commit de96081be3a40378819e14419e7e7f91845cc8c9 Author: Nick Mathewson nickm@torproject.org Date: Thu May 9 11:41:35 2019 -0400

Preliminary: add a memoization decorator

We memoize enough things in enough places that we should provide an actual decorator for this. --- lib/chutney/TorNet.py | 65 +++++++++++++++++++-------------------------------- lib/chutney/Util.py | 13 +++++++++++ 2 files changed, 37 insertions(+), 41 deletions(-)

diff --git a/lib/chutney/TorNet.py b/lib/chutney/TorNet.py index 16f4345..a8be5bc 100644 --- a/lib/chutney/TorNet.py +++ b/lib/chutney/TorNet.py @@ -25,6 +25,7 @@ from chutney.Debug import debug_flag, debug

import chutney.Templating import chutney.Traffic +import chutney.Util

_BASE_ENVIRON = None _TOR_VERSIONS = None @@ -204,49 +205,40 @@ def run_tor_gencert(cmdline, passphrase): assert empty_stderr is None return stdouterr

+@chutney.Util.memoized def get_tor_version(tor): """Return the version of the tor binary. Versions are cached for each unique tor path. """ - # find the version of the current tor binary, and cache it - if tor not in _TOR_VERSIONS: - cmdline = [ - tor, - "--version", - ] - tor_version = run_tor(cmdline) - # clean it up a bit - tor_version = tor_version.strip() - tor_version = tor_version.replace("version ", "") - tor_version = tor_version.replace(").", ")") - # check we received a tor version, and nothing else - assert re.match(r'^[-+.() A-Za-z0-9]+$', tor_version) - # cache the version for this tor binary's path - _TOR_VERSIONS[tor] = tor_version - else: - tor_version = _TOR_VERSIONS[tor] + cmdline = [ + tor, + "--version", + ] + tor_version = run_tor(cmdline) + # clean it up a bit + tor_version = tor_version.strip() + tor_version = tor_version.replace("version ", "") + tor_version = tor_version.replace(").", ")") + # check we received a tor version, and nothing else + assert re.match(r'^[-+.() A-Za-z0-9]+$', tor_version) + return tor_version

+@chutney.Util.memoized def get_torrc_options(tor): """Return the torrc options supported by the tor binary. Options are cached for each unique tor path. """ - # find the options the current tor binary supports, and cache them - if tor not in _TORRC_OPTIONS: - cmdline = [ - tor, - "--list-torrc-options", - ] - opts = run_tor(cmdline) - # check we received a list of options, and nothing else - assert re.match(r'(^\w+$)+', opts, flags=re.MULTILINE) - torrc_opts = opts.split() - # cache the options for this tor binary's path - _TORRC_OPTIONS[tor] = torrc_opts - else: - torrc_opts = _TORRC_OPTIONS[tor] - return torrc_opts + cmdline = [ + tor, + "--list-torrc-options", + ] + opts = run_tor(cmdline) + # check we received a list of options, and nothing else + assert re.match(r'(^\w+$)+', opts, flags=re.MULTILINE) + torrc_opts = opts.split()

+ return torrc_opts

class Node(object):

@@ -1319,17 +1311,8 @@ def parseArgs():

def main(): global _BASE_ENVIRON - global _TOR_VERSIONS - global _TORRC_OPTIONS global _THE_NETWORK _BASE_ENVIRON = TorEnviron(chutney.Templating.Environ(**DEFAULTS)) - # _TOR_VERSIONS gets initialised on demand as a map of - # "/path/to/tor" => "Tor version ..." - _TOR_VERSIONS = dict() - # _TORRC_OPTIONS gets initialised on demand as a map of - # "/path/to/tor" => ["SupportedOption1", "SupportedOption2", ...] - # Or it can be pre-populated as a static whitelist of options - _TORRC_OPTIONS = dict() _THE_NETWORK = Network(_BASE_ENVIRON)

args = parseArgs() diff --git a/lib/chutney/Util.py b/lib/chutney/Util.py new file mode 100644 index 0000000..f8b838e --- /dev/null +++ b/lib/chutney/Util.py @@ -0,0 +1,13 @@ + + +def memoized(fn): + """Decorator: memoize a function.""" + memory = {} + def memoized_fn(*args, **kwargs): + key = (args, tuple(sorted(kwargs.items()))) + try: + result = memory[key] + except KeyError: + result = memory[key] = fn(*args, **kwargs) + return result + return memoized_fn