Fix sensor uuid, retrofit recent event logger

Fix an issue that causes uuid field not being initialzed in
sensorservice.

MostRecentEventLogger in sensorservice is migrated to use RingBuffer
instead of a custom circular buffer. This is expected to improve
readability and maintainability of code.

Dumpsys print format is retouched to offer more information in easier
to read format.

Bug: 28305085

Change-Id: I190e43350b60a22a9fccb92a95d6eab06a471560
diff --git a/services/sensorservice/RecentEventLogger.cpp b/services/sensorservice/RecentEventLogger.cpp
new file mode 100644
index 0000000..dba7211
--- /dev/null
+++ b/services/sensorservice/RecentEventLogger.cpp
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+#include "RecentEventLogger.h"
+#include "SensorServiceUtils.h"
+
+#include <utils/Timers.h>
+
+#include <inttypes.h>
+
+namespace android {
+namespace SensorServiceUtil {
+
+namespace {
+    constexpr size_t LOG_SIZE = 10;
+    constexpr size_t LOG_SIZE_LARGE = 50;  // larger samples for debugging
+}// unnamed namespace
+
+RecentEventLogger::RecentEventLogger(int sensorType) :
+        mSensorType(sensorType), mEventSize(eventSizeBySensorType(mSensorType)),
+        mRecentEvents(logSizeBySensorType(sensorType)) {
+    // blank
+}
+
+void RecentEventLogger::addEvent(const sensors_event_t& event) {
+    std::lock_guard<std::mutex> lk(mLock);
+    mRecentEvents.emplace(event);
+}
+
+bool RecentEventLogger::isEmpty() const {
+    return mRecentEvents.size() == 0;
+}
+
+std::string RecentEventLogger::dump() const {
+    std::lock_guard<std::mutex> lk(mLock);
+
+    //TODO: replace String8 with std::string completely in this function
+    String8 buffer;
+
+    buffer.appendFormat("last %zu events\n", mRecentEvents.size());
+    int j = 0;
+    for (int i = mRecentEvents.size() - 1; i >= 0; --i) {
+        const auto& ev = mRecentEvents[i];
+        struct tm * timeinfo = localtime(&(ev.mWallTime.tv_sec));
+        buffer.appendFormat("\t%2d (ts=%.9f, wall=%02d:%02d:%02d.%03d) ",
+                ++j, ev.mEvent.timestamp/1e9, timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec,
+                (int) ns2ms(ev.mWallTime.tv_nsec));
+
+        // data
+        if (mSensorType == SENSOR_TYPE_STEP_COUNTER) {
+            buffer.appendFormat("%" PRIu64 ", ", ev.mEvent.u64.step_counter);
+        } else {
+            for (size_t k = 0; k < mEventSize; ++k) {
+                buffer.appendFormat("%.2f, ", ev.mEvent.data[k]);
+            }
+        }
+        buffer.append("\n");
+    }
+    return std::string(buffer.string());
+}
+
+bool RecentEventLogger::populateLastEvent(sensors_event_t *event) const {
+    std::lock_guard<std::mutex> lk(mLock);
+
+    if (mRecentEvents.size()) {
+        *event = mRecentEvents[mRecentEvents.size()-1].mEvent;
+        return true;
+    } else {
+        return false;
+    }
+}
+
+
+size_t RecentEventLogger::logSizeBySensorType(int sensorType) {
+    return (sensorType == SENSOR_TYPE_STEP_COUNTER ||
+            sensorType == SENSOR_TYPE_SIGNIFICANT_MOTION ||
+            sensorType == SENSOR_TYPE_ACCELEROMETER) ? LOG_SIZE_LARGE : LOG_SIZE;
+}
+
+RecentEventLogger::SensorEventLog::SensorEventLog(const sensors_event_t& e) : mEvent(e) {
+    clock_gettime(CLOCK_REALTIME, &mWallTime);
+}
+
+} // namespace SensorServiceUtil
+} // namespace android