Replace DataSpec.absoluteStreamPosition with uriPositionOffset

This is a preliminary step toward adding a DataSpec.Builder,
which is needed for sanity when adding DataSpec.customData.

The existing absoluteStreamPosition field is very error prone,
because anyone using a Builder to adjust the request position
will need to remember to adjust two values:

dataSpec
    .buildUpon()
    .setAbsoluteStreamPosition(x)
    .setPosition(x)
    .build();

Furthermore, the difference between position and
absoluteStreamPosition is irrelevant in nearly all cases. In
the core library, the difference is only relevant when initializing
AES encryption/decryption to write/read cache files.

Replacing absoluteStreamPosition with uriPositionOffset will
simplify the code block above to:

dataSpec
    .buildUpon()
    .setPosition(x)
    .build();

PiperOrigin-RevId: 294485644

library/core/src/main/java/com/google/android/exoplayer2/offline/SegmentDownloader.java

@@ -267,7 +267,7 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
   private static boolean canMergeSegments(DataSpec dataSpec1, DataSpec dataSpec2) {
     return dataSpec1.uri.equals(dataSpec2.uri)
         && dataSpec1.length != C.LENGTH_UNSET
-        && (dataSpec1.absoluteStreamPosition + dataSpec1.length == dataSpec2.absoluteStreamPosition)
+        && (dataSpec1.position + dataSpec1.length == dataSpec2.position)
         && Util.areEqual(dataSpec1.key, dataSpec2.key)
         && dataSpec1.flags == dataSpec2.flags
         && dataSpec1.httpMethod == dataSpec2.httpMethod

library/core/src/main/java/com/google/android/exoplayer2/source/chunk/ContainerMediaChunk.java

@@ -126,7 +126,7 @@ public class ContainerMediaChunk extends BaseMediaChunk {
       DataSpec loadDataSpec = dataSpec.subrange(nextLoadPosition);
       ExtractorInput input =
           new DefaultExtractorInput(
-              dataSource, loadDataSpec.absoluteStreamPosition, dataSource.open(loadDataSpec));
+              dataSource, loadDataSpec.position, dataSource.open(loadDataSpec));
       // Load and decode the sample data.
       try {
         Extractor extractor = extractorWrapper.extractor;
@@ -136,7 +136,7 @@ public class ContainerMediaChunk extends BaseMediaChunk {
         }
         Assertions.checkState(result != Extractor.RESULT_SEEK);
       } finally {
-        nextLoadPosition = input.getPosition() - dataSpec.absoluteStreamPosition;
+        nextLoadPosition = input.getPosition() - dataSpec.position;
       }
     } finally {
       Util.closeQuietly(dataSource);

library/core/src/main/java/com/google/android/exoplayer2/source/chunk/InitializationChunk.java

@@ -93,7 +93,7 @@ public final class InitializationChunk extends Chunk {
       DataSpec loadDataSpec = dataSpec.subrange(nextLoadPosition);
       ExtractorInput input =
           new DefaultExtractorInput(
-              dataSource, loadDataSpec.absoluteStreamPosition, dataSource.open(loadDataSpec));
+              dataSource, loadDataSpec.position, dataSource.open(loadDataSpec));
       // Load and decode the initialization data.
       try {
         Extractor extractor = extractorWrapper.extractor;
@@ -103,7 +103,7 @@ public final class InitializationChunk extends Chunk {
         }
         Assertions.checkState(result != Extractor.RESULT_SEEK);
       } finally {
-        nextLoadPosition = input.getPosition() - dataSpec.absoluteStreamPosition;
+        nextLoadPosition = input.getPosition() - dataSpec.position;
       }
     } finally {
       Util.closeQuietly(dataSource);

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheDataSink.java

@@ -169,9 +169,7 @@ public final class CacheDataSink implements DataSink {
         dataSpec.length == C.LENGTH_UNSET
             ? C.LENGTH_UNSET
             : Math.min(dataSpec.length - dataSpecBytesWritten, dataSpecFragmentSize);
-    file =
-        cache.startFile(
-            dataSpec.key, dataSpec.absoluteStreamPosition + dataSpecBytesWritten, length);
+    file = cache.startFile(dataSpec.key, dataSpec.position + dataSpecBytesWritten, length);
     FileOutputStream underlyingFileOutputStream = new FileOutputStream(file);
     if (bufferSize > 0) {
       if (bufferedOutputStream == null) {

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheUtil.java

@@ -79,7 +79,7 @@ public final class CacheUtil {
   public static Pair<Long, Long> getCached(
       DataSpec dataSpec, Cache cache, @Nullable CacheKeyFactory cacheKeyFactory) {
     String key = buildCacheKey(dataSpec, cacheKeyFactory);
-    long position = dataSpec.absoluteStreamPosition;
+    long position = dataSpec.position;
     long requestLength = getRequestLength(dataSpec, cache, key);
     long bytesAlreadyCached = 0;
     long bytesLeft = requestLength;
@@ -193,7 +193,7 @@ public final class CacheUtil {
       bytesLeft = getRequestLength(dataSpec, cache, key);
     }
 
-    long position = dataSpec.absoluteStreamPosition;
+    long position = dataSpec.position;
     boolean lengthUnset = bytesLeft == C.LENGTH_UNSET;
     while (bytesLeft != 0) {
       throwExceptionIfInterruptedOrCancelled(isCanceled);
@@ -238,18 +238,16 @@ public final class CacheUtil {
       return dataSpec.length;
     } else {
       long contentLength = ContentMetadata.getContentLength(cache.getContentMetadata(key));
-      return contentLength == C.LENGTH_UNSET
-          ? C.LENGTH_UNSET
-          : contentLength - dataSpec.absoluteStreamPosition;
+      return contentLength == C.LENGTH_UNSET ? C.LENGTH_UNSET : contentLength - dataSpec.position;
     }
   }
 
