Add the functionality for logging counters.

Also correct clang-format for libmetricslogger

Test: Run libmetriclogger_test
Change-Id: If61f0bdc394a43e249ec4691da70175eeaf4cec6

libmetricslogger/Android.bp

@@ -23,6 +23,7 @@ cc_defaults {
         // 524291 corresponds to sysui_histogram, from
         // frameworks/base/core/java/com/android/internal/logging/EventLogTags.logtags
         "-DHISTOGRAM_LOG_TAG=524292",
+        "-DCOUNT_LOG_TAG=524290",
     ],
 }
 

libmetricslogger/include/metricslogger/metrics_logger.h

@@ -24,13 +24,18 @@ namespace metricslogger {
 // buffer.
 void LogHistogram(const std::string& event, int32_t data);
 
+// Logs a Tron counter metric named |name| containing |val| count to the Tron
+// log buffer.
+void LogCounter(const std::string& name, int32_t val);
+
 // TODO: replace these with the metric_logger.proto definitions
 enum {
-  LOGBUILDER_CATEGORY = 757,
-  LOGBUILDER_NAME = 799,
-  LOGBUILDER_BUCKET = 801,
-  LOGBUILDER_VALUE = 802,
-  LOGBUILDER_HISTOGRAM = 804,
+    LOGBUILDER_CATEGORY = 757,
+    LOGBUILDER_NAME = 799,
+    LOGBUILDER_BUCKET = 801,
+    LOGBUILDER_VALUE = 802,
+    LOGBUILDER_COUNTER = 803,
+    LOGBUILDER_HISTOGRAM = 804,
 };
 
 }  // namespace metricslogger

libmetricslogger/metrics_logger.cpp

@@ -25,12 +25,16 @@ namespace metricslogger {
 
 // Mirror com.android.internal.logging.MetricsLogger#histogram().
 void LogHistogram(const std::string& event, int32_t data) {
-  android_log_event_list log(HISTOGRAM_LOG_TAG);
-  log << LOGBUILDER_CATEGORY << LOGBUILDER_HISTOGRAM
-      << LOGBUILDER_NAME << event
-      << LOGBUILDER_BUCKET << data
-      << LOGBUILDER_VALUE << 1
-      << LOG_ID_EVENTS;
+    android_log_event_list log(HISTOGRAM_LOG_TAG);
+    log << LOGBUILDER_CATEGORY << LOGBUILDER_HISTOGRAM << LOGBUILDER_NAME << event
+        << LOGBUILDER_BUCKET << data << LOGBUILDER_VALUE << 1 << LOG_ID_EVENTS;
+}
+
+// Mirror com.android.internal.logging.MetricsLogger#count().
+void LogCounter(const std::string& name, int32_t val) {
+    android_log_event_list log(COUNT_LOG_TAG);
+    log << LOGBUILDER_CATEGORY << LOGBUILDER_COUNTER << LOGBUILDER_NAME << name << LOGBUILDER_VALUE
+        << val << LOG_ID_EVENTS;
 }
 
 }  // namespace metricslogger

libmetricslogger/metrics_logger_test.cpp

@@ -19,6 +19,10 @@
 #include <gtest/gtest.h>
 
 TEST(MetricsLoggerTest, AddSingleBootEvent) {
-  android::metricslogger::LogHistogram("test_event", 42);
-  // TODO(jhawkins): Verify the EventLog is updated.
+    android::metricslogger::LogHistogram("test_event", 42);
+    // TODO(jhawkins): Verify the EventLog is updated.
+}
+
+TEST(MetricsLoggerTest, AddCounterVal) {
+    android::metricslogger::LogCounter("test_count", 10);
 }