/*
 * Copyright 2018 The gRPC 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 io.grpc;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.MoreObjects;
import com.google.common.base.Objects;
import java.net.SocketAddress;
import java.security.cert.Certificate;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentNavigableMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import javax.net.ssl.SSLPeerUnverifiedException;
import javax.net.ssl.SSLSession;

/**
 * This is an internal API. Do NOT use.
 */
@Internal
public final class InternalChannelz {
  private static final Logger log = Logger.getLogger(InternalChannelz.class.getName());
  private static final InternalChannelz INSTANCE = new InternalChannelz();

  private final ConcurrentNavigableMap<Long, InternalInstrumented<ServerStats>> servers
      = new ConcurrentSkipListMap<>();
  private final ConcurrentNavigableMap<Long, InternalInstrumented<ChannelStats>> rootChannels
      = new ConcurrentSkipListMap<>();
  private final ConcurrentMap<Long, InternalInstrumented<ChannelStats>> subchannels
      = new ConcurrentHashMap<>();
  // An InProcessTransport can appear in both otherSockets and perServerSockets simultaneously
  private final ConcurrentMap<Long, InternalInstrumented<SocketStats>> otherSockets
      = new ConcurrentHashMap<>();
  private final ConcurrentMap<Long, ServerSocketMap> perServerSockets
      = new ConcurrentHashMap<>();

  // A convenience class to avoid deeply nested types.
  private static final class ServerSocketMap
      extends ConcurrentSkipListMap<Long, InternalInstrumented<SocketStats>> {
    private static final long serialVersionUID = -7883772124944661414L;
  }

  @VisibleForTesting
  public InternalChannelz() {
  }

  public static InternalChannelz instance() {
    return INSTANCE;
  }

  /** Adds a server. */
  public void addServer(InternalInstrumented<ServerStats> server) {
    ServerSocketMap prev = perServerSockets.put(id(server), new ServerSocketMap());
    assert prev == null;
    add(servers, server);
  }

  /** Adds a subchannel. */
  public void addSubchannel(InternalInstrumented<ChannelStats> subchannel) {
    add(subchannels, subchannel);
  }

  /** Adds a root channel. */
  public void addRootChannel(InternalInstrumented<ChannelStats> rootChannel) {
    add(rootChannels, rootChannel);
  }

  /** Adds a socket. */
  public void addClientSocket(InternalInstrumented<SocketStats> socket) {
    add(otherSockets, socket);
  }

  public void addListenSocket(InternalInstrumented<SocketStats> socket) {
    add(otherSockets, socket);
  }

  /** Adds a server socket. */
  public void addServerSocket(
      InternalInstrumented<ServerStats> server, InternalInstrumented<SocketStats> socket) {
    ServerSocketMap serverSockets = perServerSockets.get(id(server));
    assert serverSockets != null;
    add(serverSockets, socket);
  }

  /** Removes a server. */
  public void removeServer(InternalInstrumented<ServerStats> server) {
    remove(servers, server);
    ServerSocketMap prev = perServerSockets.remove(id(server));
    assert prev != null;
    assert prev.isEmpty();
  }

  public void removeSubchannel(InternalInstrumented<ChannelStats> subchannel) {
    remove(subchannels, subchannel);
  }

  public void removeRootChannel(InternalInstrumented<ChannelStats> channel) {
    remove(rootChannels, channel);
  }

  public void removeClientSocket(InternalInstrumented<SocketStats> socket) {
    remove(otherSockets, socket);
  }

  public void removeListenSocket(InternalInstrumented<SocketStats> socket) {
    remove(otherSockets, socket);
  }

  /** Removes a server socket. */
  public void removeServerSocket(
      InternalInstrumented<ServerStats> server, InternalInstrumented<SocketStats> socket) {
    ServerSocketMap socketsOfServer = perServerSockets.get(id(server));
    assert socketsOfServer != null;
    remove(socketsOfServer, socket);
  }

