Add DownloadIndex and DefaultDownloadIndex

DownloadIndex will be used to store and query DownloadStates.

PiperOrigin-RevId: 228673766

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

@@ -156,7 +156,7 @@ public final class DownloadAction {
       ArrayList<StreamKey> mutableKeys = new ArrayList<>(keys);
       Collections.sort(mutableKeys);
       this.keys = Collections.unmodifiableList(mutableKeys);
-      this.data = data != null ? data : Util.EMPTY_BYTE_ARRAY;
+      this.data = data != null ? Arrays.copyOf(data, data.length) : Util.EMPTY_BYTE_ARRAY;
     }
   }
 

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

+/*
+ * Copyright (C) 2019 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.offline;
+
+import android.support.annotation.Nullable;
+
+/** Persists {@link DownloadState}s. */
+interface DownloadIndex {
+  /** Releases the used resources. */
+  void release();
+
+  /**
+   * Returns the {@link DownloadState} with the given {@code id}, or null.
+   *
+   * @param id ID of a {@link DownloadState}.
+   * @return The {@link DownloadState} with the given {@code id}, or null if a download state with
+   *     this id doesn't exist.
+   */
+  @Nullable
+  DownloadState getDownloadState(String id);
+
+  /**
+   * Returns a {@link DownloadStateCursor} to {@link DownloadState}s with the given {@code states}.
+   *
+   * @param states Returns only the {@link DownloadState}s with this states. If empty, returns all.
+   * @return A cursor to {@link DownloadState}s with the given {@code states}.
+   */
+  DownloadStateCursor getDownloadStates(@DownloadState.State int... states);
+
+  /**
+   * Adds or replaces a {@link DownloadState}.
+   *
+   * @param downloadState The {@link DownloadState} to be added.
+   */
+  void putDownloadState(DownloadState downloadState);
+
+  /** Removes the {@link DownloadState} with the given {@code id}. */
+  void removeDownloadState(String id);
+}

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

@@ -13,7 +13,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package com.google.android.exoplayer2.offline;
 
 import android.net.Uri;

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

+/*
+ * Copyright (C) 2019 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.offline;
+
+/** Provides random read-write access to the result set returned by a database query. */
+interface DownloadStateCursor {
+
+  /** Returns the DownloadState at the current position. */
+  DownloadState getDownloadState();
+
+  /** Returns the numbers of DownloadStates in the cursor. */
+  int getCount();
+
+  /**
+   * Returns the current position of the cursor in the DownloadState set. The value is zero-based.
+   * When the DownloadState set is first returned the cursor will be at positon -1, which is before
+   * the first DownloadState. After the last DownloadState is returned another call to next() will
+   * leave the cursor past the last entry, at a position of count().
+   *
+   * @return the current cursor position.
+   */
+  int getPosition();
+
+  /**
+   * Move the cursor to an absolute position. The valid range of values is -1 <= position <=
+   * count.
+   *
+   * <p>This method will return true if the request destination was reachable, otherwise, it returns
+   * false.
+   *
+   * @param position the zero-based position to move to.
+   * @return whether the requested move fully succeeded.
+   */
+  boolean moveToPosition(int position);
+
+  /**
+   * Move the cursor to the first DownloadState.
+   *
+   * <p>This method will return false if the cursor is empty.
+   *
+   * @return whether the move succeeded.
+   */
+  default boolean moveToFirst() {
+    return moveToPosition(0);
+  }
+
+  /**
+   * Move the cursor to the last DownloadState.
+   *
+   * <p>This method will return false if the cursor is empty.
+   *
+   * @return whether the move succeeded.
+   */
+  default boolean moveToLast() {
+    return moveToPosition(getCount() - 1);
+  }
+
+  /**
+   * Move the cursor to the next DownloadState.
+   *
+   * <p>This method will return false if the cursor is already past the last entry in the result
+   * set.
+   *
+   * @return whether the move succeeded.
+   */
+  default boolean moveToNext() {
+    return moveToPosition(getPosition() + 1);
+  }
+
+  /**
+   * Move the cursor to the previous DownloadState.
+   *
+   * <p>This method will return false if the cursor is already before the first entry in the result
+   * set.
+   *
+   * @return whether the move succeeded.
+   */
+  default boolean moveToPrevious() {
+    return moveToPosition(getPosition() - 1);
+  }
+
+  /** Returns whether the cursor is pointing to the first DownloadState. */
+  default boolean isFirst() {
+    return getPosition() == 0 && getCount() != 0;
+  }
+
+  /** Returns whether the cursor is pointing to the last DownloadState. */
+  default boolean isLast() {
+    int count = getCount();
+    return getPosition() == (count - 1) && count != 0;
+  }
+
+  /** Returns whether the cursor is pointing to the position before the first DownloadState. */
+  default boolean isBeforeFirst() {
+    if (getCount() == 0) {
+      return true;
+    }
+    return getPosition() == -1;
+  }
+
+  /** Returns whether the cursor is pointing to the position after the last DownloadState. */
+  default boolean isAfterLast() {
+    if (getCount() == 0) {
+      return true;
+    }
+    return getPosition() == getCount();
+  }
+
+  /** Closes the Cursor, releasing all of its resources and making it completely invalid. */
+  void close();
+
+  /** Returns whether the cursor is closed */
+  boolean isClosed();
+}