citadel/threads.c

   1 /*
   2  * Thread handling stuff for Citadel server
   3  *
   4  * Copyright (c) 1987-2010 by the citadel.org team
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <stdlib.h>
  22 #include <unistd.h>
  23 #include <stdio.h>
  24 #include <sys/types.h>
  25 #include <errno.h>
  26 #include <sys/socket.h>
  27 #include <unistd.h>
  28 #include <fcntl.h>
  29 #include <signal.h>
  30
  31 #include "sysdep.h"
  32 #if TIME_WITH_SYS_TIME
  33 # include <sys/time.h>
  34 # include <time.h>
  35 #else
  36 # if HAVE_SYS_TIME_H
  37 #  include <sys/time.h>
  38 # else
  39 #  include <time.h>
  40 # endif
  41 #endif
  42
  43 #ifdef HAVE_SYSCALL_H
  44 # include <syscall.h>
  45 #else
  46 # if HAVE_SYS_SYSCALL_H
  47 #  include <sys/syscall.h>
  48 # endif
  49 #endif
  50
  51 #include <libcitadel.h>
  52
  53 #include "threads.h"
  54 #include "ctdl_module.h"
  55 #include "modules_init.h"
  56 #include "housekeeping.h"
  57 #include "config.h"
  58 #include "citserver.h"
  59 #include "sysdep_decls.h"
  60 #include "context.h"
  61
  62 /*
  63  * define this to use the new worker_thread method of handling connections
  64  */
  65 //#define NEW_WORKER
  66
  67 /*
  68  * New thread interface.
  69  * To create a thread you must call one of the create thread functions.
  70  * You must pass it the address of (a pointer to a CtdlThreadNode initialised to NULL) like this
  71  * struct CtdlThreadNode *node = NULL;
  72  * pass in &node
  73  * If the thread is created *node will point to the thread control structure for the created thread.
  74  * If the thread creation fails *node remains NULL
  75  * Do not free the memory pointed to by *node, it doesn't belong to you.
  76  * This new interface duplicates much of the eCrash stuff. We should go for closer integration since that would
  77  * remove the need for the calls to eCrashRegisterThread and friends
  78  */
  79
  80 static int num_threads = 0;                     /* Current number of threads */
  81 static int num_workers = 0;                     /* Current number of worker threads */
  82 long statcount = 0;             /* are we doing a stats check? */
  83 static long stats_done = 0;
  84
  85 CtdlThreadNode *CtdlThreadList = NULL;
  86 CtdlThreadNode *CtdlThreadSchedList = NULL;
  87
  88 static CtdlThreadNode *GC_thread = NULL;
  89 static char *CtdlThreadStates[CTDL_THREAD_LAST_STATE];
  90 double CtdlThreadLoadAvg = 0;
  91 double CtdlThreadWorkerAvg = 0;
  92 citthread_key_t ThreadKey;
  93
  94 citthread_mutex_t Critters[MAX_SEMAPHORES];     /* Things needing locking */
  95
  96
  97
  98 void InitialiseSemaphores(void)
  99 {
 100         int i;
 101
 102         /* Set up a bunch of semaphores to be used for critical sections */
 103         for (i=0; i<MAX_SEMAPHORES; ++i) {
 104                 citthread_mutex_init(&Critters[i], NULL);
 105         }
 106 }
 107
 108
 109
 110
 111 /*
 112  * Obtain a semaphore lock to begin a critical section.
 113  * but only if no one else has one
 114  */
 115 int try_critical_section(int which_one)
 116 {
 117         /* For all types of critical sections except those listed here,
 118          * ensure nobody ever tries to do a critical section within a
 119          * transaction; this could lead to deadlock.
 120          */
 121         if (    (which_one != S_FLOORCACHE)
 122 #ifdef DEBUG_MEMORY_LEAKS
 123                 && (which_one != S_DEBUGMEMLEAKS)
 124 #endif
 125                 && (which_one != S_RPLIST)
 126         ) {
 127                 cdb_check_handles();
 128         }
 129         return (citthread_mutex_trylock(&Critters[which_one]));
 130 }
 131
 132
 133 /*
 134  * Obtain a semaphore lock to begin a critical section.
 135  */
 136 void begin_critical_section(int which_one)
 137 {
 138         /* CtdlLogPrintf(CTDL_DEBUG, "begin_critical_section(%d)\n", which_one); */
 139
 140         /* For all types of critical sections except those listed here,
 141          * ensure nobody ever tries to do a critical section within a
 142          * transaction; this could lead to deadlock.
 143          */
 144         if (    (which_one != S_FLOORCACHE)
 145 #ifdef DEBUG_MEMORY_LEAKS
 146                 && (which_one != S_DEBUGMEMLEAKS)
 147 #endif
 148                 && (which_one != S_RPLIST)
 149         ) {
 150                 cdb_check_handles();
 151         }
 152         citthread_mutex_lock(&Critters[which_one]);
 153 }
 154
 155 /*
 156  * Release a semaphore lock to end a critical section.
 157  */
 158 void end_critical_section(int which_one)
 159 {
 160         citthread_mutex_unlock(&Critters[which_one]);
 161 }
 162
 163
 164 /*
 165  * A function to destroy the TSD
 166  */
 167 static void ctdl_thread_internal_dest_tsd(void *arg)
 168 {
 169         if (arg != NULL) {
 170                 check_handles(arg);
 171                 free(arg);
 172         }
 173 }
 174
 175
 176 /*
 177  * A function to initialise the thread TSD
 178  */
 179 void ctdl_thread_internal_init_tsd(void)
 180 {
 181         int ret;
 182
 183         if ((ret = citthread_key_create(&ThreadKey, ctdl_thread_internal_dest_tsd))) {
 184                 CtdlLogPrintf(CTDL_EMERG, "citthread_key_create: %s\n", strerror(ret));
 185                 exit(CTDLEXIT_DB);
 186         }
 187 }
 188
 189 /*
 190  * Ensure that we have a key for thread-specific data.
