Simplify FlacExtractor (step toward enabling nullness checking)

- Inline some unnecessarily split out helper methods
- Clear ExtractorInput from FlacDecoderJni data after usage
- Clean up exception handling for StreamInfo decode failures

PiperOrigin-RevId: 256524955

extensions/flac/src/androidTest/java/com/google/android/exoplayer2/ext/flac/FlacBinarySearchSeekerTest.java

@@ -52,7 +52,7 @@ public final class FlacBinarySearchSeekerTest {
 
     FlacBinarySearchSeeker seeker =
         new FlacBinarySearchSeeker(
-            decoderJni.decodeMetadata(), /* firstFramePosition= */ 0, data.length, decoderJni);
+            decoderJni.decodeStreamInfo(), /* firstFramePosition= */ 0, data.length, decoderJni);
 
     SeekMap seekMap = seeker.getSeekMap();
     assertThat(seekMap).isNotNull();
@@ -70,7 +70,7 @@ public final class FlacBinarySearchSeekerTest {
     decoderJni.setData(input);
     FlacBinarySearchSeeker seeker =
         new FlacBinarySearchSeeker(
-            decoderJni.decodeMetadata(), /* firstFramePosition= */ 0, data.length, decoderJni);
+            decoderJni.decodeStreamInfo(), /* firstFramePosition= */ 0, data.length, decoderJni);
 
     seeker.setSeekTargetUs(/* timeUs= */ 1000);
     assertThat(seeker.isSeeking()).isTrue();

extensions/flac/src/androidTest/java/com/google/android/exoplayer2/ext/flac/FlacExtractorTest.java

@@ -28,7 +28,7 @@ import org.junit.runner.RunWith;
 public class FlacExtractorTest {
 
   @Before
-  public void setUp() throws Exception {
+  public void setUp() {
     if (!FlacLibrary.isAvailable()) {
       fail("Flac library not available.");
     }

extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacDecoder.java

@@ -17,6 +17,7 @@ package com.google.android.exoplayer2.ext.flac;
 
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.ParserException;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.decoder.SimpleDecoder;
 import com.google.android.exoplayer2.decoder.SimpleOutputBuffer;
@@ -59,14 +60,13 @@ import java.util.List;
     decoderJni.setData(ByteBuffer.wrap(initializationData.get(0)));
     FlacStreamInfo streamInfo;
     try {
-      streamInfo = decoderJni.decodeMetadata();
+      streamInfo = decoderJni.decodeStreamInfo();
+    } catch (ParserException e) {
+      throw new FlacDecoderException("Failed to decode StreamInfo", e);
     } catch (IOException | InterruptedException e) {
       // Never happens.
       throw new IllegalStateException(e);
     }
-    if (streamInfo == null) {
-      throw new FlacDecoderException("Metadata decoding failed");
-    }
 
     int initialInputBufferSize =
         maxInputBufferSize != Format.NO_VALUE ? maxInputBufferSize : streamInfo.maxFrameSize;

extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacDecoderJni.java

@@ -17,6 +17,7 @@ package com.google.android.exoplayer2.ext.flac;
 
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.ParserException;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
 import com.google.android.exoplayer2.util.FlacStreamInfo;
 import com.google.android.exoplayer2.util.Util;
@@ -47,7 +48,7 @@ import java.nio.ByteBuffer;
   @Nullable private ExtractorInput extractorInput;
   @Nullable private byte[] tempBuffer;
   private boolean endOfExtractorInput;
-  
+
   public FlacDecoderJni() throws FlacDecoderException {
     if (!FlacLibrary.isAvailable()) {
       throw new FlacDecoderException("Failed to load decoder native libraries.");
@@ -59,37 +60,46 @@ import java.nio.ByteBuffer;
   }
 
   /**
-   * Sets data to be parsed by libflac.
+   * Sets the data to be parsed.
    *
    * @param byteBufferData Source {@link ByteBuffer}.
    */
   public void setData(ByteBuffer byteBufferData) {
     this.byteBufferData = byteBufferData;
     this.extractorInput = null;
-    this.tempBuffer = null;
   }
 
   /**
-   * Sets data to be parsed by libflac.
+   * Sets the data to be parsed.
    *
    * @param extractorInput Source {@link ExtractorInput}.
    */
   public void setData(ExtractorInput extractorInput) {
     this.byteBufferData = null;
     this.extractorInput = extractorInput;
+    endOfExtractorInput = false;
     if (tempBuffer == null) {
-      this.tempBuffer = new byte[TEMP_BUFFER_SIZE];
+      tempBuffer = new byte[TEMP_BUFFER_SIZE];
     }
-    endOfExtractorInput = false;
   }
 
+  /**
+   * Returns whether the end of the data to be parsed has been reached, or true if no data was set.
+   */
   public boolean isEndOfData() {
     if (byteBufferData != null) {
       return byteBufferData.remaining() == 0;
     } else if (extractorInput != null) {
       return endOfExtractorInput;
+    } else {
+      return true;
     }
-    return true;
+  }
+
+  /** Clears the data to be parsed. */
+  public void clearData() {
+    byteBufferData = null;
+    extractorInput = null;
   }
 
   /**
@@ -98,12 +108,11 @@ import java.nio.ByteBuffer;
    * <p>This method blocks until at least one byte of data can be read, the end of the input is
    * detected or an exception is thrown.
    *
-   * <p>This method is called from the native code.
-   *
    * @param target A target {@link ByteBuffer} into which data should be written.
    * @return Returns the number of bytes read, or -1 on failure. If all of the data has already been
    *     read from the source, then 0 is returned.
    */
+  @SuppressWarnings("unused") // Called from native code.
   public int read(ByteBuffer target) throws IOException, InterruptedException {
     int byteCount = target.remaining();
     if (byteBufferData != null) {
@@ -134,8 +143,12 @@ import java.nio.ByteBuffer;
   }
 
   /** Decodes and consumes the StreamInfo section from the FLAC stream. */
-  public FlacStreamInfo decodeMetadata() throws IOException, InterruptedException {
-    return flacDecodeMetadata(nativeDecoderContext);
+  public FlacStreamInfo decodeStreamInfo() throws IOException, InterruptedException {
+    FlacStreamInfo streamInfo = flacDecodeMetadata(nativeDecoderContext);
+    if (streamInfo == null) {
+      throw new ParserException("Failed to decode StreamInfo");
+    }
+    return streamInfo;
   }
 
   /**