Smalloc Node.js v0.12.7 Manual & Documentation

# Smalloc#

    Stability: 1 - Experimental

## Class: smalloc#

Buffers are backed by a simple allocator that only handles the assignation of external raw memory. Smalloc exposes that functionality.

### smalloc.alloc(length[, receiver][, type])#

- `length` Number `<= smalloc.kMaxLength`
- `receiver` Object Default: `new Object`
- `type` Enum Default: `Uint8`

Returns `receiver` with allocated external array data. If no `receiver` is passed then a new Object will be created and returned.

This can be used to create your own Buffer-like classes. No other properties are set, so the user will need to keep track of other necessary information (e.g. `length` of the allocation).

    function SimpleData(n) {
      this.length = n;
      smalloc.alloc(this.length, this);
    }

    SimpleData.prototype = { /* ... */ };

It only checks if the `receiver` is an Object, and also not an Array. Because of this it is possible to allocate external array data to more than a plain Object.

    function allocMe() { }
    smalloc.alloc(3, allocMe);

    // { [Function allocMe] '0': 0, '1': 0, '2': 0 }

v8 does not support allocating external array data to an Array, and if passed will throw.

It's possible to specify the type of external array data you would like. All possible options are listed in `smalloc.Types`. Example usage:

    var doubleArr = smalloc.alloc(3, smalloc.Types.Double);

    for (var i = 0; i < 3; i++)
      doubleArr = i / 10;

    // { '0': 0, '1': 0.1, '2': 0.2 }

It is not possible to freeze, seal and prevent extensions of objects with external data using `Object.freeze`, `Object.seal` and `Object.preventExtensions` respectively.

### smalloc.copyOnto(source, sourceStart, dest, destStart, copyLength);#

- `source` Object with external array allocation
- `sourceStart` Number Position to begin copying from
- `dest` Object with external array allocation
- `destStart` Number Position to begin copying onto
- `copyLength` Number Length of copy

Copy memory from one external array allocation to another. No arguments are optional, and any violation will throw.

    var a = smalloc.alloc(4);
    var b = smalloc.alloc(4);

    for (var i = 0; i < 4; i++) {
      a[i] = i;
      b[i] = i * 2;
    }

    // { '0': 0, '1': 1, '2': 2, '3': 3 }
    // { '0': 0, '1': 2, '2': 4, '3': 6 }

    smalloc.copyOnto(b, 2, a, 0, 2);

    // { '0': 4, '1': 6, '2': 2, '3': 3 }

`copyOnto` automatically detects the length of the allocation internally, so no need to set any additional properties for this to work.

### smalloc.dispose(obj)#

- `obj` Object

Free memory that has been allocated to an object via `smalloc.alloc`.

    var a = {};
    smalloc.alloc(3, a);

    // { '0': 0, '1': 0, '2': 0 }

    smalloc.dispose(a);

    // {}

This is useful to reduce strain on the garbage collector, but developers must be careful. Cryptic errors may arise in applications that are difficult to trace.

    var a = smalloc.alloc(4);
    var b = smalloc.alloc(4);

    // perform this somewhere along the line
    smalloc.dispose(b);

    // now trying to copy some data out
    smalloc.copyOnto(b, 2, a, 0, 2);

    // now results in:
    // RangeError: copy_length > source_length

After `dispose()` is called object still behaves as one with external data, for example `smalloc.hasExternalData()` returns `true`. `dispose()` does not support Buffers, and will throw if passed.

### smalloc.hasExternalData(obj)#

- `obj` Object

Returns `true` if the `obj` has externally allocated memory.

### smalloc.kMaxLength#

Size of maximum allocation. This is also applicable to Buffer creation.

### smalloc.Types#

Enum of possible external array types. Contains:

- `Int8`
- `Uint8`
- `Int16`
- `Uint16`
- `Int32`
- `Uint32`
- `Float`
- `Double`
- `Uint8Clamped`