2 * Empire - A multi-player, client/server Internet based war game.
3 * Copyright (C) 1994-2008, Dave Pare, Jeff Bailey, Thomas Ruschak,
4 * Ken Stevens, Steve McClure
5 * Copyright (C) 1991-3 Stephen Crane
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 * See files README, COPYING and CREDITS in the root of the source
24 * tree for related information and legal notices. It is expected
25 * that future projects/authors will amend these files as needed.
29 * lwp.c: lightweight process creation, destruction and manipulation
31 * Known contributors to this file:
32 * Markus Armbruster, 2004-2007
40 #include "prototypes.h"
42 struct lwpQueue LwpSchedQ[LWP_MAX_PRIO], LwpDeadQ;
44 struct lwpProc *LwpCurrent = NULL;
46 int LwpMaxpri = 0; /* maximum priority so far */
47 int LwpStackGrowsDown;
49 static void lwpDestroy(struct lwpProc *proc);
50 static void lwpStackCheckInit(struct lwpProc *newp);
51 static void lwpStackCheck(struct lwpProc *newp);
52 static void lwpStackCheckUsed(struct lwpProc *newp);
54 /* check stack direction */
64 * lwpReschedule -- schedule another process. we also check for dead
65 * processes here and free them.
70 static struct lwpProc *nextp;
73 if (LwpCurrent && (LwpCurrent->flags & LWP_STACKCHECK)) {
74 lwpStackCheck(LwpCurrent);
80 /* destroy dead threads */
81 lwpStatus(LwpCurrent, "Cleaning dead queue");
82 while (NULL != (nextp = lwpGetFirst(&LwpDeadQ))) {
83 if (CANT_HAPPEN(nextp == LwpCurrent))
86 lwpStatus(LwpCurrent, "Destroying done");
89 for (i = LwpMaxpri + 1; i--;) {
90 while (NULL != (nextp = lwpGetFirst(&LwpSchedQ[i]))) {
93 /* clean up after dead bodies */
94 lwpStatus(nextp, "got a dead body");
95 if (nextp == LwpCurrent) {
96 lwpStatus(nextp, "we are in it -- will bury later");
97 lwpAddTail(&LwpDeadQ, nextp);
106 if (CANT_HAPPEN(LwpCurrent == 0 && nextp == 0))
108 if (LwpCurrent != nextp) {
109 struct lwpProc *oldp = LwpCurrent;
111 lwpStatus(oldp, "switch out");
113 *LwpContextPtr = nextp->ud;
114 lwpSwitchContext(oldp, nextp);
115 lwpStatus(nextp, "switch in %d", nextp->pri);
120 * lwpEntryPoint -- process entry point.
125 lwpStatus(LwpCurrent, "starting at entry point");
126 (*LwpCurrent->entry)(LwpCurrent->ud);
131 * lwpCreate -- create a process.
134 lwpCreate(int priority, void (*entry)(void *), int stacksz,
135 int flags, char *name, int argc, char **argv, void *ud)
137 struct lwpProc *newp;
139 if (!(newp = malloc(sizeof(struct lwpProc))))
142 newp->name = strdup(name);
148 newp->runtime = (time_t)-1;
150 if (LWP_MAX_PRIO <= priority)
151 priority = LWP_MAX_PRIO - 1;
152 if (LwpMaxpri < (newp->pri = priority))
153 LwpMaxpri = priority;
154 if (lwpNewContext(newp, stacksz) < 0) {
159 lwpStatus(newp, "creating process structure %p (sbtm %p)",
161 if (flags & LWP_STACKCHECK)
162 lwpStackCheckInit(newp);
164 lwpReady(LwpCurrent);
170 lwpDestroy(struct lwpProc *proc)
172 if (proc->flags & LWP_STACKCHECK) {
173 lwpStackCheckUsed(proc);
176 lwpStatus(proc, "destroying sbtm: %p", proc->sbtm);
183 * lwpReady -- put process on ready queue. if null, assume current.
186 lwpReady(struct lwpProc *p)
190 lwpStatus(p, "added to run queue");
191 lwpAddTail(&LwpSchedQ[p->pri], p);
198 lwpGetUD(struct lwpProc *p)
209 lwpSetUD(struct lwpProc *p, char *ud)
217 * lwpYield -- yield the processor to another thread.
