Cache support unbounded requests.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=131696858

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

+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.upstream.cache;
+
+import android.net.Uri;
+import android.test.InstrumentationTestCase;
+import android.test.MoreAsserts;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.testutil.FakeDataSource;
+import com.google.android.exoplayer2.testutil.FakeDataSource.Builder;
+import com.google.android.exoplayer2.testutil.TestUtil;
+import com.google.android.exoplayer2.upstream.DataSpec;
+import com.google.android.exoplayer2.upstream.HttpDataSource.InvalidResponseCodeException;
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+
+/** Unit tests for {@link CacheDataSource}. */
+public class CacheDataSourceTest extends InstrumentationTestCase {
+
+  private static final byte[] TEST_DATA = new byte[] {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+  private static final int MAX_CACHE_FILE_SIZE = 3;
+  private static final String KEY_1 = "key 1";
+  private static final String KEY_2 = "key 2";
+
+  private File cacheDir;
+  private SimpleCache simpleCache;
+
+  @Override
+  protected void setUp() throws Exception {
+    // Create a temporary folder
+    cacheDir = File.createTempFile("CacheDataSourceTest", null);
+    assertTrue(cacheDir.delete());
+    assertTrue(cacheDir.mkdir());
+
+    simpleCache = new SimpleCache(cacheDir, new NoOpCacheEvictor());
+  }
+
+  @Override
+  protected void tearDown() throws Exception {
+    TestUtil.recursiveDelete(cacheDir);
+  }
+
+  public void testMaxCacheFileSize() throws Exception {
+    CacheDataSource cacheDataSource = createCacheDataSource(false, false, false);
+    assertReadDataContentLength(cacheDataSource, false, false);
+    assertEquals((int) Math.ceil((double) TEST_DATA.length / MAX_CACHE_FILE_SIZE),
+        cacheDir.listFiles().length);
+  }
+
+  public void testCacheAndRead() throws Exception {
+    assertCacheAndRead(false, false);
+  }
+
+  public void testCacheAndReadUnboundedRequest() throws Exception {
+    assertCacheAndRead(true, false);
+  }
+
+  public void testCacheAndReadUnknownLength() throws Exception {
+    assertCacheAndRead(false, true);
+  }
+
+  // Disabled test as we don't support caching of definitely unknown length content
+  public void disabledTestCacheAndReadUnboundedRequestUnknownLength() throws Exception {
+    assertCacheAndRead(true, true);
+  }
+
+  public void testUnsatisfiableRange() throws Exception {
+    // Bounded request but the content length is unknown. This forces all data to be cached but not
+    // the length
+    assertCacheAndRead(false, true);
+
+    // Now do an unbounded request. This will read all of the data from cache and then try to read
+    // more from upstream which will cause to a 416 so CDS will store the length.
+    CacheDataSource cacheDataSource = createCacheDataSource(true, true, true);
+    assertReadDataContentLength(cacheDataSource, true, true);
+
+    // If the user try to access off range then it should throw an IOException
+    try {
+      cacheDataSource = createCacheDataSource(false, false, false);
+      cacheDataSource.open(new DataSpec(Uri.EMPTY, TEST_DATA.length, 5, KEY_1));
+      fail();
+    } catch (TestIOException e) {
+      // success
+    }
+  }
+
+  public void testContentLengthEdgeCases() throws Exception {
+    // Read partial at EOS but don't cross it so length is unknown
+    CacheDataSource cacheDataSource = createCacheDataSource(false, false, true);
+    assertReadData(cacheDataSource, true, TEST_DATA.length - 2, 2);
+    assertEquals(C.LENGTH_UNSET, simpleCache.getContentLength(KEY_1));
+
+    // Now do an unbounded request for whole data. This will cause a bounded request from upstream.
+    // End of data from upstream shouldn't be mixed up with EOS and cause length set wrong.
+    cacheDataSource = createCacheDataSource(true, false, true);
+    assertReadDataContentLength(cacheDataSource, true, true);
+
+    // Now the length set correctly do an unbounded request with offset
+    assertEquals(2, cacheDataSource.open(new DataSpec(Uri.EMPTY, TEST_DATA.length - 2,
+        C.LENGTH_UNSET, KEY_1)));
+
+    // An unbounded request with offset for not cached content
+    assertEquals(C.LENGTH_UNSET, cacheDataSource.open(new DataSpec(Uri.EMPTY, TEST_DATA.length - 2,
+        C.LENGTH_UNSET, KEY_2)));
+  }
+
+  private void assertCacheAndRead(boolean unboundedRequest, boolean simulateUnknownLength)
+      throws IOException {
+    // Read all data from upstream and cache
+    CacheDataSource cacheDataSource = createCacheDataSource(false, false, simulateUnknownLength);
+    assertReadDataContentLength(cacheDataSource, unboundedRequest, simulateUnknownLength);
+
+    // Just read from cache
+    cacheDataSource = createCacheDataSource(false, true, simulateUnknownLength);
+    assertReadDataContentLength(cacheDataSource, unboundedRequest,
+        false /*length is already cached*/);
+  }
+
+  /**
+   * Reads data until EOI and compares it to {@link #TEST_DATA}. Also checks content length returned
+   * from open() call and the cached content length.
+   */
+  private void assertReadDataContentLength(CacheDataSource cacheDataSource,
+      boolean unboundedRequest, boolean unknownLength) throws IOException {
+    int length = unboundedRequest ? C.LENGTH_UNSET : TEST_DATA.length;
+    assertReadData(cacheDataSource, unknownLength, 0, length);
+    assertEquals("When the range specified, CacheDataSource doesn't reach EOS so shouldn't cache "
+        + "content length", !unboundedRequest ? C.LENGTH_UNSET : TEST_DATA.length,
+        simpleCache.getContentLength(KEY_1));
+  }
+
+  private void assertReadData(CacheDataSource cacheDataSource, boolean unknownLength, int position,
+      int length) throws IOException {
+    int actualLength = TEST_DATA.length - position;
+    if (length != C.LENGTH_UNSET) {
+      actualLength = Math.min(actualLength, length);
+    }
+    assertEquals(unknownLength ? length : actualLength,
+        cacheDataSource.open(new DataSpec(Uri.EMPTY, position, length, KEY_1)));
+
+    byte[] buffer = new byte[100];
+    int index = 0;
+    while (true) {
+      int read = cacheDataSource.read(buffer, index, buffer.length - index);
+      if (read == C.RESULT_END_OF_INPUT) {
+        break;
+      }
+      index += read;
+    }
+    assertEquals(actualLength, index);
+    MoreAsserts.assertEquals(Arrays.copyOfRange(TEST_DATA, position, position + actualLength),
+        Arrays.copyOf(buffer, index));
+
+    cacheDataSource.close();
+  }
+
+  private CacheDataSource createCacheDataSource(boolean set416exception, boolean setReadException,
+      boolean simulateUnknownLength) {
+    Builder builder = new Builder();
+    if (setReadException) {
+      builder.appendReadError(new IOException("Shouldn't read from upstream"));
+    }
+    builder.setSimulateUnknownLength(simulateUnknownLength);
+    builder.appendReadData(TEST_DATA);
+    FakeDataSource upstream = builder.build();
+    upstream.setUnsatisfiableRangeException(set416exception
+        ? new InvalidResponseCodeException(416, null, null)
+        : new TestIOException());
+    return new CacheDataSource(simpleCache, upstream,
+        CacheDataSource.FLAG_BLOCK_ON_CACHE | CacheDataSource.FLAG_CACHE_UNBOUNDED_REQUESTS,
+        MAX_CACHE_FILE_SIZE);
+  }
+
+  private static class TestIOException extends IOException {}
+
+}

