Make CacheUtil only about writing

A subsequent change will rename it to CacheWriter and make it instantiable.

Issue: #5978
PiperOrigin-RevId: 312648623

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

@@ -18,7 +18,6 @@ package com.google.android.exoplayer2.offline;
 import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
 
 import android.net.Uri;
-import android.util.Pair;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.MediaItem;
@@ -30,6 +29,7 @@ import com.google.android.exoplayer2.upstream.cache.Cache;
 import com.google.android.exoplayer2.upstream.cache.CacheDataSource;
 import com.google.android.exoplayer2.upstream.cache.CacheKeyFactory;
 import com.google.android.exoplayer2.upstream.cache.CacheUtil;
+import com.google.android.exoplayer2.upstream.cache.ContentMetadata;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.PriorityTaskManager;
 import com.google.android.exoplayer2.util.Util;
@@ -136,11 +136,18 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
       long contentLength = 0;
       long bytesDownloaded = 0;
       for (int i = segments.size() - 1; i >= 0; i--) {
-        Segment segment = segments.get(i);
+        DataSpec dataSpec = segments.get(i).dataSpec;
-        Pair<Long, Long> segmentLengthAndBytesDownloaded =
+        String cacheKey = cacheKeyFactory.buildCacheKey(dataSpec);
-            CacheUtil.getCached(segment.dataSpec, cache, cacheKeyFactory);
+        long segmentLength = dataSpec.length;
-        long segmentLength = segmentLengthAndBytesDownloaded.first;
+        if (segmentLength == C.LENGTH_UNSET) {
-        long segmentBytesDownloaded = segmentLengthAndBytesDownloaded.second;
+          long resourceLength =
+              ContentMetadata.getContentLength(cache.getContentMetadata(cacheKey));
+          if (resourceLength != C.LENGTH_UNSET) {
+            segmentLength = resourceLength - dataSpec.position;
+          }
+        }
+        long segmentBytesDownloaded =
+            cache.getCachedBytes(cacheKey, dataSpec.position, segmentLength);
         bytesDownloaded += segmentBytesDownloaded;
         if (segmentLength != C.LENGTH_UNSET) {
           if (segmentLength == segmentBytesDownloaded) {

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

@@ -15,7 +15,6 @@
  */
 package com.google.android.exoplayer2.upstream.cache;
 
-import android.util.Pair;
 import androidx.annotation.Nullable;
 import androidx.annotation.WorkerThread;
 import com.google.android.exoplayer2.C;
@@ -57,38 +56,6 @@ public final class CacheUtil {
   @Deprecated
   public static final CacheKeyFactory DEFAULT_CACHE_KEY_FACTORY = CacheKeyFactory.DEFAULT;
 
-  /**
-   * Queries the cache to obtain the request length and the number of bytes already cached for a
-   * given {@link DataSpec}.
-   *
-   * @param dataSpec Defines the data to be checked.
-   * @param cache A {@link Cache} which has the data.
-   * @param cacheKeyFactory An optional factory for cache keys.
-   * @return A pair containing the request length and the number of bytes that are already cached.
-   */
-  public static Pair<Long, Long> getCached(
-      DataSpec dataSpec, Cache cache, @Nullable CacheKeyFactory cacheKeyFactory) {
-    String key = buildCacheKey(dataSpec, cacheKeyFactory);
-    long position = dataSpec.position;
-    long requestLength = getRequestLength(dataSpec, cache, key);
-    long bytesAlreadyCached = 0;
-    long bytesLeft = requestLength;
-    while (bytesLeft != 0) {
-      long blockLength = cache.getCachedLength(key, position, bytesLeft);
-      if (blockLength > 0) {
-        bytesAlreadyCached += blockLength;
-      } else {
-        blockLength = -blockLength;
-        if (blockLength == Long.MAX_VALUE) {
-          break;
-        }
-      }
-      position += blockLength;
-      bytesLeft -= bytesLeft == C.LENGTH_UNSET ? 0 : blockLength;
-    }
-    return Pair.create(requestLength, bytesAlreadyCached);
-  }
-
   /**
    * Caches the data defined by {@code dataSpec}, skipping already cached data. Caching stops early
    * if the end of the input is reached.
@@ -157,23 +124,26 @@ public final class CacheUtil {
     Assertions.checkNotNull(temporaryBuffer);
 
     Cache cache = dataSource.getCache();
-    CacheKeyFactory cacheKeyFactory = dataSource.getCacheKeyFactory();
+    String cacheKey = dataSource.getCacheKeyFactory().buildCacheKey(dataSpec);
-    String key = buildCacheKey(dataSpec, cacheKeyFactory);
+    long requestLength = dataSpec.length;
-    long bytesLeft;
+    if (requestLength == C.LENGTH_UNSET) {
+      long resourceLength = ContentMetadata.getContentLength(cache.getContentMetadata(cacheKey));
+      if (resourceLength != C.LENGTH_UNSET) {
+        requestLength = resourceLength - dataSpec.position;
+      }
+    }
+    long bytesCached = cache.getCachedBytes(cacheKey, dataSpec.position, requestLength);
     @Nullable ProgressNotifier progressNotifier = null;
     if (progressListener != null) {
       progressNotifier = new ProgressNotifier(progressListener);
-      Pair<Long, Long> lengthAndBytesAlreadyCached = getCached(dataSpec, cache, cacheKeyFactory);
+      progressNotifier.init(requestLength, bytesCached);
-      progressNotifier.init(lengthAndBytesAlreadyCached.first, lengthAndBytesAlreadyCached.second);
-      bytesLeft = lengthAndBytesAlreadyCached.first;
-    } else {
-      bytesLeft = getRequestLength(dataSpec, cache, key);
     }
 
