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simplify and optimize FILE lock handling

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This commit is contained in:
Rich Felker
2011-03-24 23:16:52 -04:00
parent d8dc2faf10
commit a37452430f
5 changed files with 14 additions and 14 deletions
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13
src/stdio/__lockfile.c
View File

@ -3,17 +3,18 @@
void __lockfile(FILE *f)
{
int spins;
if (f->owner < 0) return;
if (f->owner && f->owner == __pthread_self()->tid) {
int spins=100000;
int tid;
if (f->lock < 0) return;
tid = __pthread_self()->tid;
if (f->lock == tid) {
while (f->lockcount == INT_MAX);
f->lockcount++;
return;
}
spins = 100000;
while (a_swap(&f->lock, 1))
while (f->lock || a_cas(&f->lock, 0, tid))
if (spins) spins--, a_spin();
else syscall(SYS_sched_yield);
f->owner = __pthread_self()->tid;
f->lockcount = 1;
}

6
src/stdio/ftrylockfile.c
View File

@ -3,16 +3,16 @@
int ftrylockfile(FILE *f)
{
int tid = pthread_self()->tid;
if (!libc.lockfile) libc.lockfile = __lockfile;
if (f->owner && f->owner == pthread_self()->tid) {
if (f->lock == tid) {
if (f->lockcount == INT_MAX)
return -1;
f->lockcount++;
return 0;
}
if (a_swap(&f->lock, 1))
if (f->lock || a_cas(&f->lock, 0, tid))
return -1;
f->owner = pthread_self()->tid;
f->lockcount = 1;
return 0;
}

2
src/stdio/vsnprintf.c
View File

@ -17,7 +17,7 @@ int vsnprintf(char *s, size_t n, const char *fmt, va_list ap)
f.write = sn_write;
f.buf_size = 1;
f.buf = buf;
f.owner = -1;
f.lock = -1;
if (n > INT_MAX) {
errno = EOVERFLOW;
return -1;

2
src/stdio/vswprintf.c
View File

@ -32,7 +32,7 @@ int vswprintf(wchar_t *s, size_t n, const wchar_t *fmt, va_list ap)
f.write = sw_write;
f.buf_size = sizeof buf;
f.buf = buf;
f.owner = -1;
f.lock = -1;
f.cookie = &c;
if (!n) {
return -1;