  /** Returns a {@link RootChannelList}. */
  public RootChannelList getRootChannels(long fromId, int maxPageSize) {
    List<InternalInstrumented<ChannelStats>> channelList
        = new ArrayList<>();
    Iterator<InternalInstrumented<ChannelStats>> iterator
        = rootChannels.tailMap(fromId).values().iterator();

    while (iterator.hasNext() && channelList.size() < maxPageSize) {
      channelList.add(iterator.next());
    }
    return new RootChannelList(channelList, !iterator.hasNext());
  }

  /** Returns a channel. */
  @Nullable
  public InternalInstrumented<ChannelStats> getChannel(long id) {
    return rootChannels.get(id);
  }

  /** Returns a subchannel. */
  @Nullable
  public InternalInstrumented<ChannelStats> getSubchannel(long id) {
    return subchannels.get(id);
  }

  /** Returns a server list. */
  public ServerList getServers(long fromId, int maxPageSize) {
    List<InternalInstrumented<ServerStats>> serverList
        = new ArrayList<>(maxPageSize);
    Iterator<InternalInstrumented<ServerStats>> iterator
        = servers.tailMap(fromId).values().iterator();

    while (iterator.hasNext() && serverList.size() < maxPageSize) {
      serverList.add(iterator.next());
    }
    return new ServerList(serverList, !iterator.hasNext());
  }

  /** Returns a server. */
  @Nullable
  public InternalInstrumented<ServerStats> getServer(long id) {
    return servers.get(id);
  }

  /** Returns socket refs for a server. */
  @Nullable
  public ServerSocketsList getServerSockets(long serverId, long fromId, int maxPageSize) {
    ServerSocketMap serverSockets = perServerSockets.get(serverId);
    if (serverSockets == null) {
      return null;
    }
    List<InternalWithLogId> socketList = new ArrayList<>(maxPageSize);
    Iterator<InternalInstrumented<SocketStats>> iterator
        = serverSockets.tailMap(fromId).values().iterator();
    while (socketList.size() < maxPageSize && iterator.hasNext()) {
      socketList.add(iterator.next());
    }
    return new ServerSocketsList(socketList, !iterator.hasNext());
  }

  /** Returns a socket. */
  @Nullable
  public InternalInstrumented<SocketStats> getSocket(long id) {
    InternalInstrumented<SocketStats> clientSocket = otherSockets.get(id);
    if (clientSocket != null) {
      return clientSocket;
    }
    return getServerSocket(id);
  }

  private InternalInstrumented<SocketStats> getServerSocket(long id) {
    for (ServerSocketMap perServerSockets : perServerSockets.values()) {
      InternalInstrumented<SocketStats> serverSocket = perServerSockets.get(id);
      if (serverSocket != null) {
        return serverSocket;
      }
    }
    return null;
  }

  @VisibleForTesting
  public boolean containsServer(InternalLogId serverRef) {
    return contains(servers, serverRef);
  }

  @VisibleForTesting
  public boolean containsSubchannel(InternalLogId subchannelRef) {
    return contains(subchannels, subchannelRef);
  }

  public InternalInstrumented<ChannelStats> getRootChannel(long id) {
    return rootChannels.get(id);
  }

  @VisibleForTesting
  public boolean containsClientSocket(InternalLogId transportRef) {
    return contains(otherSockets, transportRef);
  }

  private static <T extends InternalInstrumented<?>> void add(Map<Long, T> map, T object) {
    T prev = map.put(object.getLogId().getId(), object);
    assert prev == null;
  }

  private static <T extends InternalInstrumented<?>> void remove(Map<Long, T> map, T object) {
    T prev = map.remove(id(object));
    assert prev != null;
  }

  private static <T extends InternalInstrumented<?>> boolean contains(
      Map<Long, T> map, InternalLogId id) {
    return map.containsKey(id.getId());
  }

  public static final class RootChannelList {
    public final List<InternalInstrumented<ChannelStats>> channels;
    public final boolean end;

