HADOOP-17887. Remove the wrapper class GzipOutputStream (#3377)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/GzipCodec.java

@@ -24,7 +24,6 @@ import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.IO_FILE_BUFFER_
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.util.zip.GZIPOutputStream;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
@@ -41,101 +40,10 @@ import org.apache.hadoop.io.compress.zlib.ZlibFactory;
 @InterfaceAudience.Public
 @InterfaceStability.Evolving
 public class GzipCodec extends DefaultCodec {
-  /**
-   * A bridge that wraps around a DeflaterOutputStream to make it
-   * a CompressionOutputStream.
-   */
-  @InterfaceStability.Evolving
-  protected static class GzipOutputStream extends CompressorStream {
-
-    private static class ResetableGZIPOutputStream extends GZIPOutputStream {
-      /**
-       * Fixed ten-byte gzip header. See {@link GZIPOutputStream}'s source for
-       * details.
-       */
-      private static final byte[] GZIP_HEADER = new byte[] {
-          0x1f, (byte) 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
-
-      private boolean reset = false;
-
-      public ResetableGZIPOutputStream(OutputStream out) throws IOException {
-        super(out);
-      }
-
-      public synchronized void resetState() throws IOException {
-        reset = true;
-      }
-
-      @Override
-      public synchronized void write(byte[] buf, int off, int len)
-          throws IOException {
-        if (reset) {
-          def.reset();
-          crc.reset();
-          out.write(GZIP_HEADER);
-          reset = false;
-        }
-        super.write(buf, off, len);
-      }
-
-      @Override
-      public synchronized void close() throws IOException {
-        reset = false;
-        super.close();
-      }
-
-    }
-
-    public GzipOutputStream(OutputStream out) throws IOException {
-      super(new ResetableGZIPOutputStream(out));
-    }
-
-    /**
-     * Allow children types to put a different type in here.
-     * @param out the Deflater stream to use
-     */
-    protected GzipOutputStream(CompressorStream out) {
-      super(out);
-    }
-
-    @Override
-    public void close() throws IOException {
-      out.close();
-    }
-    
-    @Override
-    public void flush() throws IOException {
-      out.flush();
-    }
-    
-    @Override
-    public void write(int b) throws IOException {
-      out.write(b);
-    }
-    
-    @Override
-    public void write(byte[] data, int offset, int length) 
-      throws IOException {
-      out.write(data, offset, length);
-    }
-    
-    @Override
-    public void finish() throws IOException {
-      ((ResetableGZIPOutputStream) out).finish();
-    }
-
-    @Override
-    public void resetState() throws IOException {
-      ((ResetableGZIPOutputStream) out).resetState();
-    }
-  }
 
   @Override
   public CompressionOutputStream createOutputStream(OutputStream out) 
     throws IOException {
-    if (!ZlibFactory.isNativeZlibLoaded(conf)) {
-      return new GzipOutputStream(out);
-    }
     return CompressionCodec.Util.
         createOutputStreamWithCodecPool(this, conf, out);
   }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zlib/BuiltInGzipCompressor.java

@@ -56,7 +56,6 @@ public class BuiltInGzipCompressor implements Compressor {
 
   private int numExtraBytesWritten = 0;
 
-  private int currentBufLen = 0;
   private int accuBufLen = 0;
 
   private final Checksum crc = DataChecksum.newCrc32();
@@ -86,10 +85,6 @@ public class BuiltInGzipCompressor implements Compressor {
 
     int compressedBytesWritten = 0;
 
-    if (currentBufLen <= 0) {
-      return compressedBytesWritten;
-    }
-
     // If we are not within uncompressed data yet, output the header.
     if (state == BuiltInGzipDecompressor.GzipStateLabel.HEADER_BASIC) {
       int outputHeaderSize = writeHeader(b, off, len);
@@ -166,7 +161,6 @@ public class BuiltInGzipCompressor implements Compressor {
   public void reinit(Configuration conf) {
     init(conf);
     numExtraBytesWritten = 0;
-    currentBufLen = 0;
     headerOff = 0;
     trailerOff = 0;
     crc.reset();
@@ -178,7 +172,6 @@ public class BuiltInGzipCompressor implements Compressor {
     deflater.reset();
     state = BuiltInGzipDecompressor.GzipStateLabel.HEADER_BASIC;
     numExtraBytesWritten = 0;
-    currentBufLen = 0;
     headerOff = 0;
     trailerOff = 0;
     crc.reset();
@@ -201,8 +194,7 @@ public class BuiltInGzipCompressor implements Compressor {
 
     deflater.setInput(b, off, len);
     crc.update(b, off, len);  // CRC-32 is on uncompressed data
-    currentBufLen = len;
+    accuBufLen += len;
-    accuBufLen += currentBufLen;
   }
 
   private int writeHeader(byte[] b, int off, int len) {
@@ -251,7 +243,6 @@ public class BuiltInGzipCompressor implements Compressor {
 
     if (trailerOff == gzipTrailerLen) {
       state = BuiltInGzipDecompressor.GzipStateLabel.FINISHED;
-      currentBufLen = 0;
       headerOff = 0;
       trailerOff = 0;
     }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/compress/TestCodec.java

@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.io.compress;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -1051,4 +1052,45 @@ public class TestCodec {
       }
     }
   }
+
+  @Test(timeout=20000)
+  public void testGzipCompressorWithEmptyInput() throws IOException {
+    // don't use native libs
+    ZlibFactory.setNativeZlibLoaded(false);
+    Configuration conf = new Configuration();
+    CompressionCodec codec = ReflectionUtils.newInstance(GzipCodec.class, conf);
+
+    Compressor compressor = codec.createCompressor();
+    assertThat(compressor).withFailMessage("should be BuiltInGzipCompressor")
+            .isInstanceOf(BuiltInGzipCompressor.class);
+
+    byte[] b = new byte[0];
+    compressor.setInput(b, 0, b.length);
+    compressor.finish();
+
+    byte[] output = new byte[100];
+    int outputOff = 0;
+
+    while (!compressor.finished()) {
+      byte[] buf = new byte[100];
+      int compressed = compressor.compress(buf, 0, buf.length);
+      System.arraycopy(buf, 0, output, outputOff, compressed);
+      outputOff += compressed;
+    }
+
+    DataInputBuffer gzbuf = new DataInputBuffer();
+    gzbuf.reset(output, outputOff);
+
+    Decompressor decom = codec.createDecompressor();
+    assertThat(decom).as("decompressor should not be null").isNotNull();
+    assertThat(decom).withFailMessage("should be BuiltInGzipDecompressor")
+            .isInstanceOf(BuiltInGzipDecompressor.class);
+    try (InputStream gzin = codec.createInputStream(gzbuf, decom);
+         DataOutputBuffer dflbuf = new DataOutputBuffer()) {
+      dflbuf.reset();
+      IOUtils.copyBytes(gzin, dflbuf, 4096);
+      final byte[] dflchk = Arrays.copyOf(dflbuf.getData(), dflbuf.getLength());
+      assertThat(b).as("check decompressed output").isEqualTo(dflchk);
+    }
+  }
 }