2 * Thread handling stuff for Citadel server
4 * Copyright (c) 1987-2015 by the citadel.org team
6 * This program is open source software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License, version 3.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
18 #include <libcitadel.h>
19 #include "modules_init.h"
20 #include "serv_extensions.h"
21 #include "ctdl_module.h"
27 int num_workers = 0; /* Current number of worker threads */
28 int active_workers = 0; /* Number of ACTIVE worker threads */
29 pthread_key_t ThreadKey;
30 pthread_mutex_t Critters[MAX_SEMAPHORES]; /* Things needing locking */
31 struct thread_tsd masterTSD;
32 int server_shutting_down = 0; /* set to nonzero during shutdown */
34 pthread_mutex_t ThreadCountMutex;;
37 void InitializeSemaphores(void)
41 /* Set up a bunch of semaphores to be used for critical sections */
42 for (i=0; i<MAX_SEMAPHORES; ++i) {
43 pthread_mutex_init(&Critters[i], NULL);
51 * Obtain a semaphore lock to begin a critical section.
52 * but only if no one else has one
54 int try_critical_section(int which_one)
56 /* For all types of critical sections except those listed here,
57 * ensure nobody ever tries to do a critical section within a
58 * transaction; this could lead to deadlock.
60 if ( (which_one != S_FLOORCACHE)
61 && (which_one != S_RPLIST)
65 return (pthread_mutex_trylock(&Critters[which_one]));
70 * Obtain a semaphore lock to begin a critical section.
72 void begin_critical_section(int which_one)
74 /* For all types of critical sections except those listed here,
75 * ensure nobody ever tries to do a critical section within a
76 * transaction; this could lead to deadlock.
78 if ( (which_one != S_FLOORCACHE)
79 && (which_one != S_RPLIST)
83 pthread_mutex_lock(&Critters[which_one]);
87 * Release a semaphore lock to end a critical section.
89 void end_critical_section(int which_one)
91 pthread_mutex_unlock(&Critters[which_one]);
98 * Return a pointer to our thread-specific (not session-specific) data.
100 struct thread_tsd *MyThread(void) {
101 register struct thread_tsd *c;
102 return ((c = (struct thread_tsd *) pthread_getspecific(ThreadKey), c == NULL) ? &masterTSD : c);
108 * Called by CtdlThreadCreate()
109 * We have to pass through here before starting our thread in order to create a set of data
110 * that is thread-specific rather than session-specific.
112 void *CTC_backend(void *supplied_start_routine)
114 struct thread_tsd *mytsd;
115 void *(*start_routine)(void*) = supplied_start_routine;
117 mytsd = (struct thread_tsd *) malloc(sizeof(struct thread_tsd));
118 memset(mytsd, 0, sizeof(struct thread_tsd));
119 pthread_setspecific(ThreadKey, (const void *) mytsd);
129 * Function to create a thread.
131 void CtdlThreadCreate(void *(*start_routine)(void*))
138 ret = pthread_attr_init(&attr);
139 ret = pthread_attr_setstacksize(&attr, THREADSTACKSIZE);
140 ret = pthread_create(&thread, &attr, CTC_backend, (void *)start_routine);
141 if (ret != 0) syslog(LOG_ERR, "pthread_create() : %m");
145 void InitializeMasterTSD(void) {
146 memset(&masterTSD, 0, sizeof(struct thread_tsd));
149 extern void ShutDownEventQueues(void);
151 int EventQShuttingDown = 0;
154 * Initialize the thread system
156 void go_threading(void)
158 if (pthread_key_create(&ThreadKey, NULL) != 0) {
159 syslog(LOG_ERR, "pthread_key_create() : %m");
163 pthread_mutex_init(&ThreadCountMutex, NULL);
165 /* Second call to module init functions now that threading is up */
166 initialise_modules(1);
168 /* Begin with one worker thread. We will expand the pool if necessary */
169 CtdlThreadCreate(worker_thread);
171 /* The supervisor thread monitors worker threads and spawns more of them if it finds that
172 * they are all in use.
174 while (!server_shutting_down) {
175 if ((active_workers == num_workers) && (num_workers < CtdlGetConfigInt("c_max_workers"))) {
176 CtdlThreadCreate(worker_thread);
181 /* When we get to this point we are getting ready to shut down our Citadel server */
182 terminate_all_sessions(); /* close all client sockets */
183 CtdlShutdownServiceHooks(); /* close all listener sockets to prevent new connections */
184 PerformSessionHooks(EVT_SHUTDOWN); /* run any registered shutdown hooks */
187 while ( (num_workers > 0) && (countdown-- > 0)) {
188 syslog(LOG_DEBUG, "Waiting %d seconds for %d worker threads to exit",
189 countdown, num_workers