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