Support of RPC scheduling (#61)

* Support of RPC scheduling

To perform operations while device is disconnected (e.g., USB is off),
RPCs need to be scheduled with certain delay before disconnection
happens.

While device is disconnected, as long as the snippet is still running,
the scheduled RPCs should be able to be executed.

The RPC result could be retrieved as cached events once device get back
online.

3 files changed, 82 insertions, 123 deletions

diff --git a/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/ReflectionSnippetManagerFactory.java b/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/ReflectionSnippetManagerFactory.java
deleted file mode 100644
index 5e4259d..0000000
--- a/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/ReflectionSnippetManagerFactory.java
+++ /dev/null
@@ -1,97 +0,0 @@
-/*
- * Copyright (C) 2016 Google Inc.
- *
- * 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.mobly.snippet.manager;
-
-import android.content.Context;
-import android.content.pm.ApplicationInfo;
-import android.content.pm.PackageManager;
-import android.os.Bundle;
-import com.google.android.mobly.snippet.Snippet;
-import com.google.android.mobly.snippet.event.EventSnippet;
-import com.google.android.mobly.snippet.util.Log;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Map;
-import java.util.Set;
-
-public class ReflectionSnippetManagerFactory implements SnippetManagerFactory {
-    private static final String METADATA_TAG_NAME = "mobly-snippets";
-
-    private final Context mContext;
-    private final Set<Class<? extends Snippet>> mClasses;
-    private final Map<Integer, SnippetManager> mSnippetManagers;
-
-    public ReflectionSnippetManagerFactory(Context context) {
-        mContext = context;
-        mClasses = loadSnippets();
-        mSnippetManagers = new HashMap<>();
-    }
-
-    @Override
-    public SnippetManager create(Integer UID) {
-        SnippetManager manager = new SnippetManager(mClasses);
-        mSnippetManagers.put(UID, manager);
-        return manager;
-    }
-
-    @Override
-    public Map<Integer, SnippetManager> getSnippetManagers() {
-        return Collections.unmodifiableMap(mSnippetManagers);
-    }
-
-    private Set<Class<? extends Snippet>> loadSnippets() {
-        ApplicationInfo appInfo;
-        try {
-            appInfo =
-                    mContext.getPackageManager()
-                            .getApplicationInfo(
-                                    mContext.getPackageName(), PackageManager.GET_META_DATA);
-        } catch (PackageManager.NameNotFoundException e) {
-            throw new IllegalStateException(
-                    "Failed to find ApplicationInfo with package name: "
-                            + mContext.getPackageName());
-        }
-        Bundle metadata = appInfo.metaData;
-        String snippets = metadata.getString(METADATA_TAG_NAME);
-        if (snippets == null) {
-            throw new IllegalStateException(
-                    "AndroidManifest.xml does not contain a <metadata> tag with "
-                            + "name=\""
-                            + METADATA_TAG_NAME
-                            + "\"");
-        }
-        String[] snippetClassNames = snippets.split("\\s*,\\s*");
-        Set<Class<? extends Snippet>> receiverSet = new HashSet<>();
-        /** Add the event snippet class which is provided within the Snippet Lib. */
-        receiverSet.add(EventSnippet.class);
-        for (String snippetClassName : snippetClassNames) {
-            try {
-                Log.i("Trying to load Snippet class: " + snippetClassName);
-                Class<?> snippetClass = Class.forName(snippetClassName);
-                receiverSet.add((Class<? extends Snippet>) snippetClass);
-            } catch (ClassNotFoundException e) {
-                Log.e("Failed to find class " + snippetClassName);
-                throw new RuntimeException(e);
-            }
-        }
-        if (receiverSet.isEmpty()) {
-            throw new IllegalStateException("Found no subclasses of Snippet.");
-        }
-        return receiverSet;
-    }
-}
diff --git a/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/SnippetManager.java b/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/SnippetManager.java
index ff0aec3..66e33b3 100644
--- a/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/SnippetManager.java
+++ b/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/SnippetManager.java
@@ -16,11 +16,17 @@
 
 package com.google.android.mobly.snippet.manager;
 
+import android.content.Context;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
 import android.os.Build;
+import android.os.Bundle;
 import com.google.android.mobly.snippet.Snippet;
+import com.google.android.mobly.snippet.event.EventSnippet;
 import com.google.android.mobly.snippet.rpc.MethodDescriptor;
 import com.google.android.mobly.snippet.rpc.RpcMinSdk;
 import com.google.android.mobly.snippet.rpc.RunOnUiThread;
+import com.google.android.mobly.snippet.schedulerpc.ScheduleRpcSnippet;
 import com.google.android.mobly.snippet.util.Log;
 import com.google.android.mobly.snippet.util.MainThread;
 import com.google.android.mobly.snippet.util.SnippetLibException;
@@ -30,18 +36,24 @@ import java.lang.reflect.Method;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Set;
 import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.concurrent.Callable;
 
 public class SnippetManager {
+    private static final String METADATA_TAG_NAME = "mobly-snippets";
     private final Map<Class<? extends Snippet>, Snippet> mSnippets;
     /** A map of strings to known RPCs. */
     private final Map<String, MethodDescriptor> mKnownRpcs;
 