    /** Creates an instance. */
    public RootChannelList(List<InternalInstrumented<ChannelStats>> channels, boolean end) {
      this.channels = checkNotNull(channels);
      this.end = end;
    }
  }

  public static final class ServerList {
    public final List<InternalInstrumented<ServerStats>> servers;
    public final boolean end;

    /** Creates an instance. */
    public ServerList(List<InternalInstrumented<ServerStats>> servers, boolean end) {
      this.servers = checkNotNull(servers);
      this.end = end;
    }
  }

  public static final class ServerSocketsList {
    public final List<InternalWithLogId> sockets;
    public final boolean end;

    /** Creates an instance. */
    public ServerSocketsList(List<InternalWithLogId> sockets, boolean end) {
      this.sockets = sockets;
      this.end = end;
    }
  }

  @Immutable
  public static final class ServerStats {
    public final long callsStarted;
    public final long callsSucceeded;
    public final long callsFailed;
    public final long lastCallStartedNanos;
    public final List<InternalInstrumented<SocketStats>> listenSockets;

    /**
     * Creates an instance.
     */
    public ServerStats(
        long callsStarted,
        long callsSucceeded,
        long callsFailed,
        long lastCallStartedNanos,
        List<InternalInstrumented<SocketStats>> listenSockets) {
      this.callsStarted = callsStarted;
      this.callsSucceeded = callsSucceeded;
      this.callsFailed = callsFailed;
      this.lastCallStartedNanos = lastCallStartedNanos;
      this.listenSockets = checkNotNull(listenSockets);
    }

    public static final class Builder {
      private long callsStarted;
      private long callsSucceeded;
      private long callsFailed;
      private long lastCallStartedNanos;
      public List<InternalInstrumented<SocketStats>> listenSockets = new ArrayList<>();

      public Builder setCallsStarted(long callsStarted) {
        this.callsStarted = callsStarted;
        return this;
      }

      public Builder setCallsSucceeded(long callsSucceeded) {
        this.callsSucceeded = callsSucceeded;
        return this;
      }

      public Builder setCallsFailed(long callsFailed) {
        this.callsFailed = callsFailed;
        return this;
      }

      public Builder setLastCallStartedNanos(long lastCallStartedNanos) {
        this.lastCallStartedNanos = lastCallStartedNanos;
        return this;
      }

      /** Sets the listen sockets. */
      public Builder addListenSockets(List<InternalInstrumented<SocketStats>> listenSockets) {
        checkNotNull(listenSockets, "listenSockets");
        for (InternalInstrumented<SocketStats> ss : listenSockets) {
          this.listenSockets.add(checkNotNull(ss, "null listen socket"));
        }
        return this;
      }

      /**
       * Builds an instance.
       */
      public ServerStats build() {
        return new ServerStats(
            callsStarted,
            callsSucceeded,
            callsFailed,
            lastCallStartedNanos,
            listenSockets);
      }
    }
  }

  /**
   * A data class to represent a channel's stats.
   */
  @Immutable
  public static final class ChannelStats {
    public final String target;
    public final ConnectivityState state;
    @Nullable public final ChannelTrace channelTrace;
    public final long callsStarted;
    public final long callsSucceeded;
    public final long callsFailed;
    public final long lastCallStartedNanos;
    public final List<InternalWithLogId> subchannels;
    public final List<InternalWithLogId> sockets;

    /**
     * Creates an instance.
     */
    private ChannelStats(
        String target,
        ConnectivityState state,
        @Nullable ChannelTrace channelTrace,
        long callsStarted,
        long callsSucceeded,
        long callsFailed,
        long lastCallStartedNanos,
        List<InternalWithLogId> subchannels,
        List<InternalWithLogId> sockets) {
      checkState(
          subchannels.isEmpty() || sockets.isEmpty(),
          "channels can have subchannels only, subchannels can have either sockets OR subchannels, "
              + "neither can have both");
      this.target = target;
      this.state = state;
      this.channelTrace = channelTrace;
      this.callsStarted = callsStarted;
      this.callsSucceeded = callsSucceeded;
      this.callsFailed = callsFailed;
      this.lastCallStartedNanos = lastCallStartedNanos;
      this.subchannels = checkNotNull(subchannels);
      this.sockets = checkNotNull(sockets);
    }

