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;
24 char locks[MAX_SEMAPHORES+1];
26 void InitializeSemaphores(void) {
29 // Set up a bunch of semaphores to be used for critical sections
30 for (i=0; i<MAX_SEMAPHORES; ++i) {
31 pthread_mutex_init(&Critters[i], NULL);
34 locks[MAX_SEMAPHORES] = 0;
38 // Obtain a semaphore lock to begin a critical section, but only if no one else has one
39 int try_critical_section(int which_one) {
40 // For all types of critical sections except those listed here,
41 // ensure nobody ever tries to do a critical section within a
42 // transaction; this could lead to deadlock.
43 if ( (which_one != S_FLOORCACHE)
44 && (which_one != S_NETCONFIGS)
48 return (pthread_mutex_trylock(&Critters[which_one]));
52 // Obtain a semaphore lock to begin a critical section.
53 void begin_critical_section(int which_one) {
54 // For all types of critical sections except those listed here,
55 // ensure nobody ever tries to do a critical section within a
56 // transaction; this could lead to deadlock.
57 if ( (which_one != S_FLOORCACHE)
58 && (which_one != S_NETCONFIGS)
63 //syslog(LOG_ERR, "\033[3%dm lock(%14p, %2d, %s)\033[0m", (which_one%6)+1, pthread_self(), which_one, locks);
64 pthread_mutex_lock(&Critters[which_one]);
65 //if (locks[which_one] != 'X') {
66 //syslog(LOG_ERR, "\033[31mThread %p had to wait to get a lock on %d\033[0m", pthread_self(), which_one);
68 locks[which_one] = 'X';
72 // Release a semaphore lock to end a critical section.
73 void end_critical_section(int which_one) {
74 locks[which_one] = '_';
75 //syslog(LOG_ERR, "\033[3%dmunlock(%14p, %2d, %s)\033[0m", (which_one%6)+1, pthread_self(), which_one, locks);
76 pthread_mutex_unlock(&Critters[which_one]);
80 // Function to create a thread.
81 void CtdlThreadCreate(void *(*start_routine)(void*)) {
86 ret = pthread_attr_init(&attr);
87 ret = pthread_attr_setstacksize(&attr, THREADSTACKSIZE);
88 ret = pthread_create(&thread, &attr, start_routine, NULL);
89 if (ret != 0) syslog(LOG_ERR, "pthread_create() : %m");
93 // Initialize the thread system
94 void go_threading(void) {
95 pthread_mutex_init(&ThreadCountMutex, NULL);
97 // Second call to module init functions now that threading is up
98 initialize_modules(1);
100 // Begin with one worker thread. We will expand the pool if necessary
101 CtdlThreadCreate(worker_thread);
103 // The supervisor thread monitors worker threads and spawns more of them if it finds that they are all in use.
104 while (!server_shutting_down) {
105 if ((active_workers == num_workers) && (num_workers < CtdlGetConfigInt("c_max_workers"))) {
106 CtdlThreadCreate(worker_thread);
111 // When we get to this point we are getting ready to shut down our Citadel server
112 terminate_all_sessions(); // close all client sockets
113 CtdlShutdownServiceHooks(); // close all listener sockets to prevent new connections
114 PerformSessionHooks(EVT_SHUTDOWN); // run any registered shutdown hooks
116 // We used to wait for all threads to exit. Fuck that. The only thing important is that the databases are
117 // cleanly unmounted. After that, exit the whole program.