Commit 7e8841bd authored by Michael Hanselmann's avatar Michael Hanselmann
Browse files

locking.LockSet: Move timeout calculation to separate class



This class can also be used by mcpu.
Signed-off-by: default avatarMichael Hanselmann <hansmi@google.com>
Reviewed-by: default avatarIustin Pop <iustin@google.com>
parent b6b87034
......@@ -52,6 +52,59 @@ def ssynchronized(lock, shared=0):
return wrap
class RunningTimeout(object):
"""Class to calculate remaining timeout when doing several operations.
"""
__slots__ = [
"_allow_negative",
"_start_time",
"_time_fn",
"_timeout",
]
def __init__(self, timeout, allow_negative, _time_fn=time.time):
"""Initializes this class.
@type timeout: float
@param timeout: Timeout duration
@type allow_negative: bool
@param allow_negative: Whether to return values below zero
@param _time_fn: Time function for unittests
"""
object.__init__(self)
if timeout is not None and timeout < 0.0:
raise ValueError("Timeout must not be negative")
self._timeout = timeout
self._allow_negative = allow_negative
self._time_fn = _time_fn
self._start_time = None
def Remaining(self):
"""Returns the remaining timeout.
"""
if self._timeout is None:
return None
# Get start time on first calculation
if self._start_time is None:
self._start_time = self._time_fn()
# Calculate remaining time
remaining_timeout = self._start_time + self._timeout - self._time_fn()
if not self._allow_negative:
# Ensure timeout is always >= 0
return max(0.0, remaining_timeout)
return remaining_timeout
class _SingleNotifyPipeConditionWaiter(object):
"""Helper class for SingleNotifyPipeCondition
......@@ -777,13 +830,7 @@ class LockSet:
# We need to keep track of how long we spent waiting for a lock. The
# timeout passed to this function is over all lock acquires.
remaining_timeout = timeout
if timeout is None:
start = None
calc_remaining_timeout = lambda: None
else:
start = time.time()
calc_remaining_timeout = lambda: max(0.0, (start + timeout) - time.time())
running_timeout = RunningTimeout(timeout, False)
try:
if names is not None:
......@@ -794,7 +841,7 @@ class LockSet:
names = sorted(names)
return self.__acquire_inner(names, False, shared,
calc_remaining_timeout, test_notify)
running_timeout.Remaining, test_notify)
else:
# If no names are given acquire the whole set by not letting new names
......@@ -807,14 +854,14 @@ class LockSet:
# anyway, though, so we'll get the list lock exclusively as well in
# order to be able to do add() on the set while owning it.
if not self.__lock.acquire(shared=shared,
timeout=calc_remaining_timeout()):
timeout=running_timeout.Remaining()):
raise _AcquireTimeout()
try:
# note we own the set-lock
self._add_owned()
return self.__acquire_inner(self.__names(), True, shared,
calc_remaining_timeout, test_notify)
running_timeout.Remaining, test_notify)
except:
# We shouldn't have problems adding the lock to the owners list, but
# if we did we'll try to release this lock and re-raise exception.
......@@ -827,7 +874,13 @@ class LockSet:
return None
def __acquire_inner(self, names, want_all, shared, timeout_fn, test_notify):
"""
"""Inner logic for acquiring a number of locks.
@param names: Names of the locks to be acquired
@param want_all: Whether all locks in the set should be acquired
@param shared: Whether to acquire in shared mode
@param timeout_fn: Function returning remaining timeout
@param test_notify: Special callback function for unittesting
"""
acquire_list = []
......@@ -863,8 +916,6 @@ class LockSet:
test_notify_fn = None
timeout = timeout_fn()
if timeout is not None and timeout < 0:
raise _AcquireTimeout()
try:
# raises LockError if the lock was deleted
......
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