/usr/lib/python2.7/dist-packages/pika/callback.py is in python-pika 0.9.13-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 | """Callback management class, common area for keeping track of all callbacks in
the Pika stack.
"""
import functools
import logging
from pika import frame
from pika import amqp_object
LOGGER = logging.getLogger(__name__)
def _name_or_value(value):
"""Will take Frame objects, classes, etc and attempt to return a valid
string identifier for them.
:param value: The value to sanitize
:type value: pika.amqp_object.AMQPObject|pika.frame.Frame|int|unicode|str
:rtype: str
"""
# Is it subclass of AMQPObject
try:
if issubclass(value, amqp_object.AMQPObject):
return value.NAME
except TypeError:
pass
# Is it a Pika frame object?
if isinstance(value, frame.Method):
return value.method.NAME
# Is it a Pika frame object (go after Method since Method extends this)
if isinstance(value, amqp_object.AMQPObject):
return value.NAME
# Cast the value to a string, encoding it if it's unicode
try:
return str(value)
except UnicodeEncodeError:
return str(value.encode('utf-8'))
def sanitize_prefix(function):
"""Automatically call _name_or_value on the prefix passed in."""
@functools.wraps(function)
def wrapper(*args, **kwargs):
args = list(args)
offset = 1
if 'prefix' in kwargs:
kwargs['prefix'] = _name_or_value(kwargs['prefix'])
elif len(args) - 1 >= offset:
args[offset] = _name_or_value(args[offset])
offset += 1
if 'key' in kwargs:
kwargs['key'] = _name_or_value(kwargs['key'])
elif len(args) - 1 >= offset:
args[offset] = _name_or_value(args[offset])
return function(*tuple(args), **kwargs)
return wrapper
def check_for_prefix_and_key(function):
"""Automatically return false if the key or prefix is not in the callbacks
for the instance.
"""
@functools.wraps(function)
def wrapper(*args, **kwargs):
offset = 1
# Sanitize the prefix
if 'prefix' in kwargs:
prefix = _name_or_value(kwargs['prefix'])
else:
prefix = _name_or_value(args[offset])
offset += 1
# Make sure to sanitize the key as well
if 'key' in kwargs:
key = _name_or_value(kwargs['key'])
else:
key = _name_or_value(args[offset])
# Make sure prefix and key are in the stack
if (prefix not in args[0]._stack or
key not in args[0]._stack[prefix]):
return False
# Execute the method
return function(*args, **kwargs)
return wrapper
class CallbackManager(object):
"""CallbackManager is a global callback system designed to be a single place
where Pika can manage callbacks and process them. It should be referenced
by the CallbackManager.instance() method instead of constructing new
instances of it.
"""
CALLS = 'calls'
ARGUMENTS = 'arguments'
DUPLICATE_WARNING = 'Duplicate callback found for "%s:%s"'
CALLBACK = 'callback'
ONE_SHOT = 'one_shot'
ONLY_CALLER = 'only'
def __init__(self):
"""Create an instance of the CallbackManager"""
self._stack = dict()
@sanitize_prefix
def add(self, prefix, key, callback, one_shot=True, only_caller=None,
arguments=None):
"""Add a callback to the stack for the specified key. If the call is
specified as one_shot, it will be removed after being fired
The prefix is usually the channel number but the class is generic
and prefix and key may be any value. If you pass in only_caller
CallbackManager will restrict processing of the callback to only
the calling function/object that you specify.
:param prefix: Categorize the callback
:type prefix: str or int
:param key: The key for the callback
:type key: object or str or dict
:param method callback: The callback to call
:param bool one_shot: Remove this callback after it is called
:param object only_caller: Only allow one_caller value to call the
event that fires the callback.
