feat: support resolving meta host through DNS

pom.xml

@@ -13,6 +13,17 @@
       <version>4.8.1</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>commons-validator</groupId>
+      <artifactId>commons-validator</artifactId>
+      <version>1.6</version>
+    </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-core</artifactId>
+      <version>2.24.5</version>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>javax.servlet</groupId>
       <artifactId>javax.servlet-api</artifactId>

scripts/format-all.sh

@@ -15,6 +15,7 @@ SRC_FILES=(src/main/java/com/xiaomi/infra/pegasus/client/*.java
            src/test/java/com/xiaomi/infra/pegasus/metrics/*.java
            src/test/java/com/xiaomi/infra/pegasus/rpc/async/*.java
            src/test/java/com/xiaomi/infra/pegasus/tools/*.java
+           src/test/java/com/xiaomi/infra/pegasus/base/*.java
            )
 
 if [ ! -f "${PROJECT_DIR}"/google-java-format-1.7-all-deps.jar ]; then

src/main/java/com/xiaomi/infra/pegasus/base/rpc_address.java

@@ -8,20 +8,19 @@
  */
 package com.xiaomi.infra.pegasus.base;
 
-import com.xiaomi.infra.pegasus.thrift.*;
-import com.xiaomi.infra.pegasus.thrift.async.*;
-import com.xiaomi.infra.pegasus.thrift.meta_data.*;
-import com.xiaomi.infra.pegasus.thrift.protocol.*;
-import com.xiaomi.infra.pegasus.thrift.transport.*;
+import com.xiaomi.infra.pegasus.thrift.TBase;
+import com.xiaomi.infra.pegasus.thrift.TException;
+import com.xiaomi.infra.pegasus.thrift.TFieldIdEnum;
+import com.xiaomi.infra.pegasus.thrift.meta_data.FieldMetaData;
+import com.xiaomi.infra.pegasus.thrift.protocol.TProtocol;
+import com.xiaomi.infra.pegasus.thrift.protocol.TStruct;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
-import java.util.Collections;
-import java.util.EnumMap;
-import java.util.EnumSet;
-import java.util.HashMap;
-import java.util.Map;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.util.*;
 
-public class rpc_address
+public final class rpc_address
     implements TBase<rpc_address, rpc_address._Fields>, java.io.Serializable, Cloneable {
   private static final TStruct STRUCT_DESC = new TStruct("rpc_address");
 
@@ -121,12 +120,9 @@ public boolean fromString(String ipPort) {
     }
 
     try {
+      // TODO(wutao1): getByName will query DNS if the given address is not valid ip:port.
       byte[] byteArray = InetAddress.getByName(pairs[0]).getAddress();
-      ip =
-          ((int) (byteArray[0] & 0xff) << 24)
-              | ((int) (byteArray[1] & 0xff) << 16)
-              | ((int) (byteArray[2] & 0xff) << 8)
-              | ((int) (byteArray[3] & 0xff));
+      ip = ByteBuffer.wrap(byteArray).order(ByteOrder.BIG_ENDIAN).getInt();
     } catch (UnknownHostException e) {
       return false;
     }
@@ -135,6 +131,12 @@ public boolean fromString(String ipPort) {
     address = ((long) ip << 32) + ((long) port << 16) + 1;
     return true;
   }
+
+  public static rpc_address fromIpPort(String ipPort) {
+    rpc_address addr = new rpc_address();
+    return addr.fromString(ipPort) ? addr : null;
+  }
+
   /** Performs a deep copy on <i>other</i>. */
   public rpc_address(rpc_address other) {
     this.address = other.address;
@@ -192,10 +194,8 @@ public int hashCode() {
   }
 
   public int compareTo(rpc_address other) {
-    if (!getClass().equals(other.getClass())) {
-      return getClass().getName().compareTo(other.getClass().getName());
-    }
-
+    if (address < other.address) return -1;
+    if (address > other.address) return 1;
     return 0;
   }
 

src/main/java/com/xiaomi/infra/pegasus/rpc/async/HostNameResolver.java

@@ -0,0 +1,42 @@
+// Copyright (c) 2019, Xiaomi, Inc.  All rights reserved.
+// This source code is licensed under the Apache License Version 2.0, which
+// can be found in the LICENSE file in the root directory of this source tree.
+package com.xiaomi.infra.pegasus.rpc.async;
+
+import com.xiaomi.infra.pegasus.base.rpc_address;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+/*
+ * Resolves host:port into a set of ip addresses.
+ * The intention of this class is to mock DNS.
+ */
+public class HostNameResolver {
+
+  public rpc_address[] resolve(String hostPort) throws IllegalArgumentException {
+    String[] pairs = hostPort.split(":");
+    if (pairs.length != 2) {
+      throw new IllegalArgumentException("Meta server host name format error!");
+    }
+
+    try {
+      Integer port = Integer.valueOf(pairs[1]);
+      InetAddress[] resolvedAddresses = InetAddress.getAllByName(pairs[0]);
+      rpc_address[] results = new rpc_address[resolvedAddresses.length];
+      int size = 0;
+      for (InetAddress addr : resolvedAddresses) {
+        rpc_address rpcAddr = new rpc_address();
+        int ip = ByteBuffer.wrap(addr.getAddress()).order(ByteOrder.BIG_ENDIAN).getInt();
+        rpcAddr.address = ((long) ip << 32) + ((long) port << 16) + 1;
+        results[size++] = rpcAddr;
+      }
+      return results;
+    } catch (UnknownHostException e) {
+      return null;
+    } catch (NumberFormatException e) {
+      throw new IllegalArgumentException("Meta server port format error!");
+    }
+  }
+}

