Ausgabe der neuen DB Einträge

venv/lib/python3.9/site-packages/twisted/_threads/_team.py

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+# -*- test-case-name: twisted._threads.test.test_team -*-
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Implementation of a L{Team} of workers; a thread-pool that can allocate work to
+workers.
+"""
+
+from __future__ import absolute_import, division, print_function
+
+from collections import deque
+from zope.interface import implementer
+
+from . import IWorker
+from ._convenience import Quit
+
+
+
+class Statistics(object):
+    """
+    Statistics about a L{Team}'s current activity.
+
+    @ivar idleWorkerCount: The number of idle workers.
+    @type idleWorkerCount: L{int}
+
+    @ivar busyWorkerCount: The number of busy workers.
+    @type busyWorkerCount: L{int}
+
+    @ivar backloggedWorkCount: The number of work items passed to L{Team.do}
+        which have not yet been sent to a worker to be performed because not
+        enough workers are available.
+    @type backloggedWorkCount: L{int}
+    """
+
+    def __init__(self, idleWorkerCount, busyWorkerCount,
+                 backloggedWorkCount):
+        self.idleWorkerCount = idleWorkerCount
+        self.busyWorkerCount = busyWorkerCount
+        self.backloggedWorkCount = backloggedWorkCount
+
+
+
+@implementer(IWorker)
+class Team(object):
+    """
+    A composite L{IWorker} implementation.
+
+    @ivar _quit: A L{Quit} flag indicating whether this L{Team} has been quit
+        yet.  This may be set by an arbitrary thread since L{Team.quit} may be
+        called from anywhere.
+
+    @ivar _coordinator: the L{IExclusiveWorker} coordinating access to this
+        L{Team}'s internal resources.
+
+    @ivar _createWorker: a callable that will create new workers.
+
+    @ivar _logException: a 0-argument callable called in an exception context
+        when there is an unhandled error from a task passed to L{Team.do}
+
+    @ivar _idle: a L{set} of idle workers.
+
+    @ivar _busyCount: the number of workers currently busy.
+
+    @ivar _pending: a C{deque} of tasks - that is, 0-argument callables passed
+        to L{Team.do} - that are outstanding.
+
+    @ivar _shouldQuitCoordinator: A flag indicating that the coordinator should
+        be quit at the next available opportunity.  Unlike L{Team._quit}, this
+        flag is only set by the coordinator.
+
+    @ivar _toShrink: the number of workers to shrink this L{Team} by at the
+        next available opportunity; set in the coordinator.
+    """
+
+    def __init__(self, coordinator, createWorker, logException):
+        """
+        @param coordinator: an L{IExclusiveWorker} which will coordinate access
+            to resources on this L{Team}; that is to say, an
+            L{IExclusiveWorker} whose C{do} method ensures that its given work
+            will be executed in a mutually exclusive context, not in parallel
+            with other work enqueued by C{do} (although possibly in parallel
+            with the caller).
+
+        @param createWorker: A 0-argument callable that will create an
+            L{IWorker} to perform work.
+
+        @param logException: A 0-argument callable called in an exception
+            context when the work passed to C{do} raises an exception.
+        """
+        self._quit = Quit()
+        self._coordinator = coordinator
+        self._createWorker = createWorker
+        self._logException = logException
+
+        # Don't touch these except from the coordinator.
+        self._idle = set()
+        self._busyCount = 0
+        self._pending = deque()
+        self._shouldQuitCoordinator = False
+        self._toShrink = 0
+
+
+    def statistics(self):
+        """
+        Gather information on the current status of this L{Team}.
+
+        @return: a L{Statistics} describing the current state of this L{Team}.
+        """
+        return Statistics(len(self._idle), self._busyCount, len(self._pending))
+
+
+    def grow(self, n):
+        """
+        Increase the the number of idle workers by C{n}.
+
+        @param n: The number of new idle workers to create.
+        @type n: L{int}
+        """
+        self._quit.check()
+        @self._coordinator.do
+        def createOneWorker():
+            for x in range(n):
+                worker = self._createWorker()
+                if worker is None:
+                    return
+                self._recycleWorker(worker)
+
+
+    def shrink(self, n=None):
+        """
+        Decrease the number of idle workers by C{n}.
+
+        @param n: The number of idle workers to shut down, or L{None} (or
+            unspecified) to shut down all workers.
+        @type n: L{int} or L{None}
+        """
+        self._quit.check()
+        self._coordinator.do(lambda: self._quitIdlers(n))
+
+
+    def _quitIdlers(self, n=None):
+        """
+        The implmentation of C{shrink}, performed by the coordinator worker.
+
+        @param n: see L{Team.shrink}
+        """
+        if n is None:
+            n = len(self._idle) + self._busyCount
+        for x in range(n):
+            if self._idle:
+                self._idle.pop().quit()
+            else:
+                self._toShrink += 1
+        if self._shouldQuitCoordinator and self._busyCount == 0:
+            self._coordinator.quit()
+
+
+    def do(self, task):
+        """
+        Perform some work in a worker created by C{createWorker}.
+
+        @param task: the callable to run
+        """
+        self._quit.check()
+        self._coordinator.do(lambda: self._coordinateThisTask(task))
+
+
+    def _coordinateThisTask(self, task):
+        """
+        Select a worker to dispatch to, either an idle one or a new one, and
+        perform it.
+
+        This method should run on the coordinator worker.
+
+        @param task: the task to dispatch
+        @type task: 0-argument callable
+        """
+        worker = (self._idle.pop() if self._idle
+                  else self._createWorker())
+        if worker is None:
+            # The createWorker method may return None if we're out of resources
+            # to create workers.
+            self._pending.append(task)
+            return
+        self._busyCount += 1
+        @worker.do
+        def doWork():
+            try:
+                task()
+            except:
+                self._logException()
+
+            @self._coordinator.do
+            def idleAndPending():
+                self._busyCount -= 1
+                self._recycleWorker(worker)
+
+
+    def _recycleWorker(self, worker):
+        """
+        Called only from coordinator.
+
+        Recycle the given worker into the idle pool.
+
+        @param worker: a worker created by C{createWorker} and now idle.
+        @type worker: L{IWorker}
+        """
+        self._idle.add(worker)
+        if self._pending:
+            # Re-try the first enqueued thing.
+            # (Explicitly do _not_ honor _quit.)
+            self._coordinateThisTask(self._pending.popleft())
+        elif self._shouldQuitCoordinator:
+            self._quitIdlers()
+        elif self._toShrink > 0:
+            self._toShrink -= 1
+            self._idle.remove(worker)
+            worker.quit()
+
+
+    def quit(self):
+        """
+        Stop doing work and shut down all idle workers.
+        """
+        self._quit.set()
+        # In case all the workers are idle when we do this.
+        @self._coordinator.do
+        def startFinishing():
+            self._shouldQuitCoordinator = True
+            self._quitIdlers()