client: next_scheduled_send()

[tattlekey] / client / tattlekey.c

diff --git a/client/tattlekey.c b/client/tattlekey.c
index 6313424dc34d11143f87a107d765ba765ef02075..f5306c28b8130dffceeef916951202f7d71b5b8f 100644 (file)
--- a/client/tattlekey.c
+++ b/client/tattlekey.c
@@ -1,16 +1,39 @@
 #include "pico/cyw43_arch.h"
 #include "pico/stdlib.h"
+#include "pico/util/pheap.h"
 #include "pico/util/queue.h"
 
 #include "blink.h"
 #include "button.h"
 #include "config.h"
 #include "net.h"
+#include "sends.h"
+
+enum event_type { BUTTONPRESS, SEND };
+typedef struct {
+  enum event_type type;
+  union {
+    struct {
+      uint32_t timestamp;
+    } buttonpress;
+  };
+} event_t;
 
 queue_t queue;
 
 uint32_t time_s() { return time_us_64() / 1000000ul; }
 
+/* Often we don't bother checking for failure (full queue) because
+ *   1. The best thing to do in this unfortunate situation is to blithely
+ *      continue, dropping some events; continuing is better than stopping.
+ *   2. Neither interrupt context nor queue-processing context can block
+ *      until space is available, or even sit around & blink the LED to
+ *      signal a problem.
+ * (We also get a bit of type safety by taking event_t* rather than void*.) */
+static void queue_try_add_ignoring_errors(queue_t *q, event_t *e) {
+  queue_try_add(q, e);
+}
+
 static void button_pressed() {
   /* This runs in interrupt context; don't linger.  */
   static uint64_t last_button_press_time = 0;
@@ -18,9 +41,73 @@ static void button_pressed() {
   uint32_t time_since_last_press = now - last_button_press_time;
   if (time_since_last_press >= config_minimum_seconds_between_button_presses) {
     last_button_press_time = now;
-    /* We don't check for failure (full queue) here because there's not much to
-     * be done about it. */
-    queue_try_add(&queue, &now);
+    event_t e;
+    e.type = BUTTONPRESS;
+    e.buttonpress.timestamp = now;
+    queue_try_add_ignoring_errors(&queue, &e);
+  }
+}
+
+static void time_to_send(uint _) {
+  /* This runs in interrupt context; don't linger.  */
+  event_t e;
+  e.type = SEND;
+  queue_try_add_ignoring_errors(&queue, &e);
+}
+
+void service_sleeps(int alarm, send_t *sleeping_sends, pheap_t *sleeps_heap) {
+  hardware_alarm_cancel(alarm);
+
+  while (1) {
+    uint32_t now = time_s();
+    int32_t act_time = next_scheduled_send(sleeping_sends, sleeps_heap);
+    if (act_time == -1)
+      return;
+    if (act_time > now) {
+      uint32_t sleep_duration = act_time - now;
+      if (hardware_alarm_set_target(
+              alarm, make_timeout_time_ms(sleep_duration * 1000)))
+        signal_error_by_blinking();
+      return;
+    }
+    pheap_node_id_t i = ph_remove_head(sleeps_heap, false);
+    send_t *send = &sleeping_sends[i];
+    uint32_t ago = now - send->timestamp;
+    send_report(send->seq, ago);
+    send->send_count++;
+    if (send->send_count < config_resend_count)
+      ph_insert_node(sleeps_heap, i);
+    else
+      ph_free_node(sleeps_heap, i);
+  }
+}
+
+void service_queue() {
+  int alarm = hardware_alarm_claim_unused(true);
+  if (alarm == -1)
+    signal_error_by_blinking();
+  hardware_alarm_set_callback(alarm, time_to_send);
+
+  send_t sleeping_sends[PICO_PHEAP_MAX_ENTRIES];
+  pheap_t *sleeps_heap =
+      ph_create(PICO_PHEAP_MAX_ENTRIES, next_send_less_than, sleeping_sends);
+  u16_t seq = 0;
+  while (1) {
+    service_sleeps(alarm, sleeping_sends, sleeps_heap);
+
+    event_t e;
+    queue_remove_blocking(&queue, &e);
+    switch (e.type) {
+    case BUTTONPRESS: {
+      create_send(sleeping_sends, sleeps_heap, e.buttonpress.timestamp, seq++);
+    } break;
+    case SEND: {
+      /* OK, we're awake. Cool. Thanks! (We actually do the sends in the
+       * service_sleeps() call at the top of the loop.)  */
+    } break;
+    default:
+      signal_error_by_blinking();
+    }
   }
 }
 
@@ -35,21 +122,9 @@ int main() {
     signal_error_by_blinking();
   signal(2, 300);
 
-  queue_init(&queue, sizeof(uint32_t), 99);
+  queue_init(&queue, sizeof(event_t), 99);
 
   begin_listening_for_button_press(button_pressed);
 
-  u16_t seq = 0;
-  while (1) {
-    uint32_t t;
-    queue_remove_blocking(&queue, &t);
-    seq++;
-    for (int i = 0; i < config_resend_count; i++) {
-      uint32_t now = time_s();
-      uint32_t ago = now - t;
-      send_report(seq, ago);
-      signal(i == 0 ? 2 : 1, 100);
-      sleep_ms(config_resend_interval_ms);
-    }
-  }
+  service_queue();
 }