:param dict arguments: Arguments to validate when processing
:rtype: tuple(prefix, key)
"""
# Prep the stack
if prefix not in self._stack:
self._stack[prefix] = dict()
if key not in self._stack[prefix]:
self._stack[prefix][key] = list()
# Check for a duplicate
for callback_dict in self._stack[prefix][key]:
if (callback_dict[self.CALLBACK] == callback and
callback_dict[self.ARGUMENTS] == arguments and
callback_dict[self.ONLY_CALLER] == only_caller):
if callback_dict[self.ONE_SHOT] is True:
callback_dict[self.CALLS] += 1
LOGGER.debug('Incremented callback reference counter: %r',
callback_dict)
else:
LOGGER.warning(self.DUPLICATE_WARNING, prefix, key)
return prefix, key
# Create the callback dictionary
callback_dict = self._callback_dict(callback, one_shot, only_caller,
arguments)
self._stack[prefix][key].append(callback_dict)
LOGGER.debug('Added: %r', callback_dict)
return prefix, key
def clear(self):
"""Clear all the callbacks if there are any defined."""
self._stack = dict()
LOGGER.debug('Callbacks cleared')
@sanitize_prefix
def cleanup(self, prefix):
"""Remove all callbacks from the stack by a prefix. Returns True
if keys were there to be removed
:param str or int prefix: The prefix for keeping track of callbacks with
:rtype: bool
"""
LOGGER.debug('Clearing out %r from the stack', prefix)
if prefix not in self._stack or not self._stack[prefix]:
return False
del self._stack[prefix]
return True
@sanitize_prefix
def pending(self, prefix, key):
"""Return count of callbacks for a given prefix or key or None
:param prefix: Categorize the callback
:type prefix: str or int
:param key: The key for the callback
:type key: object or str or dict
:rtype: None or int
"""
if not prefix in self._stack or not key in self._stack[prefix]:
return None
return len(self._stack[prefix][key])
@sanitize_prefix
@check_for_prefix_and_key
def process(self, prefix, key, caller, *args, **keywords):
"""Run through and process all the callbacks for the specified keys.
Caller should be specified at all times so that callbacks which
require a specific function to call CallbackManager.process will
not be processed.
:param prefix: Categorize the callback
:type prefix: str or int
:param key: The key for the callback
:type key: object or str or dict
:param object caller: Who is firing the event
:param list args: Any optional arguments
:param dict keywords: Optional keyword arguments
:rtype: bool
"""
LOGGER.debug('Processing %s:%s', prefix, key)
if prefix not in self._stack or key not in self._stack[prefix]:
return False
callbacks = list()
# Check each callback, append it to the list if it should be called
for callback_dict in list(self._stack[prefix][key]):
if self._should_process_callback(callback_dict, caller, list(args)):
callbacks.append(callback_dict[self.CALLBACK])
if callback_dict[self.ONE_SHOT]:
self._use_one_shot_callback(prefix, key, callback_dict)
# Call each callback
for callback in callbacks:
LOGGER.debug('Calling %s for "%s:%s"', callback, prefix, key)
callback(*args, **keywords)
return True
@sanitize_prefix
@check_for_prefix_and_key
def remove(self, prefix, key, callback_value=None, arguments=None):
"""Remove a callback from the stack by prefix, key and optionally
the callback itself. If you only pass in prefix and key, all
callbacks for that prefix and key will be removed.
:param str or int prefix: The prefix for keeping track of callbacks with
:param str key: The callback key
:param method callback_value: The method defined to call on callback
:param dict arguments: Optional arguments to check
:rtype: bool
"""
if callback_value:
offsets_to_remove = list()
for offset in xrange(len(self._stack[prefix][key]), 0, -1):
callback_dict = self._stack[prefix][key][offset - 1]
if (callback_dict[self.CALLBACK] == callback_value and
self._arguments_match(callback_dict, [arguments])):
offsets_to_remove.append(offset - 1)
for offset in offsets_to_remove:
LOGGER.debug('Removing callback #%i: %r', offset,
self._stack[prefix][key][offset])
del self._stack[prefix][key][offset]
self._cleanup_callback_dict(prefix, key)
return True
@sanitize_prefix
@check_for_prefix_and_key
def remove_all(self, prefix, key):
"""Remove all callbacks for the specified prefix and key.