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

+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.upstream.cache;
+
+import android.test.InstrumentationTestCase;
+
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.testutil.TestUtil;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.NavigableSet;
+import java.util.Set;
+
+/**
+ * Unit tests for {@link SimpleCache}.
+ */
+public class SimpleCacheTest extends InstrumentationTestCase {
+
+  private static final String KEY_1 = "key1";
+
+  private File cacheDir;
+
+  @Override
+  protected void setUp() throws Exception {
+    // Create a temporary folder
+    cacheDir = File.createTempFile("SimpleCacheTest", null);
+    assertTrue(cacheDir.delete());
+    assertTrue(cacheDir.mkdir());
+  }
+
+  @Override
+  protected void tearDown() throws Exception {
+    TestUtil.recursiveDelete(cacheDir);
+  }
+
+  public void testCommittingOneFile() throws Exception {
+    SimpleCache simpleCache = new SimpleCache(cacheDir, new NoOpCacheEvictor());
+
+    CacheSpan cacheSpan = simpleCache.startReadWrite(KEY_1, 0);
+    assertFalse(cacheSpan.isCached);
+    assertTrue(cacheSpan.isOpenEnded());
+
+    assertNull(simpleCache.startReadWriteNonBlocking(KEY_1, 0));
+
+    assertEquals(0, simpleCache.getKeys().size());
+    NavigableSet<CacheSpan> cachedSpans = simpleCache.getCachedSpans(KEY_1);
+    assertTrue(cachedSpans == null || cachedSpans.size() == 0);
+    assertEquals(0, simpleCache.getCacheSpace());
+    assertEquals(0, cacheDir.listFiles().length);
+
+    addCache(simpleCache, 0, 15);
+
+    Set<String> cachedKeys = simpleCache.getKeys();
+    assertEquals(1, cachedKeys.size());
+    assertTrue(cachedKeys.contains(KEY_1));
+    cachedSpans = simpleCache.getCachedSpans(KEY_1);
+    assertEquals(1, cachedSpans.size());
+    assertTrue(cachedSpans.contains(cacheSpan));
+    assertEquals(15, simpleCache.getCacheSpace());
+
+    cacheSpan = simpleCache.startReadWrite(KEY_1, 0);
+    assertTrue(cacheSpan.isCached);
+    assertFalse(cacheSpan.isOpenEnded());
+    assertEquals(15, cacheSpan.length);
+  }
+
+  public void testSetGetLength() throws Exception {
+    SimpleCache simpleCache = new SimpleCache(cacheDir, new NoOpCacheEvictor());
+
+    assertEquals(C.LENGTH_UNSET, simpleCache.getContentLength(KEY_1));
+    assertTrue(simpleCache.setContentLength(KEY_1, 15));
+    assertEquals(15, simpleCache.getContentLength(KEY_1));
+
+    simpleCache.startReadWrite(KEY_1, 0);
+
+    addCache(simpleCache, 0, 15);
+
+    assertTrue(simpleCache.setContentLength(KEY_1, 150));
+    assertEquals(150, simpleCache.getContentLength(KEY_1));
+
+    addCache(simpleCache, 140, 10);
+
+    // Try to set length shorter then the content
+    assertFalse(simpleCache.setContentLength(KEY_1, 15));
+    assertEquals("Content length should be unchanged.",
+        150, simpleCache.getContentLength(KEY_1));
+
+    /* TODO Enable when the length persistance is fixed
+    // Check if values are kept after cache is reloaded.
+    simpleCache = new SimpleCache(cacheDir, new NoOpCacheEvictor());
+    assertEquals(150, simpleCache.getContentLength(KEY_1));
+    CacheSpan lastSpan = simpleCache.startReadWrite(KEY_1, 145);
+
+    // Removing the last span shouldn't cause the length be change next time cache loaded
+    simpleCache.removeSpan(lastSpan);
+    simpleCache = new SimpleCache(cacheDir, new NoOpCacheEvictor());
+    assertEquals(150, simpleCache.getContentLength(KEY_1));
+     */
+  }
+
+  private void addCache(SimpleCache simpleCache, int position, int length) throws IOException {
+    File file = simpleCache.startFile(KEY_1, position, length);
+    FileOutputStream fos = new FileOutputStream(file);
+    fos.write(new byte[length]);
+    fos.close();
+    simpleCache.commitFile(file);
+  }
+
+}

