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/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <assert.h>
#include "uv.h"
#include "../uv-common.h"
#include "internal.h"
#ifdef _MSC_VER /* msvc */
# define NOINLINE __declspec (noinline)
#else /* gcc */
# define NOINLINE __attribute__ ((noinline))
#endif
static NOINLINE void uv__once_inner(uv_once_t* guard,
void (*callback)(void)) {
DWORD result;
HANDLE existing_event, created_event;
HANDLE* event_ptr;
/* Fetch and align event_ptr */
event_ptr = (HANDLE*) (((uintptr_t) &guard->event + (sizeof(HANDLE) - 1)) &
~(sizeof(HANDLE) - 1));
created_event = CreateEvent(NULL, 1, 0, NULL);
if (created_event == 0) {
/* Could fail in a low-memory situation? */
uv_fatal_error(GetLastError(), "CreateEvent");
}
existing_event = InterlockedCompareExchangePointer(event_ptr,
created_event,
NULL);
if (existing_event == NULL) {
/* We won the race */
callback();
result = SetEvent(created_event);
assert(result);
guard->ran = 1;
} else {
/* We lost the race. Destroy the event we created and wait for the */
/* existing one to become signaled. */
CloseHandle(created_event);
result = WaitForSingleObject(existing_event, INFINITE);
assert(result == WAIT_OBJECT_0);
}
}
void uv_once(uv_once_t* guard, void (*callback)(void)) {
/* Fast case - avoid WaitForSingleObject. */
if (guard->ran) {
return;
}
uv__once_inner(guard, callback);
}
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