup of the structure
 967          */
 968         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
 969         {
 970                 end_critical_section(S_THREAD_LIST);
 971                 CtdlLogPrintf(CTDL_ALERT, "Thread system, Can't create thread: %s\n",
 972                         strerror(ret));
 973                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 974                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 975                 citthread_cond_destroy(&(this_thread->ThreadCond));
 976                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 977                 citthread_cond_destroy(&(this_thread->SleepCond));
 978                 citthread_attr_destroy(&this_thread->attr);
 979                 free(this_thread);
 980                 return NULL;
 981         }
 982
 983         num_threads++;  // Increase the count of threads in the system.
 984         if(this_thread->flags & CTDLTHREAD_WORKER)
 985                 num_workers++;
 986
 987         this_thread->next = CtdlThreadList;
 988         CtdlThreadList = this_thread;
 989         if (this_thread->next)
 990                 this_thread->next->prev = this_thread;
 991         ctdl_thread_internal_calc_loadavg();
 992
 993         end_critical_section(S_THREAD_LIST);
 994
 995         return this_thread;
 996 }
 997
 998 /*
 999  * Wrapper function to create a thread
1000  * ensures the critical section and other protections are in place.
1001  * char *name = name to give to thread, if NULL, use generic name
1002  * int flags = flags to determine type of thread and standard facilities
1003  */
1004 CtdlThreadNode *CtdlThreadCreate(char *name, long flags, void *(*thread_func) (void *arg), void *args)
1005 {
1006         CtdlThreadNode *ret = NULL;
1007
1008         ret = ctdl_internal_create_thread(name, flags, thread_func, args);
1009         return ret;
1010 }
1011
1012
1013
1014 /*
1015  * Internal function to schedule a thread.
1016  * Must be called from within a S_THREAD_LIST critical section
1017  */
1018 CtdlThreadNode *CtdlThreadSchedule(char *name, long flags, void *(*thread_func) (void *arg), void *args, time_t when)
1019 {
1020         CtdlThreadNode *this_thread;
1021
1022         if (num_threads >= 32767)
1023         {
1024                 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
1025                 return NULL;
1026         }
1027
1028         this_thread = malloc(sizeof(CtdlThreadNode));
1029         if (this_thread == NULL) {
1030                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
1031                 return NULL;
1032         }
1033         /* Initialise the thread structure */
1034         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
1035         {
1036                 free(this_thread);
1037                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
1038                 return NULL;
1039         }
1040
1041         /*
1042          * If we got here we are going to create the thread so we must initilise the structure
1043          * first because most implimentations of threading can't create it in a stopped state
1044          * and it might want to do things with its structure that aren't initialised otherwise.
1045          */
1046         if(name)
1047         {
1048                 this_thread->name = name;
1049         }
1050         else
1051         {
1052                 this_thread->name = "Un-named Thread";
1053         }
1054
1055         this_thread->flags = flags;
1056         this_thread->thread_func = thread_func;
1057         this_thread->user_args = args;
1058
1059         /*
1060          * When to start this thread
1061          */
1062         this_thread->when = when;
1063
1064         begin_critical_section(S_SCHEDULE_LIST);
1065         this_thread->next = CtdlThreadSchedList;
1066         CtdlThreadSchedList = this_thread;
1067         if (this_thread->next)
1068                 this_thread->next->prev = this_thread;
1069         end_critical_section(S_SCHEDULE_LIST);
1070
1071         return this_thread;
1072 }
1073
1074
1075
1076 CtdlThreadNode *ctdl_thread_internal_start_scheduled (CtdlThreadNode *this_thread)
1077 {
1078         int ret = 0;
1079
1080         begin_critical_section(S_THREAD_LIST);
1081         /*
1082          * We pass this_thread into the thread as its args so that it can find out information
1083          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1084          * thread function needs to finish off the setup of the structure
1085          */
1086         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1087         {
1088                 end_critical_section(S_THREAD_LIST);
1089                 CtdlLogPrintf(CTDL_DEBUG, "Failed to start scheduled thread \"%s\": %s\n", this_thread->name, strerror(ret));
1090                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1091                 citthread_cond_destroy(&(this_thread->ThreadCond));
1092                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1093                 citthread_cond_destroy(&(this_thread->SleepCond));
1094                 citthread_attr_destroy(&this_thread->attr);
1095                 free(this_thread);
1096                 return NULL;
1097         }
1098
1099
1100         num_threads++;  // Increase the count of threads in the system.