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

@@ -143,11 +143,11 @@ public interface Cache {
    *
    * @param key The cache key for the data.
    * @param position The starting position of the data.
-   * @param length The length of the data to be written. Used only to ensure that there is enough
-   *     space in the cache.
+   * @param maxLength The maximum length of the data to be written. Used only to ensure that there
+   *     is enough space in the cache.
    * @return The file into which data should be written.
    */
-  File startFile(String key, long position, long length);
+  File startFile(String key, long position, long maxLength);
 
   /**
    * Commits a file into the cache. Must only be called when holding a corresponding hole
@@ -182,4 +182,22 @@ public interface Cache {
   */
   boolean isCached(String key, long position, long length);
 
+  /**
+   * Sets the content length for the given key.
+   *
+   * @param key The cache key for the data.
+   * @param length The length of the data.
+   * @return Whether the length was set successfully. Returns false if the length conflicts with the
+   *     existing contents of the cache.
+   */
+  boolean setContentLength(String key, long length);
+
+  /**
+   * Returns the content length for the given key if one set, or {@link
+   * com.google.android.exoplayer2.C#LENGTH_UNSET} otherwise.
+   *
+   * @param key The cache key for the data.
+   */
+  long getContentLength(String key);
+
 }

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

@@ -64,12 +64,12 @@ public final class CacheDataSink implements DataSink {
 
   @Override
   public void open(DataSpec dataSpec) throws CacheDataSinkException {
-    // TODO: Support caching for unbounded requests. See TODO in {@link CacheDataSource} for
-    // more details.
-    Assertions.checkState(dataSpec.length != C.LENGTH_UNSET);
+    this.dataSpec = dataSpec;
+    if (dataSpec.length == C.LENGTH_UNSET) {
+      return;
+    }
+    dataSpecBytesWritten = 0;
     try {
-      this.dataSpec = dataSpec;
-      dataSpecBytesWritten = 0;
       openNextOutputStream();
     } catch (FileNotFoundException e) {
       throw new CacheDataSinkException(e);
@@ -78,6 +78,9 @@ public final class CacheDataSink implements DataSink {
 
   @Override
   public void write(byte[] buffer, int offset, int length) throws CacheDataSinkException {
+    if (dataSpec.length == C.LENGTH_UNSET) {
+      return;
+    }
     try {
       int bytesWritten = 0;
       while (bytesWritten < length) {
@@ -99,6 +102,9 @@ public final class CacheDataSink implements DataSink {
 
   @Override
   public void close() throws CacheDataSinkException {
+    if (dataSpec == null || dataSpec.length == C.LENGTH_UNSET) {
+      return;
+    }
     try {
       closeCurrentOutputStream();
     } catch (IOException e) {

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

@@ -22,6 +22,7 @@ import com.google.android.exoplayer2.upstream.DataSink;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.upstream.FileDataSource;
+import com.google.android.exoplayer2.upstream.HttpDataSource.InvalidResponseCodeException;
 import com.google.android.exoplayer2.upstream.TeeDataSource;
 import com.google.android.exoplayer2.upstream.cache.CacheDataSink.CacheDataSinkException;
 import java.io.IOException;
@@ -35,6 +36,34 @@ import java.io.InterruptedIOException;
 public final class CacheDataSource implements DataSource {
 