 191  *
 192  * This should be called immediately after startup by any thread
 193  *
 194  */
 195 void CtdlThreadAllocTSD(void)
 196 {
 197         ThreadTSD *tsd;
 198
 199         if (citthread_getspecific(ThreadKey) != NULL)
 200                 return;
 201
 202         tsd = malloc(sizeof(ThreadTSD));
 203
 204         tsd->tid = NULL;
 205
 206         memset(tsd->cursors, 0, sizeof tsd->cursors);
 207         tsd->self = NULL;
 208
 209         citthread_setspecific(ThreadKey, tsd);
 210 }
 211
 212
 213 void ctdl_thread_internal_free_tsd(void)
 214 {
 215         ctdl_thread_internal_dest_tsd(citthread_getspecific(ThreadKey));
 216         citthread_setspecific(ThreadKey, NULL);
 217 }
 218
 219
 220 void ctdl_thread_internal_cleanup(void)
 221 {
 222         int i;
 223         CtdlThreadNode *this_thread, *that_thread;
 224
 225         for (i=0; i<CTDL_THREAD_LAST_STATE; i++)
 226         {
 227                 free (CtdlThreadStates[i]);
 228         }
 229
 230         /* Clean up the scheduled thread list */
 231         this_thread = CtdlThreadSchedList;
 232         while (this_thread)
 233         {
 234                 that_thread = this_thread;
 235                 this_thread = this_thread->next;
 236                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 237                 citthread_cond_destroy(&that_thread->ThreadCond);
 238                 citthread_mutex_destroy(&that_thread->SleepMutex);
 239                 citthread_cond_destroy(&that_thread->SleepCond);
 240                 citthread_attr_destroy(&that_thread->attr);
 241                 free(that_thread);
 242         }
 243         ctdl_thread_internal_free_tsd();
 244 }
 245
 246 void ctdl_thread_internal_init(void)
 247 {
 248         CtdlThreadNode *this_thread;
 249         int ret = 0;
 250
 251         CtdlThreadStates[CTDL_THREAD_INVALID] = strdup ("Invalid Thread");
 252         CtdlThreadStates[CTDL_THREAD_VALID] = strdup("Valid Thread");
 253         CtdlThreadStates[CTDL_THREAD_CREATE] = strdup("Thread being Created");
 254         CtdlThreadStates[CTDL_THREAD_CANCELLED] = strdup("Thread Cancelled");
 255         CtdlThreadStates[CTDL_THREAD_EXITED] = strdup("Thread Exited");
 256         CtdlThreadStates[CTDL_THREAD_STOPPING] = strdup("Thread Stopping");
 257         CtdlThreadStates[CTDL_THREAD_STOP_REQ] = strdup("Thread Stop Requested");
 258         CtdlThreadStates[CTDL_THREAD_SLEEPING] = strdup("Thread Sleeping");
 259         CtdlThreadStates[CTDL_THREAD_RUNNING] = strdup("Thread Running");
 260         CtdlThreadStates[CTDL_THREAD_BLOCKED] = strdup("Thread Blocked");
 261
 262         /* Get ourself a thread entry */
 263         this_thread = malloc(sizeof(CtdlThreadNode));
 264         if (this_thread == NULL) {
 265                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 266                 return;
 267         }
 268         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 269         memset (this_thread, 0, sizeof(CtdlThreadNode));
 270
 271         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 272         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 273         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 274         citthread_cond_init (&(this_thread->SleepCond), NULL);
 275
 276         /* We are garbage collector so create us as running */
 277         this_thread->state = CTDL_THREAD_RUNNING;
 278
 279         if ((ret = citthread_attr_init(&this_thread->attr))) {
 280                 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 281                 free(this_thread);
 282                 return;
 283         }
 284
 285         this_thread->name = "Garbage Collection Thread";
 286
 287         this_thread->tid = citthread_self();
 288         GC_thread = this_thread;
 289         CT = this_thread;
 290
 291         num_threads++;  // Increase the count of threads in the system.
 292
 293         this_thread->next = CtdlThreadList;
 294         CtdlThreadList = this_thread;
 295         if (this_thread->next)
 296                 this_thread->next->prev = this_thread;
 297         /* Set up start times */
 298         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 299         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 300 }
 301
 302
 303 /*
 304  * A function to update a threads load averages
 305  */
 306  void ctdl_thread_internal_update_avgs(CtdlThreadNode *this_thread)
 307  {
 308         struct timeval now, result;
 309         double last_duration;
 310
 311         gettimeofday(&now, NULL);
 312         timersub(&now, &(this_thread->last_state_change), &result);
 313         /* I don't think these mutex's are needed here */
 314         citthread_mutex_lock(&this_thread->ThreadMutex);
 315         // result now has a timeval for the time we spent in the last state since we last updated
 316         last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
 317         if (this_thread->state == CTDL_THREAD_SLEEPING)
 318                 this_thread->avg_sleeping += last_duration;
 319         if (this_thread->state == CTDL_THREAD_RUNNING)
 320                 this_thread->avg_running += last_duration;
 321         if (this_thread->state == CTDL_THREAD_BLOCKED)
 322                 this_thread->avg_blocked += last_duration;
 323         memcpy (&this_thread->last_state_change, &now, sizeof (struct timeval));
 324         citthread_mutex_unlock(&this_thread->ThreadMutex);
 325 }
 326
 327 /*
 328  * A function to chenge the state of a thread
 329  */
 330 void ctdl_thread_internal_change_state (CtdlThreadNode *this_thread, enum CtdlThreadState new_state)
 331 {
 332         /*
 333          * Wether we change state or not we need update the load values
 334          */
 335         ctdl_thread_internal_update_avgs(this_thread);
 336         /* This mutex not needed here? */
 337         citthread_mutex_lock(&this_thread->ThreadMutex); /* To prevent race condition of a sleeping thread */
 338         if ((new_state == CTDL_THREAD_STOP_REQ) && (this_thread->state > CTDL_THREAD_STOP_REQ))
 339                 this_thread->state = new_state;
 340         if (((new_state == CTDL_THREAD_SLEEPING) || (new_state == CTDL_THREAD_BLOCKED)) && (this_thread->state == CTDL_THREAD_RUNNING))
 341                 this_thread->state = new_state;
 342         if ((new_state == CTDL_THREAD_RUNNING) && ((this_thread->state == CTDL_THREAD_SLEEPING) || (this_thread->state == CTDL_THREAD_BLOCKED)))
 343                 this_thread->state = new_state;
 344         citthread_mutex_unlock(&this_thread->ThreadMutex);
 345 }
 346
 347
 348 /*
 349  * A function to tell all threads to exit
 350  */
 351 void CtdlThreadStopAll(void)
 352 {
 353         /* First run any registered shutdown hooks.  This probably doesn't belong here. */
 354         PerformSessionHooks(EVT_SHUTDOWN);
 355
 356         //FIXME: The signalling of the condition should not be in the critical_section
 357         // We need to build a list of threads we are going to signal and then signal them afterwards
 358
 359         CtdlThreadNode *this_thread;
 360
 361         begin_critical_section(S_THREAD_LIST);
 362         this_thread = CtdlThreadList;
 363         // Ask the GC thread to stop first so everything knows we are shutting down.
