cgo-callback.go

     1  // Copyright 2023 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  // Tests CPU profiling.
     6  
     7  //go:build ignore
     8  
     9  package main
    10  
    11  /*
    12  #include <pthread.h>
    13  
    14  void go_callback();
    15  void go_callback2();
    16  
    17  static void *thr(void *arg) {
    18      go_callback();
    19      return 0;
    20  }
    21  
    22  static void foo() {
    23      pthread_t th;
    24      pthread_attr_t attr;
    25      pthread_attr_init(&attr);
    26      pthread_attr_setstacksize(&attr, 256 << 10);
    27      pthread_create(&th, &attr, thr, 0);
    28      pthread_join(th, 0);
    29  }
    30  
    31  static void bar() {
    32      go_callback2();
    33  }
    34  */
    35  import "C"
    36  
    37  import (
    38  	"log"
    39  	"os"
    40  	"runtime"
    41  	"runtime/trace"
    42  )
    43  
    44  //export go_callback
    45  func go_callback() {
    46  	// Do another call into C, just to test that path too.
    47  	C.bar()
    48  }
    49  
    50  //export go_callback2
    51  func go_callback2() {
    52  	runtime.GC()
    53  }
    54  
    55  func main() {
    56  	// Start tracing.
    57  	if err := trace.Start(os.Stdout); err != nil {
    58  		log.Fatalf("failed to start tracing: %v", err)
    59  	}
    60  
    61  	// Do a whole bunch of cgocallbacks.
    62  	const n = 10
    63  	done := make(chan bool)
    64  	for i := 0; i < n; i++ {
    65  		go func() {
    66  			C.foo()
    67  			done <- true
    68  		}()
    69  	}
    70  	for i := 0; i < n; i++ {
    71  		<-done
    72  	}
    73  
    74  	// Do something to steal back any Ps from the Ms, just
    75  	// for coverage.
    76  	runtime.GC()
    77  
    78  	// End of traced execution.
    79  	trace.Stop()
    80  }
    81
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