1101         if(this_thread->flags & CTDLTHREAD_WORKER)
1102                 num_workers++;
1103
1104         this_thread->next = CtdlThreadList;
1105         CtdlThreadList = this_thread;
1106         if (this_thread->next)
1107                 this_thread->next->prev = this_thread;
1108
1109         ctdl_thread_internal_calc_loadavg();
1110         end_critical_section(S_THREAD_LIST);
1111
1112
1113         return this_thread;
1114 }
1115
1116
1117
1118 void ctdl_thread_internal_check_scheduled(void)
1119 {
1120         CtdlThreadNode *this_thread, *that_thread;
1121         time_t now;
1122
1123         /* Don't start scheduled threads if the system wants single user mode */
1124         if (CtdlWantSingleUser())
1125                 return;
1126
1127         if (try_critical_section(S_SCHEDULE_LIST))
1128                 return; /* If this list is locked we wait till the next chance */
1129
1130         now = time(NULL);
1131
1132 #ifdef WITH_THREADLOG
1133         CtdlLogPrintf(CTDL_DEBUG, "Checking for scheduled threads to start.\n");
1134 #endif
1135
1136         this_thread = CtdlThreadSchedList;
1137         while(this_thread)
1138         {
1139                 that_thread = this_thread;
1140                 this_thread = this_thread->next;
1141
1142                 if (now > that_thread->when)
1143                 {
1144                         /* Unlink from schedule list */
1145                         if (that_thread->prev)
1146                                 that_thread->prev->next = that_thread->next;
1147                         else
1148                                 CtdlThreadSchedList = that_thread->next;
1149                         if (that_thread->next)
1150                                 that_thread->next->prev = that_thread->prev;
1151
1152                         that_thread->next = that_thread->prev = NULL;
1153 #ifdef WITH_THREADLOG
1154                         CtdlLogPrintf(CTDL_DEBUG, "About to start scheduled thread \"%s\".\n", that_thread->name);
1155 #endif
1156                         if (CT->state > CTDL_THREAD_STOP_REQ)
1157                         {       /* Only start it if the system is not stopping */
1158                                 if (ctdl_thread_internal_start_scheduled (that_thread))
1159                                 {
1160 #ifdef WITH_THREADLOG
1161                                         CtdlLogPrintf(CTDL_INFO, "Thread system, Started a scheduled thread \"%s\" (0x%08lx).\n",
1162                                                 that_thread->name, that_thread->tid);
1163 #endif
1164                                 }
1165                         }
1166                 }
1167 #ifdef WITH_THREADLOG
1168                 else
1169                 {
1170                         CtdlLogPrintf(CTDL_DEBUG, "Thread \"%s\" will start in %ld seconds.\n",
1171                                 that_thread->name, that_thread->when - time(NULL));
1172                 }
1173 #endif
1174         }
1175         end_critical_section(S_SCHEDULE_LIST);
1176 }
1177
1178
1179 /*
1180  * A warapper function for select so we can show a thread as blocked
1181  */
1182 int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
1183 {
1184         int ret = 0;
1185
1186         ctdl_thread_internal_change_state(CT, CTDL_THREAD_BLOCKED);
1187         if (!CtdlThreadCheckStop())
1188                 ret = select(n, readfds, writefds, exceptfds, timeout);
1189         /**
1190          * If the select returned <= 0 then it failed due to an error
1191          * or timeout so this thread could stop if asked to do so.
1192          * Anything else means it needs to continue unless the system is shutting down
1193          */
1194         if (ret > 0)
1195         {
1196                 /**
1197                  * The select says this thread needs to do something useful.
