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d7d49ad3b9
This changeset add bundling capacity for simple parameters, not value or any special case are handled.
166 lines
4.2 KiB
Python
166 lines
4.2 KiB
Python
# bundle2.py - generic container format to transmit arbitrary data.
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#
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# Copyright 2013 Facebook, Inc.
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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"""Handling of the new bundle2 format
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The goal of bundle2 is to act as an atomically packet to transmit a set of
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payloads in an application agnostic way. It consist in a sequence of "parts"
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that will be handed to and processed by the application layer.
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General format architecture
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===========================
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The format is architectured as follow
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- magic string
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- stream level parameters
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- payload parts (any number)
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- end of stream marker.
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The current implementation accept some stream level option but no part.
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Details on the Binary format
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============================
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All numbers are unsigned and big endian.
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stream level parameters
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------------------------
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Binary format is as follow
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:params size: (16 bits integer)
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The total number of Bytes used by the parameters
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:params value: arbitrary number of Bytes
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A blob of `params size` containing the serialized version of all stream level
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parameters.
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The blob contains a space separated list of parameters.
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Parameter value are not supported yet.
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Special character in param name are not supported yet.
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Payload part
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------------------------
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Binary format is as follow
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:header size: (16 bits inter)
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The total number of Bytes used by the part headers. When the header is empty
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(size = 0) this is interpreted as the end of stream marker.
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Currently forced to 0 in the current state of the implementation
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"""
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import util
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import struct
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import changegroup
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from i18n import _
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_pack = struct.pack
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_unpack = struct.unpack
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_magicstring = 'HG20'
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_fstreamparamsize = '>H'
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class bundle20(object):
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"""represent an outgoing bundle2 container
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Use the `addparam` method to add stream level parameter. Then call
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`getchunks` to retrieve all the binary chunks of datathat compose the
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bundle2 container.
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This object does not support payload part yet."""
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def __init__(self):
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self._params = []
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self._parts = []
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def addparam(self, name, value=None):
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"""add a stream level parameter"""
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self._params.append((name, value))
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def getchunks(self):
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yield _magicstring
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param = self._paramchunk()
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yield _pack(_fstreamparamsize, len(param))
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if param:
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yield param
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# no support for parts
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# to be obviously fixed soon.
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assert not self._parts
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yield '\0\0'
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def _paramchunk(self):
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"""return a encoded version of all stream parameters"""
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blocks = []
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for key, value in self._params:
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# XXX no support for value yet
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assert value is None
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# XXX no escaping yet
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blocks.append(key)
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return ' '.join(blocks)
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class unbundle20(object):
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"""interpret a bundle2 stream
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(this will eventually yield parts)"""
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def __init__(self, fp):
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self._fp = fp
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header = self._readexact(4)
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magic, version = header[0:2], header[2:4]
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if magic != 'HG':
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raise util.Abort(_('not a Mercurial bundle'))
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if version != '20':
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raise util.Abort(_('unknown bundle version %s') % version)
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def _unpack(self, format):
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"""unpack this struct format from the stream"""
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data = self._readexact(struct.calcsize(format))
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return _unpack(format, data)
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def _readexact(self, size):
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"""read exactly <size> bytes from the stream"""
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return changegroup.readexactly(self._fp, size)
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@util.propertycache
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def params(self):
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"""dictionnary of stream level parameters"""
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paramsize = self._readexact(2)
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assert paramsize == '\0\0'
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return {}
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def __iter__(self):
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"""yield all parts contained in the stream"""
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# make sure param have been loaded
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self.params
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part = self._readpart()
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while part is not None:
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yield part
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part = self._readpart()
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def _readpart(self):
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"""return None when an end of stream markers is reach"""
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headersize = self._readexact(2)
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assert headersize == '\0\0'
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return None
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