[SPARK-21970][Core] Fix Redundant Throws Declarations in Java Codebase

common/kvstore/src/main/java/org/apache/spark/util/kvstore/LevelDBTypeInfo.java

@@ -249,7 +249,7 @@ Index parent() {
      * calculated only once, avoiding redundant work when multiple child indices of the
      * same parent index exist.
      */
-    byte[] childPrefix(Object value) throws Exception {
+    byte[] childPrefix(Object value) {
       Preconditions.checkState(parent == null, "Not a parent index.");
       return buildKey(name, toParentKey(value));
     }
@@ -295,7 +295,7 @@ byte[] end(byte[] prefix) {
     }
 
     /** The key for the end marker for entries with the given value. */
-    byte[] end(byte[] prefix, Object value) throws Exception {
+    byte[] end(byte[] prefix, Object value) {
       checkParent(prefix);
       return (parent != null) ? buildKey(false, prefix, name, toKey(value), END_MARKER)
         : buildKey(name, toKey(value), END_MARKER);
@@ -313,7 +313,7 @@ byte[] entityKey(byte[] prefix, Object entity) throws Exception {
       return entityKey;
     }
 
-    private void updateCount(WriteBatch batch, byte[] key, long delta) throws Exception {
+    private void updateCount(WriteBatch batch, byte[] key, long delta) {
       long updated = getCount(key) + delta;
       if (updated > 0) {
         batch.put(key, db.serializer.serialize(updated));
@@ -431,7 +431,7 @@ void remove(
       addOrRemove(batch, entity, null, null, naturalKey, prefix);
     }
 
-    long getCount(byte[] key) throws Exception {
+    long getCount(byte[] key) {
       byte[] data = db.db().get(key);
       return data != null ? db.serializer.deserializeLong(data) : 0;
     }

common/network-common/src/main/java/org/apache/spark/network/crypto/AuthEngine.java

@@ -81,7 +81,7 @@ class AuthEngine implements Closeable {
    *
    * @return A challenge to be sent the remote side.
    */
-  ClientChallenge challenge() throws GeneralSecurityException, IOException {
+  ClientChallenge challenge() throws GeneralSecurityException {
     this.authNonce = randomBytes(conf.encryptionKeyLength() / Byte.SIZE);
     SecretKeySpec authKey = generateKey(conf.keyFactoryAlgorithm(), conf.keyFactoryIterations(),
       authNonce, conf.encryptionKeyLength());
@@ -105,7 +105,7 @@ ClientChallenge challenge() throws GeneralSecurityException, IOException {
    * @return A response to be sent to the client.
    */
   ServerResponse respond(ClientChallenge clientChallenge)
-    throws GeneralSecurityException, IOException {
+    throws GeneralSecurityException {
 
     SecretKeySpec authKey = generateKey(clientChallenge.kdf, clientChallenge.iterations,
       clientChallenge.nonce, clientChallenge.keyLength);

common/network-common/src/main/java/org/apache/spark/network/sasl/SparkSaslClient.java

@@ -17,7 +17,6 @@
 
 package org.apache.spark.network.sasl;
 
-import java.io.IOException;
 import java.util.Map;
 import javax.security.auth.callback.Callback;
 import javax.security.auth.callback.CallbackHandler;
@@ -125,7 +124,7 @@ public synchronized void dispose() {
    */
   private class ClientCallbackHandler implements CallbackHandler {
     @Override
-    public void handle(Callback[] callbacks) throws IOException, UnsupportedCallbackException {
+    public void handle(Callback[] callbacks) throws UnsupportedCallbackException {
 
       for (Callback callback : callbacks) {
         if (callback instanceof NameCallback) {

common/network-common/src/main/java/org/apache/spark/network/sasl/SparkSaslServer.java

@@ -27,7 +27,6 @@
 import javax.security.sasl.Sasl;
 import javax.security.sasl.SaslException;
 import javax.security.sasl.SaslServer;
-import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.Map;
 
