Example for using AddMemoryAllocationCallback V8 method

[gihan karunarathne]

I'm trying to use AddMemoryAllocationCallback method on Ubuntu. I want to call to that method and return that size value. I came up with following code. Seems to be it's not calling to callback method.

memoryallocation.cc file

#include <nan.h>

using namespace std;
using namespace v8;

int x;

void callback(ObjectSpace space, AllocationAction action, int size) {
    x = size;
}

NAN_METHOD(GetNewSpace) {
   V8::AddMemoryAllocationCallback(callback, kObjectSpaceNewSpace, kAllocationActionAllocate);

   NanReturnVAlue(NanNew<Number>(x));
}

void Init(Handle<Object> exports) {
    exports->Set(NanNew<String>("getNewSpace"), NanNew<FunctionTemplate>(GetNewSpace)->GetFunction());
}

NODE_MODULE(memoryallocation, Init)

.gyp configuration

{
  "targets": [
    {
      "target_name": "memoryallocation",
      "sources": [ "./src/memoryallocation.cc" ],
      "include_dirs": [
        "<!(node -e \"require('nan')\")"
      ]
    }
  ]
}

.js file

var mem_alloc = require('bindings')('memoryallocation');
mem_alloc.getNewSpace();

Thank you in advance!

[Ben Noordhuis]

The callback is called when V8 allocates memory, not when you install
the callback.

[gihan karunarathne]

Thank you the reply. I'm new to V8 and C++ programming. I think, I understood what you said. 

The callback is called when V8 allocates memory, not when you install
the callback.

Does that mean, my code is correct ? So, V8 have to allocate some memory in order to trigger `callback`.

How can I test this code ? Can you provide me an example? (I spent hours and hour on this matter, but I couldn't figure out away)

Thank you in advance!

[gihan karunarathne]

Hi devs:

Can someone help me with this issue? I want to know whether I have correctly written the code below. Specially adding a callback to `V8::AddMemoryAllocationCallback`  method.

#include <nan.h>

using namespace std;
using namespace v8;

int x;

// Is this function need to be static?

void callback(ObjectSpace space, AllocationAction action, int size) {
    x = size;
}

NAN_METHOD(GetNewSpace) {
   V8::AddMemoryAllocationCallback(callback, kObjectSpaceNewSpace, kAllocationActionAllocate);

   //Or V8::AddMemoryAllocationCallback(&callback, kObjectSpaceNewSpace, kAllocationActionAllocate);

   NanReturnVAlue(NanNew<Number>(x));
}

void Init(Handle<Object> exports) {
    exports->Set(NanNew<String>("getNewSpace"), NanNew<FunctionTemplate>(GetNewSpace)->GetFunction());
}

NODE_MODULE(memoryallocation, Init)

Thank you in advance!

[gihan karunarathne]

Hi All:

I have posted a question regarding this issue [0].

[0]. http://stackoverflow.com/questions/31546224/how-to-use-v8addmemoryallocationcallback-method-in-c-nodejs-addon