Revert "third_party/protobuf: Update to HEAD (83d681ee2c)"

third_party/protobuf/java/core/src/main/java/com/google/protobuf/ByteBufferWriter.java

Index: third_party/protobuf/java/core/src/main/java/com/google/protobuf/ByteBufferWriter.java
diff --git a/third_party/protobuf/java/core/src/main/java/com/google/protobuf/ByteBufferWriter.java b/third_party/protobuf/java/core/src/main/java/com/google/protobuf/ByteBufferWriter.java
index 6157a52f50f58f9e0a28621f69332b56f0a9b1b4..0cc38175f908cd41bb6b2c4e46723d676b373fcb 100644
--- a/third_party/protobuf/java/core/src/main/java/com/google/protobuf/ByteBufferWriter.java
+++ b/third_party/protobuf/java/core/src/main/java/com/google/protobuf/ByteBufferWriter.java
@@ -33,12 +33,11 @@ package com.google.protobuf;
 import static java.lang.Math.max;
 import static java.lang.Math.min;
 
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.lang.ref.SoftReference;
-import java.lang.reflect.Field;
 import java.nio.ByteBuffer;
-import java.nio.channels.WritableByteChannel;
 
 /**
  * Utility class to provide efficient writing of {@link ByteBuffer}s to {@link OutputStream}s.
@@ -76,12 +75,6 @@ final class ByteBufferWriter {
       new ThreadLocal<SoftReference<byte[]>>();
 
   /**
-   * This is a hack for GAE, where {@code FileOutputStream} is unavailable.
-   */
-  private static final Class<?> FILE_OUTPUT_STREAM_CLASS = safeGetClass("java.io.FileOutputStream");
-  private static final long CHANNEL_FIELD_OFFSET = getChannelFieldOffset(FILE_OUTPUT_STREAM_CLASS);
-
-  /**
    * For testing purposes only. Clears the cached buffer to force a new allocation on the next
    * invocation.
    */
@@ -100,7 +93,10 @@ final class ByteBufferWriter {
         // Optimized write for array-backed buffers.
         // Note that we're taking the risk that a malicious OutputStream could modify the array.
         output.write(buffer.array(), buffer.arrayOffset() + buffer.position(), buffer.remaining());
-      } else if (!writeToChannel(buffer, output)){
+      } else if (output instanceof FileOutputStream) {
+        // Use a channel to write out the ByteBuffer. This will automatically empty the buffer.
+        ((FileOutputStream) output).getChannel().write(buffer);
+      } else {
         // Read all of the data from the buffer to an array.
         // TODO(nathanmittler): Consider performance improvements for other "known" stream types.
         final byte[] array = getOrCreateBuffer(buffer.remaining());
@@ -146,40 +142,4 @@ final class ByteBufferWriter {
   private static void setBuffer(byte[] value) {
     BUFFER.set(new SoftReference<byte[]>(value));
   }
-
-  private static boolean writeToChannel(ByteBuffer buffer, OutputStream output) throws IOException {
-    if (CHANNEL_FIELD_OFFSET >= 0 && FILE_OUTPUT_STREAM_CLASS.isInstance(output)) {
-      // Use a channel to write out the ByteBuffer. This will automatically empty the buffer.
-      WritableByteChannel channel = null;
-      try {
-        channel = (WritableByteChannel) UnsafeUtil.getObject(output, CHANNEL_FIELD_OFFSET);
-      } catch (ClassCastException e) {
-        // Absorb.
-      }
-      if (channel != null) {
-        channel.write(buffer);
-        return true;
-      }
-    }
-    return false;
-  }
-
-  private static Class<?> safeGetClass(String className) {
-    try {
-      return Class.forName(className);
-    } catch (ClassNotFoundException e) {
-      return null;
-    }
-  }
-  private static long getChannelFieldOffset(Class<?> clazz) {
-    try {
-      if (clazz != null && UnsafeUtil.hasUnsafeArrayOperations()) {
-        Field field = clazz.getDeclaredField("channel");
-        return UnsafeUtil.objectFieldOffset(field);
-      }
-    } catch (Throwable e) {
-      // Absorb
-    }
-    return -1;
-  }
 }