@@ -155,7 +154,7 @@ public byte[] unwrap(byte[] data, int offset, int len) throws SaslException {
    */
   private class DigestCallbackHandler implements CallbackHandler {
     @Override
-    public void handle(Callback[] callbacks) throws IOException, UnsupportedCallbackException {
+    public void handle(Callback[] callbacks) throws UnsupportedCallbackException {
       for (Callback callback : callbacks) {
         if (callback instanceof NameCallback) {
           logger.trace("SASL server callback: setting username");

common/network-common/src/main/java/org/apache/spark/network/server/TransportServer.java

@@ -117,7 +117,7 @@ private void init(String hostToBind, int portToBind) {
 
     bootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
       @Override
-      protected void initChannel(SocketChannel ch) throws Exception {
+      protected void initChannel(SocketChannel ch) {
         RpcHandler rpcHandler = appRpcHandler;
         for (TransportServerBootstrap bootstrap : bootstraps) {
           rpcHandler = bootstrap.doBootstrap(ch, rpcHandler);

common/network-common/src/main/java/org/apache/spark/network/util/TransportFrameDecoder.java

@@ -121,7 +121,7 @@ private long decodeFrameSize() {
     return nextFrameSize;
   }
 
-  private ByteBuf decodeNext() throws Exception {
+  private ByteBuf decodeNext() {
     long frameSize = decodeFrameSize();
     if (frameSize == UNKNOWN_FRAME_SIZE || totalSize < frameSize) {
       return null;

common/sketch/src/main/java/org/apache/spark/util/sketch/CountMinSketchImpl.java

@@ -365,7 +365,7 @@ private void writeObject(ObjectOutputStream out) throws IOException {
     this.writeTo(out);
   }
 
-  private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
+  private void readObject(ObjectInputStream in) throws IOException {
     this.readFrom0(in);
   }
 }

core/src/main/java/org/apache/spark/memory/MemoryConsumer.java

@@ -111,8 +111,6 @@ public void freeArray(LongArray array) {
   /**
    * Allocate a memory block with at least `required` bytes.
    *
-   * Throws IOException if there is not enough memory.
-   *
    * @throws OutOfMemoryError
    */
   protected MemoryBlock allocatePage(long required) {

core/src/main/java/org/apache/spark/shuffle/sort/ShuffleExternalSorter.java

@@ -140,7 +140,7 @@ final class ShuffleExternalSorter extends MemoryConsumer {
    *                   bytes written should be counted towards shuffle spill metrics rather than
    *                   shuffle write metrics.
    */
-  private void writeSortedFile(boolean isLastFile) throws IOException {
+  private void writeSortedFile(boolean isLastFile) {
 
     final ShuffleWriteMetrics writeMetricsToUse;
 
@@ -325,7 +325,7 @@ public void cleanupResources() {
    * array and grows the array if additional space is required. If the required space cannot be
    * obtained, then the in-memory data will be spilled to disk.
    */
-  private void growPointerArrayIfNecessary() throws IOException {
+  private void growPointerArrayIfNecessary() {
     assert(inMemSorter != null);
     if (!inMemSorter.hasSpaceForAnotherRecord()) {
       long used = inMemSorter.getMemoryUsage();
@@ -406,19 +406,14 @@ public void insertRecord(Object recordBase, long recordOffset, int length, int p
    * @throws IOException
    */
   public SpillInfo[] closeAndGetSpills() throws IOException {
-    try {
-      if (inMemSorter != null) {
-        // Do not count the final file towards the spill count.
-        writeSortedFile(true);
-        freeMemory();
-        inMemSorter.free();
-        inMemSorter = null;
-      }
-      return spills.toArray(new SpillInfo[spills.size()]);
-    } catch (IOException e) {
-      cleanupResources();
-      throw e;
+    if (inMemSorter != null) {
+      // Do not count the final file towards the spill count.
+      writeSortedFile(true);
+      freeMemory();
+      inMemSorter.free();
+      inMemSorter = null;
     }
+    return spills.toArray(new SpillInfo[spills.size()]);
   }
 
