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Commit 32acd19a authored by Tom Cherry's avatar Tom Cherry Committed by Automerger Merge Worker
Browse files

Merge "logd: simplify Clear() + Prune() logic" am: 7a372d16 am: b4fc12cc am: 76318e02 

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1329340

Change-Id: I50a728e666993a7d518d881b156febe8cab38259
parents e8c1dbd3 76318e02

logd/ChattyLogBuffer.cpp

+4 −9
Original line number Diff line number Diff line
@@ -327,7 +327,6 @@ class LogBufferElementLast { 
//

bool ChattyLogBuffer::Prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {

    LogReaderThread* oldest = nullptr;

    bool busy = false;

    bool clearAll = pruneRows == ULONG_MAX;



    auto reader_threads_lock = std::lock_guard{reader_list()->reader_threads_lock()};
@@ -359,17 +358,16 @@ bool ChattyLogBuffer::Prune(log_id_t id, unsigned long pruneRows, uid_t caller_u 
            }



            if (oldest && oldest->start() <= element.sequence()) {

                busy = true;

                KickReader(oldest, id, pruneRows);

                break;

                return false;

            }



            it = Erase(it);

            if (--pruneRows == 0) {

                break;

                return true;

            }

        }

        return busy;

        return true;

    }



    // prune by worst offenders; by blacklist, UID, and by PID of system UID
@@ -440,7 +438,6 @@ bool ChattyLogBuffer::Prune(log_id_t id, unsigned long pruneRows, uid_t caller_u 
            LogBufferElement& element = *it;



            if (oldest && oldest->start() <= element.sequence()) {

                busy = true;

                // Do not let chatty eliding trigger any reader mitigation

                break;

            }
@@ -577,7 +574,6 @@ bool ChattyLogBuffer::Prune(log_id_t id, unsigned long pruneRows, uid_t caller_u 
        }



        if (oldest && oldest->start() <= element.sequence()) {

            busy = true;

            if (!whitelist) KickReader(oldest, id, pruneRows);

            break;

        }
@@ -605,7 +601,6 @@ bool ChattyLogBuffer::Prune(log_id_t id, unsigned long pruneRows, uid_t caller_u 
            }



            if (oldest && oldest->start() <= element.sequence()) {

                busy = true;

                KickReader(oldest, id, pruneRows);

                break;

            }
@@ -615,5 +610,5 @@ bool ChattyLogBuffer::Prune(log_id_t id, unsigned long pruneRows, uid_t caller_u 
        }

    }



    return (pruneRows > 0) && busy;

    return pruneRows == 0 || it == logs().end();

}

logd/CommandListener.cpp

+1 −1
Original line number Diff line number Diff line
@@ -82,7 +82,7 @@ int CommandListener::ClearCmd::runCommand(SocketClient* cli, int argc, 
        return 0;

    }



    cli->sendMsg(buf()->Clear((log_id_t)id, uid) ? "busy" : "success");

    cli->sendMsg(buf()->Clear((log_id_t)id, uid) ? "success" : "busy");

    return 0;

}

logd/SimpleLogBuffer.cpp

+29 −37
Original line number Diff line number Diff line
@@ -212,24 +212,26 @@ bool SimpleLogBuffer::FlushTo( 
    return true;

}



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

bool SimpleLogBuffer::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.

    // Try three times to clear, then disconnect the readers and try one final time.

    for (int retry = 0; retry < 3; ++retry) {

        {

            auto lock = std::lock_guard{lock_};

                busy = Prune(id, 1, uid);

            if (Prune(id, ULONG_MAX, uid)) {

                return true;

            }

        }

        sleep(1);

    }

    // Check if it is still busy after the sleep, we try to 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.

    bool busy = false;

    {

        auto lock = std::lock_guard{lock_};

        busy = !Prune(id, 1, uid);

    }

            // 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.

    // It is still busy, disconnect all readers.

    if (busy) {

        auto reader_threads_lock = std::lock_guard{reader_list_->reader_threads_lock()};

        for (const auto& reader_thread : reader_list_->reader_threads()) {
@@ -240,18 +242,8 @@ bool SimpleLogBuffer::Clear(log_id_t id, uid_t uid) { 
            }

        }

    }

        }

        {

    auto lock = std::lock_guard{lock_};

            busy = Prune(id, ULONG_MAX, uid);

        }



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

            break;

        }

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

    }

    return busy;

    return Prune(id, ULONG_MAX, uid);

}



// get the total space allocated to "id"
@@ -313,16 +305,16 @@ bool SimpleLogBuffer::Prune(log_id_t id, unsigned long prune_rows, uid_t caller_ 


        if (oldest && oldest->start() <= element.sequence()) {

            KickReader(oldest, id, prune_rows);

            return true;

            return false;

        }



        stats_->Subtract(element.ToLogStatisticsElement());

        it = Erase(it);

        if (--prune_rows == 0) {

            return false;

            return true;

        }

    }

    return false;

    return true;

}



std::list<LogBufferElement>::iterator SimpleLogBuffer::Erase(