    public static final class Builder {
      private String target;
      private ConnectivityState state;
      private ChannelTrace channelTrace;
      private long callsStarted;
      private long callsSucceeded;
      private long callsFailed;
      private long lastCallStartedNanos;
      private List<InternalWithLogId> subchannels = Collections.emptyList();
      private List<InternalWithLogId> sockets = Collections.emptyList();

      public Builder setTarget(String target) {
        this.target = target;
        return this;
      }

      public Builder setState(ConnectivityState state) {
        this.state = state;
        return this;
      }

      public Builder setChannelTrace(ChannelTrace channelTrace) {
        this.channelTrace = channelTrace;
        return this;
      }

      public Builder setCallsStarted(long callsStarted) {
        this.callsStarted = callsStarted;
        return this;
      }

      public Builder setCallsSucceeded(long callsSucceeded) {
        this.callsSucceeded = callsSucceeded;
        return this;
      }

      public Builder setCallsFailed(long callsFailed) {
        this.callsFailed = callsFailed;
        return this;
      }

      public Builder setLastCallStartedNanos(long lastCallStartedNanos) {
        this.lastCallStartedNanos = lastCallStartedNanos;
        return this;
      }

      /** Sets the subchannels. */
      public Builder setSubchannels(List<InternalWithLogId> subchannels) {
        checkState(sockets.isEmpty());
        this.subchannels = Collections.unmodifiableList(checkNotNull(subchannels));
        return this;
      }

      /** Sets the sockets. */
      public Builder setSockets(List<InternalWithLogId> sockets) {
        checkState(subchannels.isEmpty());
        this.sockets = Collections.unmodifiableList(checkNotNull(sockets));
        return this;
      }

      /**
       * Builds an instance.
       */
      public ChannelStats build() {
        return new ChannelStats(
            target,
            state,
            channelTrace,
            callsStarted,
            callsSucceeded,
            callsFailed,
            lastCallStartedNanos,
            subchannels,
            sockets);
      }
    }
  }

  @Immutable
  public static final class ChannelTrace {
    public final long numEventsLogged;
    public final long creationTimeNanos;
    public final List<Event> events;

    private ChannelTrace(long numEventsLogged, long creationTimeNanos, List<Event> events) {
      this.numEventsLogged = numEventsLogged;
      this.creationTimeNanos = creationTimeNanos;
      this.events = events;
    }

    public static final class Builder {
      private Long numEventsLogged;
      private Long creationTimeNanos;
      private List<Event> events = Collections.emptyList();

      public Builder setNumEventsLogged(long numEventsLogged) {
        this.numEventsLogged = numEventsLogged;
        return this;
      }

      public Builder setCreationTimeNanos(long creationTimeNanos) {
        this.creationTimeNanos = creationTimeNanos;
        return this;
      }

      public Builder setEvents(List<Event> events) {
        this.events = Collections.unmodifiableList(new ArrayList<>(events));
        return this;
      }

      /** Builds a new ChannelTrace instance. */
      public ChannelTrace build() {
        checkNotNull(numEventsLogged, "numEventsLogged");
        checkNotNull(creationTimeNanos, "creationTimeNanos");
        return new ChannelTrace(numEventsLogged, creationTimeNanos, events);
      }
    }

    @Immutable
    public static final class Event {
      public final String description;
      public final Severity severity;
      public final long timestampNanos;

      // the oneof child_ref field in proto: one of channelRef and channelRef
      @Nullable public final InternalWithLogId channelRef;
      @Nullable public final InternalWithLogId subchannelRef;

      public enum Severity {
        CT_UNKNOWN, CT_INFO, CT_WARNING, CT_ERROR
      }

      private Event(
          String description, Severity severity, long timestampNanos,
          @Nullable InternalWithLogId channelRef, @Nullable InternalWithLogId subchannelRef) {
        this.description = description;
        this.severity = checkNotNull(severity, "severity");
        this.timestampNanos = timestampNanos;
        this.channelRef = channelRef;
        this.subchannelRef = subchannelRef;
      }

