1 files changed, 103 insertions, 0 deletions
diff --git a/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/event/EventCache.java b/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/event/EventCache.java
new file mode 100644
index 0000000..a3106f5
--- /dev/null
+++ b/third_party/sl4a/src/main/java/com/google/android/mobly/snippet/event/EventCache.java
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2017 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.event;
+
+import com.google.android.mobly.snippet.util.Log;
+import java.util.Deque;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
+import java.util.concurrent.LinkedBlockingDeque;
+
+/**
+ * Manage the event queue.
+ *
+ * <p>EventCache APIs interact with the SnippetEvent cache - a data structure that holds {@link
+ * SnippetEvent} objects posted from snippet classes. The SnippetEvent cache provides a useful means
+ * of recording background events (such as sensor data) when the phone is busy with foreground
+ * activities.
+ */
+public class EventCache {
+    private static final String EVENT_DEQUE_ID_TEMPLATE = "%s|%s";
+    private static final int EVENT_DEQUE_MAX_SIZE = 1024;
+
+    // A Map with each value being the queue for a particular type of event, and the key being the
+    // unique ID of the queue. The ID is composed of a callback ID and an event's name.
+    private final Map<String, LinkedBlockingDeque<SnippetEvent>> mEventDeques = new HashMap<>();
+
+    private static volatile EventCache mEventCache;
+
+    private EventCache() {}
+
+    public static EventCache getInstance() {
+        if (mEventCache == null) {
+            synchronized (EventCache.class) {
+                if (mEventCache == null) {
+                    mEventCache = new EventCache();
+                }
+            }
+        }
+        return mEventCache;
+    }
+
+    public static String getQueueId(String callbackId, String name) {
+        return String.format(Locale.US, EVENT_DEQUE_ID_TEMPLATE, callbackId, name);
+    }
+
+    public LinkedBlockingDeque<SnippetEvent> getEventDeque(String qId) {
+        synchronized (mEventDeques) {
+            LinkedBlockingDeque<SnippetEvent> eventDeque = mEventDeques.get(qId);
+            if (eventDeque == null) {
+                eventDeque = new LinkedBlockingDeque<>(EVENT_DEQUE_MAX_SIZE);
+                mEventDeques.put(qId, eventDeque);
+            }
+            return eventDeque;
+        }
+    }
+
+    /**
+     * Post an {@link SnippetEvent} object to the Event cache.
+     *
+     * <p>Snippet classes should use this method to post events. If EVENT_DEQUE_MAX_SIZE is reached,
+     * the oldest elements will be retired until the new event could be posted.
+     *
+     * @param snippetEvent The snippetEvent to post to {@link EventCache}.
+     */
+    public void postEvent(SnippetEvent snippetEvent) {
+        String qId = getQueueId(snippetEvent.getCallbackId(), snippetEvent.getName());
+        Deque<SnippetEvent> q = getEventDeque(qId);
+        synchronized (q) {
+            while (!q.offer(snippetEvent)) {
+                SnippetEvent retiredEvent = q.removeFirst();
+                Log.v(
+                        String.format(
+                                Locale.US,
+                                "Retired event %s due to deque reaching the size limit (%s).",
+                                retiredEvent,
+                                EVENT_DEQUE_MAX_SIZE));
+            }
+        }
+        Log.v(String.format(Locale.US, "Posted event(%s)", qId));
+    }
+
+    /** Clears all cached events. */
+    public void clearAll() {
+        synchronized (mEventDeques) {
+            mEventDeques.clear();
+        }
+    }
+}