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 aix darwin dragonfly freebsd linux netbsd openbsd solaris
7
8 #include <pthread.h>
9 #include <errno.h>
10 #include <stdio.h>
11 #include <stdlib.h>
12 #include <string.h> // strerror
13 #include <time.h>
14 #include "libcgo.h"
15 #include "libcgo_unix.h"
16
17 static pthread_cond_t runtime_init_cond = PTHREAD_COND_INITIALIZER;
18 static pthread_mutex_t runtime_init_mu = PTHREAD_MUTEX_INITIALIZER;
19 static int runtime_init_done;
20
21 // The context function, used when tracing back C calls into Go.
22 static void (*cgo_context_function)(struct context_arg*);
23
24 void
x_cgo_sys_thread_create(void * (* func)(void *),void * arg)25 x_cgo_sys_thread_create(void* (*func)(void*), void* arg) {
26 pthread_t p;
27 int err = _cgo_try_pthread_create(&p, NULL, func, arg);
28 if (err != 0) {
29 fprintf(stderr, "pthread_create failed: %s", strerror(err));
30 abort();
31 }
32 }
33
34 uintptr_t
_cgo_wait_runtime_init_done(void)35 _cgo_wait_runtime_init_done(void) {
36 void (*pfn)(struct context_arg*);
37
38 pthread_mutex_lock(&runtime_init_mu);
39 while (runtime_init_done == 0) {
40 pthread_cond_wait(&runtime_init_cond, &runtime_init_mu);
41 }
42
43 // TODO(iant): For the case of a new C thread calling into Go, such
44 // as when using -buildmode=c-archive, we know that Go runtime
45 // initialization is complete but we do not know that all Go init
46 // functions have been run. We should not fetch cgo_context_function
47 // until they have been, because that is where a call to
48 // SetCgoTraceback is likely to occur. We are going to wait for Go
49 // initialization to be complete anyhow, later, by waiting for
50 // main_init_done to be closed in cgocallbackg1. We should wait here
51 // instead. See also issue #15943.
52 pfn = cgo_context_function;
53
54 pthread_mutex_unlock(&runtime_init_mu);
55 if (pfn != nil) {
56 struct context_arg arg;
57
58 arg.Context = 0;
59 (*pfn)(&arg);
60 return arg.Context;
61 }
62 return 0;
63 }
64
65 void
x_cgo_notify_runtime_init_done(void * dummy)66 x_cgo_notify_runtime_init_done(void* dummy __attribute__ ((unused))) {
67 pthread_mutex_lock(&runtime_init_mu);
68 runtime_init_done = 1;
69 pthread_cond_broadcast(&runtime_init_cond);
70 pthread_mutex_unlock(&runtime_init_mu);
71 }
72
73 // Sets the context function to call to record the traceback context
74 // when calling a Go function from C code. Called from runtime.SetCgoTraceback.
x_cgo_set_context_function(void (* context)(struct context_arg *))75 void x_cgo_set_context_function(void (*context)(struct context_arg*)) {
76 pthread_mutex_lock(&runtime_init_mu);
77 cgo_context_function = context;
78 pthread_mutex_unlock(&runtime_init_mu);
79 }
80
81 // Gets the context function.
_cgo_get_context_function(void)82 void (*(_cgo_get_context_function(void)))(struct context_arg*) {
83 void (*ret)(struct context_arg*);
84
85 pthread_mutex_lock(&runtime_init_mu);
86 ret = cgo_context_function;
87 pthread_mutex_unlock(&runtime_init_mu);
88 return ret;
89 }
90
91 // _cgo_try_pthread_create retries pthread_create if it fails with
92 // EAGAIN.
93 int
_cgo_try_pthread_create(pthread_t * thread,const pthread_attr_t * attr,void * (* pfn)(void *),void * arg)94 _cgo_try_pthread_create(pthread_t* thread, const pthread_attr_t* attr, void* (*pfn)(void*), void* arg) {
95 int tries;
96 int err;
97 struct timespec ts;
98
99 for (tries = 0; tries < 20; tries++) {
100 err = pthread_create(thread, attr, pfn, arg);
101 if (err == 0) {
102 pthread_detach(*thread);
103 return 0;
104 }
105 if (err != EAGAIN) {
106 return err;
107 }
108 ts.tv_sec = 0;
109 ts.tv_nsec = (tries + 1) * 1000 * 1000; // Milliseconds.
110 nanosleep(&ts, nil);
111 }
112 return EAGAIN;
113 }
114