118 lines
3.7 KiB
Python
118 lines
3.7 KiB
Python
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from __future__ import unicode_literals
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import os
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from threading import Lock
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from .mmap_dict import mmap_key, MmapedDict
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class MutexValue(object):
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"""A float protected by a mutex."""
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_multiprocess = False
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def __init__(self, typ, metric_name, name, labelnames, labelvalues, **kwargs):
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self._value = 0.0
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self._lock = Lock()
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def inc(self, amount):
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with self._lock:
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self._value += amount
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def set(self, value):
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with self._lock:
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self._value = value
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def get(self):
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with self._lock:
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return self._value
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def MultiProcessValue(process_identifier=os.getpid):
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"""Returns a MmapedValue class based on a process_identifier function.
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The 'process_identifier' function MUST comply with this simple rule:
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when called in simultaneously running processes it MUST return distinct values.
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Using a different function than the default 'os.getpid' is at your own risk.
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"""
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files = {}
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values = []
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pid = {'value': process_identifier()}
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# Use a single global lock when in multi-processing mode
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# as we presume this means there is no threading going on.
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# This avoids the need to also have mutexes in __MmapDict.
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lock = Lock()
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class MmapedValue(object):
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"""A float protected by a mutex backed by a per-process mmaped file."""
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_multiprocess = True
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def __init__(self, typ, metric_name, name, labelnames, labelvalues, multiprocess_mode='', **kwargs):
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self._params = typ, metric_name, name, labelnames, labelvalues, multiprocess_mode
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with lock:
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self.__check_for_pid_change()
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self.__reset()
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values.append(self)
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def __reset(self):
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typ, metric_name, name, labelnames, labelvalues, multiprocess_mode = self._params
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if typ == 'gauge':
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file_prefix = typ + '_' + multiprocess_mode
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else:
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file_prefix = typ
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if file_prefix not in files:
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filename = os.path.join(
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os.environ['prometheus_multiproc_dir'],
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'{0}_{1}.db'.format(file_prefix, pid['value']))
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files[file_prefix] = MmapedDict(filename)
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self._file = files[file_prefix]
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self._key = mmap_key(metric_name, name, labelnames, labelvalues)
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self._value = self._file.read_value(self._key)
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def __check_for_pid_change(self):
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actual_pid = process_identifier()
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if pid['value'] != actual_pid:
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pid['value'] = actual_pid
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# There has been a fork(), reset all the values.
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for f in files.values():
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f.close()
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files.clear()
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for value in values:
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value.__reset()
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def inc(self, amount):
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with lock:
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self.__check_for_pid_change()
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self._value += amount
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self._file.write_value(self._key, self._value)
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def set(self, value):
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with lock:
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self.__check_for_pid_change()
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self._value = value
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self._file.write_value(self._key, self._value)
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def get(self):
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with lock:
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self.__check_for_pid_change()
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return self._value
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return MmapedValue
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def get_value_class():
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# Should we enable multi-process mode?
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# This needs to be chosen before the first metric is constructed,
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# and as that may be in some arbitrary library the user/admin has
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# no control over we use an environment variable.
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if 'prometheus_multiproc_dir' in os.environ:
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return MultiProcessValue()
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else:
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return MutexValue
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ValueClass = get_value_class()
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