:param str prefix: The prefix for keeping track of callbacks with
:param str key: The callback key
"""
del self._stack[prefix][key]
self._cleanup_callback_dict(prefix, key)
def _arguments_match(self, callback_dict, args):
"""Validate if the arguments passed in match the expected arguments in
the callback_dict. We expect this to be a frame passed in to *args for
process or passed in as a list from remove.
:param dict callback_dict: The callback dictionary to evaluate against
:param list args: The arguments passed in as a list
"""
if callback_dict[self.ARGUMENTS] is None:
return True
if not args:
return False
if isinstance(args[0], dict):
return self._dict_arguments_match(args[0],
callback_dict[self.ARGUMENTS])
return self._obj_arguments_match(args[0].method if hasattr(args[0],
'method')
else args[0],
callback_dict[self.ARGUMENTS])
def _callback_dict(self, callback, one_shot, only_caller, arguments):
"""Return the callback dictionary.
:param method callback: The callback to call
:param bool one_shot: Remove this callback after it is called
:param object only_caller: Only allow one_caller value to call the
event that fires the callback.
:rtype: dict
"""
value = {self.CALLBACK: callback,
self.ONE_SHOT: one_shot,
self.ONLY_CALLER: only_caller,
self.ARGUMENTS: arguments}
if one_shot:
value[self.CALLS] = 1
return value
def _cleanup_callback_dict(self, prefix, key=None):
"""Remove empty dict nodes in the callback stack.
:param str or int prefix: The prefix for keeping track of callbacks with
:param str key: The callback key
"""
if key and key in self._stack[prefix] and not self._stack[prefix][key]:
del self._stack[prefix][key]
if prefix in self._stack and not self._stack[prefix]:
del self._stack[prefix]
def _dict_arguments_match(self, value, expectation):
"""Checks an dict to see if it has attributes that meet the expectation.
:param dict value: The dict to evaluate
:param dict expectation: The values to check against
:rtype: bool
"""
LOGGER.debug('Comparing %r to %r', value, expectation)
for key in expectation:
if value.get(key) != expectation[key]:
LOGGER.debug('Values in dict do not match for %s', key)
return False
return True
def _obj_arguments_match(self, value, expectation):
"""Checks an object to see if it has attributes that meet the
expectation.
:param object value: The object to evaluate
:param dict expectation: The values to check against
:rtype: bool
"""
for key in expectation:
if not hasattr(value, key):
LOGGER.debug('%r does not have required attribute: %s',
type(value), key)
return False
if getattr(value, key) != expectation[key]:
LOGGER.debug('Values in %s do not match for %s',
type(value), key)
return False
return True
def _should_process_callback(self, callback_dict, caller, args):
"""Returns True if the callback should be processed.
:param dict callback_dict: The callback configuration
:param object caller: Who is firing the event
:param list args: Any optional arguments
:rtype: bool
"""
if not self._arguments_match(callback_dict, args):
LOGGER.debug('Arguments do not match for %r, %r',
callback_dict, args)
return False
return (callback_dict[self.ONLY_CALLER] is None or
(callback_dict[self.ONLY_CALLER] and
callback_dict[self.ONLY_CALLER] == caller))
def _use_one_shot_callback(self, prefix, key, callback_dict):
"""Process the one-shot callback, decrementing the use counter and
removing it from the stack if it's now been fully used.
:param str or int prefix: The prefix for keeping track of callbacks with
:param str key: The callback key
:param dict callback_dict: The callback dict to process
"""
LOGGER.debug('Processing use of oneshot callback')
callback_dict[self.CALLS] -= 1
LOGGER.debug('%i registered uses left', callback_dict[self.CALLS])
if callback_dict[self.CALLS] <= 0:
self.remove(prefix, key,
callback_dict[self.CALLBACK],
callback_dict[self.ARGUMENTS])
|