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ghost · 2014-09-28T22:38:36Z

Updates addons.markdown to mention AtExit() function. Addresses issue #8324.

chrisdickinson · 2014-09-29T16:16:15Z

This might be best phrased as "Registers exit hooks that run after the event loop has ended, but before the VM is killed." Also, it would be good to include the arguments, argument types, and a quick code example of how you might
use the function.

AtExit functions only run in vm, not when main node is exiting?

@sam-github the documentation is pulled from the text of the commit that introduces the function -- I think it runs right before the process ends.

Updated description, added arguments and arguments types, and quick code example.

ghost · 2014-09-30T05:35:18Z

How about:

Registers exit hooks that run after the event loop has ended, but before the VM is killed.
Callbacks are run in reverse order of registration, i.e. newest first. AtExit takes callback
and its arguments as arguments. See implementation below:

 void AtExit(void (*cb)(void* arg), void* arg) {
   AtExitCallback* p = new AtExitCallback;
   p->cb_ = cb;
   p->arg_ = arg;
   p->next_ = at_exit_functions_;
   at_exit_functions_ = p;
 }

The file binding.cc implements AtExit below:

 #undef NDEBUG
 #include <assert.h>
 #include <stdlib.h>
 #include <node.h>
 #include <v8.h>

 using node::AtExit;
 using v8::Handle;
 using v8::HandleScope;
 using v8::Local;
 using v8::Object;

 static char cookie[] = "yum yum";
 static int at_exit_cb1_called = 0;
 static int at_exit_cb2_called = 0;

 static void at_exit_cb1(void* arg) {
   HandleScope scope;
   assert(arg == 0);
   Local<Object> obj = Object::New();
   assert(!obj.IsEmpty()); // assert VM is still alive
   assert(obj->IsObject());
   at_exit_cb1_called++;
 }

 static void at_exit_cb2(void* arg) {
   assert(arg == static_cast<void*>(cookie));
   at_exit_cb2_called++;
 }

 static void sanity_check(void) {
   assert(at_exit_cb1_called == 1);
   assert(at_exit_cb2_called == 2);
 }

 void init(Handle<Object> target) {
   AtExit(at_exit_cb1);
   AtExit(at_exit_cb2, cookie);
   AtExit(at_exit_cb2, cookie);
   atexit(sanity_check);
 }

 NODE_MODULE(binding, init);

Test in JavaScript by running:

 var binding = require('./build/Release/binding');

chrisdickinson · 2014-09-30T16:31:25Z

@sjsharp great work! The only other thing I'd add is a list of the arguments after the function definition -- something like we do for javascript:

### void AtExit(callback, args)

* `callback`: `void (*)(void*)` - A pointer to the function to call at exit.
* `args`: `void*` - A pointer to pass to the callback at exit.

ghost · 2014-10-01T00:50:18Z

Like this?

void AtExit(callback, args)

callback: void (*)(void*) - A pointer to the function to call at exit.
args: void* - A pointer to pass to the callback at exit.

Registers exit hooks that run after the event loop has ended, but before the VM is killed.

Callbacks are run in reverse order of registration, i.e. newest first. AtExit takes callback
and its arguments as arguments. See implementation below:

  void AtExit(void (*cb)(void* arg), void* arg) {
    AtExitCallback* p = new AtExitCallback;
    p->cb_ = cb;
    p->arg_ = arg;
    p->next_ = at_exit_functions_;
    at_exit_functions_ = p;
  }

The file binding.cc implements AtExit below:

  #undef NDEBUG
  #include <assert.h>
  #include <stdlib.h>
  #include <node.h>
  #include <v8.h>

  using node::AtExit;
  using v8::Handle;
  using v8::HandleScope;
  using v8::Local;
  using v8::Object;

  static char cookie[] = "yum yum";
  static int at_exit_cb1_called = 0;
  static int at_exit_cb2_called = 0;

  static void at_exit_cb1(void* arg) {
    HandleScope scope;
    assert(arg == 0);
    Local<Object> obj = Object::New();
    assert(!obj.IsEmpty()); // assert VM is still alive
    assert(obj->IsObject());
    at_exit_cb1_called++;
  }

  static void at_exit_cb2(void* arg) {
    assert(arg == static_cast<void*>(cookie));
    at_exit_cb2_called++;
  }

  static void sanity_check(void) {
    assert(at_exit_cb1_called == 1);
    assert(at_exit_cb2_called == 2);
  }

  void init(Handle<Object> target) {
    AtExit(at_exit_cb1);
    AtExit(at_exit_cb2, cookie);
    AtExit(at_exit_cb2, cookie);
    atexit(sanity_check);
  }

  NODE_MODULE(binding, init);

Test in JavaScript by running:

  var binding = require('./build/Release/binding');

indutny · 2014-10-01T11:00:23Z

Yep, looking good.

Incorporated latest suggestions.

ghost · 2014-10-02T03:38:23Z

Pushed changes to patch-1 branch on sjsharp/node.

trevnorris · 2014-10-07T00:06:28Z

Run make test-addon and ensure all tests pass please.

trevnorris · 2014-10-07T00:07:16Z

Future note to whoever merges this: Add the following in the commit message:

Fixes: https://github.com/joyent/node/issues/8324

JCMais · 2015-02-28T01:43:52Z

What is the status here? Why it was not merged?

This function is very handy for addons to cleanup resources, and it's still undocumented.

trevnorris · 2015-03-03T03:41:52Z

Update addons.markdown

c6d51a1

Updates addons.markdown to mention AtExit() function. Addresses issue #8324.

Nodejs-Jenkins added pr master labels Sep 28, 2014

ghost mentioned this pull request Sep 28, 2014

please mention AtExit in the documentation #8324

Closed

chrisdickinson added the doc label Sep 29, 2014

chrisdickinson reviewed Sep 29, 2014
View reviewed changes

Update addons.markdown

79c3e88

Updated description, added arguments and arguments types, and quick code example.

Update addons.markdown

3608d09

Incorporated latest suggestions.

ghost closed this Nov 25, 2014

JCMais mentioned this pull request Feb 28, 2015

Can we document the AtExit function for addons? nodejs/node#999

Closed

This pull request was closed.

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ghost commented Sep 28, 2014

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ghost commented Sep 30, 2014

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ghost commented Oct 1, 2014

void AtExit(callback, args)

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