   /**
+   * Default maximum single cache file size.
+   *
+   * @see #CacheDataSource(Cache, DataSource, int)
+   * @see #CacheDataSource(Cache, DataSource, int, long)
+   */
+  public static final long DEFAULT_MAX_CACHE_FILE_SIZE = 2 * 1024 * 1024;
+
+  /**
+   * A flag indicating whether we will block reads if the cache key is locked. If this flag is
+   * set, then we will read from upstream if the cache key is locked.
+   */
+  public static final int FLAG_BLOCK_ON_CACHE = 1 << 0;
+
+  /**
+   * A flag indicating whether the cache is bypassed following any cache related error. If set
+   * then cache related exceptions may be thrown for one cycle of open, read and close calls.
+   * Subsequent cycles of these calls will then bypass the cache.
+   */
+  public static final int FLAG_IGNORE_CACHE_ON_ERROR = 1 << 1;
+
+  /**
+   * A flag indicating whether the response is cached if the range of the request is unbounded.
+   * Disabled by default because, as a side effect, this may allow streams with every chunk from a
+   * separate URL cached which is broken currently.
+   */
+  public static final int FLAG_CACHE_UNBOUNDED_REQUESTS = 1 << 2;
+
+  /**
    * Listener of {@link CacheDataSource} events.
    */
   public interface EventListener {
@@ -59,35 +88,44 @@ public final class CacheDataSource implements DataSource {
 
   private final boolean blockOnCache;
   private final boolean ignoreCacheOnError;
+  private final boolean bypassUnboundedRequests;
 
   private DataSource currentDataSource;
+  private boolean currentRequestUnbounded;
   private Uri uri;
   private int flags;
   private String key;
   private long readPosition;
   private long bytesRemaining;
   private CacheSpan lockedSpan;
-  private boolean ignoreCache;
+  private boolean seenCacheError;
+  private boolean currentRequestIgnoresCache;
   private long totalCachedBytesRead;
 
   /**
    * Constructs an instance with default {@link DataSource} and {@link DataSink} instances for
-   * reading and writing the cache.
+   * reading and writing the cache and with {@link #DEFAULT_MAX_CACHE_FILE_SIZE}.
    */
-  public CacheDataSource(Cache cache, DataSource upstream, boolean blockOnCache,
-      boolean ignoreCacheOnError) {
-    this(cache, upstream, blockOnCache, ignoreCacheOnError, Long.MAX_VALUE);
+  public CacheDataSource(Cache cache, DataSource upstream, int flags) {
+    this(cache, upstream, flags, DEFAULT_MAX_CACHE_FILE_SIZE);
   }
 
   /**
    * Constructs an instance with default {@link DataSource} and {@link DataSink} instances for
    * reading and writing the cache. The sink is configured to fragment data such that no single
    * cache file is greater than maxCacheFileSize bytes.
+   *
+   * @param cache The cache.
+   * @param upstream A {@link DataSource} for reading data not in the cache.
+   * @param flags A combination of {@link #FLAG_BLOCK_ON_CACHE}, {@link #FLAG_IGNORE_CACHE_ON_ERROR}
+   *     and {@link #FLAG_CACHE_UNBOUNDED_REQUESTS} or 0.
+   * @param maxCacheFileSize The maximum size of a cache file, in bytes. If the cached data size
+   *     exceeds this value, then the data will be fragmented into multiple cache files. The
+   *     finer-grained this is the finer-grained the eviction policy can be.
    */
-  public CacheDataSource(Cache cache, DataSource upstream, boolean blockOnCache,
-      boolean ignoreCacheOnError, long maxCacheFileSize) {
+  public CacheDataSource(Cache cache, DataSource upstream, int flags, long maxCacheFileSize) {
     this(cache, upstream, new FileDataSource(), new CacheDataSink(cache, maxCacheFileSize),
-        blockOnCache, ignoreCacheOnError, null);
+        flags, null);
   }
 
