HADOOP-17101. Replace Guava Function with Java8+ Function

Signed-off-by: Jonathan Eagles <jeagles@gmail.com>

hadoop-build-tools/src/main/resources/checkstyle/checkstyle.xml

@@ -123,7 +123,7 @@
           <property name="regexp" value="true"/>
           <property name="illegalPkgs" value="^sun\.[^.]+"/>
           <property name="illegalClasses"
-            value="^com\.google\.common\.base\.(Optional)"/>
+            value="^com\.google\.common\.base\.(Optional|Function), ^com\.google\.common\.collect\.(ImmutableListMultimap)"/>
         </module>
         <module name="RedundantImport"/>
         <module name="UnusedImports"/>

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/HostSet.java

@@ -17,15 +17,12 @@
  */
 package org.apache.hadoop.hdfs.server.blockmanagement;
 
-import com.google.common.base.Function;
-import com.google.common.base.Joiner;
+
 import com.google.common.base.Preconditions;
 import com.google.common.collect.HashMultimap;
-import com.google.common.collect.Iterators;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.UnmodifiableIterator;
 
-import javax.annotation.Nullable;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.util.Collection;
@@ -101,14 +98,16 @@ public class HostSet implements Iterable<InetSocketAddress> {
   @Override
   public String toString() {
     StringBuilder sb = new StringBuilder("HostSet(");
-    Joiner.on(",").appendTo(sb, Iterators.transform(iterator(),
-        new Function<InetSocketAddress, String>() {
-          @Override
-          public String apply(@Nullable InetSocketAddress addr) {
-            assert addr != null;
-            return addr.getAddress().getHostAddress() + ":" + addr.getPort();
-          }
-        }));
-    return sb.append(")").toString();
+    Iterator<InetSocketAddress> iter = iterator();
+    String sep = "";
+    while (iter.hasNext()) {
+      InetSocketAddress addr = iter.next();
+      sb.append(sep);
+      sb.append(addr.getAddress().getHostAddress());
+      sb.append(':');
+      sb.append(addr.getPort());
+      sep = ",";
+    }
+    return sb.append(')').toString();
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalSet.java

@@ -24,8 +24,10 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Map;
 import java.util.PriorityQueue;
 import java.util.SortedSet;
 import java.util.concurrent.CopyOnWriteArrayList;
@@ -38,13 +40,9 @@ import org.apache.hadoop.hdfs.server.common.StorageInfo;
 import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
 import org.apache.hadoop.hdfs.server.protocol.RemoteEditLog;
 import org.apache.hadoop.hdfs.server.protocol.RemoteEditLogManifest;
-
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
-import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Multimaps;
 import com.google.common.collect.Sets;
 
 /**
@@ -634,7 +632,7 @@ public class JournalSet implements JournalManager {
    */
   public synchronized RemoteEditLogManifest getEditLogManifest(long fromTxId) {
     // Collect RemoteEditLogs available from each FileJournalManager
-    List<RemoteEditLog> allLogs = Lists.newArrayList();
+    List<RemoteEditLog> allLogs = new ArrayList<>();
     for (JournalAndStream j : journals) {
       if (j.getManager() instanceof FileJournalManager) {
         FileJournalManager fjm = (FileJournalManager)j.getManager();
@@ -645,15 +643,17 @@ public class JournalSet implements JournalManager {
         }
       }
     }
-    
     // Group logs by their starting txid
-    ImmutableListMultimap<Long, RemoteEditLog> logsByStartTxId =
-      Multimaps.index(allLogs, RemoteEditLog.GET_START_TXID);
+    final Map<Long, List<RemoteEditLog>> logsByStartTxId = new HashMap<>();
+    allLogs.forEach(input -> {
+      long key = RemoteEditLog.GET_START_TXID.apply(input);
+      logsByStartTxId.computeIfAbsent(key, k-> new ArrayList<>()).add(input);
+    });
     long curStartTxId = fromTxId;
-
-    List<RemoteEditLog> logs = Lists.newArrayList();
+    List<RemoteEditLog> logs = new ArrayList<>();
     while (true) {
-      ImmutableList<RemoteEditLog> logGroup = logsByStartTxId.get(curStartTxId);
+      List<RemoteEditLog> logGroup =
+          logsByStartTxId.getOrDefault(curStartTxId, Collections.emptyList());
       if (logGroup.isEmpty()) {
         // we have a gap in logs - for example because we recovered some old
         // storage directory with ancient logs. Clear out any logs we've

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/RemoteEditLog.java

@@ -17,8 +17,8 @@
  */
 package org.apache.hadoop.hdfs.server.protocol;
 
-import com.google.common.base.Function;
 import com.google.common.collect.ComparisonChain;
+import java.util.function.Function;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
 
 public class RemoteEditLog implements Comparable<RemoteEditLog> {
@@ -82,16 +82,13 @@ public class RemoteEditLog implements Comparable<RemoteEditLog> {
   }
   
