Minor cleanup of comments

Test: dumpsys media.log
Change-Id: I144908ce81ec10f572c79b75fda569683b7682f5
diff --git a/media/libnbaio/NBLog.cpp b/media/libnbaio/NBLog.cpp
index c73632c..ad38390 100644
--- a/media/libnbaio/NBLog.cpp
+++ b/media/libnbaio/NBLog.cpp
@@ -12,78 +12,10 @@
  * 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.
+ *
+ *
  */
 
-/*
-* Documentation: Workflow summary for histogram data processing:
-* For more details on FIFO, please see system/media/audio_utils; doxygen
-* TODO: add this documentation to doxygen once it is further developed
-* 1) Writing buffer period timestamp to the circular buffer
-* onWork()
-*     Called every period length (e.g., 4ms)
-*     Calls LOG_HIST_TS
-* LOG_HIST_TS
-*     Hashes file name and line number, and writes single timestamp to buffer
-*     calls NBLOG::Writer::logEventHistTS once
-* NBLOG::Writer::logEventHistTS
-*     calls NBLOG::Writer::log on hash and current timestamp
-*     time is in CLOCK_MONOTONIC converted to ns
-* NBLOG::Writer::log(Event, const void*, size_t)
-*     Initializes Entry, a struct containing one log entry
-*     Entry contains the event type (mEvent), data length (mLength),
-*     and data pointer (mData)
-*     TODO: why mLength (max length of buffer data)  must be <= kMaxLength = 255?
-*     calls NBLOG::Writer::log(Entry *, bool)
-* NBLog::Writer::log(Entry *, bool)
-*     Calls copyEntryDataAt to format data as follows in temp array:
-*     [type][length][data ... ][length]
-*     calls audio_utils_fifo_writer.write on temp
-* audio_utils_fifo_writer.write
-*     calls obtain(), memcpy (reference in doxygen)
-*     returns number of frames written
-* ssize_t audio_utils_fifo_reader::obtain
-*     Determines readable buffer section via pointer arithmetic on reader
-*     and writer pointers
-* Similarly, LOG_AUDIO_STATE() is called by onStateChange whenever audio is
-* turned on or off, and writes this notification to the FIFO.
-*
-* 2) reading the data from shared memory
-* Thread::threadloop()
-* NBLog::MergeThread::threadLoop()
-*     Waits on a mutex, called periodically
-*     Calls NBLog::Merger::merge and MergeReader.getAndProcessSnapshot.
-* NBLog::Merger::merge
-*     Merges snapshots sorted by timestamp
-*     Calls Reader::getSnapshot on each individual thread buffer to in shared
-*     memory and writes all their data to the single FIFO stored in mMerger.
-* NBLog::Reader::getSnapshot
-*     copies snapshot of reader's fifo buffer into its own buffer
-*     calls mFifoReader->obtain to find readable data
-*     sets snapshot.begin() and .end() iterators to boundaries of valid entries
-*     moves the fifo reader index to after the last entry read
-*     in this case, the buffer is in shared memory. in (4), the buffer is private
-* NBLog::MergeThread::getAndProcessSnapshot
-*     Iterates through the entries in the local FIFO. Processes the data in
-*     specific ways depending on the entry type. If the data is a histogram
-*     timestamp or an audio on/off signal, writes to a map of PerformanceAnalysis
-*     class instances, where the wakeup() intervals are stored as histograms
-*     and analyzed.
-*
-* 3) Dumpsys media.log call to report the data
-* MediaLogService::dump in MediaLogService.cpp
-*     calls NBLog::Reader::dump, which calls ReportPerformance::dump
-* ReportPerformance::dump
-*     calls PerformanceAnalysis::ReportPerformance
-*     and ReportPerformance::WriteToFile
-* PerformanceAnalysis::ReportPerformance
-*     for each thread/source file location instance of PerformanceAnalysis data,
-*     combines all histograms into a single one and prints it to the console
-*     along with outlier data
-* ReportPerformance::WriteToFile
-*     writes histogram, outlier, and peak information to file separately for each
-*     instance of PerformanceAnalysis data.
-*/
-
 #define LOG_TAG "NBLog"
 
