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/LogReader.cpp b/logd/LogReader.cpp
index 3833843..06135dd 100644
--- a/logd/LogReader.cpp
+++ b/logd/LogReader.cpp
@@ -114,15 +114,17 @@
log_time &start;
uint64_t &sequence;
uint64_t last;
+ bool isMonotonic;
public:
- LogFindStart(unsigned logMask, pid_t pid, log_time &start, uint64_t &sequence) :
+ LogFindStart(unsigned logMask, pid_t pid, log_time &start, uint64_t &sequence, bool isMonotonic) :
mPid(pid),
mLogMask(logMask),
startTimeSet(false),
start(start),
sequence(sequence),
- last(sequence) {
+ last(sequence),
+ isMonotonic(isMonotonic) {
}
static int callback(const LogBufferElement *element, void *obj) {
@@ -133,20 +135,24 @@
me->sequence = element->getSequence();
me->startTimeSet = true;
return -1;
- } else {
+ } else if (!me->isMonotonic ||
+ android::isMonotonic(element->getRealTime())) {
if (me->start < element->getRealTime()) {
me->sequence = me->last;
me->startTimeSet = true;
return -1;
}
me->last = element->getSequence();
+ } else {
+ me->last = element->getSequence();
}
}
return false;
}
bool found() { return startTimeSet; }
- } logFindStart(logMask, pid, start, sequence);
+ } logFindStart(logMask, pid, start, sequence,
+ logbuf().isMonotonic() && android::isMonotonic(start));
logbuf().flushTo(cli, sequence, FlushCommand::hasReadLogs(cli),
logFindStart.callback, &logFindStart);