      @Override
      public int hashCode() {
        return Objects.hashCode(description, severity, timestampNanos, channelRef, subchannelRef);
      }

      @Override
      public boolean equals(Object o) {
        if (o instanceof Event) {
          Event that = (Event) o;
          return Objects.equal(description, that.description)
              && Objects.equal(severity, that.severity)
              && timestampNanos == that.timestampNanos
              && Objects.equal(channelRef, that.channelRef)
              && Objects.equal(subchannelRef, that.subchannelRef);
        }
        return false;
      }

      @Override
      public String toString() {
        return MoreObjects.toStringHelper(this)
            .add("description", description)
            .add("severity", severity)
            .add("timestampNanos", timestampNanos)
            .add("channelRef", channelRef)
            .add("subchannelRef", subchannelRef)
            .toString();
      }

      public static final class Builder {
        private String description;
        private Severity severity;
        private Long timestampNanos;
        private InternalWithLogId channelRef;
        private InternalWithLogId subchannelRef;

        public Builder setDescription(String description) {
          this.description = description;
          return this;
        }

        public Builder setTimestampNanos(long timestampNanos) {
          this.timestampNanos = timestampNanos;
          return this;
        }

        public Builder setSeverity(Severity severity) {
          this.severity = severity;
          return this;
        }

        public Builder setChannelRef(InternalWithLogId channelRef) {
          this.channelRef = channelRef;
          return this;
        }

        public Builder setSubchannelRef(InternalWithLogId subchannelRef) {
          this.subchannelRef = subchannelRef;
          return this;
        }

        /** Builds a new Event instance. */
        public Event build() {
          checkNotNull(description, "description");
          checkNotNull(severity, "severity");
          checkNotNull(timestampNanos, "timestampNanos");
          checkState(
              channelRef == null || subchannelRef == null,
              "at least one of channelRef and subchannelRef must be null");
          return new Event(description, severity, timestampNanos, channelRef, subchannelRef);
        }
      }
    }
  }

  public static final class Security {
    @Nullable
    public final Tls tls;
    @Nullable
    public final OtherSecurity other;

    public Security(Tls tls) {
      this.tls = checkNotNull(tls);
      this.other = null;
    }

    public Security(OtherSecurity other) {
      this.tls = null;
      this.other = checkNotNull(other);
    }
  }

  public static final class OtherSecurity {
    public final String name;
    @Nullable
    public final Object any;

    /**
     * Creates an instance.
     * @param name the name.
     * @param any a com.google.protobuf.Any object
     */
    public OtherSecurity(String name, @Nullable Object any) {
      this.name = checkNotNull(name);
      checkState(
          any == null || any.getClass().getName().endsWith("com.google.protobuf.Any"),
          "the 'any' object must be of type com.google.protobuf.Any");
      this.any = any;
    }
  }

  @Immutable
  public static final class Tls {
    public final String cipherSuiteStandardName;
    @Nullable public final Certificate localCert;
    @Nullable public final Certificate remoteCert;

    /**
     * A constructor only for testing.
     */
    public Tls(String cipherSuiteName, Certificate localCert, Certificate remoteCert) {
      this.cipherSuiteStandardName = cipherSuiteName;
      this.localCert = localCert;
      this.remoteCert = remoteCert;
    }

