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protocol: send application/mercurial-0.2 responses to capable clients...
protocol: send application/mercurial-0.2 responses to capable clients With this commit, the HTTP transport now parses the X-HgProto-<N> header to determine what media type and compression engine to use for responses. So far, we only compress responses that are already being compressed with zlib today (stream response types to specific commands). We can expand things to cover additional response types later. The practical side-effect of this commit is that non-zlib compression engines will be used if both ends support them. This means if both ends have zstd support, zstd - not zlib - will be used to compress data! When cloning the mozilla-unified repository between a local HTTP server and client, the benefits of non-zlib compression are quite noticeable: engine server CPU (s) client CPU (s) bundle size zlib (l=6) 174.1 283.2 1,148,547,026 zstd (l=1) 99.2 267.3 1,127,513,841 zstd (l=3) 103.1 266.9 1,018,861,363 zstd (l=7) 128.3 269.7 919,190,278 zstd (l=10) 162.0 - 894,547,179 none 95.3 277.2 4,097,566,064 The default zstd compression level is 3. So if you deploy zstd capable Mercurial to your clients and servers and CPU time on your server is dominated by "getbundle" requests (clients cloning and pulling) - and my experience at Mozilla tells me this is often the case - this commit could drastically reduce your server-side CPU usage *and* save on bandwidth costs! Another benefit of this change is that server operators can install *any* compression engine. While it isn't enabled by default, the "none" compression engine can now be used to disable wire protocol compression completely. Previously, commands like "getbundle" always zlib compressed output, adding considerable overhead to generating responses. If you are on a high speed network and your server is under high load, it might be advantageous to trade bandwidth for CPU. Although, zstd at level 1 doesn't use that much CPU, so I'm not convinced that disabling compression wholesale is worthwhile. And, my data seems to indicate a slow down on the client without compression. I suspect this is due to a lack of buffering resulting in an increase in socket read() calls and/or the fact we're transferring an extra 3 GB of data (parsing HTTP chunked transfer and processing extra TCP packets can add up). This is definitely worth investigating and optimizing. But since the "none" compressor isn't enabled by default, I'm inclined to punt on this issue. This commit introduces tons of tests. Some of these should arguably have been implemented on previous commits. But it was difficult to test without the server functionality in place.

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dagparser.py
480 lines | 14.4 KiB | text/x-python | PythonLexer
# dagparser.py - parser and generator for concise description of DAGs
#
# Copyright 2010 Peter Arrenbrecht <peter@arrenbrecht.ch>
#
# 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 re
import string
from .i18n import _
from . import error
def parsedag(desc):
'''parses a DAG from a concise textual description; generates events
"+n" is a linear run of n nodes based on the current default parent
"." is a single node based on the current default parent
"$" resets the default parent to -1 (implied at the start);
otherwise the default parent is always the last node created
"<p" sets the default parent to the backref p
"*p" is a fork at parent p, where p is a backref
"*p1/p2/.../pn" is a merge of parents p1..pn, where the pi are backrefs
"/p2/.../pn" is a merge of the preceding node and p2..pn
":name" defines a label for the preceding node; labels can be redefined
"@text" emits an annotation event for text
"!command" emits an action event for the current node
"!!my command\n" is like "!", but to the end of the line
"#...\n" is a comment up to the end of the line
Whitespace between the above elements is ignored.
A backref is either
* a number n, which references the node curr-n, where curr is the current
node, or
* the name of a label you placed earlier using ":name", or
* empty to denote the default parent.
All string valued-elements are either strictly alphanumeric, or must
be enclosed in double quotes ("..."), with "\" as escape character.
Generates sequence of
('n', (id, [parentids])) for node creation
('l', (id, labelname)) for labels on nodes
('a', text) for annotations
('c', command) for actions (!)
('C', command) for line actions (!!)
Examples
--------
Example of a complex graph (output not shown for brevity):
>>> len(list(parsedag("""
...
... +3 # 3 nodes in linear run
... :forkhere # a label for the last of the 3 nodes from above
... +5 # 5 more nodes on one branch
... :mergethis # label again
... <forkhere # set default parent to labeled fork node
... +10 # 10 more nodes on a parallel branch
... @stable # following nodes will be annotated as "stable"
... +5 # 5 nodes in stable
... !addfile # custom command; could trigger new file in next node
... +2 # two more nodes
... /mergethis # merge last node with labeled node
... +4 # 4 more nodes descending from merge node
...
... """)))
34
Empty list:
>>> list(parsedag(""))
[]
A simple linear run:
>>> list(parsedag("+3"))
[('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [1]))]
Some non-standard ways to define such runs:
>>> list(parsedag("+1+2"))
[('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [1]))]
>>> list(parsedag("+1*1*"))
[('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [1]))]
>>> list(parsedag("*"))
[('n', (0, [-1]))]
>>> list(parsedag("..."))
