logd: correct for number of elements in prune

Chatty logs would distort the average log size by elevating the
elements, but not the size. Add statistical collection for the
number of elements that report chatty, and subtract that from
the number of elements to improve the pruning estimate. Pick
minElements as 1% rather than 10% of the total with this more
accurate number of elements, to a minumum of 4.

Bug: 24511000
Change-Id: I3f36558138aa0b2a50e4fac6440c3a8505d95276

1 files changed, 5 insertions, 0 deletions

diff --git a/logd/LogStatistics.cpp b/logd/LogStatistics.cpp
index c3b10ad36..fdb2576d6 100644
--- a/logd/LogStatistics.cpp
+++ b/logd/LogStatistics.cpp
@@ -27,6 +27,7 @@ LogStatistics::LogStatistics() : enable(false) {
     log_id_for_each(id) {
         mSizes[id] = 0;
         mElements[id] = 0;
+        mDroppedElements[id] = 0;
         mSizesTotal[id] = 0;
         mElementsTotal[id] = 0;
     }
@@ -93,6 +94,9 @@ void LogStatistics::subtract(LogBufferElement *element) {
     unsigned short size = element->getMsgLen();
     mSizes[log_id] -= size;
     --mElements[log_id];
+    if (element->getDropped()) {
+        --mDroppedElements[log_id];
+    }
 
     if (log_id == LOG_ID_KERNEL) {
         return;
@@ -119,6 +123,7 @@ void LogStatistics::drop(LogBufferElement *element) {
     log_id_t log_id = element->getLogId();
     unsigned short size = element->getMsgLen();
     mSizes[log_id] -= size;
+    ++mDroppedElements[log_id];
 
     uidTable[log_id].drop(element->getUid(), element);