| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.nifi.controller.service; |
| |
| import org.apache.nifi.controller.ComponentNode; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Objects; |
| import java.util.concurrent.CompletableFuture; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.locks.Condition; |
| import java.util.concurrent.locks.Lock; |
| import java.util.concurrent.locks.ReadWriteLock; |
| import java.util.concurrent.locks.ReentrantReadWriteLock; |
| |
| public class ServiceStateTransition { |
| private static final Logger logger = LoggerFactory.getLogger(ServiceStateTransition.class); |
| private ControllerServiceState state = ControllerServiceState.DISABLED; |
| private final List<CompletableFuture<?>> enabledFutures = new ArrayList<>(); |
| private final List<CompletableFuture<?>> disabledFutures = new ArrayList<>(); |
| private final ControllerServiceNode controllerServiceNode; |
| |
| private final ReadWriteLock rwLock = new ReentrantReadWriteLock(); |
| private final Lock writeLock = rwLock.writeLock(); |
| private final Lock readLock = rwLock.readLock(); |
| private final Condition stateChangeCondition = writeLock.newCondition(); |
| |
| public ServiceStateTransition(final ControllerServiceNode controllerServiceNode) { |
| this.controllerServiceNode = controllerServiceNode; |
| } |
| |
| public boolean transitionToEnabling(final ControllerServiceState expectedState, final CompletableFuture<?> enabledFuture) { |
| writeLock.lock(); |
| try { |
| if (expectedState != state) { |
| return false; |
| } |
| |
| state = ControllerServiceState.ENABLING; |
| logger.debug("{} transitioned to ENABLING", controllerServiceNode); |
| |
| stateChangeCondition.signalAll(); |
| enabledFutures.add(enabledFuture); |
| return true; |
| } finally { |
| writeLock.unlock(); |
| } |
| } |
| |
| public boolean enable(final ControllerServiceReference controllerServiceReference) { |
| writeLock.lock(); |
| try { |
| if (state != ControllerServiceState.ENABLING) { |
| logger.debug("{} cannot be transitioned to enabled because it's not currently ENABLING but rather {}", controllerServiceNode, state); |
| return false; |
| } |
| |
| state = ControllerServiceState.ENABLED; |
| logger.debug("{} transitioned to ENABLED", controllerServiceNode); |
| |
| enabledFutures.forEach(future -> future.complete(null)); |
| } finally { |
| writeLock.unlock(); |
| } |
| |
| // We want to perform validation against other components outside of the write lock. Component validation could be expensive |
| // and more importantly could reference other controller services, which could result in a dead lock if we run the validation |
| // while holding this.writeLock. |
| final List<ComponentNode> referencingComponents = controllerServiceReference.findRecursiveReferences(ComponentNode.class); |
| for (final ComponentNode component : referencingComponents) { |
| component.performValidation(); |
| } |
| |
| // Now that the write lock was relinquished in order to perform validation on referencing components, we must re-acquire it |
| // in order to signal that a state change has completed. |
| writeLock.lock(); |
| try { |
| stateChangeCondition.signalAll(); |
| } finally { |
| writeLock.unlock(); |
| } |
| |
| return true; |
| } |
| |
| public boolean transitionToDisabling(final ControllerServiceState expectedState, final CompletableFuture<?> disabledFuture) { |
| writeLock.lock(); |
| try { |
| if (expectedState != state) { |
| logger.debug("{} cannot be transitioned to DISABLING because its state is {}, not the expected {}", controllerServiceNode, state, expectedState); |
| return false; |
| } |
| |
| state = ControllerServiceState.DISABLING; |
| stateChangeCondition.signalAll(); |
| disabledFutures.add(disabledFuture); |
| return true; |
| } finally { |
| writeLock.unlock(); |
| } |
| } |
| |
| public void disable() { |
| writeLock.lock(); |
| try { |
| state = ControllerServiceState.DISABLED; |
| logger.debug("{} transitioned to DISABLED", controllerServiceNode); |
| |
| stateChangeCondition.signalAll(); |
| disabledFutures.forEach(future -> future.complete(null)); |
| } finally { |
| writeLock.unlock(); |
| } |
| } |
| |
| public ControllerServiceState getState() { |
| readLock.lock(); |
| try { |
| return state; |
| } finally { |
| readLock.unlock(); |
| } |
| } |
| |
| public boolean awaitState(final ControllerServiceState desiredState, final long timePeriod, final TimeUnit timeUnit) throws InterruptedException { |
| Objects.requireNonNull(timeUnit); |
| final long timeout = System.currentTimeMillis() + timeUnit.toMillis(timePeriod); |
| |
| writeLock.lock(); |
| try { |
| while (desiredState != state) { |
| final long millisLeft = timeout - System.currentTimeMillis(); |
| if (millisLeft <= 0) { |
| return false; |
| } |
| |
| logger.debug("State of {} is currently {}. Will wait up to {} milliseconds for state to transition to {}", controllerServiceNode, state, millisLeft, desiredState); |
| |
| stateChangeCondition.await(millisLeft, TimeUnit.MILLISECONDS); |
| } |
| |
| return true; |
| } finally { |
| writeLock.unlock(); |
| } |
| } |
| } |