Mercurial > hg
view mercurial/httpclient/_readers.py @ 26755:bb0b955d050d
streamclone: support for producing and consuming stream clone bundles
Up to this point, stream clones only existed as a dynamically generated
data format produced and consumed during streaming clones. In order to
support this efficient cloning format with the clone bundles feature, we
need a more formal, on disk representation of the streaming clone data.
This patch introduces a new "bundle" type for streaming clones. Unlike
existing bundles, it does not contain changegroup data. It does,
however, share the same concepts like the 4 byte header which identifies
the type of data that follows and the 2 byte abbreviation for
compression types (of which only "UN" is currently supported).
The new bundle format is essentially the existing stream clone version 1
data format with some headers at the beginning.
Content negotiation at stream clone request time checked for repository
format/requirements compatibility before initiating a stream clone. We
can't do active content negotiation when using clone bundles. So, we put
this set of requirements inside the payload so consumers have a built-in
mechanism for checking compatibility before reading and applying lots of
data. Of course, we will also advertise this requirements set in clone
bundles. But that's for another patch.
We currently don't have a mechanism to produce and consume this new
bundle format. This will be implemented in upcoming patches.
It's worth noting that if a legacy client attempts to `hg unbundle` a
stream clone bundle (with the "HGS1" header), it will abort with:
"unknown bundle version S1," which seems appropriate.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sat, 17 Oct 2015 11:14:52 -0700 |
parents | fae47ecaa952 |
children | 1ad9da968a2e |
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# Copyright 2011, Google Inc. # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions are # met: # # * Redistributions of source code must retain the above copyright # notice, this list of conditions and the following disclaimer. # * Redistributions in binary form must reproduce the above # copyright notice, this list of conditions and the following disclaimer # in the documentation and/or other materials provided with the # distribution. # * Neither the name of Google Inc. nor the names of its # contributors may be used to endorse or promote products derived from # this software without specific prior written permission. # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. """Reader objects to abstract out different body response types. This module is package-private. It is not expected that these will have any clients outside of httpplus. """ import httplib import logging logger = logging.getLogger(__name__) class ReadNotReady(Exception): """Raised when read() is attempted but not enough data is loaded.""" class HTTPRemoteClosedError(httplib.HTTPException): """The server closed the remote socket in the middle of a response.""" class AbstractReader(object): """Abstract base class for response readers. Subclasses must implement _load, and should implement _close if it's not an error for the server to close their socket without some termination condition being detected during _load. """ def __init__(self): self._finished = False self._done_chunks = [] self.available_data = 0 def _addchunk(self, data): self._done_chunks.append(data) self.available_data += len(data) def _pushchunk(self, data): self._done_chunks.insert(0, data) self.available_data += len(data) def _popchunk(self): b = self._done_chunks.pop(0) self.available_data -= len(b) return b def done(self): """Returns true if the response body is entirely read.""" return self._finished def read(self, amt): """Read amt bytes from the response body.""" if self.available_data < amt and not self._finished: raise ReadNotReady() blocks = [] need = amt while self._done_chunks: b = self._popchunk() if len(b) > need: nb = b[:need] self._pushchunk(b[need:]) b = nb blocks.append(b) need -= len(b) if need == 0: break result = ''.join(blocks) assert len(result) == amt or (self._finished and len(result) < amt) return result def readto(self, delimstr, blocks = None): """return available data chunks up to the first one in which delimstr occurs. No data will be returned after delimstr -- the chunk in which it occurs will be split and the remainder pushed back onto the available data queue. If blocks is supplied chunks will be added to blocks, otherwise a new list will be allocated. """ if blocks is None: blocks = [] while self._done_chunks: b = self._popchunk() i = b.find(delimstr) + len(delimstr) if i: if i < len(b): self._pushchunk(b[i:]) blocks.append(b[:i]) break else: blocks.append(b) return blocks def _load(self, data): # pragma: no cover """Subclasses must implement this. As data is available to be read out of this object, it should be placed into the _done_chunks list. Subclasses should not rely on data remaining in _done_chunks forever, as it may be reaped if the client is parsing data as it comes in. """ raise NotImplementedError def _close(self): """Default implementation of close. The default implementation assumes that the reader will mark the response as finished on the _finished attribute once the entire response body has been read. In the event that this is not true, the subclass should override the implementation of close (for example, close-is-end responses have to set self._finished in the close handler.) """ if not self._finished: raise HTTPRemoteClosedError( 'server appears to have closed the socket mid-response') class AbstractSimpleReader(AbstractReader): """Abstract base class for simple readers that require no response decoding. Examples of such responses are Connection: Close (close-is-end) and responses that specify a content length. """ def _load(self, data): if data: assert not self._finished, ( 'tried to add data (%r) to a closed reader!' % data) logger.debug('%s read an additional %d data', self.name, len(data)) # pylint: disable=E1101 self._addchunk(data) class CloseIsEndReader(AbstractSimpleReader): """Reader for responses that specify Connection: Close for length.""" name = 'close-is-end' def _close(self): logger.info('Marking close-is-end reader as closed.') self._finished = True class ContentLengthReader(AbstractSimpleReader): """Reader for responses that specify an exact content length.""" name = 'content-length' def __init__(self, amount): AbstractSimpleReader.__init__(self) self._amount = amount if amount == 0: self._finished = True self._amount_seen = 0 def _load(self, data): AbstractSimpleReader._load(self, data) self._amount_seen += len(data) if self._amount_seen >= self._amount: self._finished = True logger.debug('content-length read complete') class ChunkedReader(AbstractReader): """Reader for chunked transfer encoding responses.""" def __init__(self, eol): AbstractReader.__init__(self) self._eol = eol self._leftover_skip_amt = 0 self._leftover_data = '' def _load(self, data): assert not self._finished, 'tried to add data to a closed reader!' logger.debug('chunked read an additional %d data', len(data)) position = 0 if self._leftover_data: logger.debug( 'chunked reader trying to finish block from leftover data') # TODO: avoid this string concatenation if possible data = self._leftover_data + data position = self._leftover_skip_amt self._leftover_data = '' self._leftover_skip_amt = 0 datalen = len(data) while position < datalen: split = data.find(self._eol, position) if split == -1: self._leftover_data = data self._leftover_skip_amt = position return amt = int(data[position:split], base=16) block_start = split + len(self._eol) # If the whole data chunk plus the eol trailer hasn't # loaded, we'll wait for the next load. if block_start + amt + len(self._eol) > len(data): self._leftover_data = data self._leftover_skip_amt = position return if amt == 0: self._finished = True logger.debug('closing chunked reader due to chunk of length 0') return self._addchunk(data[block_start:block_start + amt]) position = block_start + amt + len(self._eol) # no-check-code