Adding upstream version 4:7.4.7.upstream/4%7.4.7upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 70 insertions, 0 deletions

diff --git a/include/comphelper/crashzone.hxx b/include/comphelper/crashzone.hxx
new file mode 100644
index 000000000..f15f848cd
--- /dev/null
+++ b/include/comphelper/crashzone.hxx
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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef INCLUDED_COMPHELPER_CRASHZONE_H
+#define INCLUDED_COMPHELPER_CRASHZONE_H
+
+#include <sal/config.h>
+
+#include <atomic>
+#include <csignal>
+#include <type_traits>
+
+struct CrashWatchdogTimingsValues
+{
+    /// delays to take various actions in 1/4 of a second increments.
+    int mnDisableEntries;
+    int const mnAbortAfter;
+};
+
+/**
+ * A generic class for detecting if a given crash or a lock-up came from a specific
+ * area of code (such as OpenGL).
+ * Use this helper to track that.
+ * The class is a template so that there can be multiple instances of static variables.
+ */
+template <typename Dummy> class CrashZone
+{
+// gnEnterCount and gnLeaveCount are accessed both from multiple threads (cf.
+// WatchdogThread::execute; so need to be of atomic type) and from signal handlers (cf.
+// VCLExceptionSignal_impl; so need to be of lock-free atomic type).  sig_atomic_t is chosen as
+// the underlying type under the assumption that it is most likely to lead to an atomic type
+// that is actually lock-free.  However, gnEnterCount and gnLeaveCount are both monotonically
+// increasing, so will eventually overflow, so the underlying type better be unsigned, which
+// sig_atomic_t is not guaranteed to be:
+#if !defined ARM32 || (defined ARM32 && defined __ARM_PCS_VFP)
+    using AtomicCounter = std::atomic<std::make_unsigned_t<std::sig_atomic_t>>;
+    static_assert(AtomicCounter::is_always_lock_free);
+#else
+    using AtomicCounter = volatile std::make_unsigned_t<std::sig_atomic_t>;
+#endif
+
+    /// how many times have we entered a zone
+    static inline AtomicCounter gnEnterCount = 0;
+    /// how many times have we left a new zone
+    static inline AtomicCounter gnLeaveCount = 0;
+
+public:
+    CrashZone() { enter(); }
+    ~CrashZone() { leave(); }
+    static bool isInZone() { return gnEnterCount != gnLeaveCount; }
+    static const AtomicCounter& enterCount() { return gnEnterCount; }
+    // prefer creating instances to manually calling enter()/leave()
+    static void enter() { gnEnterCount++; }
+    static void leave() { gnLeaveCount++; }
+    // these should be implemented for each specific zone if needed
+    // static void hardDisable();
+    // static const CrashWatchdogTimingsValues& getCrashWatchdogTimingsValues();
+    // static void checkDebug(int nUnchanged, const CrashWatchdogTimingsValues& aTimingValues);
+    // static const char* name();
+};
+
+#endif // INCLUDED_COMPHELPER_CRASHZONE_H
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */