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fix EventSource (server and parsers)

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I was really confused about the Server-Sent Events syntax. This new one
is compatible with actual web browsers and the spec:

 http://www.w3.org/TR/eventsource/
This commit is contained in:
Brian Warner 2015-10-07 16:22:27 -07:00
parent e77b39313a
commit df3aee2a86
5 changed files with 117 additions and 52 deletions
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65
src/wormhole/blocking/eventsource.py
View File

@ -1,30 +1,18 @@
from __future__ import print_function
import six
from __future__ import print_function, unicode_literals
import requests
class EventSourceFollower:
def __init__(self, url, timeout):
self.resp = requests.get(url,
headers={"accept": "text/event-stream"},
stream=True,
timeout=timeout)
self.resp.raise_for_status()
self._resp = requests.get(url,
headers={"accept": "text/event-stream"},
stream=True,
timeout=timeout)
self._resp.raise_for_status()
self._lines_iter = self._resp.iter_lines(chunk_size=1,
decode_unicode=True)
def close(self):
self.resp.close()
def _get_fields(self, lines):
while True:
first_line = next(lines) # raises StopIteration when closed
assert isinstance(first_line, type(six.u(""))), type(first_line)
fieldname, data = first_line.split(": ", 1)
data_lines = [data]
while True:
next_line = next(lines)
if not next_line: # empty string, original was "\n"
yield (fieldname, "\n".join(data_lines))
break
data_lines.append(next_line)
self._resp.close()
def iter_events(self):
# I think Request.iter_lines and .iter_content use chunk_size= in a
@ -33,16 +21,29 @@ class EventSourceFollower:
# for a long time. I'd prefer that chunk_size behaved like
# read(size), and gave you 1<=x<=size bytes in response.
eventtype = "message"
lines_iter = self.resp.iter_lines(chunk_size=1, decode_unicode=True)
for (fieldname, data) in self._get_fields(lines_iter):
# fieldname/data are unicode on both py2 and py3. On py2, where
# ("abc"==u"abc" is True), this compares unicode against str,
# which matches. On py3, where (b"abc"=="abc" is False), this
# compares unicode against unicode, which matches.
if fieldname == "data":
yield (eventtype, data)
current_lines = []
for line in self._lines_iter:
assert isinstance(line, type(u"")), type(line)
if not line:
# blank line ends the field: deliver event, reset for next
yield (eventtype, "\n".join(current_lines))
eventtype = "message"
elif fieldname == "event":
eventtype = data
current_lines[:] = []
continue
if ":" in line:
fieldname, data = line.split(":", 1)
if data.startswith(" "):
data = data[1:]
else:
print("weird fieldname", fieldname, type(fieldname), data)
fieldname = line
data = ""
if fieldname == "event":
eventtype = data
elif fieldname == "data":
current_lines.append(data)
elif fieldname in ("id", "retry"):
# documented but unhandled
pass
else:
#log.msg("weird fieldname", fieldname, data)
pass

3
src/wormhole/servers/relay_server.py
View File

@ -34,13 +34,10 @@ class EventsProtocol:
# e.g. if name=foo, then the client web page should do:
# (new EventSource(url)).addEventListener("foo", handlerfunc)
# Note that this basically defaults to "message".
self.request.write(b"\n")
if id:
self.request.write(b"id: " + id.encode("utf-8") + b"\n")
self.request.write(b"\n")
if retry:
self.request.write(b"retry: " + retry + b"\n") # milliseconds
self.request.write(b"\n")
for line in data.splitlines():
self.request.write(b"data: " + line.encode("utf-8") + b"\n")
self.request.write(b"\n")