    /**
     * Creates an instance.
     */
    public Tls(SSLSession session) {
      String cipherSuiteStandardName = session.getCipherSuite();
      Certificate localCert = null;
      Certificate remoteCert = null;
      Certificate[] localCerts = session.getLocalCertificates();
      if (localCerts != null) {
        localCert = localCerts[0];
      }
      try {
        Certificate[] peerCerts = session.getPeerCertificates();
        if (peerCerts != null) {
          // The javadoc of getPeerCertificate states that the peer's own certificate is the first
          // element of the list.
          remoteCert = peerCerts[0];
        }
      } catch (SSLPeerUnverifiedException e) {
        // peer cert is not available
        log.log(
            Level.FINE,
            String.format("Peer cert not available for peerHost=%s", session.getPeerHost()),
            e);
      }
      this.cipherSuiteStandardName = cipherSuiteStandardName;
      this.localCert = localCert;
      this.remoteCert = remoteCert;
    }
  }

  public static final class SocketStats {
    @Nullable public final TransportStats data;
    @Nullable public final SocketAddress local;
    @Nullable public final SocketAddress remote;
    public final SocketOptions socketOptions;
    // Can be null if plaintext
    @Nullable public final Security security;

    /** Creates an instance. */
    public SocketStats(
        TransportStats data,
        @Nullable SocketAddress local,
        @Nullable SocketAddress remote,
        SocketOptions socketOptions,
        Security security) {
      this.data = data;
      this.local = checkNotNull(local, "local socket");
      this.remote = remote;
      this.socketOptions = checkNotNull(socketOptions);
      this.security = security;
    }
  }

  public static final class TcpInfo {
    public final int state;
    public final int caState;
    public final int retransmits;
    public final int probes;
    public final int backoff;
    public final int options;
    public final int sndWscale;
    public final int rcvWscale;
    public final int rto;
    public final int ato;
    public final int sndMss;
    public final int rcvMss;
    public final int unacked;
    public final int sacked;
    public final int lost;
    public final int retrans;
    public final int fackets;
    public final int lastDataSent;
    public final int lastAckSent;
    public final int lastDataRecv;
    public final int lastAckRecv;
    public final int pmtu;
    public final int rcvSsthresh;
    public final int rtt;
    public final int rttvar;
    public final int sndSsthresh;
    public final int sndCwnd;
    public final int advmss;
    public final int reordering;

    TcpInfo(int state, int caState, int retransmits, int probes, int backoff, int options,
        int sndWscale, int rcvWscale, int rto, int ato, int sndMss, int rcvMss, int unacked,
        int sacked, int lost, int retrans, int fackets, int lastDataSent, int lastAckSent,
        int lastDataRecv, int lastAckRecv, int pmtu, int rcvSsthresh, int rtt, int rttvar,
        int sndSsthresh, int sndCwnd, int advmss, int reordering) {
      this.state = state;
      this.caState = caState;
      this.retransmits = retransmits;
      this.probes = probes;
      this.backoff = backoff;
      this.options = options;
      this.sndWscale = sndWscale;
      this.rcvWscale = rcvWscale;
      this.rto = rto;
      this.ato = ato;
      this.sndMss = sndMss;
      this.rcvMss = rcvMss;
      this.unacked = unacked;
      this.sacked = sacked;
      this.lost = lost;
      this.retrans = retrans;
      this.fackets = fackets;
      this.lastDataSent = lastDataSent;
      this.lastAckSent = lastAckSent;
      this.lastDataRecv = lastDataRecv;
      this.lastAckRecv = lastAckRecv;
      this.pmtu = pmtu;
      this.rcvSsthresh = rcvSsthresh;
      this.rtt = rtt;
      this.rttvar = rttvar;
      this.sndSsthresh = sndSsthresh;
      this.sndCwnd = sndCwnd;
      this.advmss = advmss;
      this.reordering = reordering;
    }

    public static final class Builder {
      private int state;
      private int caState;
      private int retransmits;
      private int probes;
      private int backoff;
      private int options;
      private int sndWscale;
      private int rcvWscale;
      private int rto;
      private int ato;
      private int sndMss;
      private int rcvMss;
      private int unacked;
      private int sacked;
      private int lost;
      private int retrans;
      private int fackets;
      private int lastDataSent;
      private int lastAckSent;
      private int lastDataRecv;
      private int lastAckRecv;
      private int pmtu;
      private int rcvSsthresh;
      private int rtt;
      private int rttvar;
      private int sndSsthresh;
      private int sndCwnd;
      private int advmss;
      private int reordering;

