src/main/java/com/google/android/libraries/feed/piet/KeyedRecyclerPool.java

// Copyright 2018 The Feed Authors.
//
// 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.

package com.google.android.libraries.feed.piet;

import static com.google.android.libraries.feed.common.Validators.checkNotNull;

import android.util.LruCache;

/**
 * This is a simple implementation of a recycling pool for Adapters.
 *
 * <p>TODO: This should be made real so it supports control of the pool size
 */
class KeyedRecyclerPool<A extends ElementAdapter<?, ?>> implements RecyclerPool<A> {

  private final LruCache<RecyclerKey, SingleKeyRecyclerPool<A>> poolMap;
  private final int capacityPerPool;

  KeyedRecyclerPool(int maxKeys, int capacityPerPool) {
    poolMap = new LruCache<>(maxKeys);
    this.capacityPerPool = capacityPerPool;
  }

  @Override
  /*@Nullable*/
  public A get(RecyclerKey key) {
    if (key == null) {
      return null;
    }
    SingleKeyRecyclerPool<A> pool = poolMap.get(key);
    if (pool == null) {
      return null;
    } else {
      return pool.get(key);
    }
  }

  @Override
  public void put(RecyclerKey key, A adapter) {
    checkNotNull(key, "null key for %s", adapter);
    SingleKeyRecyclerPool<A> pool = poolMap.get(key);
    if (pool == null) {
      pool = new SingleKeyRecyclerPool<>(key, capacityPerPool);
      poolMap.put(key, pool);
    }
    pool.put(key, adapter);
  }

  @Override
  public void clear() {
    poolMap.evictAll();
  }
}