Add ActionFile which stores and loads DownloadActions to/from a file.

This change also replaces individual DownloadAction versions with a
single master version.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171273880

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

+/*
+ * Copyright (C) 2017 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 com.google.android.exoplayer2.offline.DownloadAction.Deserializer;
+import com.google.android.exoplayer2.util.AtomicFile;
+import com.google.android.exoplayer2.util.ClosedSource;
+import com.google.android.exoplayer2.util.Util;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+/**
+ * Stores and loads {@link DownloadAction}s to/from a file.
+ */
+@ClosedSource(reason = "Not ready yet")
+public final class ActionFile {
+
+  private final AtomicFile atomicFile;
+
+  /**
+   * @param actionFile File to be used to store and load {@link DownloadAction}s.
+   */
+  public ActionFile(File actionFile) {
+    atomicFile = new AtomicFile(actionFile);
+  }
+
+  /**
+   * Loads {@link DownloadAction}s from file.
+   *
+   * @param deserializers {@link Deserializer}s to deserialize DownloadActions.
+   * @return Loaded DownloadActions.
+   * @throws IOException If there is an error during loading.
+   */
+  public DownloadAction[] load(Deserializer... deserializers) throws IOException {
+    InputStream inputStream = null;
+    try {
+      inputStream = atomicFile.openRead();
+      DataInputStream dataInputStream = new DataInputStream(inputStream);
+      int version = dataInputStream.readInt();
+      if (version > DownloadAction.MASTER_VERSION) {
+        throw new IOException("Not supported action file version: " + version);
+      }
+      int actionCount = dataInputStream.readInt();
+      DownloadAction[] actions = new DownloadAction[actionCount];
+      for (int i = 0; i < actionCount; i++) {
+        actions[i] = DownloadAction.deserializeFromStream(deserializers, dataInputStream, version);
+      }
+      return actions;
+    } finally {
+      Util.closeQuietly(inputStream);
+    }
+  }
+
+  /**
+   * Stores {@link DownloadAction}s to file.
+   *
+   * @param downloadActions DownloadActions to store to file.
+   * @throws IOException If there is an error during storing.
+   */
+  public void store(DownloadAction... downloadActions) throws IOException {
+    OutputStream outputStream = null;
+    try {
+      outputStream = atomicFile.startWrite();
+      DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
+      dataOutputStream.writeInt(DownloadAction.MASTER_VERSION);
+      dataOutputStream.writeInt(downloadActions.length);
+      for (DownloadAction action : downloadActions) {
+        DownloadAction.serializeToStream(action, dataOutputStream);
+      }
+      atomicFile.endWrite(outputStream);
+      // Avoid calling close twice.
+      outputStream = null;
+    } finally {
+      Util.closeQuietly(outputStream);
+    }
+  }
+
+}

library/core/src/main/java/com/google/android/exoplayer2/util/Util.java

@@ -1076,12 +1076,17 @@ public final class Util {
 
   /** Creates an empty directory in the directory returned by {@link Context#getCacheDir()}. */
   public static File createTempDirectory(Context context, String prefix) throws IOException {
-    File tempFile = File.createTempFile(prefix, null, context.getCacheDir());
+    File tempFile = createTempFile(context, prefix);
     tempFile.delete(); // Delete the temp file.
     tempFile.mkdir(); // Create a directory with the same name.
     return tempFile;
   }
 
+  /** Creates a new empty file in the directory returned by {@link Context#getCacheDir()}. */
+  public static File createTempFile(Context context, String prefix) throws IOException {
+    return File.createTempFile(prefix, null, context.getCacheDir());
+  }
+
   /**
    * Returns the result of updating a CRC with the specified bytes in a "most significant bit first"
    * order.

library/core/src/test/java/com/google/android/exoplayer2/offline/ActionFileTest.java

