##// END OF EJS Templates
wireprotov2peer: stream decoded responses...
wireprotov2peer: stream decoded responses Previously, wire protocol version 2 would buffer all response data. Only once all data was received did we CBOR decode it and resolve the future associated with the command. This was obviously not desirable. In future commits that introduce large response payloads, this caused significant memory bloat and slowed down client operations due to waiting on the server. This commit refactors the response handling code so that response data can be streamed. Command response objects now contain a buffered CBOR decoder. As new data arrives, it is fed into the decoder. Decoded objects are made available to the generator as they are decoded. Because there is a separate thread processing incoming frames and feeding data into the response object, there is the potential for race conditions when mutating response objects. So a lock has been added to guard access to critical state variables. Because the generator emitting decoded objects needs to wait on those objects to become available, we've added an Event for the generator to wait on so it doesn't busy loop. This does mean there is the potential for deadlocks. And I'm pretty sure they can occur in some scenarios. We already have a handful of TODOs around this. But I've added some more. Fixing this will likely require moving the background thread receiving frames into clienthandler. We likely would have done this anyway when implementing the client bits for the SSH transport. Test output changes because the initial CBOR map holding the overall response state is now always handled internally by the response object. Differential Revision: https://phab.mercurial-scm.org/D4474

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byteify-strings.py
230 lines | 8.0 KiB | text/x-python | PythonLexer
#!/usr/bin/env python3
#
# byteify-strings.py - transform string literals to be Python 3 safe
#
# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import argparse
import contextlib
import errno
import os
import sys
import tempfile
import token
import tokenize
def adjusttokenpos(t, ofs):
"""Adjust start/end column of the given token"""
return t._replace(start=(t.start[0], t.start[1] + ofs),
end=(t.end[0], t.end[1] + ofs))
def replacetokens(tokens, opts):
"""Transform a stream of tokens from raw to Python 3.
Returns a generator of possibly rewritten tokens.
The input token list may be mutated as part of processing. However,
its changes do not necessarily match the output token stream.
"""
sysstrtokens = set()
# The following utility functions access the tokens list and i index of
# the for i, t enumerate(tokens) loop below
def _isop(j, *o):
"""Assert that tokens[j] is an OP with one of the given values"""
try:
return tokens[j].type == token.OP and tokens[j].string in o
except IndexError:
return False
def _findargnofcall(n):
"""Find arg n of a call expression (start at 0)
Returns index of the first token of that argument, or None if
there is not that many arguments.
Assumes that token[i + 1] is '('.
"""
nested = 0
for j in range(i + 2, len(tokens)):
if _isop(j, ')', ']', '}'):
# end of call, tuple, subscription or dict / set
nested -= 1
if nested < 0:
return None
elif n == 0:
# this is the starting position of arg
return j
elif _isop(j, '(', '[', '{'):
nested += 1
elif _isop(j, ',') and nested == 0:
n -= 1
return None
def _ensuresysstr(j):
"""Make sure the token at j is a system string
Remember the given token so the string transformer won't add
the byte prefix.
Ignores tokens that are not strings. Assumes bounds checking has
already been done.
"""
st = tokens[j]
if st.type == token.STRING and st.string.startswith(("'", '"')):
sysstrtokens.add(st)
coldelta = 0 # column increment for new opening parens
coloffset = -1 # column offset for the current line (-1: TBD)
parens = [(0, 0, 0)] # stack of (line, end-column, column-offset)
for i, t in enumerate(tokens):
# Compute the column offset for the current line, such that
# the current line will be aligned to the last opening paren
# as before.
if coloffset < 0:
if t.start[1] == parens[-1][1]:
coloffset = parens[-1][2]
elif t.start[1] + 1 == parens[-1][1]:
# fix misaligned indent of s/util.Abort/error.Abort/
coloffset = parens[-1][2] + (parens[-1][1] - t.start[1])
else:
coloffset = 0
# Reset per-line attributes at EOL.
if t.type in (token.NEWLINE, tokenize.NL):
yield adjusttokenpos(t, coloffset)
coldelta = 0
coloffset = -1
continue
# Remember the last paren position.
if _isop(i, '(', '[', '{'):
parens.append(t.end + (coloffset + coldelta,))
elif _isop(i, ')', ']', '}'):
parens.pop()