 364         GC_thread->state = CTDL_THREAD_STOP_REQ;
 365         while(this_thread)
 366         {
 367                 if (!citthread_equal(this_thread->tid, GC_thread->tid))
 368                         citthread_kill(this_thread->tid, SIGHUP);
 369
 370                 ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 371                 citthread_cond_signal(&this_thread->ThreadCond);
 372                 citthread_cond_signal(&this_thread->SleepCond);
 373                 this_thread->stop_ticker = time(NULL);
 374                 CtdlLogPrintf(CTDL_DEBUG, "Thread system stopping thread \"%s\" (0x%08lx).\n",
 375                         this_thread->name, this_thread->tid);
 376                 this_thread = this_thread->next;
 377         }
 378         end_critical_section(S_THREAD_LIST);
 379 }
 380
 381
 382 /*
 383  * A function to wake up all sleeping threads
 384  */
 385 void CtdlThreadWakeAll(void)
 386 {
 387         CtdlThreadNode *this_thread;
 388
 389         CtdlLogPrintf(CTDL_DEBUG, "Thread system waking all threads.\n");
 390
 391         begin_critical_section(S_THREAD_LIST);
 392         this_thread = CtdlThreadList;
 393         while(this_thread)
 394         {
 395                 if (!this_thread->thread_func)
 396                 {
 397                         citthread_cond_signal(&this_thread->ThreadCond);
 398                         citthread_cond_signal(&this_thread->SleepCond);
 399                 }
 400                 this_thread = this_thread->next;
 401         }
 402         end_critical_section(S_THREAD_LIST);
 403 }
 404
 405
 406 /*
 407  * A function to return the number of threads running in the system
 408  */
 409 int CtdlThreadGetCount(void)
 410 {
 411         return  num_threads;
 412 }
 413
 414 int CtdlThreadGetWorkers(void)
 415 {
 416         return  num_workers;
 417 }
 418
 419 double CtdlThreadGetWorkerAvg(void)
 420 {
 421         double ret;
 422
 423         begin_critical_section(S_THREAD_LIST);
 424         ret =  CtdlThreadWorkerAvg;
 425         end_critical_section(S_THREAD_LIST);
 426         return ret;
 427 }
 428
 429 double CtdlThreadGetLoadAvg(void)
 430 {
 431         double load_avg[3] = {0.0, 0.0, 0.0};
 432
 433         int ret = 0;
 434         int smp_num_cpus;
 435
 436         /* Borrowed this straight from procps */
 437         smp_num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 438         if(smp_num_cpus<1) smp_num_cpus=1; /* SPARC glibc is buggy */
 439
 440 #ifdef HAVE_GETLOADAVG
 441         ret = getloadavg(load_avg, 3);
 442 #endif
 443         if (ret < 0)
 444                 return 0;
 445         return load_avg[0] / smp_num_cpus;
 446 /*
 447  * This old chunk of code return a value that indicated the load on citserver
 448  * This value could easily reach 100 % even when citserver was doing very little and
 449  * hence the machine has much more spare capacity.
 450  * Because this value was used to determine if the machine was under heavy load conditions
 451  * from other processes in the system then citserver could be strangled un-necesarily
 452  * What we are actually trying to achieve is to strangle citserver if the machine is heavily loaded.
 453  * So we have changed this.
 454
 455         begin_critical_section(S_THREAD_LIST);
 456         ret =  CtdlThreadLoadAvg;
 457         end_critical_section(S_THREAD_LIST);
 458         return ret;
 459 */
 460 }
 461
 462
 463
 464
 465 /*
 466  * A function to rename a thread
 467  * Returns a const char *
 468  */
 469 const char *CtdlThreadName(const char *name)
 470 {
 471         const char *old_name;
 472
 473         if (!CT)
 474         {
 475                 CtdlLogPrintf(CTDL_WARNING, "Thread system WARNING. Attempt to CtdlThreadRename() a non thread. %s\n", name);
 476                 return NULL;
 477         }
 478         old_name = CT->name;
 479         if (name)
 480                 CT->name = name;
 481         return (old_name);
 482 }
 483
 484
 485 /*
 486  * A function to force a thread to exit
 487  */
 488 void CtdlThreadCancel(CtdlThreadNode *thread)
 489 {
 490         CtdlThreadNode *this_thread;
 491
 492         if (!thread)
 493                 this_thread = CT;
 494         else
 495                 this_thread = thread;
 496         if (!this_thread)
 497         {
 498                 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() a non thread.\n");
 499                 CtdlThreadStopAll();
 500                 return;
 501         }
 502
 503         if (!this_thread->thread_func)
 504         {
 505                 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC. Attempt to CtdlThreadCancel() the garbage collector.\n");
 506                 CtdlThreadStopAll();
 507                 return;
 508         }
 509
 510         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_CANCELLED);
 511         citthread_cancel(this_thread->tid);
 512 }
 513
 514
 515 /*
 516  * A function for a thread to check if it has been asked to stop
 517  */
 518 int CtdlThreadCheckStop(void)
 519 {
 520         int state;
 521
 522         if (!CT)
 523         {
 524                 CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, CtdlThreadCheckStop() called by a non thread.\n");
 525                 CtdlThreadStopAll();
 526                 return -1;
 527         }
 528
 529         state = CT->state;
 530
 531         if (CT->signal)
 532         {
 533                 CtdlLogPrintf(CTDL_DEBUG, "Thread \"%s\" caught signal %d.\n", CT->name, CT->signal);
 534                 if (CT->signal == SIGHUP)
 535                         CT->state = CTDL_THREAD_STOP_REQ;
 536                 CT->signal = 0;
 537         }
 538         if(state == CTDL_THREAD_STOP_REQ)
 539         {
 540                 CT->state = CTDL_THREAD_STOPPING;
 541                 return -1;
 542         }
 543         else if((state < CTDL_THREAD_STOP_REQ) && (state > CTDL_THREAD_CREATE))
 544         {
 545                 return -1;
 546         }
 547         return 0;
 548 }
 549
 550
 551 /*
 552  * A function to ask a thread to exit
 553  * The thread must call CtdlThreadCheckStop() periodically to determine if it should exit
 554  */
 555 void CtdlThreadStop(CtdlThreadNode *thread)
 556 {
 557         CtdlThreadNode *this_thread;
 558
 559         if (!thread)
