Use new ParsableByteArray.reset where possible.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=133384105

library/src/main/java/com/google/android/exoplayer2/extractor/DefaultTrackOutput.java

@@ -298,6 +298,7 @@ public final class DefaultTrackOutput implements TrackOutput {
     long offset = extrasHolder.offset;
 
     // Read the signal byte.
+    scratch.reset(1);
     readData(offset, scratch.data, 1);
     offset++;
     byte signalByte = scratch.data[0];
@@ -314,9 +315,9 @@ public final class DefaultTrackOutput implements TrackOutput {
     // Read the subsample count, if present.
     int subsampleCount;
     if (subsampleEncryption) {
+      scratch.reset(2);
       readData(offset, scratch.data, 2);
       offset += 2;
-      scratch.setPosition(0);
       subsampleCount = scratch.readUnsignedShort();
     } else {
       subsampleCount = 1;
@@ -333,7 +334,7 @@ public final class DefaultTrackOutput implements TrackOutput {
     }
     if (subsampleEncryption) {
       int subsampleDataLength = 6 * subsampleCount;
-      ensureCapacity(scratch, subsampleDataLength);
+      scratch.reset(subsampleDataLength);
       readData(offset, scratch.data, subsampleDataLength);
       offset += subsampleDataLength;
       scratch.setPosition(0);
@@ -412,15 +413,6 @@ public final class DefaultTrackOutput implements TrackOutput {
     }
   }
 
-  /**
-   * Ensure that the passed {@link ParsableByteArray} is of at least the specified limit.
-   */
-  private static void ensureCapacity(ParsableByteArray byteArray, int limit) {
-    if (byteArray.limit() < limit) {
-      byteArray.reset(new byte[limit], limit);
-    }
-  }
-
   // Called by the loading thread.
 
   /**

library/src/main/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractor.java

@@ -950,13 +950,9 @@ public final class MatroskaExtractor implements Extractor {
               samplePartitionCountRead = true;
             }
             int samplePartitionDataSize = samplePartitionCount * 4;
-            if (scratch.limit() < samplePartitionDataSize) {
-              scratch.reset(new byte[samplePartitionDataSize], samplePartitionDataSize);
-            }
+            scratch.reset(samplePartitionDataSize);
             input.readFully(scratch.data, 0, samplePartitionDataSize);
             sampleBytesRead += samplePartitionDataSize;
-            scratch.setPosition(0);
-            scratch.setLimit(samplePartitionDataSize);
             short subsampleCount = (short) (1 + (samplePartitionCount / 2));
             int subsampleDataSize = 2 + 6 * subsampleCount;
             if (encryptionSubsampleDataBuffer == null

library/src/main/java/com/google/android/exoplayer2/extractor/mp4/Sniffer.java

@@ -100,13 +100,14 @@ import java.io.IOException;
     while (bytesSearched < bytesToSearch) {
       // Read an atom header.
       int headerSize = Atom.HEADER_SIZE;
+      buffer.reset(headerSize);
       input.peekFully(buffer.data, 0, headerSize);
-      buffer.setPosition(0);
       long atomSize = buffer.readUnsignedInt();
       int atomType = buffer.readInt();
       if (atomSize == Atom.LONG_SIZE_PREFIX) {
         headerSize = Atom.LONG_HEADER_SIZE;
         input.peekFully(buffer.data, Atom.HEADER_SIZE, Atom.LONG_HEADER_SIZE - Atom.HEADER_SIZE);
+        buffer.setLimit(Atom.LONG_HEADER_SIZE);
         atomSize = buffer.readUnsignedLongToLong();
       }
 
@@ -139,9 +140,7 @@ import java.io.IOException;
         if (atomDataSize < 8) {
           return false;
         }
-        if (buffer.capacity() < atomDataSize) {
-          buffer.reset(new byte[atomDataSize], atomDataSize);
-        }
+        buffer.reset(atomDataSize);
         input.peekFully(buffer.data, 0, atomDataSize);
         int brandsCount = atomDataSize / 4;
         for (int i = 0; i < brandsCount; i++) {

library/src/main/java/com/google/android/exoplayer2/extractor/ts/PsExtractor.java

@@ -153,8 +153,7 @@ public final class PsExtractor implements Extractor {
       input.peekFully(psPacketBuffer.data, 0, 10);
 
       // We only care about the pack_stuffing_length in here, skip the first 77 bits.
-      psPacketBuffer.setPosition(0);
-      psPacketBuffer.skipBytes(9);
+      psPacketBuffer.setPosition(9);
 
       // Last 3 bits is the length.
       int packStuffingLength = psPacketBuffer.readUnsignedByte() & 0x07;
@@ -209,7 +208,7 @@ public final class PsExtractor implements Extractor {
       }
     }
 
-    // The next 2 bytes are the length, once we have that we can consume the complete packet.
+    // The next 2 bytes are the length. Once we have that we can consume the complete packet.
     input.peekFully(psPacketBuffer.data, 0, 2);
     psPacketBuffer.setPosition(0);
     int payloadLength = psPacketBuffer.readUnsignedShort();
@@ -219,14 +218,10 @@ public final class PsExtractor implements Extractor {
       // Just skip this data.
       input.skipFully(pesLength);
     } else {
-      if (psPacketBuffer.capacity() < pesLength) {
-        // Reallocate for this and future packets.
-        psPacketBuffer.reset(new byte[pesLength], pesLength);
-      }
+      psPacketBuffer.reset(pesLength);
       // Read the whole packet and the header for consumption.
       input.readFully(psPacketBuffer.data, 0, pesLength);
       psPacketBuffer.setPosition(6);
-      psPacketBuffer.setLimit(pesLength);
       payloadReader.consume(psPacketBuffer);
       psPacketBuffer.setLimit(psPacketBuffer.capacity());
     }

library/src/main/java/com/google/android/exoplayer2/util/ParsableByteArray.java

@@ -35,17 +35,17 @@ public final class ParsableByteArray {
   public ParsableByteArray() {}
 
   /**
-   * Creates a new instance with {@code length} bytes.
+   * Creates a new instance with {@code limit} bytes and sets the limit.
    *
-   * @param length The length of the array.
+   * @param limit The limit to set.
    */
-  public ParsableByteArray(int length) {
-    this.data = new byte[length];
-    limit = data.length;
+  public ParsableByteArray(int limit) {
+    this.data = new byte[limit];
+    this.limit = limit;
   }
 
   /**
-   * Creates a new instance wrapping {@code data}.
+   * Creates a new instance wrapping {@code data}, and sets the limit to {@code data.length}.
    *
    * @param data The array to wrap.
    */
@@ -58,7 +58,7 @@ public final class ParsableByteArray {
    * Creates a new instance that wraps an existing array.
    *
    * @param data The data to wrap.
-   * @param limit The limit.
+   * @param limit The limit to set.
    */
   public ParsableByteArray(byte[] data, int limit) {
     this.data = data;
@@ -79,7 +79,7 @@ public final class ParsableByteArray {
    * Updates the instance to wrap {@code data}, and resets the position to zero.
    *
    * @param data The array to wrap.
-   * @param limit The limit.
+   * @param limit The limit to set.
    */
   public void reset(byte[] data, int limit) {
     this.data = data;