am e66f84d7: am 784a69f8: Merge "logd: worst uid record watermark part five"
* commit 'e66f84d7e6278db6352b38d869a4ee9b8585b129': logd: worst uid record watermark part five
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commit
5e3d4e36b1
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@ -242,8 +242,8 @@ LogBufferElementCollection::iterator LogBuffer::erase(
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LogBufferElementCollection::iterator it, bool engageStats) {
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LogBufferElement *e = *it;
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log_id_t id = e->getLogId();
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LogBufferIteratorMap::iterator f = mLastWorstUid[id].find(e->getUid());
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LogBufferIteratorMap::iterator f = mLastWorstUid[id].find(e->getUid());
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if ((f != mLastWorstUid[id].end()) && (it == f->second)) {
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mLastWorstUid[id].erase(f);
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}
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@ -329,7 +329,51 @@ public:
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// prune "pruneRows" of type "id" from the buffer.
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//
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// This garbage collection task is used to expire log entries. It is called to
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// remove all logs (clear), all UID logs (unprivileged clear), or every
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// 256 or 10% of the total logs (whichever is less) to prune the logs.
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//
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// First there is a prep phase where we discover the reader region lock that
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// acts as a backstop to any pruning activity to stop there and go no further.
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//
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// There are three major pruning loops that follow. All expire from the oldest
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// entries. Since there are multiple log buffers, the Android logging facility
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// will appear to drop entries 'in the middle' when looking at multiple log
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// sources and buffers. This effect is slightly more prominent when we prune
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// the worst offender by logging source. Thus the logs slowly loose content
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// and value as you move back in time. This is preferred since chatty sources
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// invariably move the logs value down faster as less chatty sources would be
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// expired in the noise.
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//
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// The first loop performs blacklisting and worst offender pruning. Falling
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// through when there are no notable worst offenders and have not hit the
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// region lock preventing further worst offender pruning. This loop also looks
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// after managing the chatty log entries and merging to help provide
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// statistical basis for blame. The chatty entries are not a notification of
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// how much logs you may have, but instead represent how much logs you would
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// have had in a virtual log buffer that is extended to cover all the in-memory
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// logs without loss. They last much longer than the represented pruned logs
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// since they get multiplied by the gains in the non-chatty log sources.
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//
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// The second loop get complicated because an algorithm of watermarks and
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// history is maintained to reduce the order and keep processing time
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// down to a minimum at scale. These algorithms can be costly in the face
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// of larger log buffers, or severly limited processing time granted to a
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// background task at lowest priority.
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//
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// This second loop does straight-up expiration from the end of the logs
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// (again, remember for the specified log buffer id) but does some whitelist
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// preservation. Thus whitelist is a Hail Mary low priority, blacklists and
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// spam filtration all take priority. This second loop also checks if a region
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// lock is causing us to buffer too much in the logs to help the reader(s),
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// and will tell the slowest reader thread to skip log entries, and if
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// persistent and hits a further threshold, kill the reader thread.
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//
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// The third thread is optional, and only gets hit if there was a whitelist
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// and more needs to be pruned against the backstop of the region lock.
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//
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// mLogElementsLock must be held when this function is called.
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//
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void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
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LogTimeEntry *oldest = NULL;
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@ -410,7 +454,12 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
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bool kick = false;
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bool leading = true;
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it = mLogElements.begin();
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if (worst != (uid_t) -1) {
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// Perform at least one mandatory garbage collection cycle in following
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// - clear leading chatty tags
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// - merge chatty tags
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// - check age-out of preserved logs
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bool gc = pruneRows <= 1;
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if (!gc && (worst != (uid_t) -1)) {
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LogBufferIteratorMap::iterator f = mLastWorstUid[id].find(worst);
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if ((f != mLastWorstUid[id].end())
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&& (f->second != mLogElements.end())) {
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@ -481,7 +530,7 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
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// unmerged drop message
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if (dropped) {
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last.add(e);
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if ((e->getUid() == worst)
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if ((!gc && (e->getUid() == worst))
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|| (mLastWorstUid[id].find(e->getUid())
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== mLastWorstUid[id].end())) {
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mLastWorstUid[id][e->getUid()] = it;
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@ -516,7 +565,10 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
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it = erase(it, false);
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} else {
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last.add(e);
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mLastWorstUid[id][e->getUid()] = it;
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if (!gc || (mLastWorstUid[id].find(worst)
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== mLastWorstUid[id].end())) {
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mLastWorstUid[id][worst] = it;
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}
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++it;
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}
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}
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