119 lines
2.1 KiB
C
119 lines
2.1 KiB
C
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include <errno.h>
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#include "runtime.h"
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#include "go-assert.h"
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void
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runtime_initlock(Lock *l)
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{
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l->key = 0;
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if(sem_init(&l->sem, 0, 0) != 0)
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runtime_throw("sem_init failed");
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}
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static uint32
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runtime_xadd(uint32 volatile *val, int32 delta)
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{
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uint32 oval, nval;
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for(;;){
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oval = *val;
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nval = oval + delta;
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if(runtime_cas(val, oval, nval))
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return nval;
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}
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}
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// noinline so that runtime_lock doesn't have to split the stack.
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static void runtime_lock_full(Lock *l) __attribute__ ((noinline));
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static void
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runtime_lock_full(Lock *l)
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{
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for(;;){
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if(sem_wait(&l->sem) == 0)
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return;
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if(errno != EINTR)
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runtime_throw("sem_wait failed");
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}
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}
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void
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runtime_lock(Lock *l)
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{
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if(m != nil) {
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if(m->locks < 0)
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runtime_throw("lock count");
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m->locks++;
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}
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if(runtime_xadd(&l->key, 1) > 1) // someone else has it; wait
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runtime_lock_full(l);
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}
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static void runtime_unlock_full(Lock *l) __attribute__ ((noinline));
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static void
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runtime_unlock_full(Lock *l)
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{
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if(sem_post(&l->sem) != 0)
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runtime_throw("sem_post failed");
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}
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void
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runtime_unlock(Lock *l)
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{
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if(m != nil) {
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m->locks--;
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if(m->locks < 0)
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runtime_throw("lock count");
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}
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if(runtime_xadd(&l->key, -1) > 0) // someone else is waiting
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runtime_unlock_full(l);
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}
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void
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runtime_destroylock(Lock *l)
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{
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sem_destroy(&l->sem);
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}
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#ifndef HAVE_SYNC_BOOL_COMPARE_AND_SWAP_4
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// For targets which don't have the required sync support. Really
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// this should be provided by gcc itself. FIXME.
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static pthread_mutex_t sync_lock = PTHREAD_MUTEX_INITIALIZER;
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_Bool
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__sync_bool_compare_and_swap_4(uint32*, uint32, uint32)
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__attribute__((visibility("hidden")));
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_Bool
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__sync_bool_compare_and_swap_4(uint32* ptr, uint32 old, uint32 new)
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{
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int i;
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_Bool ret;
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i = pthread_mutex_lock(&sync_lock);
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__go_assert(i == 0);
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if(*ptr != old) {
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ret = 0;
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} else {
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*ptr = new;
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ret = 1;
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}
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i = pthread_mutex_unlock(&sync_lock);
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__go_assert(i == 0);
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return ret;
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}
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#endif
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