   /**
    * Reads and discards all data specified by the {@code dataSpec}.
    *
-   * @param dataSpec Defines the data to be read. {@code absoluteStreamPosition} and {@code length}
-   *     fields are overwritten by the following parameters.
-   * @param absoluteStreamPosition The absolute position of the data to be read.
+   * @param dataSpec Defines the data to be read. The {@code position} and {@code length} fields are
+   *     overwritten by the following parameters.
+   * @param position The position of the data to be read.
    * @param length Length of the data to be read, or {@link C#LENGTH_UNSET} if it is unknown.
    * @param dataSource The {@link DataSource} to read the data from.
    * @param buffer The buffer to be used while downloading.
@@ -264,7 +262,7 @@ public final class CacheUtil {
    */
   private static long readAndDiscard(
       DataSpec dataSpec,
-      long absoluteStreamPosition,
+      long position,
       long length,
       DataSource dataSource,
       byte[] buffer,
@@ -274,7 +272,7 @@ public final class CacheUtil {
       boolean isLastBlock,
       @Nullable AtomicBoolean isCanceled)
       throws IOException, InterruptedException {
-    long positionOffset = absoluteStreamPosition - dataSpec.absoluteStreamPosition;
+    long positionOffset = position - dataSpec.position;
     long initialPositionOffset = positionOffset;
     long endOffset = length != C.LENGTH_UNSET ? positionOffset + length : C.POSITION_UNSET;
     while (true) {

library/core/src/main/java/com/google/android/exoplayer2/upstream/crypto/AesCipherDataSink.java

@@ -68,8 +68,9 @@ public final class AesCipherDataSink implements DataSink {
   public void open(DataSpec dataSpec) throws IOException {
     wrappedDataSink.open(dataSpec);
     long nonce = CryptoUtil.getFNV64Hash(dataSpec.key);
-    cipher = new AesFlushingCipher(Cipher.ENCRYPT_MODE, secretKey, nonce,
-        dataSpec.absoluteStreamPosition);
+    cipher =
+        new AesFlushingCipher(
+            Cipher.ENCRYPT_MODE, secretKey, nonce, dataSpec.uriPositionOffset + dataSpec.position);
   }
 
   @Override

library/core/src/main/java/com/google/android/exoplayer2/upstream/crypto/AesCipherDataSource.java

@@ -52,8 +52,9 @@ public final class AesCipherDataSource implements DataSource {
   public long open(DataSpec dataSpec) throws IOException {
     long dataLength = upstream.open(dataSpec);
     long nonce = CryptoUtil.getFNV64Hash(dataSpec.key);
-    cipher = new AesFlushingCipher(Cipher.DECRYPT_MODE, secretKey, nonce,
-        dataSpec.absoluteStreamPosition);
+    cipher =
+        new AesFlushingCipher(
+            Cipher.DECRYPT_MODE, secretKey, nonce, dataSpec.uriPositionOffset + dataSpec.position);
     return dataLength;
   }
 

library/core/src/test/java/com/google/android/exoplayer2/upstream/cache/CacheDataSourceTest.java

@@ -546,7 +546,7 @@ public final class CacheDataSourceTest {
   private void assertReadData(
       CacheDataSource cacheDataSource, DataSpec dataSpec, boolean unknownLength)
       throws IOException {
-    int position = (int) dataSpec.absoluteStreamPosition;
+    int position = (int) dataSpec.position;
     int requestLength = (int) dataSpec.length;
     int readLength = TEST_DATA.length - position;
     if (requestLength != C.LENGTH_UNSET) {

library/core/src/test/java/com/google/android/exoplayer2/upstream/cache/CacheDataSourceTest2.java

@@ -112,7 +112,7 @@ public final class CacheDataSourceTest2 {
     byte[] scratch = new byte[4096];
     Random random = new Random(0);
     source.open(dataSpec);
-    int position = (int) dataSpec.absoluteStreamPosition;
+    int position = (int) dataSpec.position;
     int bytesRead = 0;
     while (bytesRead != C.RESULT_END_OF_INPUT) {
       int maxBytesToRead = random.nextInt(scratch.length) + 1;
@@ -134,7 +134,6 @@ public final class CacheDataSourceTest2 {
     DataSpec[] openedDataSpecs = upstreamSource.getAndClearOpenedDataSpecs();
     assertThat(openedDataSpecs).hasLength(1);
     assertThat(openedDataSpecs[0].position).isEqualTo(start);
-    assertThat(openedDataSpecs[0].absoluteStreamPosition).isEqualTo(start);
     assertThat(openedDataSpecs[0].length).isEqualTo(end - start);
   }
 

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaChunk.java

@@ -376,7 +376,7 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
           result = extractor.read(input, DUMMY_POSITION_HOLDER);
         }
       } finally {
-        nextLoadPosition = (int) (input.getPosition() - dataSpec.absoluteStreamPosition);
+        nextLoadPosition = (int) (input.getPosition() - dataSpec.position);
       }
     } finally {
       Util.closeQuietly(dataSource);
@@ -389,7 +389,7 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
       throws IOException, InterruptedException {
     long bytesToRead = dataSource.open(dataSpec);
     DefaultExtractorInput extractorInput =
-        new DefaultExtractorInput(dataSource, dataSpec.absoluteStreamPosition, bytesToRead);
+        new DefaultExtractorInput(dataSource, dataSpec.position, bytesToRead);
 
     if (extractor == null) {
       long id3Timestamp = peekId3PrivTimestamp(extractorInput);