   /**
@@ -99,20 +137,17 @@ public final class CacheDataSource implements DataSource {
    * @param upstream A {@link DataSource} for reading data not in the cache.
    * @param cacheReadDataSource A {@link DataSource} for reading data from the cache.
    * @param cacheWriteDataSink A {@link DataSink} for writing data to the cache.
-   * @param blockOnCache A flag indicating whether we will block reads if the cache key is locked.
-   *     If this flag is false, then we will read from upstream if the cache key is locked.
-   * @param ignoreCacheOnError Whether the cache is bypassed following any cache related error. If
-   *     true, then cache related exceptions may be thrown for one cycle of open, read and close
-   *     calls. Subsequent cycles of these calls will then bypass the cache.
+   * @param flags A combination of {@link #FLAG_BLOCK_ON_CACHE}, {@link #FLAG_IGNORE_CACHE_ON_ERROR}
+   *     and {@link #FLAG_CACHE_UNBOUNDED_REQUESTS} or 0.
    * @param eventListener An optional {@link EventListener} to receive events.
    */
   public CacheDataSource(Cache cache, DataSource upstream, DataSource cacheReadDataSource,
-      DataSink cacheWriteDataSink, boolean blockOnCache, boolean ignoreCacheOnError,
-      EventListener eventListener) {
+      DataSink cacheWriteDataSink, int flags, EventListener eventListener) {
     this.cache = cache;
     this.cacheReadDataSource = cacheReadDataSource;
-    this.blockOnCache = blockOnCache;
-    this.ignoreCacheOnError = ignoreCacheOnError;
+    this.blockOnCache = (flags & FLAG_BLOCK_ON_CACHE) != 0;
+    this.ignoreCacheOnError = (flags & FLAG_IGNORE_CACHE_ON_ERROR) != 0;
+    this.bypassUnboundedRequests = (flags & FLAG_CACHE_UNBOUNDED_REQUESTS) == 0;
     this.upstreamDataSource = upstream;
     if (cacheWriteDataSink != null) {
       this.cacheWriteDataSource = new TeeDataSource(upstream, cacheWriteDataSink);
@@ -129,9 +164,18 @@ public final class CacheDataSource implements DataSource {
       flags = dataSpec.flags;
       key = dataSpec.key;
       readPosition = dataSpec.position;
-      bytesRemaining = dataSpec.length;
-      openNextSource();
-      return dataSpec.length;
+      currentRequestIgnoresCache = (ignoreCacheOnError && seenCacheError)
+          || (bypassUnboundedRequests && dataSpec.length == C.LENGTH_UNSET);
+      if (dataSpec.length != C.LENGTH_UNSET || currentRequestIgnoresCache) {
+        bytesRemaining = dataSpec.length;
+      } else {
+        bytesRemaining = cache.getContentLength(key);
+        if (bytesRemaining != C.LENGTH_UNSET) {
+          bytesRemaining -= dataSpec.position;
+        }
+      }
+      openNextSource(true);
+      return bytesRemaining;
     } catch (IOException e) {
       handleBeforeThrow(e);
       throw e;
@@ -151,10 +195,17 @@ public final class CacheDataSource implements DataSource {
           bytesRemaining -= bytesRead;
         }
       } else {
+        if (currentRequestUnbounded) {
+          // We only do unbounded requests to upstream and only when we don't know the actual stream
+          // length. So we reached the end of stream.
+          setContentLength(readPosition);
+          bytesRemaining = 0;
+        }
         closeCurrentSource();
-        if (bytesRemaining > 0 && bytesRemaining != C.LENGTH_UNSET) {
-          openNextSource();
-          return read(buffer, offset, max);
+        if (bytesRemaining > 0 || bytesRemaining == C.LENGTH_UNSET) {
+          if (openNextSource(false)) {
+            return read(buffer, offset, max);
+          }
         }
       }
       return bytesRead;
@@ -185,16 +236,12 @@ public final class CacheDataSource implements DataSource {
    * Opens the next source. If the cache contains data spanning the current read position then
    * {@link #cacheReadDataSource} is opened to read from it. Else {@link #upstreamDataSource} is
    * opened to read from the upstream source and write into the cache.
+   * @param initial Whether it is the initial open call.
    */
-  private void openNextSource() throws IOException {
+  private boolean openNextSource(boolean initial) throws IOException {
     DataSpec dataSpec;
     CacheSpan span;
-    if (ignoreCache) {
-      span = null;
-    } else if (bytesRemaining == C.LENGTH_UNSET) {
-      // TODO: Support caching for unbounded requests. This requires storing the source length
-      // into the cache (the simplest approach is to incorporate it into each cache file's name).
-      Log.w(TAG, "Cache bypassed due to unbounded length.");
+    if (currentRequestIgnoresCache) {
       span = null;
     } else if (blockOnCache) {
       try {
@@ -205,6 +252,7 @@ public final class CacheDataSource implements DataSource {
     } else {
       span = cache.startReadWriteNonBlocking(key, readPosition);
     }
+
     if (span == null) {
       // The data is locked in the cache, or we're ignoring the cache. Bypass the cache and read
       // from upstream.
@@ -214,18 +262,63 @@ public final class CacheDataSource implements DataSource {
       // Data is cached, read from cache.
       Uri fileUri = Uri.fromFile(span.file);
       long filePosition = readPosition - span.position;
-      long length = Math.min(span.length - filePosition, bytesRemaining);
+      long length = span.length - filePosition;
+      if (bytesRemaining != C.LENGTH_UNSET) {
+        length = Math.min(length, bytesRemaining);
+      }
       dataSpec = new DataSpec(fileUri, readPosition, filePosition, length, key, flags);
       currentDataSource = cacheReadDataSource;
     } else {
       // Data is not cached, and data is not locked, read from upstream with cache backing.
       lockedSpan = span;
-      long length = span.isOpenEnded() ? bytesRemaining : Math.min(span.length, bytesRemaining);
+      long length;
+      if (span.isOpenEnded()) {
+        length = bytesRemaining;
+      } else {
+        length = span.length;
+        if (bytesRemaining != C.LENGTH_UNSET) {
+          length = Math.min(length, bytesRemaining);
+        }
+      }
       dataSpec = new DataSpec(uri, readPosition, length, key, flags);
       currentDataSource = cacheWriteDataSource != null ? cacheWriteDataSource
           : upstreamDataSource;
     }
-    currentDataSource.open(dataSpec);
+
+    currentRequestUnbounded = dataSpec.length == C.LENGTH_UNSET;
+    boolean successful = false;
+    long currentBytesRemaining;
+    try {
+      currentBytesRemaining = currentDataSource.open(dataSpec);
+      successful = true;
+    } catch (InvalidResponseCodeException e) {
+      // if this isn't the initial open call (we had read some bytes) and got an 'unsatisfiable
+      // byte-range' (416) response for an unbounded range request then mute the exception. We are
+      // trying to find the stream end.
+      if (!initial && e.responseCode == 416 && currentRequestUnbounded) {
+        currentBytesRemaining = 0;
+      } else {
+        throw e;
+      }
+    }
+
+    // If we did an unbounded request (which means bytesRemaining == C.LENGTH_UNSET) and got a
+    // resolved length from open() request
+    if (currentRequestUnbounded && currentBytesRemaining != C.LENGTH_UNSET) {
+      bytesRemaining = currentBytesRemaining;
+      // If writing into cache
+      if (lockedSpan != null) {
+        setContentLength(dataSpec.position + bytesRemaining);
+      }
+    }
+    return successful;
+  }
+
+  private void setContentLength(long length) {
+    if (!cache.setContentLength(key, length)) {
+      Log.e(TAG, "cache.setContentLength(" + length + ") failed. cache.getContentLength() = "
+          + cache.getContentLength(key));
+    }
   }
 