     long position = dataSpec.position;
+    long bytesLeft = requestLength;
     while (bytesLeft != 0) {
       throwExceptionIfCanceled(isCanceled);
-      long blockLength = cache.getCachedLength(key, position, bytesLeft);
+      long blockLength = cache.getCachedLength(cacheKey, position, bytesLeft);
       if (blockLength > 0) {
         // Skip already cached data.
       } else {
@@ -206,15 +176,6 @@ public final class CacheUtil {
     }
   }
 
-  private static long getRequestLength(DataSpec dataSpec, Cache cache, String key) {
-    if (dataSpec.length != C.LENGTH_UNSET) {
-      return dataSpec.length;
-    } else {
-      long contentLength = ContentMetadata.getContentLength(cache.getContentMetadata(key));
-      return contentLength == C.LENGTH_UNSET ? C.LENGTH_UNSET : contentLength - dataSpec.position;
-    }
-  }
-
   /**
    * Reads and discards all data specified by the {@code dataSpec}.
    *
@@ -309,12 +270,6 @@ public final class CacheUtil {
     }
   }
 
-  private static String buildCacheKey(
-      DataSpec dataSpec, @Nullable CacheKeyFactory cacheKeyFactory) {
-    return (cacheKeyFactory != null ? cacheKeyFactory : CacheKeyFactory.DEFAULT)
-        .buildCacheKey(dataSpec);
-  }
-
   private static void throwExceptionIfCanceled(@Nullable AtomicBoolean isCanceled)
       throws InterruptedIOException {
     if (isCanceled != null && isCanceled.get()) {

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

@@ -20,7 +20,6 @@ import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.fail;
 
 import android.net.Uri;
-import android.util.Pair;
 import androidx.test.core.app.ApplicationProvider;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.android.exoplayer2.C;
@@ -104,65 +103,6 @@ public final class CacheUtilTest {
     Util.recursiveDelete(tempFolder);
   }
 
-  @Test
-  public void getCachedNoData() {
-    Pair<Long, Long> contentLengthAndBytesCached =
-        CacheUtil.getCached(
-            new DataSpec(Uri.parse("test")), mockCache, /* cacheKeyFactory= */ null);
-
-    assertThat(contentLengthAndBytesCached.first).isEqualTo(C.LENGTH_UNSET);
-    assertThat(contentLengthAndBytesCached.second).isEqualTo(0);
-  }
-
-  @Test
-  public void getCachedDataUnknownLength() {
-    // Mock there is 100 bytes cached at the beginning
-    mockCache.spansAndGaps = new int[] {100};
-    Pair<Long, Long> contentLengthAndBytesCached =
-        CacheUtil.getCached(
-            new DataSpec(Uri.parse("test")), mockCache, /* cacheKeyFactory= */ null);
-
-    assertThat(contentLengthAndBytesCached.first).isEqualTo(C.LENGTH_UNSET);
-    assertThat(contentLengthAndBytesCached.second).isEqualTo(100);
-  }
-
-  @Test
-  public void getCachedNoDataKnownLength() {
-    mockCache.contentLength = 1000;
-    Pair<Long, Long> contentLengthAndBytesCached =
-        CacheUtil.getCached(
-            new DataSpec(Uri.parse("test")), mockCache, /* cacheKeyFactory= */ null);
-
-    assertThat(contentLengthAndBytesCached.first).isEqualTo(1000);
-    assertThat(contentLengthAndBytesCached.second).isEqualTo(0);
-  }
-
-  @Test
-  public void getCached() {
-    mockCache.contentLength = 1000;
-    mockCache.spansAndGaps = new int[] {100, 100, 200};
-    Pair<Long, Long> contentLengthAndBytesCached =
-        CacheUtil.getCached(
-            new DataSpec(Uri.parse("test")), mockCache, /* cacheKeyFactory= */ null);
-
-    assertThat(contentLengthAndBytesCached.first).isEqualTo(1000);
-    assertThat(contentLengthAndBytesCached.second).isEqualTo(300);
-  }
-
-  @Test
-  public void getCachedFromNonZeroPosition() {
-    mockCache.contentLength = 1000;
-    mockCache.spansAndGaps = new int[] {100, 100, 200};
-    Pair<Long, Long> contentLengthAndBytesCached =
-        CacheUtil.getCached(
-            new DataSpec(Uri.parse("test"), /* position= */ 100, /* length= */ C.LENGTH_UNSET),
-            mockCache,
-            /* cacheKeyFactory= */ null);
-
-    assertThat(contentLengthAndBytesCached.first).isEqualTo(900);
-    assertThat(contentLengthAndBytesCached.second).isEqualTo(200);
-  }
-
   @Test
   public void cache() throws Exception {
     FakeDataSet fakeDataSet = new FakeDataSet().setRandomData("test_data", 100);