2 * Empire - A multi-player, client/server Internet based war game.
3 * Copyright (C) 1986-2007, Dave Pare, Jeff Bailey, Thomas Ruschak,
4 * Ken Stevens, Steve McClure
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 2 of the License, or
9 * (at your option) any later version.
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.
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
22 * See files README, COPYING and CREDITS in the root of the source
23 * tree for related information and legal notices. It is expected
24 * that future projects/authors will amend these files as needed.
28 * empthread.h: Definitions for Empire threading
30 * Known contributors to this file:
34 * Markus Armbruster, 2005-2007
38 * This header defines Empire's abstract thread interface. There are
39 * several concrete implementations.
41 * Empire threads are non-preemptive, i.e. they run until they
42 * voluntarily yield the processor. The thread scheduler then picks
43 * one of the runnable threads with the highest priority. Priorities
44 * are static. Empire code relies on these properties heavily. The
45 * most common form of yielding the processor is sleeping for some
54 /* thread priorities */
69 /* Abstract data types */
71 /* empth_t * represents a thread. */
72 typedef struct lwpProc empth_t;
74 /* empth_sem_t * represents a semaphore */
75 typedef struct lwpSem empth_sem_t;
77 /* empth_rwlock_t * represents a read-write lock */
78 typedef struct lwp_rwlock empth_rwlock_t;
80 /* Flags for empth_select(): whether to sleep on input or output */
81 #define EMPTH_FD_READ LWP_FD_READ
82 #define EMPTH_FD_WRITE LWP_FD_WRITE
84 /* Flags for empth_init() and empth_create() */
85 /* Request debug prints */
86 #define EMPTH_PRINT LWP_PRINT
87 /* Request stack checking */
88 #define EMPTH_STACKCHECK LWP_STACKCHECK
90 #endif /* EMPTH_LWP */
93 #define EMPTH_FD_READ 0x1
94 #define EMPTH_FD_WRITE 0x2
96 #define EMPTH_PRINT 0x1
97 #define EMPTH_STACKCHECK 0x2
99 typedef struct empth_t empth_t;
100 typedef struct empth_sem_t empth_sem_t;
101 typedef struct empth_rwlock_t empth_rwlock_t;
103 #endif /* EMPTH_POSIX */
106 /* The Windows NT Threads */
107 #define EMPTH_FD_READ 0x1
108 #define EMPTH_FD_WRITE 0x2
110 #define EMPTH_PRINT 0x1
111 #define EMPTH_STACKCHECK 0x2
113 typedef struct loc_Thread empth_t;
114 typedef struct loc_Sem empth_sem_t;
115 typedef struct loc_RWLock empth_rwlock_t;
117 void empth_request_shutdown(void);
118 #endif /* EMPTH_W32 */
121 * Initialize thread package.
122 * CTX points to a thread context variable; see empth_create().
123 * FLAGS request optional features.
124 * Should return 0 on success, -1 on error, but currently always
127 int empth_init(void **ctx, int flags);
130 * Create a new thread.
131 * PRIO is the scheduling priority.
132 * ENTRY is the entry point. It will be called with argument UD.
133 * Thread stack is at least SIZE bytes.
134 * FLAGS should be the same as were passed to empth_init(), or zero.
135 * NAME is the thread's name, it is used for logging and debugging.
136 * UD is the value to pass to ENTRY. It is also assigned to the
137 * context variable defined with empth_init() whenever the thread gets
139 * Yield the processor.
140 * Return the thread, or NULL on error.
142 empth_t *empth_create(int prio, void (*entry)(void *),
143 int size, int flags, char *name, void *ud);
146 * Return the current thread.
148 empth_t *empth_self(void);
151 * Terminate the current thread.
152 * The current thread should not be the thread that executed main().
153 * If it is, implementations may terminate the process rather than the
157 void empth_exit(void);
160 * Yield the processor.
162 void empth_yield(void);
166 * THREAD will not be scheduled again. Instead, it will terminate as
167 * if it executed empth_exit(). It is unspecified when exactly that
169 * THREAD must not be the current thread.
171 void empth_terminate(empth_t *thread);
174 * Put current thread to sleep until file descriptor FD is ready for I/O.
175 * If FLAGS & EMPTH_FD_READ, wake up if FD is ready for input.
176 * If FLAGS & EMPTH_FD_WRITE, wake up if FD is ready for output.
177 * At most one thread may sleep on the same file descriptor.
178 * Note: Currently, Empire sleeps only on network I/O, i.e. FD is a
179 * socket. Implementations should not rely on that.
181 void empth_select(int fd, int flags);
184 * Awaken THREAD if it is sleeping in empth_select().
185 * Note: This must not awaken threads sleeping in other functions.
186 * Does not yield the processor.
188 void empth_wakeup(empth_t *thread);
191 * Put current thread to sleep until the time is UNTIL.
192 * May sleep somehwat longer, but never shorter.
194 void empth_sleep(time_t until);
197 * Wait for signal, return the signal number.
199 int empth_wait_for_signal(void);
202 * Create a semaphore.
203 * NAME is its name, it is used for debugging.
204 * COUNT is the initial count value of the semaphore, it must not be
206 * Return the semaphore, or NULL on error.
208 empth_sem_t *empth_sem_create(char *name, int count);
212 * Increase SEM's count. If threads are sleeping on it, wake up
213 * exactly one of them. If that thread has a higher priority, yield
215 * This semaphore operation is often called `down' or `V' otherwhere.
217 void empth_sem_signal(empth_sem_t *sem);
221 * If SEM has a zero count, put current thread to sleep until
222 * empth_sem_signal() awakens it. SEM will have non-zero value then.
223 * Decrement SEM's count.
224 * This semaphore operation is often called `up' or `P' otherwhere.
226 void empth_sem_wait(empth_sem_t *sem);
229 * Create a read-write lock.
230 * NAME is its name, it is used for debugging.
231 * Return the reade-write lock, or NULL on error.
233 empth_rwlock_t *empth_rwlock_create(char *name);
238 void empth_rwlock_destroy(empth_rwlock_t *rwlock);
241 * Lock RWLOCK for writing.
242 * A read-write lock can be locked for writing only when it is
243 * unlocked. If this is not the case, put the current thread to sleep
246 void empth_rwlock_wrlock(empth_rwlock_t *rwlock);
249 * Lock RWLOCK for reading.
250 * A read-write lock can be locked for reading only when it is not
251 * locked for writing. If this is not the case, put the current
252 * thread to sleep until it is. Must not starve writers, and may
253 * sleep to avoid that.
255 void empth_rwlock_rdlock(empth_rwlock_t *rwlock);
258 * Unlock read-write lock RWLOCK.
259 * The current thread must hold RWLOCK.
260 * Wake up threads that can now lock it.
262 void empth_rwlock_unlock(empth_rwlock_t *rwlock);
266 * Stuff for implementations, not for clients.
269 void empth_init_signals(void);