2 * Empire - A multi-player, client/server Internet based war game.
3 * Copyright (C) 1994-2007, 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, 2004-2006
41 #include "prototypes.h"
43 struct lwpQueue LwpSchedQ[LWP_MAX_PRIO], LwpDeadQ;
45 struct lwpProc *LwpCurrent = NULL;
47 int LwpMaxpri = 0; /* maximum priority so far */
48 int LwpStackGrowsDown;
50 static void lwpDestroy(struct lwpProc *proc);
51 static void lwpStackCheckInit(struct lwpProc *newp);
52 static void lwpStackCheck(struct lwpProc *newp);
53 static void lwpStackCheckUsed(struct lwpProc *newp);
55 /* check stack direction */
65 * lwpReschedule -- schedule another process. we also check for dead
66 * processes here and free them.
71 static struct lwpProc *nextp;
74 if (LwpCurrent && (LwpCurrent->flags & LWP_STACKCHECK)) {
75 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, int flags, char *name, char *desc, int argc, char **argv, void *ud)
136 struct lwpProc *newp;
138 if (!(newp = malloc(sizeof(struct lwpProc))))
141 newp->name = strdup(name);
142 newp->desc = strdup(desc);
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) {
160 lwpStatus(newp, "creating process structure %p (sbtm %p)",
162 if (flags & LWP_STACKCHECK)
163 lwpStackCheckInit(newp);
165 lwpReady(LwpCurrent);
171 lwpDestroy(struct lwpProc *proc)
173 if (proc->flags & LWP_STACKCHECK) {
174 lwpStackCheckUsed(proc);
177 lwpStatus(proc, "destroying sbtm: %p", proc->sbtm);
185 * lwpReady -- put process on ready queue. if null, assume current.
188 lwpReady(struct lwpProc *p)
192 lwpStatus(p, "added to run queue");
193 lwpAddTail(&LwpSchedQ[p->pri], p);
200 lwpGetUD(struct lwpProc *p)
211 lwpSetUD(struct lwpProc *p, char *ud)
222 lwpSetDesc(struct lwpProc *p, char *name, char *desc)
228 p->name = strdup(name);
229 p->desc = strdup(desc);
233 * lwpYield -- yield the processor to another thread.
238 lwpStatus(LwpCurrent, "yielding control");
239 lwpReady(LwpCurrent);
244 * cause the current process to be scheduled for deletion.
249 lwpStatus(LwpCurrent, "marking self as dead");
250 LwpCurrent->dead = 1;
255 * mark another process as dead, so it will never be rescheduled.
256 * remove any lingering FD action
259 lwpTerminate(struct lwpProc *p)
261 lwpStatus(p, "terminating process");
268 * set the thread's priority, returning the old.
269 * if the new priority is lower than the old, we reschedule.
272 lwpSetPriority(int new)
274 int old = LwpCurrent->pri;
276 if (LWP_MAX_PRIO <= new)
277 new = LWP_MAX_PRIO - 1;
280 LwpCurrent->pri = new;
281 lwpStatus(LwpCurrent, "resetting priority (%d -> %d)", old, new);
288 * initialise the coroutine structures
291 lwpInitSystem(int pri, void **ctxptr, int flags, sigset_t *waitset)
294 int i, *stack, marker;
297 LwpContextPtr = ctxptr;
300 LwpStackGrowsDown = growsdown(&marker);
301 if (!(LwpCurrent = calloc(1, sizeof(struct lwpProc))))
303 if (!(stack = malloc(64)))
305 if (LWP_MAX_PRIO <= pri)
306 pri = LWP_MAX_PRIO - 1;
309 LwpCurrent->next = 0;
310 LwpCurrent->sbtm = stack; /* dummy stack for "main" */
311 LwpCurrent->pri = pri;
312 LwpCurrent->dead = 0;
313 LwpCurrent->flags = flags & ~LWP_STACKCHECK;
314 LwpCurrent->name = "Main";
315 for (i = LWP_MAX_PRIO, q = LwpSchedQ; i--; q++)
316 q->head = q->tail = 0;
317 LwpDeadQ.head = LwpDeadQ.tail = 0;
318 lwpInitSigWait(waitset);
319 /* must be lower in priority than us for this to work right */
320 sel = lwpCreate(0, lwpSelect, 16384, flags, "EventHandler",
321 "Select (main loop) Event Handler", 0, 0, 0);
328 * Initialize the entire stack (including both redzones) with the stack
329 * check mark. Thus, we can get some indication of how much stack was
333 lwpStackCheckInit(struct lwpProc *newp)
336 int *lim = (int *)((char *)newp->sbtm + newp->size);
338 for (p = newp->sbtm; p < lim; p++)
344 * Check if the thread has overflowed/underflowed its stack.
345 * Should that happen, abort the process, as we cannot recover.
348 lwpStackCheck(struct lwpProc *newp)
350 int *btm = (int *)(newp->ustack - LWP_REDZONE);
351 int *top = (int *)(newp->ustack + newp->usize + LWP_REDZONE);
352 int n = LWP_REDZONE / sizeof(int);
353 int i, lo_clean, hi_clean, overflow, underflow;
355 for (i = 0; i < n && btm[i] == LWP_CHECKMARK; i++) ;
358 for (i = 1; i <= n && top[-i] == LWP_CHECKMARK; i++) ;
361 if (LwpStackGrowsDown) {
362 overflow = n - lo_clean;
363 underflow = n - hi_clean;
365 overflow = n - hi_clean;
366 underflow = n - lo_clean;
369 logerror("Thread %s stack overflow %d bytes",
370 newp->name, overflow * (int)sizeof(int));
372 logerror("Thread %s stack underflow %d bytes",
373 newp->name, underflow * (int)sizeof(int));
374 if (overflow || underflow)
380 * Figure out how much stack was used by this thread.
383 lwpStackCheckUsed(struct lwpProc *newp)
385 int *base = (int *)newp->ustack;
386 int *lim = (int *)(newp->ustack + newp->usize);
387 int total = (lim + 1 - base) * sizeof(int);
390 if (LwpStackGrowsDown) {
391 for (p = base; p < lim && *p == LWP_CHECKMARK; ++p) ;
392 used = (lim - p) * sizeof(int);
394 for (p = lim - 1; p >= base && *p == LWP_CHECKMARK; --p) ;
395 used = (p - base + 1) * sizeof(int);
397 lwpStatus(newp, "Thread stack %d used, %d left, %d total",
398 used, total - used, total);