Encoding slow?

[willmcgugan]

Hi,

I've discovered that my pure Python implementation of bencode encode is faster than your Cython one. Depending on what is being encoded it can range from a few percent faster to several orders of magnitude faster. Not sure why that is the case, I would expect the Cython version to be faster in all cases.

Here's my bencode encode function.

def encode(obj):
    """
    Encode data in to bencode, return bytes.

    The following objects may be encoded: int, bytes, list, dicts.

    Dict keys must be bytes, and unicode strings will be encoded in to
    utf-8.

    """
    binary = []
    append = binary.append

    def add_encode(obj):
        """Encode an object, appending bytes to `binary` list."""
        if isinstance(obj, bytes):
            append(b'%i:%b' % (len(obj), obj))
        elif isinstance(obj, memoryview):
            append(b'%i:%b' % (len(obj), obj.tobytes()))
        elif isinstance(obj, str):
            obj_bytes = obj.encode('utf-8')
            append(b"%i:%b" % (len(obj_bytes), obj_bytes))
        elif isinstance(obj, int):
            append(b"i%ie" % obj)
        elif isinstance(obj, (list, tuple)):
            append(b"l")
            for item in obj:
                add_encode(item)
            append(b'e')
        elif isinstance(obj, dict):
            append(b'd')
            try:
                for key, value in sorted(obj.items(), key=itemgetter(0)):
                    append(b"%i:%b" % (len(key), key))
                    add_encode(value)
            except TypeError:
                raise EncodeError('dict keys must be bytes')
            append(b'e')
        else:
            raise EncodeError(
                'value {!r} can not be encoded in Bencode'.format(obj)
            )
    add_encode(obj)
    return b''.join(binary)

[whtsky]

Hi, just found that using array is incredibly slow.
Switched to list and the performance looks much better now:

bencoder.pyx: 0.095112
issue-7: 0.22329099999999996