1198                  * This thread was in an idle state so it may have been asked to stop
1199                  * but if the system isn't shutting down this thread is no longer
1200                  * idle and select has given it a task to do so it must not stop
1201                  * In this condition we need to force it into the running state.
1202                  * CtdlThreadGC will clear its ticker for us.
1203                  *
1204                  * FIXME: there is still a small hole here. It is possible for the sequence of locking
1205                  * to allow the state to get changed to STOP_REQ just after this code if the other thread
1206                  * has decided to change the state before this lock, it there fore has to wait till the lock
1207                  * completes but it will continue to change the state. We need something a bit better here.
1208                  */
1209                 citthread_mutex_lock(&CT->ThreadMutex); /* To prevent race condition of a sleeping thread */
1210                 if (GC_thread->state > CTDL_THREAD_STOP_REQ && CT->state <= CTDL_THREAD_STOP_REQ)
1211                 {
1212                         CtdlLogPrintf(CTDL_DEBUG, "Thread %s (0x%08lx) refused stop request.\n", CT->name, CT->tid);
1213                         CT->state = CTDL_THREAD_RUNNING;
1214                 }
1215                 citthread_mutex_unlock(&CT->ThreadMutex);
1216         }
1217
1218         ctdl_thread_internal_change_state(CT, CTDL_THREAD_RUNNING);
1219
1220         return ret;
1221 }
1222
1223
1224
1225 void *new_worker_thread(void *arg);
1226 extern void close_masters (void);
1227
1228
1229 void *simulation_worker (void*arg) {
1230         struct CitContext *this;
1231
1232         this = CreateNewContext();
1233         CtdlThreadSleep(1);
1234         this->kill_me = 1;
1235         this->state = CON_IDLE;
1236         dead_session_purge(1);
1237         begin_critical_section(S_SESSION_TABLE);
1238         stats_done++;
1239         end_critical_section(S_SESSION_TABLE);
1240         return NULL;
1241 }
1242
1243
1244 void *simulation_thread (void *arg)
1245 {
1246         long stats = statcount;
1247
1248         while(stats && !CtdlThreadCheckStop()) {
1249                 CtdlThreadCreate("Connection simulation worker", CTDLTHREAD_BIGSTACK, simulation_worker, NULL);
1250                 stats--;
1251         }
1252         CtdlThreadStopAll();
1253         return NULL;
1254 }
1255
1256 void go_threading(void)
1257 {
1258         int i;
1259         CtdlThreadNode *last_worker;
1260         struct timeval start, now, result;
1261         double last_duration;
1262
1263         /*
1264          * Initialise the thread system
1265          */
1266         ctdl_thread_internal_init();
1267
1268         /* Second call to module init functions now that threading is up */
1269         if (!statcount) {
1270                 initialise_modules(1);
1271                 CtdlThreadCreate("select_on_master", CTDLTHREAD_BIGSTACK, select_on_master, NULL);
1272         }
1273         else {
1274                 CtdlLogPrintf(CTDL_EMERG, "Running connection simulation stats\n");
1275                 gettimeofday(&start, NULL);
1276                 CtdlThreadCreate("Connection simulation master", CTDLTHREAD_BIGSTACK, simulation_thread, NULL);
1277         }
1278
1279
1280         /*
1281          * This thread is now used for garbage collection of other threads in the thread list
1282          */
1283         CtdlLogPrintf(CTDL_INFO, "Startup thread %d becoming garbage collector,\n", citthread_self());
1284
1285         /*
1286          * We do a lot of locking and unlocking of the thread list in here.
1287          * We do this so that we can repeatedly release time for other threads
1288          * that may be waiting on the thread list.