 }

core/src/main/java/org/apache/spark/shuffle/sort/UnsafeShuffleWriter.java

@@ -208,7 +208,7 @@ public void write(scala.collection.Iterator<Product2<K, V>> records) throws IOEx
     }
   }
 
-  private void open() throws IOException {
+  private void open() {
     assert (sorter == null);
     sorter = new ShuffleExternalSorter(
       memoryManager,

core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorter.java

@@ -346,7 +346,7 @@ public void cleanupResources() {
    * array and grows the array if additional space is required. If the required space cannot be
    * obtained, then the in-memory data will be spilled to disk.
    */
-  private void growPointerArrayIfNecessary() throws IOException {
+  private void growPointerArrayIfNecessary() {
     assert(inMemSorter != null);
     if (!inMemSorter.hasSpaceForAnotherRecord()) {
       long used = inMemSorter.getMemoryUsage();

core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeSorterSpillWriter.java

@@ -79,7 +79,7 @@ public UnsafeSorterSpillWriter(
   }
 
   // Based on DataOutputStream.writeLong.
-  private void writeLongToBuffer(long v, int offset) throws IOException {
+  private void writeLongToBuffer(long v, int offset) {
     writeBuffer[offset + 0] = (byte)(v >>> 56);
     writeBuffer[offset + 1] = (byte)(v >>> 48);
     writeBuffer[offset + 2] = (byte)(v >>> 40);
@@ -91,7 +91,7 @@ private void writeLongToBuffer(long v, int offset) throws IOException {
   }
 
   // Based on DataOutputStream.writeInt.
-  private void writeIntToBuffer(int v, int offset) throws IOException {
+  private void writeIntToBuffer(int v, int offset) {
     writeBuffer[offset + 0] = (byte)(v >>> 24);
     writeBuffer[offset + 1] = (byte)(v >>> 16);
     writeBuffer[offset + 2] = (byte)(v >>>  8);

examples/src/main/java/org/apache/spark/examples/sql/streaming/JavaStructuredSessionization.java

@@ -69,7 +69,7 @@ public static void main(String[] args) throws Exception {
     FlatMapFunction<LineWithTimestamp, Event> linesToEvents =
       new FlatMapFunction<LineWithTimestamp, Event>() {
         @Override
-        public Iterator<Event> call(LineWithTimestamp lineWithTimestamp) throws Exception {
+        public Iterator<Event> call(LineWithTimestamp lineWithTimestamp) {
           ArrayList<Event> eventList = new ArrayList<Event>();
           for (String word : lineWithTimestamp.getLine().split(" ")) {
             eventList.add(new Event(word, lineWithTimestamp.getTimestamp()));
@@ -91,8 +91,7 @@ public Iterator<Event> call(LineWithTimestamp lineWithTimestamp) throws Exceptio
     MapGroupsWithStateFunction<String, Event, SessionInfo, SessionUpdate> stateUpdateFunc =
       new MapGroupsWithStateFunction<String, Event, SessionInfo, SessionUpdate>() {
         @Override public SessionUpdate call(
-            String sessionId, Iterator<Event> events, GroupState<SessionInfo> state)
-              throws Exception {
+            String sessionId, Iterator<Event> events, GroupState<SessionInfo> state) {
           // If timed out, then remove session and send final update
           if (state.hasTimedOut()) {
             SessionUpdate finalUpdate = new SessionUpdate(
@@ -138,7 +137,7 @@ public Iterator<Event> call(LineWithTimestamp lineWithTimestamp) throws Exceptio
     Dataset<SessionUpdate> sessionUpdates = events
         .groupByKey(
             new MapFunction<Event, String>() {
-              @Override public String call(Event event) throws Exception {
+              @Override public String call(Event event) {
                 return event.getSessionId();
               }
             }, Encoders.STRING())

launcher/src/main/java/org/apache/spark/launcher/SparkLauncher.java

@@ -605,7 +605,7 @@ private ProcessBuilder createBuilder() throws IOException {
   }
 
