/*
 * 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.phoenix.cache;

import static org.apache.phoenix.query.QueryServices.MAX_MEMORY_PERC_ATTRIB;
import static org.apache.phoenix.query.QueryServices.MAX_MEMORY_SIZE_ATTRIB;
import static org.apache.phoenix.query.QueryServices.MAX_TENANT_MEMORY_PERC_ATTRIB;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.phoenix.hbase.index.util.ImmutableBytesPtr;
import org.apache.phoenix.memory.ChildMemoryManager;
import org.apache.phoenix.memory.GlobalMemoryManager;
import org.apache.phoenix.query.QueryServices;
import org.apache.phoenix.query.QueryServicesOptions;
import org.apache.phoenix.schema.PMetaDataEntity;
import org.apache.phoenix.schema.metrics.MetricsMetadataSource;
import org.apache.phoenix.util.SizedUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.phoenix.thirdparty.com.google.common.cache.Cache;
import org.apache.phoenix.thirdparty.com.google.common.cache.CacheBuilder;
import org.apache.phoenix.thirdparty.com.google.common.cache.Weigher;

/**
 * Global root cache for the server. Each tenant is managed as a child tenant cache of this one.
 * Queries not associated with a particular tenant use this as their tenant cache.
 * @since 0.1
 */
public class GlobalCache extends TenantCacheImpl {
  private static final Logger LOGGER = LoggerFactory.getLogger(GlobalCache.class);
  private static volatile GlobalCache INSTANCE;

  private final Configuration config;
  // TODO: Use Guava cache with auto removal after lack of access
  private final ConcurrentMap<ImmutableBytesWritable, TenantCache> perTenantCacheMap =
    new ConcurrentHashMap<ImmutableBytesWritable, TenantCache>();
  // Cache for lastest PTable for a given Phoenix table
  private volatile Cache<ImmutableBytesPtr, PMetaDataEntity> metaDataCache;
  private MetricsMetadataSource metricsSource;

  public long clearTenantCache() {
    long unfreedBytes = getMemoryManager().getMaxMemory() - getMemoryManager().getAvailableMemory();
    if (unfreedBytes != 0 && LOGGER.isDebugEnabled()) {
      LOGGER.debug(
        "Found " + (getMemoryManager().getMaxMemory() - getMemoryManager().getAvailableMemory())
          + " bytes not freed from global cache");
    }
    removeAllServerCache();
    for (Map.Entry<ImmutableBytesWritable, TenantCache> entry : perTenantCacheMap.entrySet()) {
      TenantCache cache = entry.getValue();
      long unfreedTenantBytes =
        cache.getMemoryManager().getMaxMemory() - cache.getMemoryManager().getAvailableMemory();
      if (unfreedTenantBytes != 0 && LOGGER.isDebugEnabled()) {
        ImmutableBytesWritable cacheId = entry.getKey();
        LOGGER.debug("Found " + unfreedTenantBytes + " bytes not freed for tenant "
          + Bytes.toStringBinary(cacheId.get(), cacheId.getOffset(), cacheId.getLength()));
      }
      unfreedBytes += unfreedTenantBytes;
      cache.removeAllServerCache();
    }
    perTenantCacheMap.clear();
    return unfreedBytes;
  }

  public Cache<ImmutableBytesPtr, PMetaDataEntity> getMetaDataCache() {
    // Lazy initialize QueryServices so that we only attempt to create an HBase Configuration
    // object upon the first attempt to connect to any cluster. Otherwise, an attempt will be
    // made at driver initialization time which is too early for some systems.
    Cache<ImmutableBytesPtr, PMetaDataEntity> result = metaDataCache;
    if (result == null) {
      synchronized (this) {
        result = metaDataCache;
        if (result == null) {
          long maxTTL =
            config.getLong(QueryServices.MAX_SERVER_METADATA_CACHE_TIME_TO_LIVE_MS_ATTRIB,
              QueryServicesOptions.DEFAULT_MAX_SERVER_METADATA_CACHE_TIME_TO_LIVE_MS);
          long maxSize = config.getLongBytes(QueryServices.MAX_SERVER_METADATA_CACHE_SIZE_ATTRIB,
            QueryServicesOptions.DEFAULT_MAX_SERVER_METADATA_CACHE_SIZE);
          metaDataCache = result = CacheBuilder.newBuilder().maximumWeight(maxSize)
            .expireAfterAccess(maxTTL, TimeUnit.MILLISECONDS)
            .weigher(new Weigher<ImmutableBytesPtr, PMetaDataEntity>() {
              @Override
              public int weigh(ImmutableBytesPtr key, PMetaDataEntity table) {
                return SizedUtil.IMMUTABLE_BYTES_PTR_SIZE + key.getLength()
                  + table.getEstimatedSize();
              }
            }).removalListener(notification -> {
              if (this.metricsSource != null) {
                if (notification.wasEvicted()) {
                  metricsSource.incrementMetadataCacheEvictionCount();
                } else {
                  metricsSource.incrementMetadataCacheRemovalCount();
                }
                if (notification.getValue() != null) {
                  metricsSource
                    .decrementMetadataCacheUsedSize(notification.getValue().getEstimatedSize());
                }
              }
            }).build();
        }
      }
    }
    return result;
  }

