+++ /dev/null
-/*-
- * ============LICENSE_START=======================================================
- * ONAP : APPC
- * ================================================================================
- * Copyright (C) 2017-2018 AT&T Intellectual Property. All rights reserved.
- * ================================================================================
- * Copyright (C) 2017 Amdocs
- * =============================================================================
- * Licensed 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.
- *
- * ============LICENSE_END=========================================================
- */
-
-
-
-package org.onap.appc.pool;
-
-import java.io.Closeable;
-import java.util.ArrayDeque;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Deque;
-import java.util.List;
-import java.util.ListIterator;
-import java.util.Properties;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.locks.Lock;
-import java.util.concurrent.locks.ReadWriteLock;
-import java.util.concurrent.locks.ReentrantReadWriteLock;
-
-/**
- * This class is used to manage a pool of things.
- * <p>
- * The class is parameterized so that the type of objects maintained in the pool is definable by some provided type.
- * This type must implement the <code>Comparable</code> interface so that it can be managed in the pool.
- * </p>
- *
- * @param <T>
- * The type of element being pooled
- */
-
-public class Pool<T extends Closeable> {
- private Deque<T> free;
- private List<T> allocated;
- private int minPool;
- private int maxPool;
- private Allocator<T> allocator;
- private Destructor<T> destructor;
- private ReadWriteLock lock;
- private AtomicBoolean drained;
- private Properties properties;
-
- /**
- * Create the pool
- *
- * @param minPool
- * The minimum size of the pool
- * @param maxPool
- * The maximum size of the pool, set to zero (0) for unbounded
- * @throws PoolSpecificationException
- * If the minimum size is less than 0, or if the max size is non-zero and less than the min size.
- */
- public Pool(int minPool, int maxPool) throws PoolSpecificationException {
-
- if (minPool < 0) {
- throw new PoolSpecificationException(String.format("The minimum pool size must be a "
- + "positive value or zero, %d is not valid.", minPool));
- }
- if (maxPool != 0 && maxPool < minPool) {
- throw new PoolSpecificationException(String.format("The maximum pool size must be a "
- + "positive value greater than the minimum size, or zero. %d is not valid.", maxPool));
- }
-
- this.minPool = minPool;
- this.maxPool = maxPool;
-
- properties = new Properties();
- free = new ArrayDeque<T>();
- allocated = new ArrayList<T>();
- lock = new ReentrantReadWriteLock();
- drained = new AtomicBoolean(false);
- }
-
- /**
- * Returns the amount of objects on the free collection
- *
- * @return The number of objects on the free collection
- */
- public int getFreeSize() {
- Lock readLock = lock.readLock();
- readLock.lock();
- try {
- return free.size();
- } finally {
- readLock.unlock();
- }
- }
-
- /**
- * Returns the value for a specified property of this pool, if defined.
- *
- * @param key
- * The key of the desired property
- * @return The value of the property, or null if not defined
- */
- public String getProperty(String key) {
- return properties.getProperty(key);
- }
-
- /**
- * Sets the value of the specified property or replaces it if it already exists
- *
- * @param key
- * The key of the property to be set
- * @param value
- * The value to set the property to
- */
- public void setProperty(String key, String value) {
- properties.setProperty(key, value);
- }
-
- /**
- * @return The properties object for the pool
- */
- public Properties getProperties() {
- return properties;
- }
-
- /**
- * Returns the number of objects that are currently allocated
- *
- * @return The allocate collection size
- */
- public int getAllocatedSize() {
- Lock readLock = lock.readLock();
- readLock.lock();
- try {
- return allocated.size();
- } finally {
- readLock.unlock();
- }
- }
-
- /**
- * @return the value of allocator
- */
- public Allocator<T> getAllocator() {
- return allocator;
- }
-
- /**
- * @param allocator
- * the value for allocator
- */
- public void setAllocator(Allocator<T> allocator) {
- this.allocator = allocator;
- }
-
- /**
- * @return the value of destructor
- */
- public Destructor<T> getDestructor() {
- return destructor;
- }
-
- /**
- * @return the value of minPool
- */
- public int getMinPool() {
- return minPool;
- }
-
- /**
- * @return the value of maxPool
- */
- public int getMaxPool() {
- return maxPool;
- }
-
- /**
- * @param destructor
- * the value for destructor
- */
- public void setDestructor(Destructor<T> destructor) {
- this.destructor = destructor;
- }
-
- /**
- * Drains the pool, releasing and destroying all pooled objects, even if they are currently allocated.
