commit 64e9016351bf789bfb70b64753449507f5cfc684
author Tom Cherry <tomcherry@google.com> Thu May 07 14:44:43 2020 -0700
committer Tom Cherry <tomcherry@google.com> Mon May 11 07:55:52 2020 -0700
tree 238b8bd56c578cf311f8eba3cbf888d3a6a23b22
parent b6b78e9bb4fb3d9d4b06cefdc8cad01b2f15b741

logd: separate LogStatistics from LogBuffer

LogStatistics is intertwined with LogBuffer, even relying on it for
thread safety.  This needs to change to have a proper
LogBufferInterface, so this CL separates them.  Specifically:

1) Adding a lock to LogStatistics and adding thread annotations to
   ensure that data structures are protected appropriately.
2) Moving prune_rows calculation into LogStatistics so it is done
   while holding this lock.
3) Using LogStatistics instead of LogBuffer where appropriate.

Note that there should not be a significant performance regression
with this lock, as it will almost always been uncontended.  If
anything, it should alleviate pressure from LogBuffer's lock.

Test: logging unit tests
Change-Id: I9d6dde2c96c9f024fa0341711c7bc63379e8e406

logd/LogBufferElement.cpp

diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
index 916ed42..cc68ba4 100644
--- a/logd/LogBufferElement.cpp
+++ b/logd/LogBufferElement.cpp
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "LogBufferElement.h"
+
 #include <ctype.h>
 #include <endian.h>
 #include <fcntl.h>
@@ -26,7 +28,6 @@
 #include <private/android_logger.h>
 
 #include "LogBuffer.h"
-#include "LogBufferElement.h"
 #include "LogCommand.h"
 #include "LogReader.h"
 #include "LogUtils.h"
@@ -153,7 +154,7 @@
 }
 
 // assumption: mMsg == NULL
-size_t LogBufferElement::populateDroppedMessage(char*& buffer, LogBuffer* parent,
+size_t LogBufferElement::populateDroppedMessage(char*& buffer, LogStatistics* stats,
                                                 bool lastSame) {
     static const char tag[] = "chatty";
 
@@ -163,17 +164,13 @@
     }
 
     static const char format_uid[] = "uid=%u%s%s %s %u line%s";
-    parent->wrlock();
-    const char* name = parent->uidToName(mUid);
-    parent->unlock();
+    const char* name = stats->UidToName(mUid);
     const char* commName = android::tidToName(mTid);
     if (!commName && (mTid != mPid)) {
         commName = android::tidToName(mPid);
     }
     if (!commName) {
-        parent->wrlock();
-        commName = parent->pidToName(mPid);
-        parent->unlock();
+        commName = stats->PidToName(mPid);
     }
     if (name && name[0] && commName && (name[0] == commName[0])) {
         size_t len = strlen(name + 1);
@@ -246,7 +243,7 @@
     return retval;
 }
 
-uint64_t LogBufferElement::flushTo(SocketClient* reader, LogBuffer* parent, bool lastSame) {
+uint64_t LogBufferElement::flushTo(SocketClient* reader, LogStatistics* stats, bool lastSame) {
     struct logger_entry entry = {};
 
     entry.hdr_size = sizeof(struct logger_entry);
@@ -264,7 +261,7 @@
     char* buffer = nullptr;
 
     if (mDropped) {
-        entry.len = populateDroppedMessage(buffer, parent, lastSame);
+        entry.len = populateDroppedMessage(buffer, stats, lastSame);
         if (!entry.len) return mSequence;
         iovec[1].iov_base = buffer;
     } else {