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win: simplify uv_once implementation

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* win: simplify uv_once implementation

InitOnceExecuteOnce is available in Windows >= Vista.

Ref: https://learn.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-initonceexecuteonce
This commit is contained in:
Saúl Ibarra Corretgé 2024-03-25 11:57:52 +01:00 committed by GitHub
parent 6adeeacee7
commit abc9767034
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GPG Key ID: B5690EEEBB952194
2 changed files with 13 additions and 35 deletions
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4
include/uv/win.h
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@ -290,8 +290,8 @@ typedef struct {
#define UV_ONCE_INIT { 0, NULL } #define UV_ONCE_INIT { 0, NULL }
typedef struct uv_once_s { typedef struct uv_once_s {
unsigned char ran; unsigned char unused;
HANDLE event; INIT_ONCE init_once;
} uv_once_t; } uv_once_t;
/* Platform-specific definitions for uv_spawn support. */ /* Platform-specific definitions for uv_spawn support. */

50
src/win/thread.c
View File

@ -32,45 +32,23 @@
#include "uv.h" #include "uv.h"
#include "internal.h" #include "internal.h"
static void uv__once_inner(uv_once_t* guard, void (*callback)(void)) { typedef void (*uv__once_cb)(void);
DWORD result;
HANDLE existing_event, created_event;
created_event = CreateEvent(NULL, 1, 0, NULL); typedef struct {
if (created_event == 0) { uv__once_cb callback;
/* Could fail in a low-memory situation? */ } uv__once_data_t;
uv_fatal_error(GetLastError(), "CreateEvent");
static BOOL WINAPI uv__once_inner(INIT_ONCE *once, void* param, void** context) {
uv__once_data_t* data = param;
data->callback();
return TRUE;
} }
existing_event = InterlockedCompareExchangePointer(&guard->event, void uv_once(uv_once_t* guard, uv__once_cb callback) {
created_event, uv__once_data_t data = { .callback = callback };
NULL); InitOnceExecuteOnce(&guard->init_once, uv__once_inner, (void*) &data, 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);
} }