/**
     * A counter of the number of reads since the last write, used to drain queues on a small
     * fraction of read operations.
     */
    final AtomicInteger readCount = new AtomicInteger();

    /**
     * A queue of elements currently in the map, ordered by write time. Elements are added to the
     * tail of the queue on write.
     */
    @GuardedBy("this")

import java.util.concurrent.Executors
import java.util.concurrent.SynchronousQueue
import java.util.concurrent.TimeUnit
import java.util.concurrent.atomic.AtomicBoolean
import java.util.concurrent.atomic.AtomicInteger
import java.util.concurrent.atomic.AtomicReference
import javax.net.ssl.SSLException
import javax.net.ssl.SSLHandshakeException
import javax.net.ssl.SSLPeerUnverifiedException
import javax.net.ssl.SSLProtocolException