/*
    * 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.commons.pool2;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.commons.pool2.impl.DefaultPooledObject;
  
  /**
   * Object factory with configurable latencies for object lifecycle methods.
   * This factory will also track and enforce maxActive, maxActivePerKey contracts.
   * If the factory's maxActive / maxActivePerKey are set to match those of the
   * pool, makeObject will throw IllegalStateException if the number of makes - destroys
   * (per key) exceeds the configured max.
   *
   * @param <K> The type of keys managed by this factory.
   */
  public class WaiterFactory<K> implements PooledObjectFactory<Waiter>, KeyedPooledObjectFactory<K, Waiter> {
  
      /** Integer value 0. */
      private static final Integer ZERO = Integer.valueOf(0);
  
      /** Integer value 1. */
      private static final Integer ONE = Integer.valueOf(1);
  
      /** Latency of activateObject */
      private final long activateLatency;
  
      /** Latency of destroyObject */
      private final long destroyLatency;
  
      /** Latency of makeObject */
      private final long makeLatency;
  
      /** Latency of passivateObject */
      private final long passivateLatency;
  
      /** Latency of validateObject */
      private final long validateLatency;
  
      /** Latency of doWait for Waiter instances created by this factory */
      private final long waiterLatency;
  
      /** Probability that passivation will invalidate Waiter instances */
      private final double passivateInvalidationProbability;
  
      /** Count of (makes - destroys) since last reset */
      private long activeCount;
  
      /** Count of (makes - destroys) per key since last reset */
      private final Map<K, Integer> activeCounts = new HashMap<>();
  
      /** Maximum of (makes - destroys) - if exceeded IllegalStateException */
      private final long maxActive;  // GKOP 1.x calls this maxTotal
  
      /** Maximum of (makes - destroys) per key */
      private final long maxActivePerKey;  // GKOP 1.x calls this maxActive
  
      public WaiterFactory(final long activateLatency, final long destroyLatency, final long makeLatency, final long passivateLatency, final long validateLatency,
              final long waiterLatency) {
          this(activateLatency, destroyLatency, makeLatency, passivateLatency, validateLatency, waiterLatency, Long.MAX_VALUE, Long.MAX_VALUE, 0);
      }
  
      public WaiterFactory(final long activateLatency, final long destroyLatency, final long makeLatency, final long passivateLatency, final long validateLatency,
              final long waiterLatency, final long maxActive) {
          this(activateLatency, destroyLatency, makeLatency, passivateLatency, validateLatency, waiterLatency, maxActive, Long.MAX_VALUE, 0);
      }
  
      public WaiterFactory(final long activateLatency, final long destroyLatency, final long makeLatency, final long passivateLatency, final long validateLatency,
              final long waiterLatency, final long maxActive, final long maxActivePerKey, final double passivateInvalidationProbability) {
          this.activateLatency = activateLatency;
          this.destroyLatency = destroyLatency;
          this.makeLatency = makeLatency;
          this.passivateLatency = passivateLatency;
          this.validateLatency = validateLatency;
          this.waiterLatency = waiterLatency;
          this.maxActive = maxActive;
          this.maxActivePerKey = maxActivePerKey;
          this.passivateInvalidationProbability = passivateInvalidationProbability;
      }
  
      @Override
      public void activateObject(final K key, final PooledObject<Waiter> obj) {
         activateObject(obj);
     }
 
     @Override
     public void activateObject(final PooledObject<Waiter> obj) {
         doWait(activateLatency);
         obj.getObject().setActive(true);
     }
 
     @Override
     public void destroyObject(final K key, final PooledObject<Waiter> obj) {
         destroyObject(obj);
         synchronized (this) {
             activeCounts.computeIfPresent(key, (k, v) -> Integer.valueOf(v.intValue() - 1));
         }
     }
 
     @Override
     public void destroyObject(final PooledObject<Waiter> obj) {
         doWait(destroyLatency);
         obj.getObject().setValid(false);
         obj.getObject().setActive(false);
         // Decrement *after* destroy
         synchronized (this) {
             activeCount--;
         }
     }
 
     protected void doWait(final long latency) {
         if (latency == 0) {
             return;
         }
         Waiter.sleepQuietly(latency);
     }
 
     /**
      * @return the maxActive
      */
     public synchronized long getMaxActive() {
         return maxActive;
     }
 
     @Override
     public PooledObject<Waiter> makeObject() {
         // Increment and test *before* make
         synchronized (this) {
             if (activeCount >= maxActive) {
                 throw new IllegalStateException("Too many active instances: " +
                 activeCount + " in circulation with maxActive = " + maxActive);
             }
             activeCount++;
         }
         doWait(makeLatency);
         return new DefaultPooledObject<>(new Waiter(false, true, waiterLatency));
     }
 
     @Override
     public PooledObject<Waiter> makeObject(final K key) {
         synchronized (this) {
             activeCounts.merge(key, ONE, (v1, v2) -> {
                 if (v1.intValue() >= maxActivePerKey) {
                     throw new IllegalStateException("Too many active " +
                     "instances for key = " + key + ": " + v1.intValue() +
                     " in circulation " + "with maxActivePerKey = " +
                     maxActivePerKey);
                 }
                 return Integer.valueOf(v1.intValue() + 1);
             });
         }
         return makeObject();
     }
 
     @Override
     public void passivateObject(final K key, final PooledObject<Waiter> obj) {
         passivateObject(obj);
     }
 
     @Override
     public void passivateObject(final PooledObject<Waiter> obj) {
         obj.getObject().setActive(false);
         doWait(passivateLatency);
         if (Math.random() < passivateInvalidationProbability) {
             obj.getObject().setValid(false);
         }
     }
 
     public synchronized void reset() {
         activeCount = 0;
         if (activeCounts.isEmpty()) {
             return;
         }
         for (K key : activeCounts.keySet()) {
             activeCounts.put(key, ZERO);
         }
     }
 
     @Override
     public boolean validateObject(final K key, final PooledObject<Waiter> obj) {
         return validateObject(obj);
     }
 
     @Override
     public boolean validateObject(final PooledObject<Waiter> obj) {
         doWait(validateLatency);
         return obj.getObject().isValid();
     }
 
 }