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Use pthread_once() when available

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This commit is contained in:
Nicolas Williams
2015-11-30 11:03:56 -06:00
parent 9e359ac98f
commit 2cac8ca703
2 changed files with 83 additions and 1 deletions
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72
lib/base/heimbase.c
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@@ -357,6 +357,41 @@ _heim_type_get_tid(heim_type_t type)
return type->tid;
}
#if !defined(WIN32) && !defined(HAVE_DISPATCH_DISPATCH_H) && defined(ENABLE_PTHREAD_SUPPORT)
static pthread_once_t once_arg_key_once = PTHREAD_ONCE_INIT;
static pthread_key_t once_arg_key;
static void
once_arg_key_once_init(void)
{
errno = pthread_key_create(&once_arg_key, NULL);
if (errno != 0) {
fprintf(stderr,
"Error: pthread_key_create() failed, cannot continue: %s\n",
strerror(errno));
abort();
}
}
struct once_callback {
void (*fn)(void *);
void *data;
};
static void
once_callback_caller(void)
{
struct once_callback *once_callback = pthread_getspecific(once_arg_key);
if (once_callback == NULL) {
fprintf(stderr, "Error: pthread_once() calls callback on "
"different thread?! Cannot continue.\n");
abort();
}
once_callback->fn(once_callback->data);
}
#endif
/**
* Call func once and only once
*
@@ -370,6 +405,18 @@ heim_base_once_f(heim_base_once_t *once, void *ctx, void (*func)(void *))
{
#if defined(WIN32)
/*
* With a libroken wrapper for some CAS function and a libroken yield()
* wrapper we could make this the default implementation when we have
* neither Grand Central nor POSX threads.
*
* We could also adapt the double-checked lock pattern with CAS
* providing the necessary memory barriers in the absence of
* portable explicit memory barrier APIs.
*/
/*
* We use CAS operations in large part to provide implied memory
* barriers.
*
* State 0 means that func() has never executed.
* State 1 means that func() is executing.
* State 2 means that func() has completed execution.
@@ -390,6 +437,31 @@ heim_base_once_f(heim_base_once_t *once, void *ctx, void (*func)(void *))
}
#elif defined(HAVE_DISPATCH_DISPATCH_H)
dispatch_once_f(once, ctx, func);
#elif defined(ENABLE_PTHREAD_SUPPORT)
struct once_callback once_callback;
once_callback.fn = func;
once_callback.data = ctx;
errno = pthread_once(&once_arg_key_once, once_arg_key_once_init);
if (errno != 0) {
fprintf(stderr, "Error: pthread_once() failed, cannot continue: %s\n",
strerror(errno));
abort();
}
errno = pthread_setspecific(once_arg_key, &once_callback);
if (errno != 0) {
fprintf(stderr,
"Error: pthread_setspecific() failed, cannot continue: %s\n",
strerror(errno));
abort();
}
errno = pthread_once(once, once_callback_caller);
if (errno != 0) {
fprintf(stderr, "Error: pthread_once() failed, cannot continue: %s\n",
strerror(errno));
abort();
}
#else
static HEIMDAL_MUTEX mutex = HEIMDAL_MUTEX_INITIALIZER;
HEIMDAL_MUTEX_lock(&mutex);

12
lib/base/heimbase.h
View File

@@ -37,6 +37,9 @@
#define HEIM_BASE_H 1
#include <sys/types.h>
#if !defined(WIN32) && !defined(HAVE_DISPATCH_DISPATCH_H) && defined(ENABLE_PTHREAD_SUPPORT)
#include <pthread.h>
#endif
#include <krb5-types.h>
#include <stdarg.h>
#ifdef HAVE_STDBOOL_H
@@ -56,11 +59,18 @@ typedef void * heim_object_t;
typedef unsigned int heim_tid_t;
typedef heim_object_t heim_bool_t;
typedef heim_object_t heim_null_t;
# define HEIM_BASE_ONCE_INIT 0
#ifdef WIN32
typedef LONG heim_base_once_t;
#define HEIM_BASE_ONCE_INIT 0
#elif defined(HAVE_DISPATCH_DISPATCH_H)
typedef long heim_base_once_t; /* XXX arch dependant */
#define HEIM_BASE_ONCE_INIT 0
#elif defined(ENABLE_PTHREAD_SUPPORT)
typedef pthread_once_t heim_base_once_t;
#define HEIM_BASE_ONCE_INIT PTHREAD_ONCE_INIT
#else
typedef long heim_base_once_t; /* XXX arch dependant */
#define HEIM_BASE_ONCE_INIT 0
#endif
#if !defined(__has_extension)