Persist content redirected URI in CacheDataSource

Issue: #2360

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=190597773

RELEASENOTES.md

@@ -38,6 +38,8 @@
   * Add release method to Cache interface.
   * Prevent multiple instances of SimpleCache in the same folder.
     Previous instance must be released.
+  * Store redirected URI
+  ([#2360](https://github.com/google/ExoPlayer/issues/2360)).
 * DRM:
   * Allow multiple listeners for `DefaultDrmSessionManager`.
   * Pass `DrmSessionManager` to `ExoPlayerFactory` instead of `RendererFactory`.

library/core/src/androidTest/java/com/google/android/exoplayer2/upstream/cache/CachedContentIndexTest.java

@@ -21,11 +21,11 @@ public class CachedContentIndexTest extends InstrumentationTestCase {
       0, 0, 0, 1, // version
       0, 0, 0, 0, // flags
       0, 0, 0, 2, // number_of_CachedContent
-      0, 0, 0, 5, // cache_id
-      0, 5, 65, 66, 67, 68, 69, // cache_key
+      0, 0, 0, 5, // cache_id 5
+      0, 5, 65, 66, 67, 68, 69, // cache_key "ABCDE"
       0, 0, 0, 0, 0, 0, 0, 10, // original_content_length
-      0, 0, 0, 2, // cache_id
-      0, 5, 75, 76, 77, 78, 79, // cache_key
+      0, 0, 0, 2, // cache_id 2
+      0, 5, 75, 76, 77, 78, 79, // cache_key "KLMNO"
       0, 0, 0, 0, 0, 0, 10, 0, // original_content_length
       (byte) 0xF6, (byte) 0xFB, 0x50, 0x41 // hashcode_of_CachedContent_array
   };
@@ -285,8 +285,7 @@ public class CachedContentIndexTest extends InstrumentationTestCase {
     Set<String> keys2 = index2.getKeys();
     assertThat(keys2).isEqualTo(keys);
     for (String key : keys) {
-      assertThat(index2.getContentLength(key)).isEqualTo(index.getContentLength(key));
-      assertThat(index2.get(key).getSpans()).isEqualTo(index.get(key).getSpans());
+      assertThat(index2.get(key)).isEqualTo(index.get(key));
     }
   }
 }

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

@@ -18,6 +18,7 @@ package com.google.android.exoplayer2.upstream.cache;
 import android.net.Uri;
 import android.support.annotation.IntDef;
 import android.support.annotation.Nullable;
+import android.util.Log;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.upstream.DataSink;
 import com.google.android.exoplayer2.upstream.DataSource;
@@ -51,6 +52,8 @@ public final class CacheDataSource implements DataSource {
    */
   public static final long DEFAULT_MAX_CACHE_FILE_SIZE = 2 * 1024 * 1024;
 
+  private static final String TAG = "CacheDataSource";
+
   /**
    * Flags controlling the cache's behavior.
    */
@@ -125,6 +128,7 @@ public final class CacheDataSource implements DataSource {
   private DataSource currentDataSource;
   private boolean currentDataSpecLengthUnset;
   private Uri uri;
+  private Uri actualUri;
   private int flags;
   private String key;
   private long readPosition;
@@ -212,9 +216,10 @@ public final class CacheDataSource implements DataSource {
   @Override
   public long open(DataSpec dataSpec) throws IOException {
     try {
+      key = CacheUtil.getKey(dataSpec);
       uri = dataSpec.uri;
+      actualUri = loadRedirectedUriOrReturnGivenUri(cache, key, uri);
       flags = dataSpec.flags;
-      key = CacheUtil.getKey(dataSpec);
       readPosition = dataSpec.position;
       currentRequestIgnoresCache = (ignoreCacheOnError && seenCacheError)
           || (dataSpec.length == C.LENGTH_UNSET && ignoreCacheForUnsetLengthRequests);
@@ -251,7 +256,7 @@ public final class CacheDataSource implements DataSource {
       }
       int bytesRead = currentDataSource.read(buffer, offset, readLength);
       if (bytesRead != C.RESULT_END_OF_INPUT) {
-        if (currentDataSource == cacheReadDataSource) {
+        if (isReadingFromCache()) {
           totalCachedBytesRead += bytesRead;
         }
         readPosition += bytesRead;
@@ -259,7 +264,7 @@ public final class CacheDataSource implements DataSource {
           bytesRemaining -= bytesRead;
         }
       } else if (currentDataSpecLengthUnset) {
-        setBytesRemaining(0);
+        setBytesRemainingAndMaybeStoreLength(0);
       } else if (bytesRemaining > 0 || bytesRemaining == C.LENGTH_UNSET) {
         closeCurrentSource();
         openNextSource(false);
@@ -268,7 +273,7 @@ public final class CacheDataSource implements DataSource {
       return bytesRead;
     } catch (IOException e) {
       if (currentDataSpecLengthUnset && isCausedByPositionOutOfRange(e)) {
-        setBytesRemaining(0);
+        setBytesRemainingAndMaybeStoreLength(0);
         return C.RESULT_END_OF_INPUT;
       }
       handleBeforeThrow(e);
@@ -278,12 +283,13 @@ public final class CacheDataSource implements DataSource {
 