  public static GlobalCache getInstance(RegionCoprocessorEnvironment env) {
    GlobalCache result = INSTANCE;
    if (result == null) {
      synchronized (GlobalCache.class) {
        result = INSTANCE;
        if (result == null) {
          INSTANCE = result = new GlobalCache(env.getConfiguration());
        }
      }
    }
    return result;
  }

  /**
   * Get the tenant cache associated with the tenantId. If tenantId is not applicable, null may be
   * used in which case a global tenant cache is returned.
   * @param env      the HBase configuration
   * @param tenantId the tenant ID or null if not applicable.
   */
  public static TenantCache getTenantCache(RegionCoprocessorEnvironment env,
    ImmutableBytesPtr tenantId) {
    GlobalCache globalCache = GlobalCache.getInstance(env);
    TenantCache tenantCache =
      tenantId == null ? globalCache : globalCache.getChildTenantCache(tenantId);
    return tenantCache;
  }

  private static long getMaxMemorySize(Configuration config) {
    long maxSize = Runtime.getRuntime().maxMemory()
      * config.getInt(MAX_MEMORY_PERC_ATTRIB, QueryServicesOptions.DEFAULT_MAX_MEMORY_PERC) / 100;
    maxSize = Math.min(maxSize, config.getLongBytes(MAX_MEMORY_SIZE_ATTRIB, Long.MAX_VALUE));
    return maxSize;
  }

  private GlobalCache(Configuration config) {
    super(new GlobalMemoryManager(getMaxMemorySize(config)),
      config.getInt(QueryServices.MAX_SERVER_CACHE_TIME_TO_LIVE_MS_ATTRIB,
        QueryServicesOptions.DEFAULT_MAX_SERVER_CACHE_TIME_TO_LIVE_MS),
      config.getInt(QueryServices.MAX_SERVER_CACHE_PERSISTENCE_TIME_TO_LIVE_MS_ATTRIB,
        QueryServicesOptions.DEFAULT_MAX_SERVER_CACHE_PERSISTENCE_TIME_TO_LIVE_MS));
    this.config = config;
  }

  public Configuration getConfig() {
    return config;
  }

  /**
   * Retrieve the tenant cache given an tenantId.
   * @param tenantId the ID that identifies the tenant
   * @return the existing or newly created TenantCache
   */
  public TenantCache getChildTenantCache(ImmutableBytesPtr tenantId) {
    TenantCache tenantCache = perTenantCacheMap.get(tenantId);
    if (tenantCache == null) {
      int maxTenantMemoryPerc = config.getInt(MAX_TENANT_MEMORY_PERC_ATTRIB,
        QueryServicesOptions.DEFAULT_MAX_TENANT_MEMORY_PERC);
      int maxServerCacheTimeToLive =
        config.getInt(QueryServices.MAX_SERVER_CACHE_TIME_TO_LIVE_MS_ATTRIB,
          QueryServicesOptions.DEFAULT_MAX_SERVER_CACHE_TIME_TO_LIVE_MS);
      int maxServerCachePersistenceTimeToLive =
        config.getInt(QueryServices.MAX_SERVER_CACHE_PERSISTENCE_TIME_TO_LIVE_MS_ATTRIB,
          QueryServicesOptions.DEFAULT_MAX_SERVER_CACHE_PERSISTENCE_TIME_TO_LIVE_MS);
      TenantCacheImpl newTenantCache =
        new TenantCacheImpl(new ChildMemoryManager(getMemoryManager(), maxTenantMemoryPerc),
          maxServerCacheTimeToLive, maxServerCachePersistenceTimeToLive);
      tenantCache = perTenantCacheMap.putIfAbsent(tenantId, newTenantCache);
      if (tenantCache == null) {
        tenantCache = newTenantCache;
      }
    }
    return tenantCache;
  }

  public void setMetricsSource(MetricsMetadataSource metricsSource) {
    this.metricsSource = metricsSource;
  }

  public static class FunctionBytesPtr extends ImmutableBytesPtr {

    public FunctionBytesPtr(byte[] key) {
      super(key);
    }

    @Override
    public boolean equals(Object obj) {
      if (obj instanceof FunctionBytesPtr) return super.equals(obj);
      return false;
    }

    @Override
    public int hashCode() {
      return super.hashCode();
    }
  }
}
