diff options
Diffstat (limited to 'src/corelib/io/qlockfile.cpp')
| -rw-r--r-- | src/corelib/io/qlockfile.cpp | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/src/corelib/io/qlockfile.cpp b/src/corelib/io/qlockfile.cpp index 4f5aeff395..2bd996d213 100644 --- a/src/corelib/io/qlockfile.cpp +++ b/src/corelib/io/qlockfile.cpp @@ -1,6 +1,7 @@ /**************************************************************************** ** ** Copyright (C) 2013 David Faure <faure+bluesystems@kde.org> +** Copyright (C) 2015 The Qt Company Ltd. ** Contact: http://www.qt.io/licensing/ ** ** This file is part of the QtCore module of the Qt Toolkit. @@ -66,9 +67,12 @@ QT_BEGIN_NAMESPACE If the process holding the lock crashes, the lock file stays on disk and can prevent any other process from accessing the shared resource, ever. For this reason, QLockFile - tries to detect such a "stale" lock file, based on the process ID written into the file, - and (in case that process ID got reused meanwhile), on the last modification time of - the lock file (30s by default, for the use case of a short-lived operation). + tries to detect such a "stale" lock file, based on the process ID written into the file. + To cover the situation that the process ID got reused meanwhile, the current process name is + compared to the name of the process that corresponds to the process ID from the lock file. + If the process names differ, the lock file is considered stale. + Additionally, the last modification time of the lock file (30s by default, for the use case of a + short-lived operation) is taken into account. If the lock file is found to be stale, it will be deleted. For the use case of protecting a resource over a long time, you should therefore call @@ -122,7 +126,7 @@ QLockFile::~QLockFile() The value of \a staleLockTime is used by lock() and tryLock() in order to determine when an existing lock file is considered stale, i.e. left over by a crashed process. This is useful for the case where the PID got reused - meanwhile, so the only way to detect a stale lock file is by the fact that + meanwhile, so one way to detect a stale lock file is by the fact that it has been around for a long time. \sa staleLockTime() |