   @Override
   public Uri getUri() {
-    return currentDataSource == upstreamDataSource ? currentDataSource.getUri() : uri;
+    return actualUri;
   }
 
   @Override
   public void close() throws IOException {
     uri = null;
+    actualUri = null;
     notifyBytesRead();
     try {
       closeCurrentSource();
@@ -371,7 +377,7 @@ public final class CacheDataSource implements DataSource {
             ? readPosition + MIN_READ_BEFORE_CHECKING_CACHE
             : Long.MAX_VALUE;
     if (checkCache) {
-      Assertions.checkState(currentDataSource == upstreamDataSource);
+      Assertions.checkState(isBypassingCache());
       if (nextDataSource == upstreamDataSource) {
         // Continue reading from upstream.
         return;
@@ -395,8 +401,45 @@ public final class CacheDataSource implements DataSource {
     currentDataSpecLengthUnset = nextDataSpec.length == C.LENGTH_UNSET;
     long resolvedLength = nextDataSource.open(nextDataSpec);
     if (currentDataSpecLengthUnset && resolvedLength != C.LENGTH_UNSET) {
-      setBytesRemaining(resolvedLength);
+      setBytesRemainingAndMaybeStoreLength(resolvedLength);
+    }
+    // TODO find a way to store length and redirected uri in one metadata mutation.
+    maybeUpdateActualUriFieldAndRedirectedUriMetadata();
+  }
+
+  private void maybeUpdateActualUriFieldAndRedirectedUriMetadata() {
+    if (!isReadingFromUpstream()) {
+      return;
     }
+    actualUri = currentDataSource.getUri();
+    maybeUpdateRedirectedUriMetadata();
+  }
+
+  private void maybeUpdateRedirectedUriMetadata() {
+    if (!isWritingToCache()) {
+      return;
+    }
+    ContentMetadataMutations mutations = new ContentMetadataMutations();
+    boolean isRedirected = !uri.equals(actualUri);
+    if (isRedirected) {
+      mutations.set(ContentMetadata.METADATA_NAME_REDIRECTED_URI, actualUri.toString());
+    } else {
+      mutations.remove(ContentMetadata.METADATA_NAME_REDIRECTED_URI);
+    }
+    try {
+      cache.applyContentMetadataMutations(key, mutations);
+    } catch (CacheException e) {
+      String message =
+          "Couldn't update redirected URI. "
+              + "This might cause relative URIs get resolved incorrectly.";
+      Log.w(TAG, message, e);
+    }
+  }
+
+  private static Uri loadRedirectedUriOrReturnGivenUri(Cache cache, String key, Uri uri) {
+    ContentMetadata metadata = cache.getContentMetadata(key);
+    String redirection = metadata.get(ContentMetadata.METADATA_NAME_REDIRECTED_URI, (String) null);
+    return redirection == null ? uri : Uri.parse(redirection);
   }
 
   private static boolean isCausedByPositionOutOfRange(IOException e) {
@@ -413,13 +456,25 @@ public final class CacheDataSource implements DataSource {
     return false;
   }
 