   /**
-   * Guava <code>Function</code> which applies {@link #getStartTxId()} 
+   * Java <code>Function</code> which applies {@link #getStartTxId()}
    */
   public static final Function<RemoteEditLog, Long> GET_START_TXID =
-    new Function<RemoteEditLog, Long>() {
-      @Override
-      public Long apply(RemoteEditLog log) {
+      log -> {
         if (null == log) {
           return HdfsServerConstants.INVALID_TXID;
         }
         return log.getStartTxId();
-      }
-    };
+      };
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/HATestUtil.java

@@ -37,9 +37,7 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.LongAccumulator;
 
-import com.google.common.base.Function;
 import com.google.common.base.Joiner;
-import com.google.common.collect.Iterables;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -304,15 +302,11 @@ public abstract class HATestUtil {
   public static <P extends FailoverProxyProvider<?>> void
       setFailoverConfigurations(Configuration conf, String logicalName,
       List<InetSocketAddress> nnAddresses, Class<P> classFPP) {
-    setFailoverConfigurations(conf, logicalName,
-        Iterables.transform(nnAddresses, new Function<InetSocketAddress, String>() {
-
-          // transform the inet address to a simple string
-          @Override
-          public String apply(InetSocketAddress addr) {
-            return "hdfs://" + addr.getHostName() + ":" + addr.getPort();
-          }
-        }), classFPP);
+    final List<String> addresses = new ArrayList();
+    nnAddresses.forEach(
+        addr -> addresses.add(
+            "hdfs://" + addr.getHostName() + ":" + addr.getPort()));
+    setFailoverConfigurations(conf, logicalName, addresses, classFPP);
   }
 
   public static <P extends FailoverProxyProvider<?>>

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/lib/input/TestFileInputFormat.java

@@ -23,8 +23,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
 import java.util.Set;
-
-import javax.annotation.Nullable;
+import java.util.stream.Collectors;
 
 import org.junit.Assert;
 
@@ -55,8 +54,6 @@ import org.junit.runners.Parameterized.Parameters;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.google.common.base.Function;
-import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 
@@ -403,13 +400,10 @@ public class TestFileInputFormat {
       List<FileStatus> fetchedStatuses, final FileSystem localFs) {
     Assert.assertEquals(expectedPaths.size(), fetchedStatuses.size());
 
-    Iterable<Path> fqExpectedPaths = Iterables.transform(expectedPaths,
-        new Function<Path, Path>() {
-          @Override
-          public Path apply(Path input) {
-            return localFs.makeQualified(input);
-          }
-        });
+    Iterable<Path> fqExpectedPaths =
+        expectedPaths.stream().map(
+            input -> localFs.makeQualified(input)).collect(Collectors.toList());
+
 
     Set<Path> expectedPathSet = Sets.newHashSet(fqExpectedPaths);
     for (FileStatus fileStatus : fetchedStatuses) {
@@ -424,13 +418,10 @@ public class TestFileInputFormat {
 
 
   private void verifySplits(List<String> expected, List<InputSplit> splits) {
-    Iterable<String> pathsFromSplits = Iterables.transform(splits,
-        new Function<InputSplit, String>() {
-          @Override
-          public String apply(@Nullable InputSplit input) {
-            return ((FileSplit) input).getPath().toString();
-          }
-        });
+    Iterable<String> pathsFromSplits =
+        splits.stream().map(
+            input-> ((FileSplit) input).getPath().toString())
+            .collect(Collectors.toList());
 
     Set<String> expectedSet = Sets.newHashSet(expected);
     for (String splitPathString : pathsFromSplits) {

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/api/protocolrecords/impl/pb/GetApplicationsRequestPBImpl.java

@@ -22,7 +22,6 @@ import java.util.EnumSet;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
-
 import org.apache.commons.lang3.Range;
 import org.apache.hadoop.classification.InterfaceAudience.Private;
 import org.apache.hadoop.classification.InterfaceStability.Unstable;
@@ -35,8 +34,6 @@ import org.apache.hadoop.yarn.proto.YarnProtos.YarnApplicationStateProto;
 import org.apache.hadoop.yarn.proto.YarnServiceProtos.GetApplicationsRequestProto;
 import org.apache.hadoop.yarn.proto.YarnServiceProtos.GetApplicationsRequestProtoOrBuilder;
 
-import com.google.common.base.Function;
-import com.google.common.collect.Iterables;
 import org.apache.hadoop.thirdparty.protobuf.TextFormat;
 
 @Private
@@ -88,13 +85,8 @@ public class GetApplicationsRequestPBImpl extends GetApplicationsRequest {
     }
     if (applicationStates != null && !applicationStates.isEmpty()) {
       builder.clearApplicationStates();
-      builder.addAllApplicationStates(Iterables.transform(applicationStates,
-          new Function<YarnApplicationState, YarnApplicationStateProto>() {
-            @Override
-            public YarnApplicationStateProto apply(YarnApplicationState input) {
-              return ProtoUtils.convertToProtoFormat(input);
-            }
-          }));
+      applicationStates.forEach(input ->
+          builder.addApplicationStates(ProtoUtils.convertToProtoFormat(input)));
     }
     if (applicationTags != null && !applicationTags.isEmpty()) {
       builder.clearApplicationTags();