refactor flockfile not to duplicate lock mechanism logic

This commit is contained in:
Rich Felker 2018-04-18 00:16:12 -04:00
parent c21f750727
commit c1014a812c
2 changed files with 14 additions and 12 deletions

View File

@ -1,14 +1,11 @@
#include "stdio_impl.h" #include "stdio_impl.h"
#include "pthread_impl.h" #include "pthread_impl.h"
#define MAYBE_WAITERS 0x40000000 void __register_locked_file(FILE *, pthread_t);
void flockfile(FILE *f) void flockfile(FILE *f)
{ {
while (ftrylockfile(f)) { if (!ftrylockfile(f)) return;
int owner = f->lock; __lockfile(f);
if (!owner) continue; __register_locked_file(f, __pthread_self());
a_cas(&f->lock, owner, owner|MAYBE_WAITERS);
__futexwait(&f->lock, owner|MAYBE_WAITERS, 1);
}
} }

View File

@ -20,6 +20,15 @@ void __unlist_locked_file(FILE *f)
} }
} }
void __register_locked_file(FILE *f, pthread_t self)
{
f->lockcount = 1;
f->prev_locked = 0;
f->next_locked = self->stdio_locks;
if (f->next_locked) f->next_locked->prev_locked = f;
self->stdio_locks = f;
}
int ftrylockfile(FILE *f) int ftrylockfile(FILE *f)
{ {
pthread_t self = __pthread_self(); pthread_t self = __pthread_self();
@ -34,10 +43,6 @@ int ftrylockfile(FILE *f)
if (owner < 0) f->lock = owner = 0; if (owner < 0) f->lock = owner = 0;
if (owner || a_cas(&f->lock, 0, tid)) if (owner || a_cas(&f->lock, 0, tid))
return -1; return -1;
f->lockcount = 1; __register_locked_file(f, self);
f->prev_locked = 0;
f->next_locked = self->stdio_locks;
if (f->next_locked) f->next_locked->prev_locked = f;
self->stdio_locks = f;
return 0; return 0;
} }