 560                 this_thread = CT;
 561         else
 562                 this_thread = thread;
 563         if (!this_thread)
 564                 return;
 565         if (!(this_thread->thread_func))
 566                 return;         // Don't stop garbage collector
 567
 568         if (!citthread_equal(this_thread->tid, GC_thread->tid))
 569                 citthread_kill(this_thread->tid, SIGHUP);
 570
 571         ctdl_thread_internal_change_state (this_thread, CTDL_THREAD_STOP_REQ);
 572         citthread_cond_signal(&this_thread->ThreadCond);
 573         citthread_cond_signal(&this_thread->SleepCond);
 574         this_thread->stop_ticker = time(NULL);
 575 }
 576
 577 /*
 578  * So we now have a sleep command that works with threads but it is in seconds
 579  */
 580 void CtdlThreadSleep(int secs)
 581 {
 582         struct timespec wake_time;
 583         struct timeval time_now;
 584
 585
 586         if (!CT)
 587         {
 588                 CtdlLogPrintf(CTDL_WARNING, "CtdlThreadSleep() called by something that is not a thread. Should we die?\n");
 589                 return;
 590         }
 591
 592         memset (&wake_time, 0, sizeof(struct timespec));
 593         gettimeofday(&time_now, NULL);
 594         wake_time.tv_sec = time_now.tv_sec + secs;
 595         wake_time.tv_nsec = time_now.tv_usec * 10;
 596
 597         ctdl_thread_internal_change_state (CT, CTDL_THREAD_SLEEPING);
 598
 599         citthread_mutex_lock(&CT->ThreadMutex); /* Prevent something asking us to awaken before we've gone to sleep */
 600         citthread_cond_timedwait(&CT->SleepCond, &CT->ThreadMutex, &wake_time);
 601         citthread_mutex_unlock(&CT->ThreadMutex);
 602
 603         ctdl_thread_internal_change_state (CT, CTDL_THREAD_RUNNING);
 604 }
 605
 606
 607 /*
 608  * Routine to clean up our thread function on exit
 609  */
 610 static void ctdl_internal_thread_cleanup(void *arg)
 611 {
 612         /*
 613          * In here we were called by the current thread because it is exiting
 614          * NB. WE ARE THE CURRENT THREAD
 615          */
 616         if (CT)
 617         {
 618                 const char *name = CT->name;
 619                 const pid_t tid = CT->tid;
 620
 621                 CtdlLogPrintf(CTDL_NOTICE, "Thread \"%s\" (0x%08lx) exited.\n", name, tid);
 622         }
 623         else
 624         {
 625                 CtdlLogPrintf(CTDL_NOTICE, "some ((unknown ? ? ?) Thread exited.\n");
 626         }
 627
 628         #ifdef HAVE_BACKTRACE
 629 ///     eCrash_UnregisterThread();
 630         #endif
 631
 632         citthread_mutex_lock(&CT->ThreadMutex);
 633         CT->state = CTDL_THREAD_EXITED; // needs to be last thing else house keeping will unlink us too early
 634         citthread_mutex_unlock(&CT->ThreadMutex);
 635 }
 636
 637 /*
 638  * A quick function to show the load averages
 639  */
 640 void ctdl_thread_internal_calc_loadavg(void)
 641 {
 642         CtdlThreadNode *that_thread;
 643         double load_avg, worker_avg;
 644         int workers = 0;
 645
 646         that_thread = CtdlThreadList;
 647         load_avg = 0;
 648         worker_avg = 0;
 649         while(that_thread)
 650         {
 651                 /* Update load averages */
 652                 ctdl_thread_internal_update_avgs(that_thread);
 653                 citthread_mutex_lock(&that_thread->ThreadMutex);
 654                 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;
 655                 that_thread->avg_sleeping /= 2;
 656                 that_thread->avg_running /= 2;
 657                 that_thread->avg_blocked /= 2;
 658                 load_avg += that_thread->load_avg;
 659                 if (that_thread->flags & CTDLTHREAD_WORKER)
 660                 {
 661                         worker_avg += that_thread->load_avg;
 662                         workers++;
 663                 }
 664 #ifdef WITH_THREADLOG
 665                 CtdlLogPrintf(CTDL_DEBUG, "CtdlThread, \"%s\" (%lu) \"%s\" %.2f %.2f %.2f %.2f\n",
 666                         that_thread->name,
 667                         that_thread->tid,
 668                         CtdlThreadStates[that_thread->state],
 669                         that_thread->avg_sleeping,
 670                         that_thread->avg_running,
 671                         that_thread->avg_blocked,
 672                         that_thread->load_avg);
 673 #endif
 674                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 675                 that_thread = that_thread->next;
 676         }
 677         CtdlThreadLoadAvg = load_avg/num_threads;
 678         CtdlThreadWorkerAvg = worker_avg/workers;
 679 #ifdef WITH_THREADLOG
 680         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);
 681 #endif
 682 }
 683
 684
 685 /*
 686  * Garbage collection routine.
 687  * Gets called by main() in a loop to clean up the thread list periodically.
 688  */
 689 void CtdlThreadGC (void)
 690 {
 691         CtdlThreadNode *this_thread, *that_thread;
 692         int workers = 0, sys_workers;
 693         int ret=0;
 694
 695         begin_critical_section(S_THREAD_LIST);
 696
 697         /* Handle exiting of garbage collector thread */
 698         if(num_threads == 1)
 699                 CtdlThreadList->state = CTDL_THREAD_EXITED;
 700
 701 #ifdef WITH_THREADLOG
 702         CtdlLogPrintf(CTDL_DEBUG, "Thread system running garbage collection.\n");
 703 #endif
 704         /*
 705          * Woke up to do garbage collection
 706          */
 707         this_thread = CtdlThreadList;
 708         while(this_thread)
 709         {
 710                 that_thread = this_thread;
 711                 this_thread = this_thread->next;
 712
 713                 if ((that_thread->state == CTDL_THREAD_STOP_REQ || that_thread->state == CTDL_THREAD_STOPPING)
 714                         && (!citthread_equal(that_thread->tid, citthread_self())))
 715                                 CtdlLogPrintf(CTDL_DEBUG, "Waiting for thread %s (0x%08lx) to exit.\n", that_thread->name, that_thread->tid);
 716                 else
 717                 {
 718                         /**
 719                          * Catch the situation where a worker was asked to stop but couldn't and we are not
 720                          * shutting down.
