fixes

src/concurrency/PeriodicTask.h

@@ -0,0 +1,55 @@
+#pragma once
+
+#include "PeriodicScheduler.h"
+#include "../time.h"
+
+namespace concurrency {
+
+/**
+ * A base class for tasks that want their doTask() method invoked periodically
+ *
+ * FIXME: currently just syntatic sugar for polling in loop (you must call .loop), but eventually
+ * generalize with the freertos scheduler so we can save lots of power by having everything either in
+ * something like this or triggered off of an irq.
+ */
+class PeriodicTask
+{
+    friend class PeriodicScheduler;
+
+    uint32_t lastMsec = 0;
+    uint32_t period = 1; // call soon after creation
+
+  public:
+    virtual ~PeriodicTask() { periodicScheduler.unschedule(this); }
+
+    /**
+     * Constructor (will schedule with the global PeriodicScheduler)
+     */
+    PeriodicTask(uint32_t initialPeriod = 1);
+
+    /** MUST be be called once at startup (but after threading is running - i.e. not from a constructor)
+     */
+    void setup();
+
+    /**
+     * Set a new period in msecs (can be called from doTask or elsewhere and the scheduler will cope)
+     * While zero this task is disabled and will not run
+     */
+    void setPeriod(uint32_t p)
+    {
+        lastMsec = time::millis(); // reset starting from now
+        period = p;
+    }
+
+    uint32_t getPeriod() const { return period; }
+
+    /**
+     * Syntatic sugar for suspending tasks
+     */
+    void disable() { setPeriod(0); }
+
+  protected:
+    virtual void doTask() = 0;
+};
+
+} // namespace concurrency