32
src/wormhole/test/test_blocking.py
View File

@ -4,6 +4,7 @@ from twisted.trial import unittest
from twisted.internet.defer import gatherResults, succeed
from twisted.internet.threads import deferToThread
from ..blocking.transcribe import Wormhole, UsageError, ChannelManager
from ..blocking.eventsource import EventSourceFollower
from .common import ServerBase
APPID = u"appid"
@ -297,3 +298,34 @@ class Blocking(ServerBase, unittest.TestCase):
d.addCallback(_done)
return d
test_serialize.skip = "not yet implemented for the blocking flavor"
data1 = u"""\
event: welcome
data: one and a
data: two
data:.
data: three
: this line is ignored
event: e2
: this line is ignored too
i am a dataless field name
data: four
"""
class NoNetworkESF(EventSourceFollower):
def __init__(self, text):
self._lines_iter = iter(text.splitlines())
class EventSourceClient(unittest.TestCase):
def test_parser(self):
events = []
f = NoNetworkESF(data1)
events = list(f.iter_events())
self.failUnlessEqual(events,
[(u"welcome", u"one and a\ntwo\n."),
(u"message", u"three"),
(u"e2", u"four"),
])

33
src/wormhole/test/test_twisted.py
View File

@ -3,6 +3,7 @@ import sys, json
from twisted.trial import unittest
from twisted.internet.defer import gatherResults, succeed
from ..twisted.transcribe import Wormhole, UsageError, ChannelManager
from ..twisted.eventsource_twisted import EventSourceParser
from .common import ServerBase
APPID = u"appid"
@ -284,9 +285,41 @@ class Basic(ServerBase, unittest.TestCase):
d.addCallback(_done)
return d
data1 = u"""\
event: welcome
data: one and a
data: two
data:.
data: three
: this line is ignored
event: e2
: this line is ignored too
i am a dataless field name
data: four
"""
class FakeTransport:
disconnecting = False
class EventSourceClient(unittest.TestCase):
def test_parser(self):
events = []
p = EventSourceParser(lambda t,d: events.append((t,d)))
p.transport = FakeTransport()
p.dataReceived(data1)
self.failUnlessEqual(events,
[(u"welcome", u"one and a\ntwo\n."),
(u"message", u"three"),
(u"e2", u"four"),
])
if sys.version_info[0] >= 3:
Channel.skip = "twisted is not yet sufficiently ported to py3"
Basic.skip = "twisted is not yet sufficiently ported to py3"
EventSourceClient.skip = "twisted is not yet sufficiently ported to py3"
# as of 15.4.0, Twisted is still missing:
# * web.client.Agent (for all non-EventSource POSTs in transcribe.py)
# * python.logfile (to allow daemonization of 'wormhole server')

36
src/wormhole/twisted/eventsource_twisted.py
View File

@ -14,6 +14,7 @@ from ..util.eventual import eventually
# to_unicode = str
class EventSourceParser(basic.LineOnlyReceiver):
# http://www.w3.org/TR/eventsource/
delimiter = "\n"
def __init__(self, handler):
@ -21,7 +22,7 @@ class EventSourceParser(basic.LineOnlyReceiver):
self.current_lines = []
self.handler = handler
self.done_deferred = defer.Deferred()
self.eventtype = "message"
self.eventtype = u"message"
self.encoding = "utf-8"
def set_encoding(self, encoding):
@ -44,27 +45,28 @@ class EventSourceParser(basic.LineOnlyReceiver):
raise
def lineReceived(self, line):
#line = to_unicode(line, self.encoding)
line = line.decode(self.encoding)
if not line:
# blank line ends the field
self.fieldReceived(self.current_field,
"\n".join(self.current_lines))
self.current_field = None
# blank line ends the field: deliver event, reset for next
self.eventReceived(self.eventtype, "\n".join(self.current_lines))
self.eventtype = u"message"
self.current_lines[:] = []
return
line = line.decode(self.encoding)
#line = to_unicode(line, self.encoding)
if self.current_field is None:
self.current_field, data = line.split(": ", 1)
self.current_lines.append(data)
if u":" in line:
fieldname, data = line.split(u":", 1)
if data.startswith(u" "):
data = data[1:]
else:
self.current_lines.append(line)
def fieldReceived(self, fieldname, data):
if fieldname == "event":
fieldname = line
data = u""
if fieldname == u"event":
self.eventtype = data
elif fieldname == "data":
self.eventReceived(self.eventtype, data)
self.eventtype = "message"
elif fieldname == u"data":
self.current_lines.append(data)
elif fieldname in (u"id", u"retry"):
# documented but unhandled
pass
else:
log.msg("weird fieldname", fieldname, data)