github.com/MangoDowner/go-gm@v0.0.0-20180818020936-8baa2bd4408c/src/runtime/cgo/gcc_libinit_windows.c (about)

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build cgo
     6  #define WIN64_LEAN_AND_MEAN
     7  #include <windows.h>
     8  #include <process.h>
     9  
    10  #include <stdio.h>
    11  #include <stdlib.h>
    12  
    13  #include "libcgo.h"
    14  
    15  static volatile LONG runtime_init_once_gate = 0;
    16  static volatile LONG runtime_init_once_done = 0;
    17  
    18  static CRITICAL_SECTION runtime_init_cs;
    19  
    20  static HANDLE runtime_init_wait;
    21  static int runtime_init_done;
    22  
    23  // Pre-initialize the runtime synchronization objects
    24  void
    25  _cgo_preinit_init() {
    26  	 runtime_init_wait = CreateEvent(NULL, TRUE, FALSE, NULL);
    27  	 if (runtime_init_wait == NULL) {
    28  		fprintf(stderr, "runtime: failed to create runtime initialization wait event.\n");
    29  		abort();
    30  	 }
    31  
    32  	 InitializeCriticalSection(&runtime_init_cs);
    33  }
    34  
    35  // Make sure that the preinit sequence has run.
    36  void
    37  _cgo_maybe_run_preinit() {
    38  	 if (!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
    39  			if (InterlockedIncrement(&runtime_init_once_gate) == 1) {
    40  				 _cgo_preinit_init();
    41  				 InterlockedIncrement(&runtime_init_once_done);
    42  			} else {
    43  				 // Decrement to avoid overflow.
    44  				 InterlockedDecrement(&runtime_init_once_gate);
    45  				 while(!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
    46  						Sleep(0);
    47  				 }
    48  			}
    49  	 }
    50  }
    51  
    52  void
    53  x_cgo_sys_thread_create(void (*func)(void*), void* arg) {
    54  	uintptr_t thandle;
    55  
    56  	thandle = _beginthread(func, 0, arg);
    57  	if(thandle == -1) {
    58  		fprintf(stderr, "runtime: failed to create new OS thread (%d)\n", errno);
    59  		abort();
    60  	}
    61  }
    62  
    63  int
    64  _cgo_is_runtime_initialized() {
    65  	 EnterCriticalSection(&runtime_init_cs);
    66  	 int status = runtime_init_done;
    67  	 LeaveCriticalSection(&runtime_init_cs);
    68  	 return status;
    69  }
    70  
    71  uintptr_t
    72  _cgo_wait_runtime_init_done() {
    73  	void (*pfn)(struct context_arg*);
    74  
    75  	 _cgo_maybe_run_preinit();
    76  	while (!_cgo_is_runtime_initialized()) {
    77  			WaitForSingleObject(runtime_init_wait, INFINITE);
    78  	}
    79  	pfn = _cgo_get_context_function();
    80  	if (pfn != nil) {
    81  		struct context_arg arg;
    82  
    83  		arg.Context = 0;
    84  		(*pfn)(&arg);
    85  		return arg.Context;
    86  	}
    87  	return 0;
    88  }
    89  
    90  void
    91  x_cgo_notify_runtime_init_done(void* dummy) {
    92  	 _cgo_maybe_run_preinit();
    93  
    94  	 EnterCriticalSection(&runtime_init_cs);
    95  	runtime_init_done = 1;
    96  	 LeaveCriticalSection(&runtime_init_cs);
    97  
    98  	 if (!SetEvent(runtime_init_wait)) {
    99  		fprintf(stderr, "runtime: failed to signal runtime initialization complete.\n");
   100  		abort();
   101  	}
   102  }
   103  
   104  // The context function, used when tracing back C calls into Go.
   105  static void (*cgo_context_function)(struct context_arg*);
   106  
   107  // Sets the context function to call to record the traceback context
   108  // when calling a Go function from C code. Called from runtime.SetCgoTraceback.
   109  void x_cgo_set_context_function(void (*context)(struct context_arg*)) {
   110  	EnterCriticalSection(&runtime_init_cs);
   111  	cgo_context_function = context;
   112  	LeaveCriticalSection(&runtime_init_cs);
   113  }
   114  
   115  // Gets the context function.
   116  void (*(_cgo_get_context_function(void)))(struct context_arg*) {
   117  	void (*ret)(struct context_arg*);
   118  
   119  	EnterCriticalSection(&runtime_init_cs);
   120  	ret = cgo_context_function;
   121  	LeaveCriticalSection(&runtime_init_cs);
   122  	return ret;
   123  }