1 files changed, 88 insertions, 0 deletions
diff --git a/Source/ablastr/utils/SignalHandling.H b/Source/ablastr/utils/SignalHandling.H
new file mode 100644
index 000000000..b633c3860
--- /dev/null
+++ b/Source/ablastr/utils/SignalHandling.H
@@ -0,0 +1,88 @@
+/* Copyright 2022 Philip Miller
+ *
+ * This file is part of WarpX.
+ *
+ * License: BSD-3-Clause-LBNL
+ */
+
+#ifndef ABLASTR_SIGNAL_HANDLING_H_
+#define ABLASTR_SIGNAL_HANDLING_H_
+
+#include <AMReX_Config.H>
+
+#if defined(AMREX_USE_MPI)
+#   include <mpi.h>
+#endif
+
+#include <atomic>
+#include <string>
+
+namespace ablastr::utils {
+
+/**
+ * \brief
+ * Signal handling
+ *
+ * Rank 0 will accept signals and asynchronously broadcast the
+ * configured response; other processes will ignore them and
+ * follow the lead of rank 0 to avoid potential for deadlocks or
+ * timestep-skewed response.
+ *
+ * Variables and functions are static rather than per-instance
+ * because signal handlers are configured at the process level.
+ */
+class SignalHandling
+{
+public:
+    //! The range of signal values to accept
+    static constexpr int NUM_SIGNALS = 32;
+
+    //! Labels for indexed positions in signal_actions_requests
+    enum signal_action_requested_labels {
+        //! Cleanly stop execution, as if the simulation reached its configured end
+        SIGNAL_REQUESTS_BREAK = 0,
+        //! Produce a checkpoint
+        SIGNAL_REQUESTS_CHECKPOINT = 1,
+        SIGNAL_REQUESTS_SIZE = 2 // This should always be 1 greater than the last valid value
+    };
+
+    //! Whether configuration requests the code take a particular action on a particular signal
+    static bool signal_conf_requests[SIGNAL_REQUESTS_SIZE][NUM_SIGNALS];
+
+    //! Take a string and convert it to a corresponding signal number if possible
+    static int parseSignalNameToNumber (const std::string &str);
+
+    //! Set up signal handlers based on input configuration provided in `signal_conf_requests_*`
+    static void InitSignalHandling ();
+
+    //! Check and clear signal flags and asynchronously broadcast them from process 0
+    static void CheckSignals ();
+    //! Complete the asynchronous broadcast of signal flags
+    static void WaitSignals ();
+
+    //! Check whether a given action has been requested, and reset the associated flag
+    static bool TestAndResetActionRequestFlag (int action_to_test);
+
+private:
+    //! On process 0, whether a given signal has been received since the last check
+    static std::atomic<bool> signal_received_flags[NUM_SIGNALS];
+
+#if defined(AMREX_USE_MPI)
+    //! MPI requests for the asynchronous broadcasts of the signal-requested actions
+    static MPI_Request signal_mpi_ibcast_request;
+#endif
+
+    //! Signal handler to set flags on process 0 (other processes ignore configured signals)
+    static void SignalSetFlag (int signal_number);
+
+    //! Boolean flags transmitted between CheckSignals() and
+    //! HandleSignals() to indicate actions requested by signals
+    static bool signal_actions_requested[SIGNAL_REQUESTS_SIZE];
+
+     // Don't allow clients to incorrectly try to construct and use an instance of this type
+    SignalHandling() = delete;
+};
+
+} // namespace ablastr::utils
+
+#endif // ABLASTR_SIGNAL_HANDLING_H_