222 lwpStatus(LwpCurrent, "yielding control");
223 lwpReady(LwpCurrent);
228 * cause the current process to be scheduled for deletion.
233 lwpStatus(LwpCurrent, "marking self as dead");
234 LwpCurrent->dead = 1;
239 * mark another process as dead, so it will never be rescheduled.
240 * remove any lingering FD action
243 lwpTerminate(struct lwpProc *p)
245 lwpStatus(p, "terminating process");
251 * set the thread's priority, returning the old.
252 * if the new priority is lower than the old, we reschedule.
255 lwpSetPriority(int new)
257 int old = LwpCurrent->pri;
259 if (LWP_MAX_PRIO <= new)
260 new = LWP_MAX_PRIO - 1;
263 LwpCurrent->pri = new;
264 lwpStatus(LwpCurrent, "resetting priority (%d -> %d)", old, new);
271 * initialise the coroutine structures
274 lwpInitSystem(int pri, void **ctxptr, int flags, sigset_t *waitset)
277 int i, *stack, marker;
280 LwpContextPtr = ctxptr;
283 LwpStackGrowsDown = growsdown(&marker);
284 if (!(LwpCurrent = calloc(1, sizeof(struct lwpProc))))
286 if (!(stack = malloc(64)))
288 if (LWP_MAX_PRIO <= pri)
289 pri = LWP_MAX_PRIO - 1;
292 LwpCurrent->next = 0;
293 LwpCurrent->sbtm = stack; /* dummy stack for "main" */
294 LwpCurrent->pri = pri;
295 LwpCurrent->dead = 0;
296 LwpCurrent->flags = flags & ~LWP_STACKCHECK;
297 LwpCurrent->name = "Main";
298 for (i = LWP_MAX_PRIO, q = LwpSchedQ; i--; q++)
299 q->head = q->tail = 0;
300 LwpDeadQ.head = LwpDeadQ.tail = 0;
301 lwpInitSigWait(waitset);
302 /* must be lower in priority than us for this to work right */
303 sel = lwpCreate(0, lwpSelect, 16384, flags, "EventHandler", 0, 0, 0);
310 * Initialize the entire stack (including both redzones) with the stack
311 * check mark. Thus, we can get some indication of how much stack was
315 lwpStackCheckInit(struct lwpProc *newp)
318 int *lim = (int *)((char *)newp->sbtm + newp->size);
320 for (p = newp->sbtm; p < lim; p++)
326 * Check if the thread has overflowed/underflowed its stack.
327 * Should that happen, abort the process, as we cannot recover.
330 lwpStackCheck(struct lwpProc *newp)
332 int *btm = (int *)(newp->ustack - LWP_REDZONE);
333 int *top = (int *)(newp->ustack + newp->usize + LWP_REDZONE);
334 int n = LWP_REDZONE / sizeof(int);
335 int i, lo_clean, hi_clean, overflow, underflow;
337 for (i = 0; i < n && btm[i] == LWP_CHECKMARK; i++) ;
340 for (i = 1; i <= n && top[-i] == LWP_CHECKMARK; i++) ;
343 if (LwpStackGrowsDown) {
344 overflow = n - lo_clean;
345 underflow = n - hi_clean;
347 overflow = n - hi_clean;
348 underflow = n - lo_clean;
351 logerror("Thread %s stack overflow %d bytes",
352 newp->name, overflow * (int)sizeof(int));
354 logerror("Thread %s stack underflow %d bytes",
355 newp->name, underflow * (int)sizeof(int));
356 if (overflow || underflow)
362 * Figure out how much stack was used by this thread.
365 lwpStackCheckUsed(struct lwpProc *newp)
367 int *base = (int *)newp->ustack;
368 int *lim = (int *)(newp->ustack + newp->usize);
369 int total = (lim + 1 - base) * sizeof(int);
372 if (LwpStackGrowsDown) {
373 for (p = base; p < lim && *p == LWP_CHECKMARK; ++p) ;
374 used = (lim - p) * sizeof(int);
376 for (p = lim - 1; p >= base && *p == LWP_CHECKMARK; --p) ;
377 used = (p - base + 1) * sizeof(int);
379 lwpStatus(newp, "Thread stack %d used, %d left, %d total",
380 used, total - used, total);