1 // Thread handling stuff for the Citadel server
3 // Copyright (c) 1987-2023 by the citadel.org team
5 // This program is open source software. Use, duplication, or disclosure
6 // is subject to the terms of the GNU General Public License, version 3.
11 #include <libcitadel.h>
12 #include "modules_init.h"
13 #include "serv_extensions.h"
14 #include "ctdl_module.h"
19 int num_workers = 0; // Current number of worker threads
20 int active_workers = 0; // Number of ACTIVE worker threads
21 pthread_mutex_t Critters[MAX_SEMAPHORES]; // Things needing locking
22 int server_shutting_down = 0; // set to nonzero during shutdown
23 pthread_mutex_t ThreadCountMutex;
25 void InitializeSemaphores(void) {
28 // Set up a bunch of semaphores to be used for critical sections
29 for (i=0; i<MAX_SEMAPHORES; ++i) {
30 pthread_mutex_init(&Critters[i], NULL);
35 // Obtain a semaphore lock to begin a critical section, but only if no one else has one
36 int try_critical_section(int which_one) {
37 // For all types of critical sections except those listed here,
38 // ensure nobody ever tries to do a critical section within a
39 // transaction; this could lead to deadlock.
40 if ( (which_one != S_FLOORCACHE)
41 && (which_one != S_NETCONFIGS)
45 return (pthread_mutex_trylock(&Critters[which_one]));
49 // Obtain a semaphore lock to begin a critical section.
50 void begin_critical_section(int which_one) {
51 // For all types of critical sections except those listed here,
52 // ensure nobody ever tries to do a critical section within a
53 // transaction; this could lead to deadlock.
54 if ( (which_one != S_FLOORCACHE)
55 && (which_one != S_NETCONFIGS)
60 pthread_mutex_lock(&Critters[which_one]);
64 // Release a semaphore lock to end a critical section.
65 void end_critical_section(int which_one) {
66 pthread_mutex_unlock(&Critters[which_one]);
70 // Function to create a thread.
71 void CtdlThreadCreate(void *(*start_routine)(void*)) {
76 ret = pthread_attr_init(&attr);
77 ret = pthread_attr_setstacksize(&attr, THREADSTACKSIZE);
78 ret = pthread_create(&thread, &attr, start_routine, NULL);
79 if (ret != 0) syslog(LOG_ERR, "pthread_create() : %m");
83 // Initialize the thread system
84 void go_threading(void) {
85 pthread_mutex_init(&ThreadCountMutex, NULL);
87 // Second call to module init functions now that threading is up
88 initialize_modules(1);
90 // Begin with one worker thread. We will expand the pool if necessary
91 CtdlThreadCreate(worker_thread);
93 // The supervisor thread monitors worker threads and spawns more of them if it finds that they are all in use.
94 while (!server_shutting_down) {
95 if ((active_workers == num_workers) && (num_workers < CtdlGetConfigInt("c_max_workers"))) {
96 CtdlThreadCreate(worker_thread);
101 // When we get to this point we are getting ready to shut down our Citadel server
102 terminate_all_sessions(); // close all client sockets
103 CtdlShutdownServiceHooks(); // close all listener sockets to prevent new connections
104 PerformSessionHooks(EVT_SHUTDOWN); // run any registered shutdown hooks
106 // We used to wait for all threads to exit. Fuck that. The only thing important is that the databases are
107 // cleanly unmounted. After that, exit the whole program.