Harden USB logging and persist watchdog events in management reports

src/helpers/UsbLoggingClientActivity.cpp

@@ -0,0 +1,53 @@
+#include "UsbLoggingClientActivity.h"
+
+#if defined(ARDUINO)
+#include <Arduino.h>
+#include "UsbLogging.h"
+#if MESH_USB_CONSOLE_COOPERATIVE
+#include <atomic>
+
+namespace mesh {
+namespace {
+std::atomic<uint32_t> session_generation{1};
+std::atomic<uint32_t> stats_generation{0};
+std::atomic<uint32_t> stats_deadline{0};
+}
+
+void noteUsbLoggingStatsCommand(const char* command) {
+  if (!isUsbLoggingStatsCommand(command)) return;
+  const uint32_t generation = session_generation.load(std::memory_order_acquire);
+  uint32_t deadline = millis() + USB_LOGGING_CLIENT_LEASE_MS;
+  if (!deadline) deadline = UINT32_MAX;  // Reserve zero; at most 1 ms early.
+  stats_deadline.store(deadline, std::memory_order_relaxed);
+  stats_generation.store(generation, std::memory_order_release);
+}
+
+bool isUsbLoggingClientActive() {
+  const uint32_t generation = stats_generation.load(std::memory_order_acquire);
+  if (!generation || generation != session_generation.load(std::memory_order_acquire))
+    return false;
+  uint32_t deadline = stats_deadline.load(std::memory_order_relaxed);
+  if (!deadline) return false;
+  if (int32_t(deadline - millis()) > 0) return true;
+  // Latch expiry, so millis wrapping weeks later cannot revive an old poll.
+  // Compare the timestamp, not just the session: an owner-task renewal that
+  // raced this expiry must retain its new deadline.
+  stats_deadline.compare_exchange_strong(deadline, 0);
+  return false;
+}
+
+void clearUsbLoggingClientActivity() {
+  // A callback racing a poll invalidates that poll's old generation without
+  // blocking either the USB owner task or the application loop.
+  session_generation.fetch_add(1, std::memory_order_acq_rel);
+}
+
+}  // namespace mesh
+#else
+namespace mesh {
+void noteUsbLoggingStatsCommand(const char*) {}
+bool isUsbLoggingClientActive() { return false; }
+void clearUsbLoggingClientActivity() {}
+}  // namespace mesh
+#endif  // MESH_USB_CONSOLE_COOPERATIVE
+#endif  // ARDUINO