Core Library Proposal: Watchdog-safe iterators

fw/src/mgos_iterator.cpp

@@ -0,0 +1,71 @@
+#include <stdlib.h>
+#include "mgos.h"
+#include "mgos_iterator.h"
+#include "mgos_timers.h"
+
+struct mgos_iterator_ctx {
+ predicate has_next;
+ callable next;
+ mgos_timer_id timer_id;
+ void *param;
+};
+
+struct mgos_iterator_count {
+ int current;
+ int limit;
+ callable_with_index cb;
+ mgos_iterator_id iterator;
+ void *param;
+};
+
+static void mgos_iterator_step(void *arg) {
+ struct mgos_iterator_ctx *mi = (struct mgos_iterator_ctx *)arg;
+ if (mi->has_next(mi->param)) {
+ mi->next(mi->param);
+ } else {
+ mgos_clear_iterator((mgos_iterator_id)mi);
+ }
+}
+
+mgos_iterator_id mgos_iterator(int msecs, predicate has_next, timer_callback cb, void *param) {
+ struct mgos_iterator_ctx *mi = new struct mgos_iterator_ctx;
+ mi->has_next = has_next;
+ mi->next = (callable) cb;
+ mi->timer_id = mgos_set_timer(msecs, true, mgos_iterator_step, mi);
+ mi->param = param;
+ return (mgos_iterator_id) mi;
+}
+
+bool mgos_iterator_count_has_next(void *arg) {
+ struct mgos_iterator_count *ctx = (struct mgos_iterator_count *)arg;
+ return ctx->current < ctx->limit;
+}
+
+void mgos_iterator_count_next(void *arg) {
+ struct mgos_iterator_count *ctx = (struct mgos_iterator_count *)arg;
+ ctx->cb(ctx->param, ctx->current);
+ ctx->current += 1;
+}
+
+void mgos_clear_iterator_count(mgos_iterator_count_id arg) {
+ struct mgos_iterator_count *ctx = (struct mgos_iterator_count *)arg;
+ mgos_clear_iterator(ctx->iterator);
+ delete ctx;
+}
+
+mgos_iterator_count_id mgos_iterator_count(int msecs, int limit, callable_with_index cb, void *param) {
+ struct mgos_iterator_count *mic = new struct mgos_iterator_count;
+ LOG(LL_INFO, ("New count iterator w/ limit %d and param %p", limit, param));
+ mic->limit = limit;
+ mic->current = 0;
+ mic->cb = cb;
+ mic->param = param;
+ mic->iterator = mgos_iterator(msecs, mgos_iterator_count_has_next, mgos_iterator_count_next, mic);
+ return (mgos_iterator_count_id) mic;
+}
+
+void mgos_clear_iterator(mgos_iterator_id iterator_id) {
+ struct mgos_iterator_ctx *ctx = (struct mgos_iterator_ctx *)iterator_id;
+ mgos_clear_timer(ctx->timer_id);
+ delete ctx;
+}

fw/src/mgos_iterator.h

@@ -0,0 +1,43 @@
+#ifndef _MGOS_ITERATOR_H_
+#define _MGOS_ITERATOR_H_
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "mgos_timers.h"
+
+typedef void (*callable)(void *param);
+typedef bool (*predicate)(void *param);
+typedef void (*callable_with_index)(void *param, int i);
+
+typedef uintptr_t mgos_iterator_id;
+typedef uintptr_t mgos_iterator_count_id;
+
+/*
+ * Setup an iterator with `msecs` timeout (see mgos_set_timer).
+ *
+ * `has_next` is a predicate function to determine if this iterator has any work left to do
+ * `cb` is the callback that does the work for a given step
+ * `arg` is a parameter passed to `cb`.
+ * Returns an iterator id that can be used with `mgos_clear_iterator`
+ */
+mgos_iterator_id mgos_iterator(int msecs, predicate has_next, timer_callback cb, void *arg);
+
+/*
+ * Setup a counted iteration.
+ *
+ * This iteration will run at most `limit` times and step every `msecs`.
+ *
+ * `cb` is a callback called with the `arg` and the current iteration value (0, 1, 2, ...)
+ *
+ * Returns an id that can be used with mgos_clear_iterator_count();
+ */
+
+mgos_iterator_count_id mgos_iterator_count(int msecs, int limit, callable_with_index cb, void *arg);
+
+/* Clear an iterator created previously with `mgos_iterator_count` */
+void mgos_clear_iterator_count(mgos_iterator_count_id arg);
+
+/* Clear an iterator created previously with `mgos_iterator` */
+void mgos_clear_iterator(mgos_iterator_id iterator_id);
+
+#endif /* _MGOS_ITERATOR_H_ */