[('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [1]))]
A fork and a join, using numeric back references:
>>> list(parsedag("+2*2*/2"))
[('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [0])), ('n', (3, [2, 1]))]
>>> list(parsedag("+2<2+1/2"))
[('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [0])), ('n', (3, [2, 1]))]
Placing a label:
>>> list(parsedag("+1 :mylabel +1"))
[('n', (0, [-1])), ('l', (0, 'mylabel')), ('n', (1, [0]))]
An empty label (silly, really):
>>> list(parsedag("+1:+1"))
[('n', (0, [-1])), ('l', (0, '')), ('n', (1, [0]))]
Fork and join, but with labels instead of numeric back references:
>>> list(parsedag("+1:f +1:p2 *f */p2"))
[('n', (0, [-1])), ('l', (0, 'f')), ('n', (1, [0])), ('l', (1, 'p2')),
('n', (2, [0])), ('n', (3, [2, 1]))]
>>> list(parsedag("+1:f +1:p2 <f +1 /p2"))
[('n', (0, [-1])), ('l', (0, 'f')), ('n', (1, [0])), ('l', (1, 'p2')),
('n', (2, [0])), ('n', (3, [2, 1]))]
Restarting from the root:
>>> list(parsedag("+1 $ +1"))
[('n', (0, [-1])), ('n', (1, [-1]))]
Annotations, which are meant to introduce sticky state for subsequent nodes:
>>> list(parsedag("+1 @ann +1"))
[('n', (0, [-1])), ('a', 'ann'), ('n', (1, [0]))]
>>> list(parsedag('+1 @"my annotation" +1'))
[('n', (0, [-1])), ('a', 'my annotation'), ('n', (1, [0]))]
Commands, which are meant to operate on the most recently created node:
>>> list(parsedag("+1 !cmd +1"))
[('n', (0, [-1])), ('c', 'cmd'), ('n', (1, [0]))]
>>> list(parsedag('+1 !"my command" +1'))
[('n', (0, [-1])), ('c', 'my command'), ('n', (1, [0]))]
>>> list(parsedag('+1 !!my command line\\n +1'))
[('n', (0, [-1])), ('C', 'my command line'), ('n', (1, [0]))]
Comments, which extend to the end of the line:
>>> list(parsedag('+1 # comment\\n+1'))
[('n', (0, [-1])), ('n', (1, [0]))]
Error:
>>> try: list(parsedag('+1 bad'))
... except Exception, e: print e
invalid character in dag description: bad...
'''
if not desc:
return
wordchars = string.ascii_letters + string.digits
labels = {}
p1 = -1
r = 0
def resolve(ref):
if not ref:
return p1
elif ref[0] in string.digits:
return r - int(ref)
else:
return labels[ref]
chiter = (c for c in desc)
def nextch():
return next(chiter, '\0')
def nextrun(c, allow):
s = ''
while c in allow:
s += c
c = nextch()
return c, s
def nextdelimited(c, limit, escape):
s = ''
while c != limit:
if c == escape:
c = nextch()
s += c
c = nextch()
return nextch(), s
def nextstring(c):
if c == '"':
return nextdelimited(nextch(), '"', '\\')
else:
return nextrun(c, wordchars)
c = nextch()
while c != '\0':
while c in string.whitespace:
c = nextch()
if c == '.':
yield 'n', (r, [p1])
p1 = r
r += 1
c = nextch()
elif c == '+':
c, digs = nextrun(nextch(), string.digits)
n = int(digs)
for i in xrange(0, n):
yield 'n', (r, [p1])
p1 = r
r += 1
elif c in '*/':
if c == '*':
c = nextch()
c, pref = nextstring(c)
prefs = [pref]
while c == '/':
c, pref = nextstring(nextch())
prefs.append(pref)
ps = [resolve(ref) for ref in prefs]
yield 'n', (r, ps)
p1 = r
r += 1
elif c == '<':
c, ref = nextstring(nextch())
p1 = resolve(ref)
elif c == ':':
c, name = nextstring(nextch())
labels[name] = p1
yield 'l', (p1, name)
elif c == '@':
c, text = nextstring(nextch())
yield 'a', text
elif c == '!':
c = nextch()
if c == '!':
cmd = ''
c = nextch()
while c not in '\n\r\0':
cmd += c
c = nextch()
yield 'C', cmd
else:
c, cmd = nextstring(c)
yield 'c', cmd
elif c == '#':
while c not in '\n\r\0':
c = nextch()
elif c == '$':
p1 = -1
c = nextch()
elif c == '\0':
return # in case it was preceded by whitespace
else:
s = ''
i = 0
while c != '\0' and i < 10:
s += c
i += 1
c = nextch()
raise error.Abort(_('invalid character in dag description: '
'%s...') % s)
def dagtextlines(events,
addspaces=True,
wraplabels=False,
wrapannotations=False,
wrapcommands=False,
wrapnonlinear=False,
usedots=False,
maxlinewidth=70):
'''generates single lines for dagtext()'''
def wrapstring(text):
if re.match("^[0-9a-z]*$", text):
return text
return '"' + text.replace('\\', '\\\\').replace('"', '\"') + '"'
def gen():
labels = {}
run = 0
wantr = 0
needroot = False
for kind, data in events:
if kind == 'n':
r, ps = data
# sanity check
if r != wantr:
raise error.Abort(_("expected id %i, got %i") % (wantr, r))
if not ps:
ps = [-1]
else:
for p in ps:
if p >= r:
raise error.Abort(_("parent id %i is larger than "
"current id %i") % (p, r))