-  private void setBytesRemaining(long bytesRemaining) throws IOException {
+  private void setBytesRemainingAndMaybeStoreLength(long bytesRemaining) throws IOException {
     this.bytesRemaining = bytesRemaining;
     if (isWritingToCache()) {
       cache.setContentLength(key, readPosition + bytesRemaining);
     }
   }
 
+  private boolean isReadingFromUpstream() {
+    return !isReadingFromCache();
+  }
+
+  private boolean isBypassingCache() {
+    return currentDataSource == upstreamDataSource;
+  }
+
+  private boolean isReadingFromCache() {
+    return currentDataSource == cacheReadDataSource;
+  }
+
   private boolean isWritingToCache() {
     return currentDataSource == cacheWriteDataSource;
   }
@@ -441,7 +496,7 @@ public final class CacheDataSource implements DataSource {
   }
 
   private void handleBeforeThrow(IOException exception) {
-    if (currentDataSource == cacheReadDataSource || exception instanceof CacheException) {
+    if (isReadingFromCache() || exception instanceof CacheException) {
       seenCacheError = true;
     }
   }

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

@@ -29,8 +29,7 @@ import java.util.TreeSet;
 /*package*/ final class CachedContent {
 
   private static final int VERSION_METADATA_INTRODUCED = 2;
-  private static final String EXOPLAYER_METADATA_NAME_PREFIX = "exo_";
-  private static final String METADATA_NAME_LENGTH = EXOPLAYER_METADATA_NAME_PREFIX + "len";
+  private static final int VERSION_MAX = Integer.MAX_VALUE;
 
   /** The cache file id that uniquely identifies the original stream. */
   public final int id;
@@ -94,21 +93,28 @@ import java.util.TreeSet;
     return metadata;
   }
 
-  /** Applies {@code mutations} to the metadata. */
-  public void applyMetadataMutations(ContentMetadataMutations mutations) {
-    this.metadata = new DefaultContentMetadata(metadata, mutations);
+  /**
+   * Applies {@code mutations} to the metadata.
+   *
+   * @return Whether {@code mutations} changed any metadata.
+   */
+  public boolean applyMetadataMutations(ContentMetadataMutations mutations) {
+    DefaultContentMetadata oldMetadata = metadata;
+    metadata = metadata.copyWithMutationsApplied(mutations);
+    return metadata.equals(oldMetadata);
   }
 
   /**
    * Returns the length of the original stream, or {@link C#LENGTH_UNSET} if the length is unknown.
    */
   public long getLength() {
-    return metadata.get(METADATA_NAME_LENGTH, C.LENGTH_UNSET);
+    return metadata.get(ContentMetadata.METADATA_NAME_LENGTH, C.LENGTH_UNSET);
   }
 
   /** Sets the length of the content. */
   public void setLength(long length) {
-    applyMetadataMutations(new ContentMetadataMutations().set(METADATA_NAME_LENGTH, length));
+    applyMetadataMutations(
+        new ContentMetadataMutations().set(ContentMetadata.METADATA_NAME_LENGTH, length));
   }
 
   /** Returns whether the content is locked. */
@@ -234,4 +240,25 @@ import java.util.TreeSet;
     return result;
   }
 
+  @Override
+  public int hashCode() {
+    int result = headerHashCode(VERSION_MAX);
+    result = 31 * result + cachedSpans.hashCode();
+    return result;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    CachedContent that = (CachedContent) o;
+    return id == that.id
+        && key.equals(that.key)
+        && cachedSpans.equals(that.cachedSpans)
+        && metadata.equals(that.metadata);
+  }
 }

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

@@ -224,7 +224,9 @@ import javax.crypto.spec.SecretKeySpec;
    */
   public void applyContentMetadataMutations(String key, ContentMetadataMutations mutations) {
     CachedContent cachedContent = getOrAdd(key);
-    cachedContent.applyMetadataMutations(mutations);
+    if (cachedContent.applyMetadataMutations(mutations)) {
+      changed = true;
+    }
   }
 
   /** Returns a {@link ContentMetadata} for the given key. */

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

@@ -15,9 +15,21 @@
  */
 package com.google.android.exoplayer2.upstream.cache;
 