   private void closeCurrentSource() throws IOException {
@@ -235,6 +328,7 @@ public final class CacheDataSource implements DataSource {
     try {
       currentDataSource.close();
       currentDataSource = null;
+      currentRequestUnbounded = false;
     } finally {
       if (lockedSpan != null) {
         cache.releaseHoleSpan(lockedSpan);
@@ -244,10 +338,8 @@ public final class CacheDataSource implements DataSource {
   }
 
   private void handleBeforeThrow(IOException exception) {
-    if (ignoreCacheOnError && (currentDataSource == cacheReadDataSource
-        || exception instanceof CacheDataSinkException)) {
-      // Ignore the cache from now on.
-      ignoreCache = true;
+    if (currentDataSource == cacheReadDataSource || exception instanceof CacheDataSinkException) {
+      seenCacheError = true;
     }
   }
 

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

@@ -32,8 +32,8 @@ public interface CacheEvictor extends Cache.Listener {
    * @param cache The source of the event.
    * @param key The key being written.
    * @param position The starting position of the data being written.
-   * @param length The maximum length of the data being written.
+   * @param maxLength The maximum length of the data being written.
    */
-  void onStartFile(Cache cache, String key, long position, long length);
+  void onStartFile(Cache cache, String key, long position, long maxLength);
 
 }

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

@@ -39,8 +39,8 @@ public final class LeastRecentlyUsedCacheEvictor implements CacheEvictor, Compar
   }
 
   @Override
-  public void onStartFile(Cache cache, String key, long position, long length) {
-    evictCache(cache, length);
+  public void onStartFile(Cache cache, String key, long position, long maxLength) {
+    evictCache(cache, maxLength);
   }
 
   @Override

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

@@ -30,7 +30,7 @@ public final class NoOpCacheEvictor implements CacheEvictor {
   }
 
   @Override
-  public void onStartFile(Cache cache, String key, long position, long length) {
+  public void onStartFile(Cache cache, String key, long position, long maxLength) {
     // Do nothing.
   }
 

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

@@ -16,6 +16,9 @@
 package com.google.android.exoplayer2.upstream.cache;
 
 import android.os.ConditionVariable;
+
+import android.util.Pair;
+import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.util.Assertions;
 import java.io.File;
 import java.util.ArrayList;
@@ -35,7 +38,7 @@ public final class SimpleCache implements Cache {
   private final File cacheDir;
   private final CacheEvictor evictor;
   private final HashMap<String, CacheSpan> lockedSpans;
-  private final HashMap<String, TreeSet<CacheSpan>> cachedSpans;
+  private final HashMap<String, Pair<Long, TreeSet<CacheSpan>>> cachedSpans;
   private final HashMap<String, ArrayList<Listener>> listeners;
   private long totalSpace = 0;
 
@@ -89,7 +92,7 @@ public final class SimpleCache implements Cache {
 
   @Override
   public synchronized NavigableSet<CacheSpan> getCachedSpans(String key) {
-    TreeSet<CacheSpan> spansForKey = cachedSpans.get(key);
+    TreeSet<CacheSpan> spansForKey = getSpansForKey(key);
     return spansForKey == null ? null : new TreeSet<>(spansForKey);
   }
 
@@ -127,26 +130,21 @@ public final class SimpleCache implements Cache {
   }
 
   private synchronized CacheSpan startReadWriteNonBlocking(CacheSpan lookupSpan) {
-    CacheSpan spanningRegion = getSpan(lookupSpan);
+    CacheSpan cacheSpan = getSpan(lookupSpan);
 