 721                          */
 722                         that_thread->stop_ticker = 0;
 723                 }
 724
 725                 if (that_thread->stop_ticker + 5 == time(NULL))
 726                 {
 727                         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);
 728                         if ((that_thread->flags & CTDLTHREAD_WORKER) == 0)
 729                                 CtdlLogPrintf(CTDL_INFO, "Thread System: A non worker thread would have been canceled this may cause message loss.\n");
 730 //                      that_thread->state = CTDL_THREAD_CANCELLED;
 731                         that_thread->stop_ticker++;
 732 //                      citthread_cancel(that_thread->tid);
 733 //                      continue;
 734                 }
 735
 736                 /* Do we need to clean up this thread? */
 737                 if ((that_thread->state != CTDL_THREAD_EXITED) && (that_thread->state != CTDL_THREAD_CANCELLED))
 738                 {
 739                         if(that_thread->flags & CTDLTHREAD_WORKER)
 740                                 workers++;      /* Sanity check on number of worker threads */
 741                         continue;
 742                 }
 743
 744                 if (citthread_equal(that_thread->tid, citthread_self()) && that_thread->thread_func)
 745                 {       /* Sanity check */
 746                         end_critical_section(S_THREAD_LIST);
 747                         CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, a thread is trying to clean up after itself.\n");
 748                         abort();
 749                         return;
 750                 }
 751
 752                 if (num_threads <= 0)
 753                 {       /* Sanity check */
 754                         end_critical_section(S_THREAD_LIST);
 755                         CtdlLogPrintf(CTDL_EMERG, "Thread system PANIC, num_threads <= 0 and trying to do Garbage Collection.\n");
 756                         abort();
 757                         return;
 758                 }
 759
 760                 if(that_thread->flags & CTDLTHREAD_WORKER)
 761                         num_workers--;  /* This is a wroker thread so reduce the count. */
 762                 num_threads--;
 763                 /* If we are unlinking the list head then the next becomes the list head */
 764                 if(that_thread->prev)
 765                         that_thread->prev->next = that_thread->next;
 766                 else
 767                         CtdlThreadList = that_thread->next;
 768                 if(that_thread->next)
 769                         that_thread->next->prev = that_thread->prev;
 770
 771                 citthread_cond_signal(&that_thread->ThreadCond);
 772                 citthread_cond_signal(&that_thread->SleepCond); // Make sure this thread is awake
 773                 citthread_mutex_lock(&that_thread->ThreadMutex);        // Make sure it has done what its doing
 774                 citthread_mutex_unlock(&that_thread->ThreadMutex);
 775                 /*
 776                  * Join on the thread to do clean up and prevent memory leaks
 777                  * Also makes sure the thread has cleaned up after itself before we remove it from the list
 778                  * We can join on the garbage collector thread the join should just return EDEADLCK
 779                  */
 780                 ret = citthread_join (that_thread->tid, NULL);
 781                 if (ret == EDEADLK)
 782                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection on own thread.\n");
 783                 else if (ret == EINVAL)
 784                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, that thread already joined on.\n");
 785                 else if (ret == ESRCH)
 786                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, no thread to join on.\n");
 787                 else if (ret != 0)
 788                         CtdlLogPrintf(CTDL_DEBUG, "Garbage collection, citthread_join returned an unknown error(%d).\n", ret);
 789                 /*
 790                  * Now we own that thread entry
 791                  */
 792                 CtdlLogPrintf(CTDL_INFO, "Garbage Collection for thread \"%s\" (0x%08lx).\n",
 793                         that_thread->name, that_thread->tid);
 794                 citthread_mutex_destroy(&that_thread->ThreadMutex);
 795                 citthread_cond_destroy(&that_thread->ThreadCond);
 796                 citthread_mutex_destroy(&that_thread->SleepMutex);
 797                 citthread_cond_destroy(&that_thread->SleepCond);
 798                 citthread_attr_destroy(&that_thread->attr);
 799                 free(that_thread);
 800         }
 801         sys_workers = num_workers;
 802         end_critical_section(S_THREAD_LIST);
 803
 804         /* Sanity check number of worker threads */
 805         if (workers != sys_workers)
 806         {
 807                 CtdlLogPrintf(CTDL_EMERG,
 808                         "Thread system PANIC, discrepancy in number of worker threads. Counted %d, should be %d.\n",
 809                         workers, sys_workers
 810                         );
 811                 abort();
 812         }
 813 }
 814
 815
 816
 817
 818 /*
 819  * Runtime function for a Citadel Thread.
 820  * This initialises the threads environment and then calls the user supplied thread function
 821  * Note that this is the REAL thread function and wraps the users thread function.
 822  */
 823 static void *ctdl_internal_thread_func (void *arg)
 824 {
 825         CtdlThreadNode *this_thread;
 826         void *ret = NULL;
 827
 828         /* lock and unlock the thread list.
 829          * This causes this thread to wait until all its creation stuff has finished before it
 830          * can continue its execution.
 831          */
 832         begin_critical_section(S_THREAD_LIST);
 833         this_thread = (CtdlThreadNode *) arg;
 834         gettimeofday(&this_thread->start_time, NULL);           /* Time this thread started */
 835
 836         // Register the cleanup function to take care of when we exit.
 837         citthread_cleanup_push(ctdl_internal_thread_cleanup, NULL);
 838         // Get our thread data structure
 839         CtdlThreadAllocTSD();
 840         CT = this_thread;
 841         this_thread->pid = getpid();
 842         memcpy(&this_thread->last_state_change, &this_thread->start_time, sizeof (struct timeval));     /* Changed state so mark it. */
 843         /* Only change to running state if we weren't asked to stop during the create cycle
 844          * Other wise there is a window to allow this threads creation to continue to full grown and
 845          * therby prevent a shutdown of the server.
 846          */
 847         if (!CtdlThreadCheckStop())
 848         {
 849                 citthread_mutex_lock(&this_thread->ThreadMutex);
 850                 this_thread->state = CTDL_THREAD_RUNNING;
 851                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 852         }
 853         end_critical_section(S_THREAD_LIST);
 854
 855         // Register for tracing
 856         #ifdef HAVE_BACKTRACE
 857 ///     eCrash_RegisterThread(this_thread->name, 0);
 858         #endif
 859
 860         // Tell the world we are here
 861 #if defined(HAVE_SYSCALL_H) && defined (SYS_gettid)
 862         this_thread->reltid = syscall(SYS_gettid);
 863 #endif
 864         CtdlLogPrintf(CTDL_NOTICE, "Created a new thread \"%s\" (0x%08lx).\n",
 865                 this_thread->name, this_thread->tid);
 866
 867         /*
 868          * run the thread to do the work but only if we haven't been asked to stop
 869          */
 870         if (!CtdlThreadCheckStop())
 871                 ret = (this_thread->thread_func)(this_thread->user_args);
 872
 873         /*
 874          * Our thread is exiting either because it wanted to end or because the server is stopping
 875          * We need to clean up
 876          */
 877         citthread_cleanup_pop(1);       // Execute our cleanup routine and remove it
 878
 879         return(ret);
 880 }
 881
 882
 883
 884
 885 /*
 886  * Function to initialise an empty thread structure
 887  */
 888 CtdlThreadNode *ctdl_internal_init_thread_struct(CtdlThreadNode *this_thread, long flags)
 889 {
 890         int ret = 0;
 891
 892         // Ensuring this is zero'd means we make sure the thread doesn't start doing its thing until we are ready.
 893         memset (this_thread, 0, sizeof(CtdlThreadNode));
 894
 895         /* Create the mutex's early so we can use them */
 896         citthread_mutex_init (&(this_thread->ThreadMutex), NULL);
 897         citthread_cond_init (&(this_thread->ThreadCond), NULL);
 898         citthread_mutex_init (&(this_thread->SleepMutex), NULL);
 899         citthread_cond_init (&(this_thread->SleepCond), NULL);
 900
 901         this_thread->state = CTDL_THREAD_CREATE;
 902
 903         if ((ret = citthread_attr_init(&this_thread->attr))) {
 904                 citthread_mutex_unlock(&this_thread->ThreadMutex);
 905                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
 906                 citthread_cond_destroy(&(this_thread->ThreadCond));
 907                 citthread_mutex_destroy(&(this_thread->SleepMutex));
 908                 citthread_cond_destroy(&(this_thread->SleepCond));
 909                 CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_init: %s\n", strerror(ret));
 910                 free(this_thread);
 911                 return NULL;
 912         }
 913
 914         /* Our per-thread stacks need to be bigger than the default size,
 915          * otherwise the MIME parser crashes on FreeBSD, and the IMAP service
 916          * crashes on 64-bit Linux.