   // Visible for testing.
-  String findSparkSubmit() throws IOException {
+  String findSparkSubmit() {
     String script = isWindows() ? "spark-submit.cmd" : "spark-submit";
     return join(File.separator, builder.getSparkHome(), "bin", script);
   }

sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/VectorizedColumnReader.java

@@ -350,14 +350,13 @@ private void decodeDictionaryIds(
    * is guaranteed that num is smaller than the number of values left in the current page.
    */
 
-  private void readBooleanBatch(int rowId, int num, WritableColumnVector column)
-      throws IOException {
+  private void readBooleanBatch(int rowId, int num, WritableColumnVector column) {
     assert(column.dataType() == DataTypes.BooleanType);
     defColumn.readBooleans(
         num, column, rowId, maxDefLevel, (VectorizedValuesReader) dataColumn);
   }
 
-  private void readIntBatch(int rowId, int num, WritableColumnVector column) throws IOException {
+  private void readIntBatch(int rowId, int num, WritableColumnVector column) {
     // This is where we implement support for the valid type conversions.
     // TODO: implement remaining type conversions
     if (column.dataType() == DataTypes.IntegerType || column.dataType() == DataTypes.DateType ||
@@ -375,7 +374,7 @@ private void readIntBatch(int rowId, int num, WritableColumnVector column) throw
     }
   }
 
-  private void readLongBatch(int rowId, int num, WritableColumnVector column) throws IOException {
+  private void readLongBatch(int rowId, int num, WritableColumnVector column) {
     // This is where we implement support for the valid type conversions.
     if (column.dataType() == DataTypes.LongType ||
         DecimalType.is64BitDecimalType(column.dataType())) {
@@ -394,7 +393,7 @@ private void readLongBatch(int rowId, int num, WritableColumnVector column) thro
     }
   }
 
-  private void readFloatBatch(int rowId, int num, WritableColumnVector column) throws IOException {
+  private void readFloatBatch(int rowId, int num, WritableColumnVector column) {
     // This is where we implement support for the valid type conversions.
     // TODO: support implicit cast to double?
     if (column.dataType() == DataTypes.FloatType) {
@@ -405,7 +404,7 @@ private void readFloatBatch(int rowId, int num, WritableColumnVector column) thr
     }
   }
 
-  private void readDoubleBatch(int rowId, int num, WritableColumnVector column) throws IOException {
+  private void readDoubleBatch(int rowId, int num, WritableColumnVector column) {
     // This is where we implement support for the valid type conversions.
     // TODO: implement remaining type conversions
     if (column.dataType() == DataTypes.DoubleType) {
@@ -416,7 +415,7 @@ private void readDoubleBatch(int rowId, int num, WritableColumnVector column) th
     }
   }
 
-  private void readBinaryBatch(int rowId, int num, WritableColumnVector column) throws IOException {
+  private void readBinaryBatch(int rowId, int num, WritableColumnVector column) {
     // This is where we implement support for the valid type conversions.
     // TODO: implement remaining type conversions
     VectorizedValuesReader data = (VectorizedValuesReader) dataColumn;
@@ -441,7 +440,7 @@ private void readFixedLenByteArrayBatch(
       int rowId,
       int num,
       WritableColumnVector column,
-      int arrayLen) throws IOException {
+      int arrayLen) {
     VectorizedValuesReader data = (VectorizedValuesReader) dataColumn;
     // This is where we implement support for the valid type conversions.
     // TODO: implement remaining type conversions
@@ -476,7 +475,7 @@ private void readFixedLenByteArrayBatch(
     }
   }
 
-  private void readPage() throws IOException {
+  private void readPage() {
     DataPage page = pageReader.readPage();
     // TODO: Why is this a visitor?
     page.accept(new DataPage.Visitor<Void>() {