comparison mercurial/bundle2.py @ 20876:ddd56f3eb786

bundle2: support for bundling and unbundling payload

We add the ability to bundle and unbundle a payload in parts. The payload is the
actual binary data of the part. It is used to convey all the applicative data.
For now we stick to very simple implementation with all the data fit in single
chunk. This open the door to some bundle2 testing usage. This will be improved before
bundle2 get used for real. We need to be able to stream the payload in multiple
part to exchange any changegroup efficiently. This simple version will do for
now.

Bundling and unbundling are done in the same changeset because the test for
parts is less modular. However, the result is not too complex.

20875:cc62c9d6887a

    :typename: alphanumerical part name
    :option: we do not support option yet this denoted by two 16 bites zero.

:payload:

    The current payload is a 32bit integer with a value of 0. This is
    considered an "empty" payload.
"""

import util
import struct
import urllib

_magicstring = 'HG20'

_fstreamparamsize = '>H'
_fpartheadersize = '>H'
_fparttypesize = '>B'

class bundle20(object):
    """represent an outgoing bundle2 container

    Use the `addparam` method to add stream level parameter. and `addpart` to

            self._offset = offset + size
            return data
        typesize = _unpack(_fparttypesize, fromheader(1))[0]
        parttype = fromheader(typesize)
        self.ui.debug('part type: "%s"\n' % parttype)
        current = part(parttype)
        assert fromheader(2) == '\0\0' # no option for now
        del self._offset # clean up layer, nobody saw anything.
        self.ui.debug('part parameters: 0\n')
        assert self._readexact(4) == '\0\0\0\0' #empty payload
        self.ui.debug('payload chunk size: 0\n')
        return current


class part(object):
    """A bundle2 part contains application level payload

                  '\0\0', # No option support for now.
                 ]
        headerchunk = ''.join(header)
        yield _pack(_fpartheadersize, len(headerchunk))
        yield headerchunk
        # force empty part for now
        yield '\0\0\0\0'

20876:ddd56f3eb786

    :typename: alphanumerical part name
    :option: we do not support option yet this denoted by two 16 bites zero.

:payload:

    payload is a series of `<chunksize><chunkdata>`.

    `chunksize` is a 32 bits integer, `chunkdata` are plain bytes (as much as
    `chunksize` says)` The payload part is concluded by a zero size chunk.

    The current implementation always produces either zero or one chunk.
    This is an implementation limitation that will ultimatly be lifted.
"""

import util
import struct
import urllib

_magicstring = 'HG20'

_fstreamparamsize = '>H'
_fpartheadersize = '>H'
_fparttypesize = '>B'
_fpayloadsize = '>I'

class bundle20(object):
    """represent an outgoing bundle2 container

    Use the `addparam` method to add stream level parameter. and `addpart` to

            self._offset = offset + size
            return data
        typesize = _unpack(_fparttypesize, fromheader(1))[0]
        parttype = fromheader(typesize)
        self.ui.debug('part type: "%s"\n' % parttype)
        assert fromheader(2) == '\0\0' # no option for now
        del self._offset # clean up layer, nobody saw anything.
        self.ui.debug('part parameters: 0\n')
        payload = []
        payloadsize = self._unpack(_fpayloadsize)[0]
        self.ui.debug('payload chunk size: %i\n' % payloadsize)
        while payloadsize:
            payload.append(self._readexact(payloadsize))
            payloadsize = self._unpack(_fpayloadsize)[0]
            self.ui.debug('payload chunk size: %i\n' % payloadsize)
        payload = ''.join(payload)
        current = part(parttype, data=payload)
        return current


class part(object):
    """A bundle2 part contains application level payload

                  '\0\0', # No option support for now.
                 ]
        headerchunk = ''.join(header)
        yield _pack(_fpartheadersize, len(headerchunk))
        yield headerchunk
        # we only support fixed size data now.
        # This will be improved in the future.
        if len(self.data):
            yield _pack(_fpayloadsize, len(self.data))
            yield self.data
        # end of payload
        yield _pack(_fpayloadsize, 0)