wantr += 1
# new root?
p1 = r - 1
if len(ps) == 1 and ps[0] == -1:
if needroot:
if run:
yield '+' + str(run)
run = 0
if wrapnonlinear:
yield '\n'
yield '$'
p1 = -1
else:
needroot = True
if len(ps) == 1 and ps[0] == p1:
if usedots:
yield "."
else:
run += 1
else:
if run:
yield '+' + str(run)
run = 0
if wrapnonlinear:
yield '\n'
prefs = []
for p in ps:
if p == p1:
prefs.append('')
elif p in labels:
prefs.append(labels[p])
else:
prefs.append(str(r - p))
yield '*' + '/'.join(prefs)
else:
if run:
yield '+' + str(run)
run = 0
if kind == 'l':
rid, name = data
labels[rid] = name
yield ':' + name
if wraplabels:
yield '\n'
elif kind == 'c':
yield '!' + wrapstring(data)
if wrapcommands:
yield '\n'
elif kind == 'C':
yield '!!' + data
yield '\n'
elif kind == 'a':
if wrapannotations:
yield '\n'
yield '@' + wrapstring(data)
elif kind == '#':
yield '#' + data
yield '\n'
else:
raise error.Abort(_("invalid event type in dag: %s")
% str((type, data)))
if run:
yield '+' + str(run)
line = ''
for part in gen():
if part == '\n':
if line:
yield line
line = ''
else:
if len(line) + len(part) >= maxlinewidth:
yield line
line = ''
elif addspaces and line and part != '.':
line += ' '
line += part
if line:
yield line
def dagtext(dag,
addspaces=True,
wraplabels=False,
wrapannotations=False,
wrapcommands=False,
wrapnonlinear=False,
usedots=False,
maxlinewidth=70):
'''generates lines of a textual representation for a dag event stream
events should generate what parsedag() does, so:
('n', (id, [parentids])) for node creation
('l', (id, labelname)) for labels on nodes
('a', text) for annotations
('c', text) for commands
('C', text) for line commands ('!!')
('#', text) for comment lines
Parent nodes must come before child nodes.
Examples
--------
Linear run:
>>> dagtext([('n', (0, [-1])), ('n', (1, [0]))])
'+2'
Two roots:
>>> dagtext([('n', (0, [-1])), ('n', (1, [-1]))])
'+1 $ +1'
Fork and join:
>>> dagtext([('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [0])),
... ('n', (3, [2, 1]))])
'+2 *2 */2'
Fork and join with labels:
>>> dagtext([('n', (0, [-1])), ('l', (0, 'f')), ('n', (1, [0])),
... ('l', (1, 'p2')), ('n', (2, [0])), ('n', (3, [2, 1]))])
'+1 :f +1 :p2 *f */p2'
Annotations:
>>> dagtext([('n', (0, [-1])), ('a', 'ann'), ('n', (1, [0]))])
'+1 @ann +1'
>>> dagtext([('n', (0, [-1])),
... ('a', 'my annotation'),
... ('n', (1, [0]))])
'+1 @"my annotation" +1'
Commands:
>>> dagtext([('n', (0, [-1])), ('c', 'cmd'), ('n', (1, [0]))])
'+1 !cmd +1'
>>> dagtext([('n', (0, [-1])), ('c', 'my command'), ('n', (1, [0]))])
'+1 !"my command" +1'
>>> dagtext([('n', (0, [-1])),
... ('C', 'my command line'),
... ('n', (1, [0]))])
'+1 !!my command line\\n+1'
Comments:
>>> dagtext([('n', (0, [-1])), ('#', ' comment'), ('n', (1, [0]))])
'+1 # comment\\n+1'
>>> dagtext([])
''
Combining parsedag and dagtext:
>>> dagtext(parsedag('+1 :f +1 :p2 *f */p2'))
'+1 :f +1 :p2 *f */p2'
'''
return "\n".join(dagtextlines(dag,
addspaces,
wraplabels,
wrapannotations,
wrapcommands,
wrapnonlinear,
usedots,
maxlinewidth))