+/*
+ * Copyright (C) 2017 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 static com.google.common.truth.Truth.assertThat;
+
+import com.google.android.exoplayer2.offline.DownloadAction.Deserializer;
+import com.google.android.exoplayer2.util.ClosedSource;
+import com.google.android.exoplayer2.util.Util;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+
+/**
+ * Unit tests for {@link ProgressiveDownloadAction}.
+ */
+@ClosedSource(reason = "Not ready yet")
+@RunWith(RobolectricTestRunner.class)
+@Config(sdk = Config.TARGET_SDK, manifest = Config.NONE)
+public class ActionFileTest {
+
+  private File tempFile;
+
+  @Before
+  public void setUp() throws Exception {
+    tempFile = Util.createTempFile(RuntimeEnvironment.application, "ExoPlayerTest");
+  }
+
+  @After
+  public void tearDown() throws Exception {
+    tempFile.delete();
+  }
+
+  @Test
+  public void testLoadNoDataThrowsIOException() throws Exception {
+    try {
+      loadActions(new Object[] {});
+      Assert.fail();
+    } catch (IOException e) {
+      // Expected exception.
+    }
+  }
+
+  @Test
+  public void testLoadIncompleteHeaderThrowsIOException() throws Exception {
+    try {
+      loadActions(new Object[] {DownloadAction.MASTER_VERSION});
+      Assert.fail();
+    } catch (IOException e) {
+      // Expected exception.
+    }
+  }
+
+  @Test
+  public void testLoadCompleteHeaderZeroAction() throws Exception {
+    DownloadAction[] actions =
+        loadActions(new Object[] {DownloadAction.MASTER_VERSION, /*action count*/0});
+    assertThat(actions).isNotNull();
+    assertThat(actions).hasLength(0);
+  }
+
+  @Test
+  public void testLoadAction() throws Exception {
+    DownloadAction[] actions = loadActions(
+        new Object[] {DownloadAction.MASTER_VERSION, /*action count*/1, /*action 1*/"type2", 321},
+        new FakeDeserializer("type2"));
+    assertThat(actions).isNotNull();
+    assertThat(actions).hasLength(1);
+    assertAction(actions[0], "type2", DownloadAction.MASTER_VERSION, 321);
+  }
+
+  @Test
+  public void testLoadActions() throws Exception {
+    DownloadAction[] actions = loadActions(
+        new Object[] {DownloadAction.MASTER_VERSION, /*action count*/2, /*action 1*/"type1", 123,
+            /*action 2*/"type2", 321}, // Action 2
+        new FakeDeserializer("type1"), new FakeDeserializer("type2"));
+    assertThat(actions).isNotNull();
+    assertThat(actions).hasLength(2);
+    assertAction(actions[0], "type1", DownloadAction.MASTER_VERSION, 123);
+    assertAction(actions[1], "type2", DownloadAction.MASTER_VERSION, 321);
+  }
+
+  @Test
+  public void testLoadNotSupportedVersion() throws Exception {
+    try {
+      loadActions(new Object[] {DownloadAction.MASTER_VERSION + 1, /*action count*/1,
+              /*action 1*/"type2", 321}, new FakeDeserializer("type2"));
+      Assert.fail();
+    } catch (IOException e) {
+      // Expected exception.
+    }
+  }
+
+  @Test
+  public void testLoadNotSupportedType() throws Exception {
+    try {
+      loadActions(new Object[] {DownloadAction.MASTER_VERSION, /*action count*/1,
+              /*action 1*/"type2", 321}, new FakeDeserializer("type1"));
+      Assert.fail();
+    } catch (DownloadException e) {
+      // Expected exception.
+    }
+  }
+
+  @Test
+  public void testStoreAndLoadNoActions() throws Exception {
+    doTestSerializationRoundTrip(new DownloadAction[0]);
+  }
+
+  @Test
+  public void testStoreAndLoadActions() throws Exception {
+    doTestSerializationRoundTrip(new DownloadAction[] {
+        new FakeDownloadAction("type1", DownloadAction.MASTER_VERSION, 123),
+        new FakeDownloadAction("type2", DownloadAction.MASTER_VERSION, 321),
+    }, new FakeDeserializer("type1"), new FakeDeserializer("type2"));
+  }
+
