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