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Commit 2c9d909a authored by Mark Salyzyn's avatar Mark Salyzyn
Browse files

logd: better drop message merging 

- Former algorithm anlo coalesced adjacent records
- New algorithm maintains a hash list of all drop
  records and coalesces them all.

Bug: 20334069
Bug: 20370119
Change-Id: Idc15ce31fc1087c2cfa39da60c62feade8b88761
parent b2b06de5

logd/LogBuffer.cpp

+70 −18
Original line number Diff line number Diff line
@@ -226,6 +226,68 @@ LogBufferElementCollection::iterator LogBuffer::erase(LogBufferElementCollection 
    return it;

}



// Define a temporary mechanism to report the last LogBufferElement pointer

// for the specified uid, pid and tid. Used below to help merge-sort when

// pruning for worst UID.

class LogBufferElementKey {

    const union {

        struct {

            uint16_t uid;

            uint16_t pid;

            uint16_t tid;

            uint16_t padding;

        } __packed;

        uint64_t value;

    } __packed;



public:

    LogBufferElementKey(uid_t u, pid_t p, pid_t t):uid(u),pid(p),tid(t),padding(0) { }

    LogBufferElementKey(uint64_t k):value(k) { }



    uint64_t getKey() { return value; }

};



struct LogBufferElementEntry {

    const uint64_t key;

    LogBufferElement *last;



public:

    LogBufferElementEntry(const uint64_t &k, LogBufferElement *e):key(k),last(e) { }



    const uint64_t&getKey() const { return key; }



    LogBufferElement *getLast() { return last; }

};



struct LogBufferElementLast : public android::BasicHashtable<uint64_t, LogBufferElementEntry> {



    bool merge(LogBufferElement *e, unsigned short dropped) {

        LogBufferElementKey key(e->getUid(), e->getPid(), e->getTid());

        android::hash_t hash = android::hash_type(key.getKey());

        ssize_t index = find(-1, hash, key.getKey());

        if (index != -1) {

            LogBufferElementEntry &entry = editEntryAt(index);

            LogBufferElement *l = entry.getLast();

            unsigned short d = l->getDropped();

            if ((dropped + d) > USHRT_MAX) {

                removeAt(index);

            } else {

                l->setDropped(dropped + d);

                return true;

            }

        }

        return false;

    }



    size_t add(LogBufferElement *e) {

        LogBufferElementKey key(e->getUid(), e->getPid(), e->getTid());

        android::hash_t hash = android::hash_type(key.getKey());

        return android::BasicHashtable<uint64_t, LogBufferElementEntry>::

            add(hash, LogBufferElementEntry(key.getKey(), e));

    }



};



// prune "pruneRows" of type "id" from the buffer.

//

// mLogElementsLock must be held when this function is called.
@@ -301,7 +363,7 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 


        bool kick = false;

        bool leading = true;

        LogBufferElement *last = NULL;

        LogBufferElementLast last;

        for(it = mLogElements.begin(); it != mLogElements.end();) {

            LogBufferElement *e = *it;
@@ -322,24 +384,18 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
                continue;

            }



            pid_t pid = e->getPid();



            // merge any drops

            if (last && dropped

             && ((dropped + last->getDropped()) < USHRT_MAX)

             && (last->getPid() == pid)

             && (last->getTid() == e->getTid())) {

            if (dropped && last.merge(e, dropped)) {

                it = mLogElements.erase(it);

                stats.erase(e);

                delete e;

                last->setDropped(dropped + last->getDropped());

                continue;

            }



            leading = false;



            if (hasBlacklist && mPrune.naughty(e)) {

                last = NULL;

                last.clear();

                it = erase(it);

                if (dropped) {

                    continue;
@@ -361,13 +417,13 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
            }



            if (dropped) {

                last = e;

                last.add(e);

                ++it;

                continue;

            }



            if (e->getUid() != worst) {

                last = NULL;

                last.clear();

                ++it;

                continue;

            }
@@ -382,17 +438,12 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
            unsigned short len = e->getMsgLen();

            stats.drop(e);

            e->setDropped(1);

            // merge any drops

            if (last

             && (last->getDropped() < (USHRT_MAX - 1))

             && (last->getPid() == pid)

             && (last->getTid() == e->getTid())) {

            if (last.merge(e, 1)) {

                it = mLogElements.erase(it);

                stats.erase(e);

                delete e;

                last->setDropped(last->getDropped() + 1);

            } else {

                last = e;

                last.add(e);

                ++it;

            }

            if (worst_sizes < second_worst_sizes) {
@@ -400,6 +451,7 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
            }

            worst_sizes -= len;

        }

        last.clear();



        if (!kick || !mPrune.worstUidEnabled()) {

            break; // the following loop will ask bad clients to skip/drop