github.com/sbinet/go@v0.0.0-20160827155028-54d7de7dd62b/src/runtime/cgo/gcc_libinit.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  // +build darwin dragonfly freebsd linux netbsd solaris
     7  
     8  #include <pthread.h>
     9  #include <stdio.h>
    10  #include <stdlib.h>
    11  #include <string.h> // strerror
    12  #include "libcgo.h"
    13  
    14  static pthread_cond_t runtime_init_cond = PTHREAD_COND_INITIALIZER;
    15  static pthread_mutex_t runtime_init_mu = PTHREAD_MUTEX_INITIALIZER;
    16  static int runtime_init_done;
    17  
    18  // The context function, used when tracing back C calls into Go.
    19  static void (*cgo_context_function)(struct context_arg*);
    20  
    21  void
    22  x_cgo_sys_thread_create(void* (*func)(void*), void* arg) {
    23  	pthread_t p;
    24  	int err = pthread_create(&p, NULL, func, arg);
    25  	if (err != 0) {
    26  		fprintf(stderr, "pthread_create failed: %s", strerror(err));
    27  		abort();
    28  	}
    29  }
    30  
    31  uintptr_t
    32  _cgo_wait_runtime_init_done() {
    33  	void (*pfn)(struct context_arg*);
    34  
    35  	pthread_mutex_lock(&runtime_init_mu);
    36  	while (runtime_init_done == 0) {
    37  		pthread_cond_wait(&runtime_init_cond, &runtime_init_mu);
    38  	}
    39  
    40  	// TODO(iant): For the case of a new C thread calling into Go, such
    41  	// as when using -buildmode=c-archive, we know that Go runtime
    42  	// initialization is complete but we do not know that all Go init
    43  	// functions have been run. We should not fetch cgo_context_function
    44  	// until they have been, because that is where a call to
    45  	// SetCgoTraceback is likely to occur. We are going to wait for Go
    46  	// initialization to be complete anyhow, later, by waiting for
    47  	// main_init_done to be closed in cgocallbackg1. We should wait here
    48  	// instead. See also issue #15943.
    49  	pfn = cgo_context_function;
    50  
    51  	pthread_mutex_unlock(&runtime_init_mu);
    52  	if (pfn != nil) {
    53  		struct context_arg arg;
    54  
    55  		arg.Context = 0;
    56  		(*pfn)(&arg);
    57  		return arg.Context;
    58  	}
    59  	return 0;
    60  }
    61  
    62  void
    63  x_cgo_notify_runtime_init_done(void* dummy) {
    64  	pthread_mutex_lock(&runtime_init_mu);
    65  	runtime_init_done = 1;
    66  	pthread_cond_broadcast(&runtime_init_cond);
    67  	pthread_mutex_unlock(&runtime_init_mu);
    68  }
    69  
    70  // Sets the context function to call to record the traceback context
    71  // when calling a Go function from C code. Called from runtime.SetCgoTraceback.
    72  void x_cgo_set_context_function(void (*context)(struct context_arg*)) {
    73  	pthread_mutex_lock(&runtime_init_mu);
    74  	cgo_context_function = context;
    75  	pthread_mutex_unlock(&runtime_init_mu);
    76  }
    77  
    78  // Gets the context function.
    79  void (*(_cgo_get_context_function(void)))(struct context_arg*) {
    80  	void (*ret)(struct context_arg*);
    81  
    82  	pthread_mutex_lock(&runtime_init_mu);
    83  	ret = cgo_context_function;
    84  	pthread_mutex_unlock(&runtime_init_mu);
    85  	return ret;
    86  }