src/main/java/com/xiaomi/infra/pegasus/rpc/async/MetaSession.java

@@ -9,31 +9,40 @@
 import com.xiaomi.infra.pegasus.operator.query_cfg_operator;
 import com.xiaomi.infra.pegasus.replication.partition_configuration;
 import io.netty.channel.EventLoopGroup;
-import java.util.ArrayList;
-import java.util.List;
+import java.util.*;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.FutureTask;
 import java.util.concurrent.TimeUnit;
+import org.apache.commons.validator.routines.InetAddressValidator;
 
-/** Created by weijiesun on 17-9-13. */
-public class MetaSession {
+public class MetaSession extends HostNameResolver {
   public MetaSession(
       ClusterManager manager,
-      String addrList[],
+      String[] addrList,
       int eachQueryTimeoutInMills,
       int defaultMaxQueryCount,
       EventLoopGroup g)
       throws IllegalArgumentException {
     clusterManager = manager;
     metaList = new ArrayList<ReplicaSession>();
-    for (String addr : addrList) {
-      rpc_address rpc_addr = new rpc_address();
-      if (rpc_addr.fromString(addr)) {
-        logger.info("add {} as meta server", addr);
-        metaList.add(clusterManager.getReplicaSession(rpc_addr));
-      } else {
-        logger.error("invalid address {}", addr);
+
+    if (addrList.length == 1 && !InetAddressValidator.getInstance().isValid(addrList[0])) {
+      // if the given string is not a valid ip address,
+      // then take it as a hostname for a try.
+      resolveHost(addrList[0]);
+      if (!metaList.isEmpty()) {
+        hostPort = addrList[0];
+      }
+    } else {
+      for (String addr : addrList) {
+        rpc_address rpcAddr = new rpc_address();
+        if (rpcAddr.fromString(addr)) {
+          logger.info("add {} as meta server", addr);
+          metaList.add(clusterManager.getReplicaSession(rpcAddr));
+        } else {
+          logger.error("invalid address {}", addr);
+        }
       }
     }
     if (metaList.isEmpty()) {
@@ -46,13 +55,13 @@ public MetaSession(
     this.group = g;
   }
 
-  public static final error_types getMetaServiceError(client_operator metaQueryOp) {
+  public static error_types getMetaServiceError(client_operator metaQueryOp) {
     if (metaQueryOp.rpc_error.errno != error_types.ERR_OK) return metaQueryOp.rpc_error.errno;
     query_cfg_operator op = (query_cfg_operator) metaQueryOp;
     return op.get_response().getErr().errno;
   }
 
-  public static final rpc_address getMetaServiceForwardAddress(client_operator metaQueryOp) {
+  public static rpc_address getMetaServiceForwardAddress(client_operator metaQueryOp) {
     if (metaQueryOp.rpc_error.errno != error_types.ERR_OK) return null;
     query_cfg_operator op = (query_cfg_operator) metaQueryOp;
     if (op.get_response().getErr().errno != error_types.ERR_FORWARD_TO_OTHERS) return null;
@@ -63,18 +72,21 @@ public static final rpc_address getMetaServiceForwardAddress(client_operator met
     return addr;
   }
 
-  public final void asyncQuery(client_operator op, Runnable callbackFunc, int maxQueryCount) {
+  public final void asyncQuery(
+      client_operator op, Runnable callbackFunc, int maxQueryCount, int maxResolveCount) {
     if (maxQueryCount == 0) {
       maxQueryCount = defaultMaxQueryCount;
     }
     MetaRequestRound round;
     synchronized (this) {
-      round = new MetaRequestRound(op, callbackFunc, maxQueryCount, metaList.get(curLeader));
+      round =
+          new MetaRequestRound(
+              op, callbackFunc, maxQueryCount, maxResolveCount, metaList.get(curLeader));
     }
     asyncCall(round);
   }
 
-  public final void query(client_operator op, int maxQueryCount) {
+  public final void query(client_operator op, int maxQueryCount, int maxResolveCount) {
     FutureTask<Void> v =
         new FutureTask<Void>(
             new Callable<Void>() {
@@ -83,7 +95,7 @@ public Void call() throws Exception {
                 return null;
               }
             });
-    asyncQuery(op, v, maxQueryCount);
+    asyncQuery(op, v, maxQueryCount, maxResolveCount);
     while (true) {
       try {
         v.get();
@@ -104,7 +116,7 @@ public final void closeSession() {
     }
   }
 