1289          * We are a low priority thread so we can afford to do this
1290          */
1291
1292         while (CtdlThreadGetCount())
1293         {
1294                 if (CT->signal)
1295                         exit_signal = CT->signal;
1296                 if (exit_signal)
1297                 {
1298                         CtdlThreadStopAll();
1299                 }
1300                 check_sched_shutdown();
1301                 if (CT->state > CTDL_THREAD_STOP_REQ)
1302                 {
1303                         begin_critical_section(S_THREAD_LIST);
1304                         ctdl_thread_internal_calc_loadavg();
1305                         end_critical_section(S_THREAD_LIST);
1306
1307                         ctdl_thread_internal_check_scheduled(); /* start scheduled threads */
1308                 }
1309
1310                 /* Reduce the size of the worker thread pool if necessary. */
1311                 if ((CtdlThreadGetWorkers() > config.c_min_workers + 1) && (CtdlThreadWorkerAvg < 20) && (CT->state > CTDL_THREAD_STOP_REQ))
1312                 {
1313                         /* Ask a worker thread to stop as we no longer need it */
1314                         begin_critical_section(S_THREAD_LIST);
1315                         last_worker = CtdlThreadList;
1316                         while (last_worker)
1317                         {
1318                                 citthread_mutex_lock(&last_worker->ThreadMutex);
1319                                 if (last_worker->flags & CTDLTHREAD_WORKER && (last_worker->state > CTDL_THREAD_STOPPING) && (last_worker->Context == NULL))
1320                                 {
1321                                         citthread_mutex_unlock(&last_worker->ThreadMutex);
1322                                         break;
1323                                 }
1324                                 citthread_mutex_unlock(&last_worker->ThreadMutex);
1325                                 last_worker = last_worker->next;
1326                         }
1327                         end_critical_section(S_THREAD_LIST);
1328                         if (last_worker)
1329                         {
1330 #ifdef WITH_THREADLOG
1331                                 CtdlLogPrintf(CTDL_DEBUG, "Thread system, stopping excess worker thread \"%s\" (0x%08lx).\n",
1332                                         last_worker->name,
1333                                         last_worker->tid
1334                                         );
1335 #endif
1336                                 CtdlThreadStop(last_worker);
1337                         }
1338                 }
1339
1340                 /*
1341                  * If all our workers are working hard, start some more to help out
1342                  * with things
1343                  */
1344                 /* FIXME: come up with a better way to dynamically alter the number of threads
1345                  * based on the system load
1346                  */
1347                 if (!statcount) {
1348                 if ((((CtdlThreadGetWorkers() < config.c_max_workers) && (CtdlThreadGetWorkerAvg() > 60)) || CtdlThreadGetWorkers() < config.c_min_workers) && (CT->state > CTDL_THREAD_STOP_REQ))
1349                 {
1350                         /* Only start new threads if we are not going to overload the machine */
1351                         /* Temporarily set to 10 should be enough to make sure we don't stranglew the server
1352                          * at least until we make this a config option */
1353                         if (CtdlThreadGetLoadAvg() < ((double)10.00)) {
1354                                 for (i=0; i<5 ; i++) {
1355                                         CtdlThreadCreate("Worker Thread",
1356                                                 CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER,
1357                                                 worker_thread,
1358                                                 NULL
1359                                                 );
1360                                 }
1361                         }
1362                         else
1363                                 CtdlLogPrintf (CTDL_WARNING, "Server strangled due to machine load average too high.\n");
1364                 }
1365                 }
1366
1367                 CtdlThreadGC();
1368
1369                 if (CtdlThreadGetCount() <= 1) // Shutting down clean up the garbage collector
1370                 {
1371                         CtdlThreadGC();
1372                 }
1373
1374 #ifdef THREADS_USESIGNALS
1375                 if (CtdlThreadGetCount() && CT->state > CTDL_THREAD_STOP_REQ)
1376 #else
1377                 if (CtdlThreadGetCount())
1378 #endif
1379                         CtdlThreadSleep(1);
1380         }
1381         /*
1382          * If the above loop exits we must be shutting down since we obviously have no threads
1383          */
1384         ctdl_thread_internal_cleanup();
1385
1386         if (statcount) {
1387                 gettimeofday(&now, NULL);
1388                 timersub(&now, &start, &result);
1389                 last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
1390                 CtdlLogPrintf(CTDL_EMERG, "Simulated %ld connections in %f seconds\n", stats_done, last_duration);
1391         }
1392 }
1393
1394
1395
1396