 917          */
 918         if (flags & CTDLTHREAD_BIGSTACK)
 919         {
 920 #ifdef WITH_THREADLOG
 921                 CtdlLogPrintf(CTDL_INFO, "Thread system. Creating BIG STACK thread.\n");
 922 #endif
 923                 if ((ret = citthread_attr_setstacksize(&this_thread->attr, THREADSTACKSIZE))) {
 924                         citthread_mutex_unlock(&this_thread->ThreadMutex);
 925                         citthread_mutex_destroy(&(this_thread->ThreadMutex));
 926                         citthread_cond_destroy(&(this_thread->ThreadCond));
 927                         citthread_mutex_destroy(&(this_thread->SleepMutex));
 928                         citthread_cond_destroy(&(this_thread->SleepCond));
 929                         citthread_attr_destroy(&this_thread->attr);
 930                         CtdlLogPrintf(CTDL_EMERG, "Thread system, citthread_attr_setstacksize: %s\n",
 931                                 strerror(ret));
 932                         free(this_thread);
 933                         return NULL;
 934                 }
 935         }
 936
 937         /* Set this new thread with an avg_blocked of 2. We do this so that its creation affects the
 938          * load average for the system. If we don't do this then we create a mass of threads at the same time
 939          * because the creation didn't affect the load average.
 940          */
 941         this_thread->avg_blocked = 2;
 942
 943         return (this_thread);
 944 }
 945
 946
 947
 948
 949 /*
 950  * Internal function to create a thread.
 951  */
 952 CtdlThreadNode *ctdl_internal_create_thread(char *name, long flags, void *(*thread_func) (void *arg), void *args)
 953 {
 954         int ret = 0;
 955         CtdlThreadNode *this_thread;
 956
 957         if (num_threads >= 32767)
 958         {
 959                 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
 960                 return NULL;
 961         }
 962
 963         this_thread = malloc(sizeof(CtdlThreadNode));
 964         if (this_thread == NULL) {
 965                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
 966                 return NULL;
 967         }
 968
 969         /* Initialise the thread structure */
 970         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
 971         {
 972                 free(this_thread);
 973                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
 974                 return NULL;
 975         }
 976         /*
 977          * If we got here we are going to create the thread so we must initilise the structure
 978          * first because most implimentations of threading can't create it in a stopped state
 979          * and it might want to do things with its structure that aren't initialised otherwise.
 980          */
 981         if(name)
 982         {
 983                 this_thread->name = name;
 984         }
 985         else
 986         {
 987                 this_thread->name = "Un-named Thread";
 988         }
 989
 990         this_thread->flags = flags;
 991         this_thread->thread_func = thread_func;
 992         this_thread->user_args = args;
 993
 994         begin_critical_section(S_THREAD_LIST);
 995         /*
 996          * We pass this_thread into the thread as its args so that it can find out information
 997          * about itself and it has a bit of storage space for itself, not to mention that the REAL
 998          * thread function needs to finish off the setup of the structure
 999          */
1000         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1001         {
1002                 end_critical_section(S_THREAD_LIST);
1003                 CtdlLogPrintf(CTDL_ALERT, "Thread system, Can't create thread: %s\n",
1004                         strerror(ret));
1005                 citthread_mutex_unlock(&this_thread->ThreadMutex);
1006                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1007                 citthread_cond_destroy(&(this_thread->ThreadCond));
1008                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1009                 citthread_cond_destroy(&(this_thread->SleepCond));
1010                 citthread_attr_destroy(&this_thread->attr);
1011                 free(this_thread);
1012                 return NULL;
1013         }
1014         num_threads++;  // Increase the count of threads in the system.
1015         if(this_thread->flags & CTDLTHREAD_WORKER)
1016                 num_workers++;
1017
1018         this_thread->next = CtdlThreadList;
1019         CtdlThreadList = this_thread;
1020         if (this_thread->next)
1021                 this_thread->next->prev = this_thread;
1022         ctdl_thread_internal_calc_loadavg();
1023
1024         end_critical_section(S_THREAD_LIST);
1025
1026         return this_thread;
1027 }
1028
1029 /*
1030  * Wrapper function to create a thread
1031  * ensures the critical section and other protections are in place.
1032  * char *name = name to give to thread, if NULL, use generic name
1033  * int flags = flags to determine type of thread and standard facilities
1034  */
1035 CtdlThreadNode *CtdlThreadCreate(char *name, long flags, void *(*thread_func) (void *arg), void *args)
1036 {
1037         CtdlThreadNode *ret = NULL;
1038
1039         ret = ctdl_internal_create_thread(name, flags, thread_func, args);
1040         return ret;
1041 }
1042
1043
1044
1045 /*
1046  * Internal function to schedule a thread.
1047  * Must be called from within a S_THREAD_LIST critical section
1048  */
1049 CtdlThreadNode *CtdlThreadSchedule(char *name, long flags, void *(*thread_func) (void *arg), void *args, time_t when)
1050 {
1051         CtdlThreadNode *this_thread;
1052
1053         if (num_threads >= 32767)
1054         {
1055                 CtdlLogPrintf(CTDL_EMERG, "Thread system. Thread list full.\n");
1056                 return NULL;
1057         }
1058
1059         this_thread = malloc(sizeof(CtdlThreadNode));
1060         if (this_thread == NULL) {
1061                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't allocate CtdlThreadNode, exiting\n");
1062                 return NULL;
1063         }
1064         /* Initialise the thread structure */
1065         if (ctdl_internal_init_thread_struct(this_thread, flags) == NULL)
1066         {
1067                 free(this_thread);
1068                 CtdlLogPrintf(CTDL_EMERG, "Thread system, can't initialise CtdlThreadNode, exiting\n");
1069                 return NULL;
1070         }
1071
1072         /*
1073          * If we got here we are going to create the thread so we must initilise the structure
1074          * first because most implimentations of threading can't create it in a stopped state
1075          * and it might want to do things with its structure that aren't initialised otherwise.