-  private final void asyncCall(final MetaRequestRound round) {
+  private void asyncCall(final MetaRequestRound round) {
     round.lastSession.asyncSend(
         round.op,
         new Runnable() {
@@ -116,7 +128,7 @@ public void run() {
         eachQueryTimeoutInMills);
   }
 
-  private final void onFinishQueryMeta(final MetaRequestRound round) {
+  void onFinishQueryMeta(final MetaRequestRound round) {
     client_operator op = round.op;
 
     boolean needDelay = false;
@@ -177,6 +189,12 @@ private final void onFinishQueryMeta(final MetaRequestRound round) {
           }
         } else if (metaList.get(curLeader) == round.lastSession) {
           curLeader = (curLeader + 1) % metaList.size();
+          // try refresh the meta list from DNS
+          if (curLeader == 0 && hostPort != null && round.maxResolveCount != 0) {
+            round.maxResolveCount--;
+            round.maxQueryCount = (metaList.size() * 2 - 1);
+            resolveHost(hostPort);
+          }
         }
       }
       round.lastSession = metaList.get(curLeader);
@@ -187,6 +205,10 @@ private final void onFinishQueryMeta(final MetaRequestRound round) {
       return;
     }
 
+    retryQueryMeta(round, needDelay);
+  }
+
+  void retryQueryMeta(final MetaRequestRound round, boolean needDelay) {
     group.schedule(
         new Runnable() {
           @Override
@@ -198,26 +220,77 @@ public void run() {
         TimeUnit.SECONDS);
   }
 
-  private static final class MetaRequestRound {
+  static final class MetaRequestRound {
     public client_operator op;
     public Runnable callbackFunc;
     public int maxQueryCount;
+    public int maxResolveCount;
     public ReplicaSession lastSession;
 
-    public MetaRequestRound(client_operator o, Runnable r, int q, ReplicaSession l) {
+    public MetaRequestRound(client_operator o, Runnable r, int qc, int rc, ReplicaSession l) {
       op = o;
       callbackFunc = r;
-      maxQueryCount = q;
+      maxQueryCount = qc;
+      maxResolveCount = rc;
       lastSession = l;
     }
   }
 
+  /*
+   * Resolves hostname:port into a set of ip addresses.
+   */
+  void resolveHost(String hostPort) throws IllegalArgumentException {
+    rpc_address[] addrs = resolve(hostPort);
+    if (addrs == null) {
+      logger.error("failed to resolve address \"{}\" as host:port", hostPort);
+      return;
+    }
+
+    Set<rpc_address> newSet = new TreeSet<rpc_address>(Arrays.asList(addrs));
+    Set<rpc_address> oldSet = new TreeSet<rpc_address>();
+    for (ReplicaSession meta : metaList) {
+      oldSet.add(meta.getAddress());
+    }
+
+    // fast path: do nothing if meta list is unchanged.
+    if (newSet.equals(oldSet)) {
+      return;
+    }
+
+    // removed metas
+    Set<rpc_address> removed = new HashSet<rpc_address>(oldSet);
+    removed.removeAll(newSet);
+    for (rpc_address addr : removed) {
+      logger.info("meta server {} was removed", addr);
+      for (int i = 0; i < metaList.size(); i++) {
+        if (metaList.get(i).getAddress().equals(addr)) {
+          ReplicaSession session = metaList.remove(i);
+          session.closeSession();
+        }
+      }
+    }
+
+    // newly added metas
+    Set<rpc_address> added = new HashSet<rpc_address>(newSet);
+    added.removeAll(oldSet);
+    for (rpc_address addr : added) {
+      metaList.add(clusterManager.getReplicaSession(addr));
+      logger.info("add {} as meta server", addr);
+    }
+  }
+
+  // Only for test.
+  List<ReplicaSession> getMetaList() {
+    return metaList;
+  }
+
   private ClusterManager clusterManager;
   private List<ReplicaSession> metaList;
   private int curLeader;
   private int eachQueryTimeoutInMills;
   private int defaultMaxQueryCount;
   private EventLoopGroup group;
+  private String hostPort;
 
   private static final org.slf4j.Logger logger =
       org.slf4j.LoggerFactory.getLogger(MetaSession.class);

src/main/java/com/xiaomi/infra/pegasus/rpc/async/ReplicaSession.java

@@ -124,6 +124,9 @@ public void closeSession() {
     VolatileFields f = fields;
     if (f.state == ConnState.CONNECTED && f.nettyChannel != null) {
       try {
+        // close().sync() means calling system API `close()` synchronously,
+        // but the connection may not be completely closed then, that is,
+        // the state may not be marked as DISCONNECTED immediately.
         f.nettyChannel.close().sync();
         logger.info("channel to {} closed", address.toString());
       } catch (Exception ex) {
@@ -146,7 +149,7 @@ public final rpc_address getAddress() {
     return address;
   }
 
-  private void doConnect() {
+  void doConnect() {
     try {
       // we will receive the channel connect event in DefaultHandler.ChannelActive
       boot.connect(address.get_ip(), address.get_port())