Pointer#toBuffer throws "TypeError: First argument must be a Buffer"

[heroboy]

This doesn't occur everytime, seldom.
Here is the code:

function PointerToBuffer(ptr,length)
{
    try
    {
        return ptr.toBuffer(length);
    }
    catch(e)
    {
        console.log("ptr=" + ptr);
        console.log("len=" + length);
        console.dir(ptr);
        throw e;
    }
}

and output:

ptr=[object Pointer]
len=75
<Pointer address="475304984" allocated="8392" free="true">
[jsbs1126]onData: catch error,TypeError: First argument must be a Buffer

D:\project\nodehall\GameLink.js:291
                                throw e;
          ^
TypeError: First argument must be a Buffer
    at new Buffer (buffer.js:266:14)
    at PointerToBuffer (D:\project\nodehall\NetLink.js:69:14)
    at Object.decryptCmd (D:\project\nodehall\NetLink.js:222:37)
    at Object.tryParse (D:\project\nodehall\NetLink.js:226:15)
    at GameLink.onData (D:\project\nodehall\GameLink.js:279:25)
    at Socket.<anonymous> (D:\project\nodehall\GameLink.js:141:55)
    at Socket.emit (events.js:67:17)
    at TCP.onread (net.js:329:14)

[TooTallNate]

Can you give me a more complete example that reproduces the error?

[heroboy]

var ffi = require("./node-ffi");
var arr = [];
for(i=0;i<1000000;++i)
{
    var ptr = new ffi.Pointer(100+i%1000);
    ptr.toBuffer();
    arr.push([ptr,ptr.toBuffer()]);
}

output

TypeError: First argument must be a Buffer
    at new Buffer (buffer.js:266:14)
    at Object.<anonymous> (D:\project\nodehall\test.js:6:6)
    at Module._compile (module.js:432:26)
    at Object..js (module.js:450:10)
    at Module.load (module.js:351:31)
    at Function._load (module.js:310:12)
    at Array.0 (module.js:470:10)
    at EventEmitter._tickCallback (node.js:192:40)

I think create Buffer in c++,you should use String::NewSymbol("Buffer"),not String::New("Buffer").
I write my own wrapper of my c++ functions.
Here is my function to create Buffer:

Handle<Value> NewNodeBuffer(void * buf,int len)
{
    v8::HandleScope scope;
    node::Buffer * slowBuffer = node::Buffer::New((char*)buf,len);
    assert(!slowBuffer->handle_.IsEmpty());
    Local<Object> global = v8::Context::GetCurrent()->Global();
    Local<Value> bv = global->Get(String::NewSymbol("Buffer"));
    assert(bv->IsFunction());
    Local<Function> b = Local<Function>::Cast(bv);
    Handle<Value> argv[3] = { slowBuffer->handle_, Integer::New(len) , Integer::New(0) };
    Handle<Object> instance = b->NewInstance(3, argv);
    return scope.Close(instance);
}

If I change NewSymbol to New,it will crash after my program runs a while.

[TooTallNate]

Interesting. Indeed, your script crashes for me, and the proposed fix fixes that. But I've come to realize that there's absolutely no benefit in doing the "SlowBuffer -> Buffer" dance, so I'm gonna just return the SlowBuffer instance directly.

[santigimeno]

Hi,

Sorry to hijack this thread, but I was looking for information about the "SlowBuffer->Buffer dance" and found your comment about not having any benefit. Why is that? Is this a general comment or it only applies to this commit?

Thanks!

[TooTallNate]

@santigimeno It applies to any time you create a SlowBuffer instance, which is what we were doing already. Wrapping it in a JS-buffer doesn't magically make it any faster, it's just another object wrapping the SlowBuffer we already created.