diff options
Diffstat (limited to 'powerline/lib/config.py')
| -rw-r--r-- | powerline/lib/config.py | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/powerline/lib/config.py b/powerline/lib/config.py new file mode 100644 index 0000000..0c95e47 --- /dev/null +++ b/powerline/lib/config.py @@ -0,0 +1,218 @@ +# vim:fileencoding=utf-8:noet +from __future__ import (unicode_literals, division, absolute_import, print_function) + +import json +import codecs + +from copy import deepcopy +from threading import Event, Lock +from collections import defaultdict + +from powerline.lib.threaded import MultiRunnedThread +from powerline.lib.watcher import create_file_watcher + + +def open_file(path): + return codecs.open(path, encoding='utf-8') + + +def load_json_config(config_file_path, load=json.load, open_file=open_file): + with open_file(config_file_path) as config_file_fp: + return load(config_file_fp) + + +class DummyWatcher(object): + def __call__(self, *args, **kwargs): + return False + + def watch(self, *args, **kwargs): + pass + + +class DeferredWatcher(object): + def __init__(self, *args, **kwargs): + self.args = args + self.kwargs = kwargs + self.calls = [] + + def __call__(self, *args, **kwargs): + self.calls.append(('__call__', args, kwargs)) + + def watch(self, *args, **kwargs): + self.calls.append(('watch', args, kwargs)) + + def unwatch(self, *args, **kwargs): + self.calls.append(('unwatch', args, kwargs)) + + def transfer_calls(self, watcher): + for attr, args, kwargs in self.calls: + getattr(watcher, attr)(*args, **kwargs) + + +class ConfigLoader(MultiRunnedThread): + def __init__(self, shutdown_event=None, watcher=None, watcher_type=None, load=load_json_config, run_once=False): + super(ConfigLoader, self).__init__() + self.shutdown_event = shutdown_event or Event() + if run_once: + self.watcher = DummyWatcher() + self.watcher_type = 'dummy' + else: + self.watcher = watcher or DeferredWatcher() + if watcher: + if not watcher_type: + raise ValueError('When specifying watcher you must also specify watcher type') + self.watcher_type = watcher_type + else: + self.watcher_type = 'deferred' + self._load = load + + self.pl = None + self.interval = None + + self.lock = Lock() + + self.watched = defaultdict(set) + self.missing = defaultdict(set) + self.loaded = {} + + def set_watcher(self, watcher_type, force=False): + if watcher_type == self.watcher_type: + return + watcher = create_file_watcher(self.pl, watcher_type) + with self.lock: + if self.watcher_type == 'deferred': + self.watcher.transfer_calls(watcher) + self.watcher = watcher + self.watcher_type = watcher_type + + def set_pl(self, pl): + self.pl = pl + + def set_interval(self, interval): + self.interval = interval + + def register(self, function, path): + '''Register function that will be run when file changes. + + :param function function: + Function that will be called when file at the given path changes. + :param str path: + Path that will be watched for. + ''' + with self.lock: + self.watched[path].add(function) + self.watcher.watch(path) + + def register_missing(self, condition_function, function, key): + '''Register any function that will be called with given key each + interval seconds (interval is defined at __init__). Its result is then + passed to ``function``, but only if the result is true. + + :param function condition_function: + Function which will be called each ``interval`` seconds. All + exceptions from it will be logged and ignored. IOError exception + will be ignored without logging. + :param function function: + Function which will be called if condition_function returns + something that is true. Accepts result of condition_function as an + argument. + :param str key: + Any value, it will be passed to condition_function on each call. + + Note: registered functions will be automatically removed if + condition_function results in something true. + ''' + with self.lock: + self.missing[key].add((condition_function, function)) + + def unregister_functions(self, removed_functions): + '''Unregister files handled by these functions. + + :param set removed_functions: + Set of functions previously passed to ``.register()`` method. + ''' + with self.lock: + for path, functions in list(self.watched.items()): + functions -= removed_functions + if not functions: + self.watched.pop(path) + self.loaded.pop(path, None) + + def unregister_missing(self, removed_functions): + '''Unregister files handled by these functions. + + :param set removed_functions: + Set of pairs (2-tuples) representing ``(condition_function, + function)`` function pairs previously passed as an arguments to + ``.register_missing()`` method. + ''' + with self.lock: + for key, functions in list(self.missing.items()): + functions -= removed_functions + if not functions: + self.missing.pop(key) + + def load(self, path): + try: + # No locks: GIL does what we need + return deepcopy(self.loaded[path]) + except KeyError: + r = self._load(path) + self.loaded[path] = deepcopy(r) + return r + + def update(self): + toload = [] + with self.lock: + for path, functions in self.watched.items(): + for function in functions: + try: + modified = self.watcher(path) + except OSError as e: + modified = True + self.exception('Error while running watcher for path {0}: {1}', path, str(e)) + else: + if modified: + toload.append(path) + if modified: + function(path) + with self.lock: + for key, functions in list(self.missing.items()): + for condition_function, function in list(functions): + try: + path = condition_function(key) + except IOError: + pass + except Exception as e: + self.exception('Error while running condition function for key {0}: {1}', key, str(e)) + else: + if path: + toload.append(path) + function(path) + functions.remove((condition_function, function)) + if not functions: + self.missing.pop(key) + for path in toload: + try: + self.loaded[path] = deepcopy(self._load(path)) + except Exception as e: + self.exception('Error while loading {0}: {1}', path, str(e)) + try: + self.loaded.pop(path) + except KeyError: + pass + try: + self.loaded.pop(path) + except KeyError: + pass + + def run(self): + while self.interval is not None and not self.shutdown_event.is_set(): + self.update() + self.shutdown_event.wait(self.interval) + + def exception(self, msg, *args, **kwargs): + if self.pl: + self.pl.exception(msg, prefix='config_loader', *args, **kwargs) + else: + raise |