1076          */
1077         if(name)
1078         {
1079                 this_thread->name = name;
1080         }
1081         else
1082         {
1083                 this_thread->name = "Un-named Thread";
1084         }
1085
1086         this_thread->flags = flags;
1087         this_thread->thread_func = thread_func;
1088         this_thread->user_args = args;
1089
1090         /*
1091          * When to start this thread
1092          */
1093         this_thread->when = when;
1094
1095         begin_critical_section(S_SCHEDULE_LIST);
1096         this_thread->next = CtdlThreadSchedList;
1097         CtdlThreadSchedList = this_thread;
1098         if (this_thread->next)
1099                 this_thread->next->prev = this_thread;
1100         end_critical_section(S_SCHEDULE_LIST);
1101
1102         return this_thread;
1103 }
1104
1105
1106
1107 CtdlThreadNode *ctdl_thread_internal_start_scheduled (CtdlThreadNode *this_thread)
1108 {
1109         int ret = 0;
1110
1111         begin_critical_section(S_THREAD_LIST);
1112         /*
1113          * We pass this_thread into the thread as its args so that it can find out information
1114          * about itself and it has a bit of storage space for itself, not to mention that the REAL
1115          * thread function needs to finish off the setup of the structure
1116          */
1117         if ((ret = citthread_create(&this_thread->tid, &this_thread->attr, ctdl_internal_thread_func, this_thread) != 0))
1118         {
1119                 end_critical_section(S_THREAD_LIST);
1120                 CtdlLogPrintf(CTDL_DEBUG, "Failed to start scheduled thread \"%s\": %s\n", this_thread->name, strerror(ret));
1121                 citthread_mutex_destroy(&(this_thread->ThreadMutex));
1122                 citthread_cond_destroy(&(this_thread->ThreadCond));
1123                 citthread_mutex_destroy(&(this_thread->SleepMutex));
1124                 citthread_cond_destroy(&(this_thread->SleepCond));
1125                 citthread_attr_destroy(&this_thread->attr);
1126                 free(this_thread);
1127                 return NULL;
1128         }
1129
1130
1131         num_threads++;  // Increase the count of threads in the system.
1132         if(this_thread->flags & CTDLTHREAD_WORKER)
1133                 num_workers++;
1134
1135         this_thread->next = CtdlThreadList;
1136         CtdlThreadList = this_thread;
1137         if (this_thread->next)
1138                 this_thread->next->prev = this_thread;
1139
1140         ctdl_thread_internal_calc_loadavg();
1141         end_critical_section(S_THREAD_LIST);
1142
1143
1144         return this_thread;
1145 }
1146
1147
1148
1149 void ctdl_thread_internal_check_scheduled(void)
1150 {
1151         CtdlThreadNode *this_thread, *that_thread;
1152         time_t now;
1153
1154         /* Don't start scheduled threads if the system wants single user mode */
1155         if (CtdlWantSingleUser())
1156                 return;
1157
1158         if (try_critical_section(S_SCHEDULE_LIST))
1159                 return; /* If this list is locked we wait till the next chance */
1160
1161         now = time(NULL);
1162
1163 #ifdef WITH_THREADLOG
1164         CtdlLogPrintf(CTDL_DEBUG, "Checking for scheduled threads to start.\n");
1165 #endif
1166
1167         this_thread = CtdlThreadSchedList;
1168         while(this_thread)
1169         {
1170                 that_thread = this_thread;
1171                 this_thread = this_thread->next;
1172
1173                 if (now > that_thread->when)
1174                 {
1175                         /* Unlink from schedule list */
1176                         if (that_thread->prev)
1177                                 that_thread->prev->next = that_thread->next;
1178                         else
1179                                 CtdlThreadSchedList = that_thread->next;
1180                         if (that_thread->next)
1181                                 that_thread->next->prev = that_thread->prev;
1182
1183                         that_thread->next = that_thread->prev = NULL;
1184 #ifdef WITH_THREADLOG
1185                         CtdlLogPrintf(CTDL_DEBUG, "About to start scheduled thread \"%s\".\n", that_thread->name);
1186 #endif
1187                         if (CT->state > CTDL_THREAD_STOP_REQ)
1188                         {       /* Only start it if the system is not stopping */
1189                                 if (ctdl_thread_internal_start_scheduled (that_thread))
1190                                 {
1191 #ifdef WITH_THREADLOG
1192                                         CtdlLogPrintf(CTDL_INFO, "Thread system, Started a scheduled thread \"%s\" (0x%08lx).\n",
1193                                                 that_thread->name, that_thread->tid);
1194 #endif
1195                                 }
1196                         }
1197                 }
1198 #ifdef WITH_THREADLOG
1199                 else
1200                 {
1201                         CtdlLogPrintf(CTDL_DEBUG, "Thread \"%s\" will start in %ld seconds.\n",
1202                                 that_thread->name, that_thread->when - time(NULL));
1203                 }
1204 #endif
1205         }
1206         end_critical_section(S_SCHEDULE_LIST);
1207 }
1208
1209
1210 /*
1211  * A warapper function for select so we can show a thread as blocked
1212  */
1213 int CtdlThreadSelect(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
1214 {
1215         int ret = 0;
1216
1217         ctdl_thread_internal_change_state(CT, CTDL_THREAD_BLOCKED);
1218         if (!CtdlThreadCheckStop())
1219                 ret = select(n, readfds, writefds, exceptfds, timeout);
1220         /**
1221          * If the select returned <= 0 then it failed due to an error
1222          * or timeout so this thread could stop if asked to do so.
1223          * Anything else means it needs to continue unless the system is shutting down
1224          */
1225         if (ret > 0)
1226         {
1227                 /**
1228                  * The select says this thread needs to do something useful.
1229                  * This thread was in an idle state so it may have been asked to stop
1230                  * but if the system isn't shutting down this thread is no longer
1231                  * idle and select has given it a task to do so it must not stop
1232                  * In this condition we need to force it into the running state.
1233                  * CtdlThreadGC will clear its ticker for us.
1234                  *
1235                  * FIXME: there is still a small hole here. It is possible for the sequence of locking
1236                  * to allow the state to get changed to STOP_REQ just after this code if the other thread
1237                  * has decided to change the state before this lock, it there fore has to wait till the lock
1238                  * completes but it will continue to change the state. We need something a bit better here.