      public Builder setState(int state) {
        this.state = state;
        return this;
      }

      public Builder setCaState(int caState) {
        this.caState = caState;
        return this;
      }

      public Builder setRetransmits(int retransmits) {
        this.retransmits = retransmits;
        return this;
      }

      public Builder setProbes(int probes) {
        this.probes = probes;
        return this;
      }

      public Builder setBackoff(int backoff) {
        this.backoff = backoff;
        return this;
      }

      public Builder setOptions(int options) {
        this.options = options;
        return this;
      }

      public Builder setSndWscale(int sndWscale) {
        this.sndWscale = sndWscale;
        return this;
      }

      public Builder setRcvWscale(int rcvWscale) {
        this.rcvWscale = rcvWscale;
        return this;
      }

      public Builder setRto(int rto) {
        this.rto = rto;
        return this;
      }

      public Builder setAto(int ato) {
        this.ato = ato;
        return this;
      }

      public Builder setSndMss(int sndMss) {
        this.sndMss = sndMss;
        return this;
      }

      public Builder setRcvMss(int rcvMss) {
        this.rcvMss = rcvMss;
        return this;
      }

      public Builder setUnacked(int unacked) {
        this.unacked = unacked;
        return this;
      }

      public Builder setSacked(int sacked) {
        this.sacked = sacked;
        return this;
      }

      public Builder setLost(int lost) {
        this.lost = lost;
        return this;
      }

      public Builder setRetrans(int retrans) {
        this.retrans = retrans;
        return this;
      }

      public Builder setFackets(int fackets) {
        this.fackets = fackets;
        return this;
      }

      public Builder setLastDataSent(int lastDataSent) {
        this.lastDataSent = lastDataSent;
        return this;
      }

      public Builder setLastAckSent(int lastAckSent) {
        this.lastAckSent = lastAckSent;
        return this;
      }

      public Builder setLastDataRecv(int lastDataRecv) {
        this.lastDataRecv = lastDataRecv;
        return this;
      }

      public Builder setLastAckRecv(int lastAckRecv) {
        this.lastAckRecv = lastAckRecv;
        return this;
      }

      public Builder setPmtu(int pmtu) {
        this.pmtu = pmtu;
        return this;
      }

      public Builder setRcvSsthresh(int rcvSsthresh) {
        this.rcvSsthresh = rcvSsthresh;
        return this;
      }

      public Builder setRtt(int rtt) {
        this.rtt = rtt;
        return this;
      }

      public Builder setRttvar(int rttvar) {
        this.rttvar = rttvar;
        return this;
      }

      public Builder setSndSsthresh(int sndSsthresh) {
        this.sndSsthresh = sndSsthresh;
        return this;
      }

      public Builder setSndCwnd(int sndCwnd) {
        this.sndCwnd = sndCwnd;
        return this;
      }

      public Builder setAdvmss(int advmss) {
        this.advmss = advmss;
        return this;
      }

      public Builder setReordering(int reordering) {
        this.reordering = reordering;
        return this;
      }

      /** Builds an instance. */
      public TcpInfo build() {
        return new TcpInfo(
            state, caState, retransmits, probes, backoff, options, sndWscale, rcvWscale,
            rto, ato, sndMss, rcvMss, unacked, sacked, lost, retrans, fackets, lastDataSent,
            lastAckSent, lastDataRecv, lastAckRecv, pmtu, rcvSsthresh, rtt, rttvar, sndSsthresh,
            sndCwnd, advmss, reordering);
      }
    }
  }

  public static final class SocketOptions {
    public final Map<String, String> others;
    // In netty, the value of a channel option may be null.
    @Nullable public final Integer soTimeoutMillis;
    @Nullable public final Integer lingerSeconds;
    @Nullable public final TcpInfo tcpInfo;