+  private void doTestSerializationRoundTrip(DownloadAction[] actions,
+      Deserializer... deserializers) throws IOException {
+    ActionFile actionFile = new ActionFile(tempFile);
+    actionFile.store(actions);
+    assertThat(actionFile.load(deserializers)).isEqualTo(actions);
+  }
+
+  private DownloadAction[] loadActions(Object[] values, Deserializer... deserializers)
+      throws IOException {
+    FileOutputStream fileOutputStream = new FileOutputStream(tempFile);
+    DataOutputStream dataOutputStream = new DataOutputStream(fileOutputStream);
+    try {
+      for (Object value : values) {
+        if (value instanceof Integer) {
+          dataOutputStream.writeInt((Integer) value); // Action count
+        } else if (value instanceof String) {
+          dataOutputStream.writeUTF((String) value); // Action count
+        } else {
+          throw new IllegalArgumentException();
+        }
+      }
+    } finally {
+      dataOutputStream.close();
+    }
+    return new ActionFile(tempFile).load(deserializers);
+  }
+
+  private static void assertAction(DownloadAction action, String type, int version, int data) {
+    assertThat(action).isInstanceOf(FakeDownloadAction.class);
+    assertThat(action.getType()).isEqualTo(type);
+    assertThat(((FakeDownloadAction) action).version).isEqualTo(version);
+    assertThat(((FakeDownloadAction) action).data).isEqualTo(data);
+  }
+
+  private static class FakeDeserializer implements Deserializer {
+    final String type;
+
+    FakeDeserializer(String type) {
+      this.type = type;
+    }
+
+    @Override
+    public String getType() {
+      return type;
+    }
+
+    @Override
+    public DownloadAction readFromStream(int version, DataInputStream input) throws IOException {
+      return new FakeDownloadAction(type, version, input.readInt());
+    }
+  }
+
+  private static class FakeDownloadAction extends DownloadAction {
+    final String type;
+    final int version;
+    final int data;
+
+    private FakeDownloadAction(String type, int version, int data) {
+      this.type = type;
+      this.version = version;
+      this.data = data;
+    }
+
+    @Override
+    protected String getType() {
+      return type;
+    }
+
+    @Override
+    protected void writeToStream(DataOutputStream output) throws IOException {
+      output.writeInt(data);
+    }
+
+    @Override
+    protected boolean isRemoveAction() {
+      return false;
+    }
+
+    @Override
+    protected boolean isSameMedia(DownloadAction other) {
+      return false;
+    }
+
+    @Override
+    protected Downloader createDownloader(DownloaderConstructorHelper downloaderConstructorHelper) {
+      return null;
+    }
+
+    // auto generated code
+
+    @Override
+    public boolean equals(Object o) {
+      if (this == o) {
+        return true;
+      }
+      if (o == null || getClass() != o.getClass()) {
+        return false;
+      }
+      FakeDownloadAction that = (FakeDownloadAction) o;
+      return version == that.version && data == that.data && type.equals(that.type);
+    }
+
+    @Override
+    public int hashCode() {
+      int result = type.hashCode();
+      result = 31 * result + version;
+      result = 31 * result + data;
+      return result;
+    }
+  }
+
+}

library/core/src/test/java/com/google/android/exoplayer2/offline/ProgressiveDownloadActionTest.java

@@ -136,7 +136,7 @@ public class ProgressiveDownloadActionTest {
     ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
     DataInputStream input = new DataInputStream(in);
     DownloadAction action2 =
-        ProgressiveDownloadAction.DESERIALIZER.readFromStream(action1.getVersion(), input);
+        ProgressiveDownloadAction.DESERIALIZER.readFromStream(DownloadAction.MASTER_VERSION, input);
 
     assertThat(action2).isEqualTo(action1);
   }