mercurial-scm/hg: mercurial/wireprotoframing.py comparison

comparison mercurial/wireprotoframing.py @ 37056:861e9d37e56e

wireproto: buffer output frames when in half duplex mode Previously, when told that a response was ready, the server reactor would instruct the caller to send frames immediately. This was OK as an initial implementation. But it would not work for half-duplex connections where the sender can't receive until all data has been transmitted - such as httplib based clients. In this commit, we teach the reactor that output frames should be buffered until end of input is seen. This required a new event to inform the reactor of end of input. The result from that event will instruct the consumer to send all buffered frames. The HTTP server is buffered by default. This change effectively hides the complexity of buffering within the reactor so that transports need not be concerned about it. This helps keep the transports "dumb" and will make implementing multiple requests-responses per atomic exchange (like an HTTP request) much simpler. Differential Revision: https://phab.mercurial-scm.org/D2860

author	Gregory Szorc <gregory.szorc@gmail.com>
date	Wed, 14 Mar 2018 14:01:16 -0700
parents	61393f888dfe
children	2ec1fb9de638

comparison

equal deleted inserted replaced

-:61393f888dfe
+:861e9d37e56e
 of the command to run are given in the data structure.
 wantframe
 Indicates that nothing of interest happened and the server is waiting on
 more frames from the client before anything interesting can be done.
+noop
+Indicates no additional action is required.
 """
-def __init__(self):
+def __init__(self, deferoutput=False):
+"""Construct a new server reactor.
+``deferoutput`` can be used to indicate that no output frames should be
+instructed to be sent until input has been exhausted. In this mode,
+events that would normally generate output frames (such as a command
+response being ready) will instead defer instructing the consumer to
+send those frames. This is useful for half-duplex transports where the
+sender cannot receive until all data has been transmitted.
+"""
+self._deferoutput = deferoutput
 self._state = 'idle'
+self._bufferedframegens = []
 self._activecommand = None
 self._activeargs = None
 self._activedata = None
 self._expectingargs = None
 self._expectingdata = None
 def onbytesresponseready(self, data):
 """Signal that a bytes response is ready to be sent to the client.
 The raw bytes response is passed as an argument.
 """
+framegen = createbytesresponseframesfrombytes(data)
+if self._deferoutput:
+self._bufferedframegens.append(framegen)
+return 'noop', {}
+else:
+return 'sendframes', {
+'framegen': framegen,
+}
+def oninputeof(self):
+"""Signals that end of input has been received.
+No more frames will be received. All pending activity should be
+completed.
+"""
+if not self._deferoutput or not self._bufferedframegens:
+return 'noop', {}
+# If we buffered all our responses, emit those.
+def makegen():
+for gen in self._bufferedframegens:
+for frame in gen:
+yield frame
 return 'sendframes', {
-'framegen': createbytesresponseframesfrombytes(data),
+'framegen': makegen(),
 }
 def onapplicationerror(self, msg):
 return 'sendframes', {
 'framegen': createerrorframe(msg, application=True),

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comparison mercurial/wireprotoframing.py @ 37056:861e9d37e56e