-/** Interface for an immutable snapshot of keyed metadata. */
+/**
+ * Interface for an immutable snapshot of keyed metadata.
+ *
+ * <p>Internal metadata names are prefixed with {@value #INTERNAL_METADATA_NAME_PREFIX}. Custom
+ * metadata names should avoid this prefix to prevent clashes.
+ */
 public interface ContentMetadata {
 
+  /** Prefix of internal metadata names. */
+  String INTERNAL_METADATA_NAME_PREFIX = "exo_";
+  /** Name of internal metadata to hold redirected URI. */
+  String METADATA_NAME_REDIRECTED_URI = INTERNAL_METADATA_NAME_PREFIX + "redir";
+  /** Name of internal metadata to hold content length. */
+  String METADATA_NAME_LENGTH = INTERNAL_METADATA_NAME_PREFIX + "len";
+
   /**
    * Returns a metadata value.
    *

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

@@ -63,19 +63,23 @@ public final class DefaultContentMetadata implements ContentMetadata {
 
   private final Map<String, byte[]> metadata;
 
-  /**
-   * Constructs a {@link DefaultContentMetadata} by copying metadata values from {@code other} and
-   * applying {@code mutations}.
-   */
-  public DefaultContentMetadata(DefaultContentMetadata other, ContentMetadataMutations mutations) {
-    this(applyMutations(other.metadata, mutations));
-  }
-
   private DefaultContentMetadata(Map<String, byte[]> metadata) {
     this.metadata = Collections.unmodifiableMap(metadata);
   }
 
   /**
+   * Returns a copy {@link DefaultContentMetadata} with {@code mutations} applied. If {@code
+   * mutations} don't change anything, returns this instance.
+   */
+  public DefaultContentMetadata copyWithMutationsApplied(ContentMetadataMutations mutations) {
+    Map<String, byte[]> mutatedMetadata = applyMutations(metadata, mutations);
+    if (isMetadataEqual(mutatedMetadata)) {
+      return this;
+    }
+    return new DefaultContentMetadata(mutatedMetadata);
+  }
+
+  /**
    * Serializes itself to a {@link DataOutputStream}.
    *
    * @param output Output stream to store the values.
@@ -134,8 +138,10 @@ public final class DefaultContentMetadata implements ContentMetadata {
     if (o == null || getClass() != o.getClass()) {
       return false;
     }
-    DefaultContentMetadata that = (DefaultContentMetadata) o;
-    Map<String, byte[]> otherMetadata = that.metadata;
+    return isMetadataEqual(((DefaultContentMetadata) o).metadata);
+  }
+
+  private boolean isMetadataEqual(Map<String, byte[]> otherMetadata) {
     if (metadata.size() != otherMetadata.size()) {
       return false;
     }

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

@@ -309,6 +309,18 @@ public final class SimpleCache implements Cache {
     return index.getContentLength(key);
   }
 
+  @Override
+  public void applyContentMetadataMutations(String key, ContentMetadataMutations mutations)
+      throws CacheException {
+    index.applyContentMetadataMutations(key, mutations);
+    index.store();
+  }
+
+  @Override
+  public ContentMetadata getContentMetadata(String key) {
+    return index.getContentMetadata(key);
+  }
+
   /**
    * Returns the cache {@link SimpleCacheSpan} corresponding to the provided lookup {@link
    * SimpleCacheSpan}.
@@ -458,15 +470,4 @@ public final class SimpleCache implements Cache {
   private static synchronized void releaseFolder(File cacheDir) {
     lockedCacheDirs.remove(cacheDir.getAbsoluteFile());
   }
-  @Override
-  public void applyContentMetadataMutations(String key, ContentMetadataMutations mutations)
-      throws CacheException {
-    index.applyContentMetadataMutations(key, mutations);
-    index.store();
-  }
-
-  @Override
-  public ContentMetadata getContentMetadata(String key) {
-    return index.getContentMetadata(key);
-  }
 }

