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Commit c5dc970e authored by Mark Salyzyn's avatar Mark Salyzyn
Browse files

logd: clear return and deal with busy if readers locked 

- Propagate to caller the clearing errors, busy blocked by reader.
- For clear, perform retries within logd with a one second lul each,
  telling readers to skip, but on final retry to kill all readers if
  problem still persists due to block reader (or high volume logspammer).

Bug: 23711431
Change-Id: Ie4c46bc9480a7f49b96a81fae25a95c603270c33
parent de4bb9c1

logd/CommandListener.cpp

+1 −2
Original line number Diff line number Diff line
@@ -96,8 +96,7 @@ int CommandListener::ClearCmd::runCommand(SocketClient *cli, 
        return 0;

    }



    mBuf.clear((log_id_t) id, uid);

    cli->sendMsg("success");

    cli->sendMsg(mBuf.clear((log_id_t) id, uid) ? "busy" : "success");

    return 0;

}

logd/LogBuffer.cpp

+50 −6
Original line number Diff line number Diff line
@@ -374,8 +374,9 @@ public: 
//

// mLogElementsLock must be held when this function is called.

//

void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {

bool LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {

    LogTimeEntry *oldest = NULL;

    bool busy = false;



    LogTimeEntry::lock();
@@ -397,6 +398,8 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
            LogBufferElement *e = *it;



            if (oldest && (oldest->mStart <= e->getSequence())) {

                oldest->triggerSkip_Locked(id, pruneRows);

                busy = true;

                break;

            }
@@ -416,7 +419,7 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
            }

        }

        LogTimeEntry::unlock();

        return;

        return busy;

    }



    // prune by worst offender by uid
@@ -478,6 +481,7 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
            LogBufferElement *e = *it;



            if (oldest && (oldest->mStart <= e->getSequence())) {

                busy = true;

                break;

            }
@@ -596,6 +600,8 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
        }



        if (oldest && (oldest->mStart <= e->getSequence())) {

            busy = true;



            if (whitelist) {

                break;

            }
@@ -631,6 +637,7 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
            }



            if (oldest && (oldest->mStart <= e->getSequence())) {

                busy = true;

                if (stats.sizes(id) > (2 * log_buffer_size(id))) {

                    // kick a misbehaving log reader client off the island

                    oldest->release_Locked();
@@ -646,13 +653,50 @@ void LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) { 
    }



    LogTimeEntry::unlock();



    return (pruneRows > 0) && busy;

}



// clear all rows of type "id" from the buffer.

void LogBuffer::clear(log_id_t id, uid_t uid) {

bool LogBuffer::clear(log_id_t id, uid_t uid) {

    bool busy = true;

    // If it takes more than 4 tries (seconds) to clear, then kill reader(s)

    for (int retry = 4;;) {

        if (retry == 1) { // last pass

            // Check if it is still busy after the sleep, we say prune

            // one entry, not another clear run, so we are looking for

            // the quick side effect of the return value to tell us if

            // we have a _blocked_ reader.

            pthread_mutex_lock(&mLogElementsLock);

            busy = prune(id, 1, uid);

            pthread_mutex_unlock(&mLogElementsLock);

            // It is still busy, blocked reader(s), lets kill them all!

            // otherwise, lets be a good citizen and preserve the slow

            // readers and let the clear run (below) deal with determining

            // if we are still blocked and return an error code to caller.

            if (busy) {

                LogTimeEntry::lock();

                LastLogTimes::iterator times = mTimes.begin();

                while (times != mTimes.end()) {

                    LogTimeEntry *entry = (*times);

                    // Killer punch

                    if (entry->owned_Locked() && entry->isWatching(id)) {

                        entry->release_Locked();

                    }

                    times++;

                }

                LogTimeEntry::unlock();

            }

        }

        pthread_mutex_lock(&mLogElementsLock);

    prune(id, ULONG_MAX, uid);

        busy = prune(id, ULONG_MAX, uid);

        pthread_mutex_unlock(&mLogElementsLock);

        if (!busy || !--retry) {

            break;

        }

        sleep (1); // Let reader(s) catch up after notification

    }

    return busy;

}



// get the used space associated with "id".

logd/LogBuffer.h

+2 −2
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ public: 
                     int (*filter)(const LogBufferElement *element, void *arg) = NULL,

                     void *arg = NULL);



    void clear(log_id_t id, uid_t uid = AID_ROOT);

    bool clear(log_id_t id, uid_t uid = AID_ROOT);

    unsigned long getSize(log_id_t id);

    int setSize(log_id_t id, unsigned long size);

    unsigned long getSizeUsed(log_id_t id);
@@ -86,7 +86,7 @@ public: 


private:

    void maybePrune(log_id_t id);

    void prune(log_id_t id, unsigned long pruneRows, uid_t uid = AID_ROOT);

    bool prune(log_id_t id, unsigned long pruneRows, uid_t uid = AID_ROOT);

    LogBufferElementCollection::iterator erase(

        LogBufferElementCollection::iterator it, bool engageStats = true);

};