     // Read case.
-    if (spanningRegion.isCached) {
-      CacheSpan oldCacheSpan = spanningRegion;
-      // Remove the old span from the in-memory representation.
-      TreeSet<CacheSpan> spansForKey = cachedSpans.get(oldCacheSpan.key);
-      Assertions.checkState(spansForKey.remove(oldCacheSpan));
+    if (cacheSpan.isCached) {
       // Obtain a new span with updated last access timestamp.
-      spanningRegion = oldCacheSpan.touch();
-      // Add the updated span back into the in-memory representation.
-      spansForKey.add(spanningRegion);
-      notifySpanTouched(oldCacheSpan, spanningRegion);
-      return spanningRegion;
+      CacheSpan newCacheSpan = cacheSpan.touch();
+      replaceSpan(cacheSpan, newCacheSpan);
+      notifySpanTouched(cacheSpan, newCacheSpan);
+      return newCacheSpan;
     }
 
     // Write case, lock available.
     if (!lockedSpans.containsKey(lookupSpan.key)) {
-      lockedSpans.put(lookupSpan.key, spanningRegion);
-      return spanningRegion;
+      lockedSpans.put(lookupSpan.key, cacheSpan);
+      return cacheSpan;
     }
 
     // Write case, lock not available.
@@ -154,14 +152,14 @@ public final class SimpleCache implements Cache {
   }
 
   @Override
-  public synchronized File startFile(String key, long position, long length) {
+  public synchronized File startFile(String key, long position, long maxLength) {
     Assertions.checkState(lockedSpans.containsKey(key));
     if (!cacheDir.exists()) {
       // For some reason the cache directory doesn't exist. Make a best effort to create it.
       removeStaleSpans();
       cacheDir.mkdirs();
     }
-    evictor.onStartFile(this, key, position, length);
+    evictor.onStartFile(this, key, position, maxLength);
     return CacheSpan.getCacheFileName(cacheDir, key, position, System.currentTimeMillis(), false);
   }
 
@@ -175,11 +173,15 @@ public final class SimpleCache implements Cache {
       return;
     }
     // If the file has length 0, delete it and don't add it to the in-memory representation.
-    long length = file.length();
-    if (length == 0) {
+    if (file.length() == 0) {
       file.delete();
       return;
     }
+    // Check if the span conflicts with the set content length
+    Long length = getContentLength(span.key);
+    if (length != C.LENGTH_UNSET) {
+      Assertions.checkState((span.position + span.length) <= length);
+    }
     addSpan(span);
     notifyAll();
   }
@@ -204,7 +206,7 @@ public final class SimpleCache implements Cache {
   private CacheSpan getSpan(CacheSpan lookupSpan) {
     String key = lookupSpan.key;
     long offset = lookupSpan.position;
-    TreeSet<CacheSpan> entries = cachedSpans.get(key);
+    TreeSet<CacheSpan> entries = getSpansForKey(key);
     if (entries == null) {
       return CacheSpan.createOpenHole(key, lookupSpan.position);
     }
@@ -260,10 +262,13 @@ public final class SimpleCache implements Cache {
    * @param span The span to be added.
    */
   private void addSpan(CacheSpan span) {
-    TreeSet<CacheSpan> spansForKey = cachedSpans.get(span.key);
-    if (spansForKey == null) {
+    Pair<Long, TreeSet<CacheSpan>> entryForKey = cachedSpans.get(span.key);
+    TreeSet<CacheSpan> spansForKey;
+    if (entryForKey == null) {
       spansForKey = new TreeSet<>();
-      cachedSpans.put(span.key, spansForKey);
+      setKeyValue(span.key, C.LENGTH_UNSET, spansForKey);
+    } else {
+      spansForKey = entryForKey.second;
     }
     spansForKey.add(span);
     totalSpace += span.length;
@@ -272,7 +277,7 @@ public final class SimpleCache implements Cache {
 
   @Override
   public synchronized void removeSpan(CacheSpan span) {
-    TreeSet<CacheSpan> spansForKey = cachedSpans.get(span.key);
+    TreeSet<CacheSpan> spansForKey = getSpansForKey(span.key);
     totalSpace -= span.length;
     Assertions.checkState(spansForKey.remove(span));
     span.file.delete();
@@ -287,10 +292,11 @@ public final class SimpleCache implements Cache {
    * no longer exist.
    */
   private void removeStaleSpans() {
-    Iterator<Entry<String, TreeSet<CacheSpan>>> iterator = cachedSpans.entrySet().iterator();
+    Iterator<Entry<String, Pair<Long, TreeSet<CacheSpan>>>> iterator =
+        cachedSpans.entrySet().iterator();
     while (iterator.hasNext()) {
-      Entry<String, TreeSet<CacheSpan>> next = iterator.next();
-      Iterator<CacheSpan> spanIterator = next.getValue().iterator();
+      Entry<String, Pair<Long, TreeSet<CacheSpan>>> next = iterator.next();
+      Iterator<CacheSpan> spanIterator = next.getValue().second.iterator();
       boolean isEmpty = true;
       while (spanIterator.hasNext()) {
         CacheSpan span = spanIterator.next();
@@ -342,7 +348,7 @@ public final class SimpleCache implements Cache {
 