-    public SnippetManager(Collection<Class<? extends Snippet>> classList) {
+    private static SnippetManager sInstance = null;
+    private boolean mShutdown = false;
+
+    private SnippetManager(Collection<Class<? extends Snippet>> classList) {
         // Synchronized for multiple connections on the same session. Can't use ConcurrentHashMap
         // because we have to put in a value of 'null' before the class is constructed, but
         // ConcurrentHashMap does not allow null values.
@@ -65,6 +77,25 @@ public class SnippetManager {
         mKnownRpcs = Collections.unmodifiableMap(knownRpcs);
     }
 
+    public static synchronized SnippetManager initSnippetManager(Context context) {
+        if (sInstance != null) {
+            throw new IllegalStateException("SnippetManager should not be re-initialized");
+        }
+        Collection<Class<? extends Snippet>> classList = findSnippetClassesFromMetadata(context);
+        sInstance = new SnippetManager(classList);
+        return sInstance;
+    }
+
+    public static SnippetManager getInstance() {
+        if (sInstance == null) {
+            throw new IllegalStateException("getInstance() called before init()");
+        }
+        if (sInstance.isShutdown()) {
+            throw new IllegalStateException("shutdown() called before getInstance()");
+        }
+        return sInstance;
+    }
+
     public MethodDescriptor getMethodDescriptor(String methodName) {
         return mKnownRpcs.get(methodName);
     }
@@ -114,6 +145,56 @@ public class SnippetManager {
                 entry.getValue().shutdown();
             }
         }
+        mSnippets.clear();
+        mKnownRpcs.clear();
+        mShutdown = true;
+    }
+
+    public boolean isShutdown() {
+        return mShutdown;
+    }
+
+    private static Set<Class<? extends Snippet>> findSnippetClassesFromMetadata(Context context) {
+        ApplicationInfo appInfo;
+        try {
+            appInfo =
+                    context.getPackageManager()
+                            .getApplicationInfo(
+                                    context.getPackageName(), PackageManager.GET_META_DATA);
+        } catch (PackageManager.NameNotFoundException e) {
+            throw new IllegalStateException(
+                    "Failed to find ApplicationInfo with package name: "
+                            + context.getPackageName());
+        }
+        Bundle metadata = appInfo.metaData;
+        String snippets = metadata.getString(METADATA_TAG_NAME);
+        if (snippets == null) {
+            throw new IllegalStateException(
+                    "AndroidManifest.xml does not contain a <metadata> tag with "
+                            + "name=\""
+                            + METADATA_TAG_NAME
+                            + "\"");
+        }
+        String[] snippetClassNames = snippets.split("\\s*,\\s*");
+        Set<Class<? extends Snippet>> receiverSet = new HashSet<>();
+        /** Add the event snippet class which is provided within the Snippet Lib. */
+        receiverSet.add(EventSnippet.class);
+        /** Add the schedule RPC snippet class which is provided within the Snippet Lib. */
+        receiverSet.add(ScheduleRpcSnippet.class);
+        for (String snippetClassName : snippetClassNames) {
+            try {
+                Log.i("Trying to load Snippet class: " + snippetClassName);
+                Class<?> snippetClass = Class.forName(snippetClassName);
+                receiverSet.add((Class<? extends Snippet>) snippetClass);
+            } catch (ClassNotFoundException e) {
+                Log.e("Failed to find class " + snippetClassName);
+                throw new RuntimeException(e);
+            }
+        }
+        if (receiverSet.isEmpty()) {
+            throw new IllegalStateException("Found no subclasses of Snippet.");
+        }
+        return receiverSet;
     }
 
     private Snippet get(Class<? extends Snippet> clazz) throws Exception {
diff --git a/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/SnippetManagerFactory.java b/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/SnippetManagerFactory.java
deleted file mode 100644
index 50a3552..0000000
--- a/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/manager/SnippetManagerFactory.java
+++ /dev/null
@@ -1,25 +0,0 @@
-/*
- * Copyright (C) 2016 Google Inc.
- *
- * 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.mobly.snippet.manager;
-
-import java.util.Map;
-
-public interface SnippetManagerFactory {
-    SnippetManager create(Integer UID);
-
-    Map<Integer, SnippetManager> getSnippetManagers();
-}