# Convert most string literals to byte literals. String literals
# in Python 2 are bytes. String literals in Python 3 are unicode.
# Most strings in Mercurial are bytes and unicode strings are rare.
# Rather than rewrite all string literals to use ``b''`` to indicate
# byte strings, we apply this token transformer to insert the ``b``
# prefix nearly everywhere.
if t.type == token.STRING and t not in sysstrtokens:
s = t.string
# Preserve docstrings as string literals. This is inconsistent
# with regular unprefixed strings. However, the
# "from __future__" parsing (which allows a module docstring to
# exist before it) doesn't properly handle the docstring if it
# is b''' prefixed, leading to a SyntaxError. We leave all
# docstrings as unprefixed to avoid this. This means Mercurial
# components touching docstrings need to handle unicode,
# unfortunately.
if s[0:3] in ("'''", '"""'):
yield adjusttokenpos(t, coloffset)
continue
# If the first character isn't a quote, it is likely a string
# prefixing character (such as 'b', 'u', or 'r'. Ignore.
if s[0] not in ("'", '"'):
yield adjusttokenpos(t, coloffset)
continue
# String literal. Prefix to make a b'' string.
yield adjusttokenpos(t._replace(string='b%s' % t.string),
coloffset)
coldelta += 1
continue
# This looks like a function call.
if t.type == token.NAME and _isop(i + 1, '('):
fn = t.string
# *attr() builtins don't accept byte strings to 2nd argument.
if (fn in ('getattr', 'setattr', 'hasattr', 'safehasattr') and
not _isop(i - 1, '.')):
arg1idx = _findargnofcall(1)
if arg1idx is not None:
_ensuresysstr(arg1idx)
# .encode() and .decode() on str/bytes/unicode don't accept
# byte strings on Python 3.
elif fn in ('encode', 'decode') and _isop(i - 1, '.'):
for argn in range(2):
argidx = _findargnofcall(argn)
if argidx is not None:
_ensuresysstr(argidx)
# It changes iteritems/values to items/values as they are not
# present in Python 3 world.
elif opts['dictiter'] and fn in ('iteritems', 'itervalues'):
yield adjusttokenpos(t._replace(string=fn[4:]), coloffset)
continue
# Looks like "if __name__ == '__main__'".
if (t.type == token.NAME and t.string == '__name__'
and _isop(i + 1, '==')):
_ensuresysstr(i + 2)
# Emit unmodified token.
yield adjusttokenpos(t, coloffset)
def process(fin, fout, opts):
tokens = tokenize.tokenize(fin.readline)
tokens = replacetokens(list(tokens), opts)
fout.write(tokenize.untokenize(tokens))
def tryunlink(fname):
try:
os.unlink(fname)
except OSError as err:
if err.errno != errno.ENOENT:
raise
@contextlib.contextmanager
def editinplace(fname):
n = os.path.basename(fname)
d = os.path.dirname(fname)
fp = tempfile.NamedTemporaryFile(prefix='.%s-' % n, suffix='~', dir=d,
delete=False)
try:
yield fp
fp.close()
if os.name == 'nt':
tryunlink(fname)
os.rename(fp.name, fname)
finally:
fp.close()
tryunlink(fp.name)
def main():
ap = argparse.ArgumentParser()
ap.add_argument('-i', '--inplace', action='store_true', default=False,
help='edit files in place')
ap.add_argument('--dictiter', action='store_true', default=False,
help='rewrite iteritems() and itervalues()'),
ap.add_argument('files', metavar='FILE', nargs='+', help='source file')
args = ap.parse_args()
opts = {
'dictiter': args.dictiter,
}
for fname in args.files:
if args.inplace:
with editinplace(fname) as fout:
with open(fname, 'rb') as fin:
process(fin, fout, opts)
else:
with open(fname, 'rb') as fin:
fout = sys.stdout.buffer
process(fin, fout, opts)
if __name__ == '__main__':
main()