 #include <algorithm>
@@ -875,14 +807,6 @@
 void NBLog::MergeReader::getAndProcessSnapshot(NBLog::Reader::Snapshot &snapshot)
 {
     String8 timestamp, body;
-    // TODO: check: is this thread safe?
-    // TODO: add lost data information and notification to ReportPerformance
-    size_t lost = snapshot.lost() + (snapshot.begin() - EntryIterator(snapshot.data()));
-    if (lost > 0) {
-        // TODO: ultimately, this will be += and reset to 0. TODO: check that this is
-        // obsolete now that Merger::merge is called periodically. No data should be lost
-        mLost = lost;
-    }
 
     for (auto entry = snapshot.begin(); entry != snapshot.end();) {
         switch (entry->type) {
diff --git a/media/libnbaio/PerformanceAnalysis.cpp b/media/libnbaio/PerformanceAnalysis.cpp
index 4e446a4..9e0f84d 100644
--- a/media/libnbaio/PerformanceAnalysis.cpp
+++ b/media/libnbaio/PerformanceAnalysis.cpp
@@ -46,9 +46,8 @@
 
 namespace ReportPerformance {
 
-// Given a the most recent timestamp of a series of audio processing
-// wakeup timestamps,
-// buckets the time interval into a histogram, searches for
+// Given an audio processing wakeup timestamp, buckets the time interval
+// since the previous timestamp into a histogram, searches for
 // outliers, analyzes the outlier series for unexpectedly
 // small or large values and stores these as peaks
 void PerformanceAnalysis::logTsEntry(timestamp ts) {
@@ -75,7 +74,6 @@
     // NormalMixer times vary much more than FastMixer times.
     // TODO: mOutlierFactor values are set empirically based on what appears to be
     // an outlier. Learn these values from the data.
-    // TODO: the current settings are too high, change after next data collection is over
     mBufferPeriod.mOutlierFactor = mBufferPeriod.mMean < kFastMixerMax ? 1.8 : 2.0;
     // set outlier threshold
     mBufferPeriod.mOutlier = mBufferPeriod.mMean * mBufferPeriod.mOutlierFactor;
@@ -265,7 +263,6 @@
     timestamp startingTs = mHists[0].first;
 
     // histogram which stores .1 precision ms counts instead of Jiffy multiple counts
-    // TODO: when there is more data, print many histograms, possibly separated at peaks
     std::map<double, int> buckets;
     for (const auto &shortHist: mHists) {
         for (const auto &countPair : shortHist.second) {
diff --git a/media/libnbaio/include/media/nbaio/NBLog.h b/media/libnbaio/include/media/nbaio/NBLog.h
index 5549728..2c00386 100644
--- a/media/libnbaio/include/media/nbaio/NBLog.h
+++ b/media/libnbaio/include/media/nbaio/NBLog.h
@@ -475,12 +475,6 @@
         audio_utils_fifo_reader * const mFifoReader;    // used to read from FIFO,
         // non-NULL unless constructor fails
 
-        // TODO: it might be clearer, instead of a direct map from source location to vector of
-        // timestamps, if we instead first mapped from source location to an object that
-        // represented that location. And one_of its fields would be a vector of timestamps.
-        // That would allow us to record other information about the source location beyond
-        // timestamps.
-
         // Searches for the last entry of type <type> in the range [front, back)
         // back has to be entry-aligned. Returns nullptr if none enconuntered.
         static const uint8_t *findLastEntryOfTypes(const uint8_t *front, const uint8_t *back,
diff --git a/media/libnbaio/include/media/nbaio/PerformanceAnalysis.h b/media/libnbaio/include/media/nbaio/PerformanceAnalysis.h
index fe73551..50367be 100644
--- a/media/libnbaio/include/media/nbaio/PerformanceAnalysis.h
+++ b/media/libnbaio/include/media/nbaio/PerformanceAnalysis.h
@@ -35,9 +35,9 @@
 
 class PerformanceAnalysis {
     // This class stores and analyzes audio processing wakeup timestamps from NBLog
-    // FIXME: currently, all performance data is stored in deques. Need to add a mutex.
-    // FIXME: continue this way until analysis is done in a separate thread. Then, use
-    // the fifo writer utilities.
+    // FIXME: currently, all performance data is stored in deques. Turn these into circular
+    // buffers.
+    // TODO: add a mutex.
 public:
 