1239                  */
1240                 citthread_mutex_lock(&CT->ThreadMutex); /* To prevent race condition of a sleeping thread */
1241                 if (GC_thread->state > CTDL_THREAD_STOP_REQ && CT->state <= CTDL_THREAD_STOP_REQ)
1242                 {
1243                         CtdlLogPrintf(CTDL_DEBUG, "Thread %s (0x%08lx) refused stop request.\n", CT->name, CT->tid);
1244                         CT->state = CTDL_THREAD_RUNNING;
1245                 }
1246                 citthread_mutex_unlock(&CT->ThreadMutex);
1247         }
1248
1249         ctdl_thread_internal_change_state(CT, CTDL_THREAD_RUNNING);
1250
1251         return ret;
1252 }
1253
1254
1255
1256 void *new_worker_thread(void *arg);
1257 extern void close_masters (void);
1258
1259
1260 void *simulation_worker (void*arg) {
1261         struct CitContext *this;
1262
1263         this = CreateNewContext();
1264         CtdlThreadSleep(1);
1265         this->kill_me = 1;
1266         this->state = CON_IDLE;
1267         dead_session_purge(1);
1268         begin_critical_section(S_SESSION_TABLE);
1269         stats_done++;
1270         end_critical_section(S_SESSION_TABLE);
1271         return NULL;
1272 }
1273
1274
1275 void *simulation_thread (void *arg)
1276 {
1277         long stats = statcount;
1278
1279         while(stats && !CtdlThreadCheckStop()) {
1280                 CtdlThreadCreate("Connection simulation worker", CTDLTHREAD_BIGSTACK, simulation_worker, NULL);
1281                 stats--;
1282         }
1283         CtdlThreadStopAll();
1284         return NULL;
1285 }
1286
1287 void go_threading(void)
1288 {
1289         int i;
1290         CtdlThreadNode *last_worker;
1291         struct timeval start, now, result;
1292         double last_duration;
1293
1294         /*
1295          * Initialise the thread system
1296          */
1297         ctdl_thread_internal_init();
1298
1299         /* Second call to module init functions now that threading is up */
1300         if (!statcount) {
1301                 initialise_modules(1);
1302                 CtdlThreadCreate("select_on_master", CTDLTHREAD_BIGSTACK, select_on_master, NULL);
1303         }
1304         else {
1305                 CtdlLogPrintf(CTDL_EMERG, "Running connection simulation stats\n");
1306                 gettimeofday(&start, NULL);
1307                 CtdlThreadCreate("Connection simulation master", CTDLTHREAD_BIGSTACK, simulation_thread, NULL);
1308         }
1309
1310
1311         /*
1312          * This thread is now used for garbage collection of other threads in the thread list
1313          */
1314         CtdlLogPrintf(CTDL_INFO, "Startup thread %d becoming garbage collector,\n", citthread_self());
1315
1316         /*
1317          * We do a lot of locking and unlocking of the thread list in here.
1318          * We do this so that we can repeatedly release time for other threads
1319          * that may be waiting on the thread list.
1320          * We are a low priority thread so we can afford to do this
1321          */
1322
1323         while (CtdlThreadGetCount())
1324         {
1325                 if (CT->signal)
1326                         exit_signal = CT->signal;
1327                 if (exit_signal)
1328                 {
1329                         CtdlThreadStopAll();
1330                 }
1331                 check_sched_shutdown();
1332                 if (CT->state > CTDL_THREAD_STOP_REQ)
1333                 {
1334                         begin_critical_section(S_THREAD_LIST);
1335                         ctdl_thread_internal_calc_loadavg();
1336                         end_critical_section(S_THREAD_LIST);
1337
1338                         ctdl_thread_internal_check_scheduled(); /* start scheduled threads */
1339                 }
1340
1341                 /* Reduce the size of the worker thread pool if necessary. */
1342                 if ((CtdlThreadGetWorkers() > config.c_min_workers + 1) && (CtdlThreadWorkerAvg < 20) && (CT->state > CTDL_THREAD_STOP_REQ))
1343                 {
1344                         /* Ask a worker thread to stop as we no longer need it */
1345                         begin_critical_section(S_THREAD_LIST);
1346                         last_worker = CtdlThreadList;
1347                         while (last_worker)
1348                         {
1349                                 citthread_mutex_lock(&last_worker->ThreadMutex);
1350                                 if (last_worker->flags & CTDLTHREAD_WORKER && (last_worker->state > CTDL_THREAD_STOPPING) && (last_worker->Context == NULL))
1351                                 {
1352                                         citthread_mutex_unlock(&last_worker->ThreadMutex);
1353                                         break;
1354                                 }
1355                                 citthread_mutex_unlock(&last_worker->ThreadMutex);
1356                                 last_worker = last_worker->next;
1357                         }
1358                         end_critical_section(S_THREAD_LIST);
1359                         if (last_worker)
1360                         {
1361 #ifdef WITH_THREADLOG
1362                                 CtdlLogPrintf(CTDL_DEBUG, "Thread system, stopping excess worker thread \"%s\" (0x%08lx).\n",
1363                                         last_worker->name,
1364                                         last_worker->tid
1365                                         );
1366 #endif
1367                                 CtdlThreadStop(last_worker);
1368                         }
1369                 }
1370
1371                 /*
1372                  * If all our workers are working hard, start some more to help out
1373                  * with things
1374                  */
1375                 /* FIXME: come up with a better way to dynamically alter the number of threads
1376                  * based on the system load
1377                  */
1378                 if (!statcount) {
1379                 if ((((CtdlThreadGetWorkers() < config.c_max_workers) && (CtdlThreadGetWorkerAvg() > 60)) || CtdlThreadGetWorkers() < config.c_min_workers) && (CT->state > CTDL_THREAD_STOP_REQ))
1380                 {
1381                         /* Only start new threads if we are not going to overload the machine */
1382                         /* Temporarily set to 10 should be enough to make sure we don't stranglew the server
1383                          * at least until we make this a config option */
1384                         if (CtdlThreadGetLoadAvg() < ((double)10.00)) {
1385                                 for (i=0; i<5 ; i++) {
1386                                         CtdlThreadCreate("Worker Thread",
1387                                                 CTDLTHREAD_BIGSTACK + CTDLTHREAD_WORKER,
1388                                                 worker_thread,
1389                                                 NULL
1390                                                 );
1391                                 }
1392                         }
1393                         else
1394                                 CtdlLogPrintf (CTDL_WARNING, "Server strangled due to machine load average too high.\n");
1395                 }
1396                 }
1397
1398                 CtdlThreadGC();
1399
1400                 if (CtdlThreadGetCount() <= 1) // Shutting down clean up the garbage collector
1401                 {
1402                         CtdlThreadGC();
1403                 }
1404
1405 #ifdef THREADS_USESIGNALS
1406                 if (CtdlThreadGetCount() && CT->state > CTDL_THREAD_STOP_REQ)
1407 #else
1408                 if (CtdlThreadGetCount())
1409 #endif
1410                         CtdlThreadSleep(1);
1411         }
1412         /*
1413          * If the above loop exits we must be shutting down since we obviously have no threads
1414          */
1415         ctdl_thread_internal_cleanup();
1416
1417         if (statcount) {
1418                 gettimeofday(&now, NULL);
1419                 timersub(&now, &start, &result);
1420                 last_duration = (double)result.tv_sec + ((double)result.tv_usec / (double) 1000000);
1421                 CtdlLogPrintf(CTDL_EMERG, "Simulated %ld connections in %f seconds\n", stats_done, last_duration);
1422         }
1423 }
1424
1425
1426
1427