- */
- public void drain() {
- if (drained.compareAndSet(false, true)) {
- Lock writeLock = lock.writeLock();
- writeLock.lock();
- try {
- int size = getAllocatedSize();
- /*
- * We can't use the "release" method call here because we are modifying the list we are iterating
- */
- ListIterator<T> it = allocated.listIterator();
- while (it.hasNext()) {
- T obj = it.next();
- it.remove();
- free.addFirst(obj);
- }
- size = getFreeSize();
- trim(size);
- } finally {
- writeLock.unlock();
- }
- }
- }
-
- /**
- * Returns an indication if the pool has been drained
- *
- * @return True indicates that the pool has been drained. Once a pool has been drained, it can no longer be used.
- */
- public boolean isDrained() {
- return drained.get();
- }
-
- /**
- * Reserves an object of type T from the pool for the caller and returns it
- *
- * @return The object of type T to be used by the caller
- * @throws PoolExtensionException
- * If the pool cannot be extended
- * @throws PoolDrainedException
- * If the caller is trying to reserve an element from a drained pool
- */
- @SuppressWarnings("unchecked")
- public T reserve() throws PoolExtensionException, PoolDrainedException {
- if (isDrained()) {
- throw new PoolDrainedException("The pool has been drained and cannot be used.");
- }
-
- T obj = null;
- Lock writeLock = lock.writeLock();
- writeLock.lock();
- try {
- int freeSize = getFreeSize();
- int allocatedSize = getAllocatedSize();
-
- if (freeSize == 0) {
- if (allocatedSize == 0) {
- extend(minPool == 0 ? 1 : minPool);
- } else if (allocatedSize >= maxPool && maxPool > 0) {
- throw new PoolExtensionException(String.format("Unable to add "
- + "more elements, pool is at maximum size of %d", maxPool));
- } else {
- extend(1);
- }
- }
-
- obj = free.removeFirst();
- allocated.add(obj);
- } finally {
- writeLock.unlock();
- }
-
- /*
- * Now that we have the real object, lets wrap it in a dynamic proxy so that we can intercept the close call and
- * just return the context to the free pool. obj.getClass().getInterfaces(). We need to find ALL interfaces that
- * the object (and all superclasses) implement and have the proxy implement them too
- */
- Class<?> cls = obj.getClass();
- Class<?>[] array;
- List<Class<?>> interfaces = new ArrayList<Class<?>>();
- while (!cls.equals(Object.class)) {
- array = cls.getInterfaces();
- for (Class<?> item : array) {
- if (!interfaces.contains(item)) {
- interfaces.add(item);
- }
- }
- cls = cls.getSuperclass();
- }
- array = new Class<?>[interfaces.size()];
- array = interfaces.toArray(array);
- return CachedElement.newInstance(this, obj, array);
- }
-
- /**
- * releases the allocated object back to the free pool to be used by another request.
- *
- * @param obj
- * The object to be returned to the pool
- * @throws PoolDrainedException
- * If the caller is trying to release an element to a drained pool
- */
- public void release(T obj) throws PoolDrainedException {
- if (isDrained()) {
- throw new PoolDrainedException("The pool has been drained and cannot be used.");
- }
- Lock writeLock = lock.writeLock();
- writeLock.lock();
- try {
- if (allocated.remove(obj)) {
- free.addFirst(obj);
- }
- } finally {
- writeLock.unlock();
- }
- }
-
- /**
- * Extend the free pool by some number of elements
- *
- * @param count
- * The number of elements to add to the pool
- * @throws PoolExtensionException
- * if the pool cannot be extended because no allocator has been specified.
- */
- private void extend(int count) throws PoolExtensionException {
- if (allocator == null) {
- throw new PoolExtensionException(String.format("Unable to extend pool "
- + "because no allocator has been specified"));
- }
- Lock writeLock = lock.writeLock();
- writeLock.lock();
- try {
- for (int index = 0; index < count; index++) {
- T obj = allocator.allocate(this);
- if (obj == null) {
- throw new PoolExtensionException(
- "The allocator failed to allocate a new context to extend the pool.");
- }
- free.push(obj);
- }
- } finally {
- writeLock.unlock();
- }
- }
-
- /**
- * Used to trim the free collection by some specified number of elements, or the free element count, whichever is
- * less. The elements are removed from the end of the free element deque, thus trimming the oldest elements first.
- *
- * @param count
- * The number of elements to trim
- */
- private void trim(int count) {
- Lock writeLock = lock.writeLock();
- writeLock.lock();
- try {
- int trimCount = count;
- if (getFreeSize() < count) {
- trimCount = getFreeSize();
- }
- for (int i = 0; i < trimCount; i++) {
- T obj = free.removeLast();
- if (destructor != null) {
- destructor.destroy(obj, this);
- }
- }
- } finally {
- writeLock.unlock();
- }
- }
-}
Code Review / appc.git / blobdiff