   @Override
   public synchronized boolean isCached(String key, long position, long length) {
-    TreeSet<CacheSpan> entries = cachedSpans.get(key);
+    TreeSet<CacheSpan> entries = getSpansForKey(key);
     if (entries == null) {
       return false;
     }
@@ -375,4 +381,49 @@ public final class SimpleCache implements Cache {
     return false;
   }
 
+  @Override
+  public synchronized boolean setContentLength(String key, long length) {
+    Pair<Long, TreeSet<CacheSpan>> entryForKey = cachedSpans.get(key);
+    TreeSet<CacheSpan> entries;
+    if (entryForKey != null) {
+      entries = entryForKey.second;
+      if (entries != null && !entries.isEmpty()) {
+        CacheSpan last = entries.last();
+        long end = last.position + last.length;
+        if (end > length) {
+          return false;
+        }
+      }
+    } else {
+      entries = new TreeSet<>();
+    }
+    // TODO persist the length value
+    setKeyValue(key, length, entries);
+    return true;
+  }
+
+  @Override
+  public synchronized long getContentLength(String key) {
+    Pair<Long, TreeSet<CacheSpan>> entryForKey = cachedSpans.get(key);
+    return entryForKey == null ? C.LENGTH_UNSET : entryForKey.first;
+  }
+
+
+  private TreeSet<CacheSpan> getSpansForKey(String key) {
+    Pair<Long, TreeSet<CacheSpan>> entryForKey = cachedSpans.get(key);
+    return entryForKey != null ? entryForKey.second : null;
+  }
+
+  private void setKeyValue(String key, long length, TreeSet<CacheSpan> entries) {
+    cachedSpans.put(key, Pair.create(length, entries));
+  }
+
+  private void replaceSpan(CacheSpan oldSpan, CacheSpan newSpan) {
+    // Remove the old span from the in-memory representation.
+    TreeSet<CacheSpan> spansForKey = getSpansForKey(oldSpan.key);
+    Assertions.checkState(spansForKey.remove(oldSpan));
+    // Add the updated span back into the in-memory representation.
+    spansForKey.add(newSpan);
+  }
+
 }

testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeDataSource.java

@@ -49,6 +49,7 @@ public final class FakeDataSource implements DataSource {
   private boolean opened;
   private int currentSegmentIndex;
   private long bytesRemaining;
+  private IOException unsatisfiableRangeException;
 
   private FakeDataSource(boolean simulateUnknownLength, ArrayList<Segment> segments) {
     this.simulateUnknownLength = simulateUnknownLength;
@@ -59,6 +60,7 @@ public final class FakeDataSource implements DataSource {
     }
     this.totalLength = totalLength;
     openedDataSpecs = new ArrayList<>();
+    unsatisfiableRangeException = new IOException("Unsatisfiable range");
   }
 
   @Override
@@ -69,11 +71,9 @@ public final class FakeDataSource implements DataSource {
     uri = dataSpec.uri;
     openedDataSpecs.add(dataSpec);
     // If the source knows that the request is unsatisfiable then fail.
-    if (dataSpec.position >= totalLength) {
-      throw new IOException("Unsatisfiable position");
-    } else if (dataSpec.length != C.LENGTH_UNSET
-        && dataSpec.position + dataSpec.length > totalLength) {
-      throw new IOException("Unsatisfiable range");
+    if (dataSpec.position >= totalLength || (dataSpec.length != C.LENGTH_UNSET
+        && (dataSpec.position + dataSpec.length > totalLength))) {
+      throw (IOException) unsatisfiableRangeException.fillInStackTrace();
     }
     // Scan through the segments, configuring them for the current read.
     boolean findingCurrentSegmentIndex = true;
@@ -107,10 +107,10 @@ public final class FakeDataSource implements DataSource {
         return C.RESULT_END_OF_INPUT;
       }
       Segment current = segments.get(currentSegmentIndex);
-      if (current.exception != null) {
+      if (current.isErrorSegment()) {
         if (!current.exceptionCleared) {
           current.exceptionThrown = true;
-          throw current.exception;
+          throw (IOException) current.exception.fillInStackTrace();
         } else {
           currentSegmentIndex++;
         }
@@ -160,6 +160,10 @@ public final class FakeDataSource implements DataSource {
     return dataSpecs;
   }
 
+  public void setUnsatisfiableRangeException(IOException unsatisfiableRangeException) {
+    this.unsatisfiableRangeException = unsatisfiableRangeException;
+  }
+
   private static class Segment {
 
     public final IOException exception;

testutils/src/main/java/com/google/android/exoplayer2/testutil/TestUtil.java

@@ -24,6 +24,7 @@ import com.google.android.exoplayer2.extractor.SeekMap;
 import com.google.android.exoplayer2.testutil.FakeExtractorInput.SimulatedIOException;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.Arrays;
@@ -303,4 +304,13 @@ public class TestUtil {
     return extractorOutput;
   }
 
+  public static void recursiveDelete(File fileOrDirectory) {
+    if (fileOrDirectory.isDirectory()) {
+      for (File child : fileOrDirectory.listFiles()) {
+        recursiveDelete(child);
+      }
+    }
+    fileOrDirectory.delete();
+  }
+
 }