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

@@ -62,14 +62,14 @@ public class DefaultContentMetadataTest {
   @Test
   public void testEmptyMutationDoesNotFail() throws Exception {
     ContentMetadataMutations mutations = new ContentMetadataMutations();
-    new DefaultContentMetadata(DefaultContentMetadata.EMPTY, mutations);
+    DefaultContentMetadata.EMPTY.copyWithMutationsApplied(mutations);
   }
 
   @Test
   public void testAddNewMetadata() throws Exception {
     ContentMetadataMutations mutations = new ContentMetadataMutations();
     mutations.set("metadata name", "value");
-    contentMetadata = new DefaultContentMetadata(contentMetadata, mutations);
+    contentMetadata = contentMetadata.copyWithMutationsApplied(mutations);
     assertThat(contentMetadata.get("metadata name", "default value")).isEqualTo("value");
   }
 
@@ -77,7 +77,7 @@ public class DefaultContentMetadataTest {
   public void testAddNewIntMetadata() throws Exception {
     ContentMetadataMutations mutations = new ContentMetadataMutations();
     mutations.set("metadata name", 5);
-    contentMetadata = new DefaultContentMetadata(contentMetadata, mutations);
+    contentMetadata = contentMetadata.copyWithMutationsApplied(mutations);
     assertThat(contentMetadata.get("metadata name", 0)).isEqualTo(5);
   }
 
@@ -86,7 +86,7 @@ public class DefaultContentMetadataTest {
     ContentMetadataMutations mutations = new ContentMetadataMutations();
     byte[] value = {1, 2, 3};
     mutations.set("metadata name", value);
-    contentMetadata = new DefaultContentMetadata(contentMetadata, mutations);
+    contentMetadata = contentMetadata.copyWithMutationsApplied(mutations);
     assertThat(contentMetadata.get("metadata name", new byte[] {})).isEqualTo(value);
   }
 
@@ -102,7 +102,7 @@ public class DefaultContentMetadataTest {
     contentMetadata = createContentMetadata("metadata name", "value");
     ContentMetadataMutations mutations = new ContentMetadataMutations();
     mutations.set("metadata name", "edited value");
-    contentMetadata = new DefaultContentMetadata(contentMetadata, mutations);
+    contentMetadata = contentMetadata.copyWithMutationsApplied(mutations);
     assertThat(contentMetadata.get("metadata name", "default value")).isEqualTo("edited value");
   }
 
@@ -111,7 +111,7 @@ public class DefaultContentMetadataTest {
     contentMetadata = createContentMetadata("metadata name", "value");
     ContentMetadataMutations mutations = new ContentMetadataMutations();
     mutations.remove("metadata name");
-    contentMetadata = new DefaultContentMetadata(contentMetadata, mutations);
+    contentMetadata = contentMetadata.copyWithMutationsApplied(mutations);
     assertThat(contentMetadata.get("metadata name", "default value")).isEqualTo("default value");
   }
 
@@ -120,7 +120,7 @@ public class DefaultContentMetadataTest {
     ContentMetadataMutations mutations = new ContentMetadataMutations();
     mutations.set("metadata name", "value");
     mutations.remove("metadata name");
-    contentMetadata = new DefaultContentMetadata(contentMetadata, mutations);
+    contentMetadata = contentMetadata.copyWithMutationsApplied(mutations);
     assertThat(contentMetadata.get("metadata name", "default value")).isEqualTo("default value");
   }
 
@@ -129,7 +129,7 @@ public class DefaultContentMetadataTest {
     ContentMetadataMutations mutations = new ContentMetadataMutations();
     mutations.remove("metadata name");
     mutations.set("metadata name", "value");
-    contentMetadata = new DefaultContentMetadata(contentMetadata, mutations);
+    contentMetadata = contentMetadata.copyWithMutationsApplied(mutations);
     assertThat(contentMetadata.get("metadata name", "default value")).isEqualTo("value");
   }
 
@@ -194,6 +194,6 @@ public class DefaultContentMetadataTest {
         throw new IllegalArgumentException();
       }
     }
-    return new DefaultContentMetadata(DefaultContentMetadata.EMPTY, mutations);
+    return DefaultContentMetadata.EMPTY.copyWithMutationsApplied(mutations);
   }
 }