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76 lines
2.1 KiB
76 lines
2.1 KiB
2 years ago
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"""Resource Manager."""
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import logging
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import time
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from threading import Condition
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from threading import Lock
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from threading import Thread
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LOGGER = logging.getLogger(__name__)
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class Resource:
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def __init__(self, manager, resources: int):
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self._manager = manager
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self._resources = resources
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def release(self):
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LOGGER.debug("Resource of %d will be returned", self._resources)
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self._manager.release(self._resources)
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@property
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def resources(self):
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return self._resources
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class ResourceManager:
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def __init__(self, total_resources: int):
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self._total_resources = total_resources
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self._cond = Condition(Lock())
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LOGGER.debug("Created a manager with %d resources", self._total_resources)
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def grab(self, resources: int):
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"""Grab a number of resources; if there are not enough resources
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available, blocks till they become available.
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"""
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LOGGER.debug("Requesting %d resources; %d avaialble", resources, self._total_resources)
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with self._cond:
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self._cond.wait_for(lambda : self._total_resources >= resources)
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self._total_resources -= resources
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return Resource(self, resources)
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def release(self, resources: int):
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"""Return the number of resources to the pool."""
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with self._cond:
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self._total_resources += resources
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self._cond.notify()
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LOGGER.debug("%d resources returned, %d available", resources, self._total_resources)
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def worker(pid, resources):
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LOGGER.debug("Thread %d is holding %d resources", pid, resources.resources)
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time.sleep(10)
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LOGGER.debug("Thread %d finished, releasing %d resources", pid, resources.resources)
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resources.release()
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def main():
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logging.basicConfig(level=logging.DEBUG)
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manager = ResourceManager(10)
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threads = []
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for i in range(10):
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resources = manager.grab(i+1)
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w = Thread(target=worker, args=[i, resources])
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threads.append(w)
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w.start()
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for t in threads:
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t.join()
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if __name__ == '__main__':
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main()
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