     PerformanceAnalysis() {};
@@ -45,20 +45,11 @@
     friend void dump(int fd, int indent,
                      PerformanceAnalysisMap &threadPerformanceAnalysis);
 
-    // Given a series of audio processing wakeup timestamps,
-    // compresses and and analyzes the data, and flushes
-    // the timestamp series from memory.
-    void processAndFlushTimeStampSeries();
-
-    // Called when an audio on/off event is read from the buffer,
-    // e.g. EVENT_AUDIO_STATE.
-    // calls flushTimeStampSeries on the data up to the event,
-    // effectively discarding the idle audio time interval
+    // Called in the case of an audio on/off event, e.g., EVENT_AUDIO_STATE.
+    // Used to discard idle time intervals
     void handleStateChange();
 
     // Writes wakeup timestamp entry to log and runs analysis
-    // TODO: make this thread safe. Each thread should have its own instance
-    // of PerformanceAnalysis.
     void logTsEntry(timestamp ts);
 
     // FIXME: make peakdetector and storeOutlierData a single function
@@ -67,13 +58,11 @@
     // writes timestamps of significant changes to mPeakTimestamps
     bool detectAndStorePeak(msInterval delta, timestamp ts);
 
-    // runs analysis on timestamp series before it is converted to a histogram
-    // finds outliers
+    // stores timestamps of intervals above a threshold: these are assumed outliers.
     // writes to mOutlierData <time elapsed since previous outlier, outlier timestamp>
     bool detectAndStoreOutlier(const msInterval diffMs);
 
     // Generates a string of analysis of the buffer periods and prints to console
-    // TODO: WIP write more detailed analysis
     // FIXME: move this data visualization to a separate class. Model/view/controller
     void reportPerformance(String8 *body, int author, log_hash_t hash,
                            int maxHeight = 10);
diff --git a/media/libnbaio/include/media/nbaio/ReportPerformance.h b/media/libnbaio/include/media/nbaio/ReportPerformance.h
index af12812..ec0842f 100644
--- a/media/libnbaio/include/media/nbaio/ReportPerformance.h
+++ b/media/libnbaio/include/media/nbaio/ReportPerformance.h
@@ -23,8 +23,7 @@
 
 namespace android {
 
-// This class is used by reportPerformance function
-// TODO move PerformanceAnalysis::reportPerformance function to ReportPerformance.cpp
+// The String8 class is used by reportPerformance function
 class String8;
 
 namespace ReportPerformance {
@@ -35,7 +34,6 @@
 constexpr int kJiffyPerMs = 10; // time unit for histogram as a multiple of milliseconds
 
 // stores a histogram: key: observed buffer period (multiple of jiffy). value: count
-// TODO: unsigned, unsigned
 using Histogram = std::map<int, int>;
 
 using msInterval = double;
@@ -45,7 +43,6 @@
 
 using log_hash_t = uint64_t;
 
-// TODO: should this return an int64_t?
 static inline int deltaMs(int64_t ns1, int64_t ns2) {
     return (ns2 - ns1) / (1000 * 1000);
 }
@@ -59,8 +56,7 @@
     return 31 - __builtin_clz(x);
 }
 
-// Writes outlier intervals, timestamps, and histograms spanning long time
-// intervals to a file.
+// Writes outlier intervals, timestamps, peaks timestamps, and histograms to a file.
 void writeToFile(const std::deque<std::pair<timestamp, Histogram>> &hists,
                  const std::deque<std::pair<msInterval, timestamp>> &outlierData,
                  const std::deque<timestamp> &peakTimestamps,