def __init__(self, max_idle_time=60):
"""
Create a new instance.
max_idle_time - max idle time in seconds
"""
if self.__class__._instance:
msg = "FileHandleManager is a singleton. Call get_instance()"
raise ValueError(msg)
self.max_idle_time = max_idle_time
self.cache = OrderedDict()
self.__class__._instance = self
def __init__(self, max_idle_time=60):
"""
Create a new instance.
max_idle_time - max idle time in seconds
"""
if self.__class__._instance:
msg = "FileHandleManager is a singleton. Call get_instance()"
raise ValueError(msg)
self.max_idle_time = max_idle_time
self.cache = OrderedDict()
self.__class__._instance = self
class FileHandleManager(object):
"""Creates FileHandleWrappers, closes handles when they have
been inactive for a period of time, and transparently re-open the next
time they are needed. All files are opened in append mode.
This class is singleton. An already configured instance can be
retrieving by using get_instance() (and will be created if None),
max_idle_time can be set by calling the classmethod set_max_idle_time()
"""
_instance = None
def __init__(self, max_idle_time=60):
"""
Create a new instance.
max_idle_time - max idle time in seconds
"""
if self.__class__._instance:
msg = "FileHandleManager is a singleton. Call get_instance()"
raise ValueError(msg)
self.max_idle_time = max_idle_time
self.cache = OrderedDict()
self.__class__._instance = self
@classmethod
def set_max_idle_time(cls, max_idle_time):
inst = cls.get_instance()
inst.max_idle_time = max_idle_time
@classmethod
def get_instance(cls):
if cls._instance is None:
cls._instance = cls()
return cls._instance
@classmethod
def reset(cls):
"""Empty the cache and reset the instance to it's original state."""
inst = cls.get_instance()
for fh_wrapper in inst.cache.values():
inst.remove(fh_wrapper)
def open(self, filename):
"""Retrieve a file handle from the cache based on name. Returns a
FileHandleWrapper. If the handle is not in the cache, create a new
instance.
"""
if filename in self.cache:
return self.cache[filename]
fhw = FileHandleWrapper(self, filename)
self.cache[filename] = fhw
return fhw
def cleanup(self, time_func=time.time):
"""Close any file handles that have been idle for longer than
max_idle_time. time_func is primary used for testing.
"""
if not self.cache:
return
cur_time = time_func()
for name, fh_wrapper in self.cache.items():
if cur_time - fh_wrapper.last_accessed > self.max_idle_time:
fh_wrapper.close()
else:
break
def remove(self, fh_wrapper):
"""Remove the fh_wrapper from the cache and access_order."""
if fh_wrapper.name in self.cache:
del self.cache[fh_wrapper.name]
def update(self, fh_wrapper):
"""Remove and re-add the file handle to the cache so that it's keys
are still ordered by last access. Calls cleanup() to remove any file
handles that have been idle for too long.
"""
self.remove(fh_wrapper)
self.cache[fh_wrapper.name] = fh_wrapper
self.cleanup()
class FileHandleManager(object):
"""Creates FileHandleWrappers, closes handles when they have
been inactive for a period of time, and transparently re-open the next
time they are needed. All files are opened in append mode.
This class is singleton. An already configured instance can be
retrieving by using get_instance() (and will be created if None),
max_idle_time can be set by calling the classmethod set_max_idle_time()
"""
_instance = None
def __init__(self, max_idle_time=60):
"""
Create a new instance.
max_idle_time - max idle time in seconds
"""
if self.__class__._instance:
msg = "FileHandleManager is a singleton. Call get_instance()"
raise ValueError(msg)
self.max_idle_time = max_idle_time
self.cache = OrderedDict()
self.__class__._instance = self
@classmethod
def set_max_idle_time(cls, max_idle_time):
inst = cls.get_instance()
inst.max_idle_time = max_idle_time
@classmethod
def get_instance(cls):
if cls._instance is None:
cls._instance = cls()
return cls._instance
@classmethod
def reset(cls):
"""Empty the cache and reset the instance to it's original state."""
inst = cls.get_instance()
for fh_wrapper in inst.cache.values():
inst.remove(fh_wrapper)
def open(self, filename):
"""Retrieve a file handle from the cache based on name. Returns a
FileHandleWrapper. If the handle is not in the cache, create a new
instance.
"""
if filename in self.cache:
return self.cache[filename]
fhw = FileHandleWrapper(self, filename)
self.cache[filename] = fhw
return fhw
def cleanup(self, time_func=time.time):
"""Close any file handles that have been idle for longer than
max_idle_time. time_func is primary used for testing.
"""
if not self.cache:
return
cur_time = time_func()
for name, fh_wrapper in self.cache.items():
if cur_time - fh_wrapper.last_accessed > self.max_idle_time:
fh_wrapper.close()
else:
break
def remove(self, fh_wrapper):
"""Remove the fh_wrapper from the cache and access_order."""
if fh_wrapper.name in self.cache:
del self.cache[fh_wrapper.name]
def update(self, fh_wrapper):
"""Remove and re-add the file handle to the cache so that it's keys
are still ordered by last access. Calls cleanup() to remove any file
handles that have been idle for too long.
"""
self.remove(fh_wrapper)
self.cache[fh_wrapper.name] = fh_wrapper
self.cleanup()