    /** Creates an instance. */
    public SocketOptions(
        @Nullable Integer timeoutMillis,
        @Nullable Integer lingerSeconds,
        @Nullable TcpInfo tcpInfo,
        Map<String, String> others) {
      checkNotNull(others);
      this.soTimeoutMillis = timeoutMillis;
      this.lingerSeconds = lingerSeconds;
      this.tcpInfo = tcpInfo;
      this.others = Collections.unmodifiableMap(new HashMap<>(others));
    }

    public static final class Builder {
      private final Map<String, String> others = new HashMap<>();

      private TcpInfo tcpInfo;
      private Integer timeoutMillis;
      private Integer lingerSeconds;

      /** The value of {@link java.net.Socket#getSoTimeout()}. */
      public Builder setSocketOptionTimeoutMillis(Integer timeoutMillis) {
        this.timeoutMillis = timeoutMillis;
        return this;
      }

      /** The value of {@link java.net.Socket#getSoLinger()}.
       * Note: SO_LINGER is typically expressed in seconds.
       */
      public Builder setSocketOptionLingerSeconds(Integer lingerSeconds) {
        this.lingerSeconds = lingerSeconds;
        return this;
      }

      public Builder setTcpInfo(TcpInfo tcpInfo) {
        this.tcpInfo = tcpInfo;
        return this;
      }

      public Builder addOption(String name, String value) {
        others.put(name, checkNotNull(value));
        return this;
      }

      public Builder addOption(String name, int value) {
        others.put(name, Integer.toString(value));
        return this;
      }

      public Builder addOption(String name, boolean value) {
        others.put(name, Boolean.toString(value));
        return this;
      }

      public SocketOptions build() {
        return new SocketOptions(timeoutMillis, lingerSeconds, tcpInfo, others);
      }
    }
  }

  /**
   * A data class to represent transport stats.
   */
  @Immutable
  public static final class TransportStats {
    public final long streamsStarted;
    public final long lastLocalStreamCreatedTimeNanos;
    public final long lastRemoteStreamCreatedTimeNanos;
    public final long streamsSucceeded;
    public final long streamsFailed;
    public final long messagesSent;
    public final long messagesReceived;
    public final long keepAlivesSent;
    public final long lastMessageSentTimeNanos;
    public final long lastMessageReceivedTimeNanos;
    public final long localFlowControlWindow;
    public final long remoteFlowControlWindow;
    // TODO(zpencer): report socket flags and other info

    /**
     * Creates an instance.
     */
    public TransportStats(
        long streamsStarted,
        long lastLocalStreamCreatedTimeNanos,
        long lastRemoteStreamCreatedTimeNanos,
        long streamsSucceeded,
        long streamsFailed,
        long messagesSent,
        long messagesReceived,
        long keepAlivesSent,
        long lastMessageSentTimeNanos,
        long lastMessageReceivedTimeNanos,
        long localFlowControlWindow,
        long remoteFlowControlWindow) {
      this.streamsStarted = streamsStarted;
      this.lastLocalStreamCreatedTimeNanos = lastLocalStreamCreatedTimeNanos;
      this.lastRemoteStreamCreatedTimeNanos = lastRemoteStreamCreatedTimeNanos;
      this.streamsSucceeded = streamsSucceeded;
      this.streamsFailed = streamsFailed;
      this.messagesSent = messagesSent;
      this.messagesReceived = messagesReceived;
      this.keepAlivesSent = keepAlivesSent;
      this.lastMessageSentTimeNanos = lastMessageSentTimeNanos;
      this.lastMessageReceivedTimeNanos = lastMessageReceivedTimeNanos;
      this.localFlowControlWindow = localFlowControlWindow;
      this.remoteFlowControlWindow = remoteFlowControlWindow;
    }
  }

  /** Unwraps a {@link InternalLogId} to return a {@code long}. */
  public static long id(InternalWithLogId withLogId) {
    return withLogId.getLogId().getId();
  }
}
