MemcachedMonitor.java

package org.apereo.cas.monitor;

import net.spy.memcached.MemcachedClientIF;

import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

/**
 * Monitors the memcached hosts known to an instance of {@link net.spy.memcached.MemcachedClientIF}.
 *
 * @author Marvin S. Addison
 * @since 3.5.1
 */
public class MemcachedMonitor extends AbstractCacheMonitor {

    private final MemcachedClientIF memcachedClient;

    /**
     * Creates a new monitor that observes the given memcached client.
     *
     * @param client Memcached client.
     */
    public MemcachedMonitor(final MemcachedClientIF client) {
        super(MemcachedMonitor.class.getSimpleName());
        this.memcachedClient = client;
    }

    /**
     * Supersede the default cache status algorithm by considering unavailable memcached nodes above cache statistics.
     * If all nodes are unavailable, raise an error; if one or more nodes are unavailable, raise a warning; otherwise
     * delegate to examination of cache statistics.
     *
     * @return Cache status descriptor.
     */
    @Override
    public CacheStatus observe() {
        if (this.memcachedClient.getAvailableServers().isEmpty()) {
            return new CacheStatus(StatusCode.ERROR, "No memcached servers available.");
        }
        final Collection<SocketAddress> unavailableList = this.memcachedClient.getUnavailableServers();
        final CacheStatus status;
        if (!unavailableList.isEmpty()) {
            final String description = "One or more memcached servers is unavailable: " + unavailableList;
            status = new CacheStatus(StatusCode.WARN, description, getStatistics());
        } else {
            status = super.observe();
        }
        return status;
    }


    /**
     * Get cache statistics for all memcached hosts known to {@link MemcachedClientIF}.
     *
     * @return Statistics for all available hosts.
     */
    @Override
    protected CacheStatistics[] getStatistics() {
        final List<CacheStatistics> statsList = new ArrayList<>();
        if (this.memcachedClient != null) {
            this.memcachedClient.getStats().forEach((key, statsMap) -> {
                if (!statsMap.isEmpty()) {
                    final long size = Long.parseLong(statsMap.get("bytes"));
                    final long capacity = Long.parseLong(statsMap.get("limit_maxbytes"));
                    final long evictions = Long.parseLong(statsMap.get("evictions"));

                    final String name;
                    if (key instanceof InetSocketAddress) {
                        name = ((InetSocketAddress) key).getHostName();
                    } else {
                        name = key.toString();
                    }
                    statsList.add(new SimpleCacheStatistics(size, capacity, evictions, name));
                }
            });
        }
        return statsList.toArray(new CacheStatistics[statsList.size()]);
    }
}