liblog: logd: support logd.timestamp = monotonic
if ro.logd.timestamp or persist.logd.timestamp are set to the value
monotonic then liblog writer, liblog printing and logd all switch to
recording/printing monotonic time rather than realtime. If reinit
detects a change for presist.logd.timestamp, correct the older entry
timestamps in place.
ToDo: A corner case condition where new log entries in monotonic time
occur before logd reinit detects persist.logd.timestamp, there
will be a few out-of-order entries, but with accurate
timestamps. This problem does not happen for ro.logd.timestamp
as it is set before logd starts.
NB: This offers a nano second time accuracy on all log entries
that may be more suitable for merging with other system
activities, such as systrace, that also use monotonic time. This
feature is for debugging.
Bug: 23668800
Change-Id: Iee6dab7140061b1a6627254921411f61b01aa5c2
diff --git a/logd/LogBuffer.cpp b/logd/LogBuffer.cpp
index 1de8e64..c661203 100644
--- a/logd/LogBuffer.cpp
+++ b/logd/LogBuffer.cpp
@@ -28,6 +28,7 @@
#include <log/logger.h>
#include "LogBuffer.h"
+#include "LogKlog.h"
#include "LogReader.h"
// Default
@@ -126,9 +127,48 @@
setSize(i, LOG_BUFFER_MIN_SIZE);
}
}
+ bool lastMonotonic = monotonic;
+ monotonic = android_log_timestamp() == 'm';
+ if (lastMonotonic == monotonic) {
+ return;
+ }
+
+ //
+ // Fixup all timestamps, may not be 100% accurate, but better than
+ // throwing what we have away when we get 'surprised' by a change.
+ // In-place element fixup so no need to check reader-lock. Entries
+ // should already be in timestamp order, but we could end up with a
+ // few out-of-order entries if new monotonics come in before we
+ // are notified of the reinit change in status. A Typical example would
+ // be:
+ // --------- beginning of system
+ // 10.494082 184 201 D Cryptfs : Just triggered post_fs_data
+ // --------- beginning of kernel
+ // 0.000000 0 0 I : Initializing cgroup subsys cpuacct
+ // as the act of mounting /data would trigger persist.logd.timestamp to
+ // be corrected. 1/30 corner case YMMV.
+ //
+ pthread_mutex_lock(&mLogElementsLock);
+ LogBufferElementCollection::iterator it = mLogElements.begin();
+ while((it != mLogElements.end())) {
+ LogBufferElement *e = *it;
+ if (monotonic) {
+ if (!android::isMonotonic(e->mRealTime)) {
+ LogKlog::convertRealToMonotonic(e->mRealTime);
+ }
+ } else {
+ if (android::isMonotonic(e->mRealTime)) {
+ LogKlog::convertMonotonicToReal(e->mRealTime);
+ }
+ }
+ ++it;
+ }
+ pthread_mutex_unlock(&mLogElementsLock);
}
-LogBuffer::LogBuffer(LastLogTimes *times) : mTimes(*times) {
+LogBuffer::LogBuffer(LastLogTimes *times):
+ monotonic(android_log_timestamp() == 'm'),
+ mTimes(*times) {
pthread_mutex_init(&mLogElementsLock, NULL);
init();