logd: Add Tag statistics

- Optional class of statistics for events Tags
- export tagToName from LogBuffer (located in main.cp to address
  https://android-review.googlesource.com/#/c/110204)
- Can not handle dropped because getTag() can not work,
  will need to be fixed if we start filtering.

Bug: 19608965
Change-Id: I7b90607ca588bf37bab71f19b1570a290e772776

1 files changed, 7 insertions, 0 deletions

diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
index 6a057000d..164faa9f8 100644
--- a/logd/LogBufferElement.cpp
+++ b/logd/LogBufferElement.cpp
@@ -50,6 +50,13 @@ LogBufferElement::~LogBufferElement() {
     delete [] mMsg;
 }
 
+uint32_t LogBufferElement::getTag() const {
+    if ((mLogId != LOG_ID_EVENTS) || !mMsg || (mMsgLen < sizeof(uint32_t))) {
+        return 0;
+    }
+    return le32toh(reinterpret_cast<android_event_header_t *>(mMsg)->tag);
+}
+
 // caller must own and free character string
 static char *tidToName(pid_t tid) {
     char *retval = NULL;