client: Extract pending-send object as send_t

[tattlekey] / client / tattlekey.c

diff --git a/client/tattlekey.c b/client/tattlekey.c
index 6313424dc34d11143f87a107d765ba765ef02075..78d1dcfd8925c576b362d6fa0d20e09f7686de54 100644 (file)
--- a/client/tattlekey.c
+++ b/client/tattlekey.c
@@ -7,10 +7,38 @@
 #include "config.h"
 #include "net.h"
 
+typedef struct {
+  uint32_t timestamp;
+  u16_t seq;
+  u8_t send_count;
+} send_t;
+
+enum event_type { BUTTONPRESS, SEND };
+typedef struct {
+  enum event_type type;
+  union {
+    struct {
+      uint32_t timestamp;
+    } buttonpress;
+    send_t send;
+  };
+} 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 +46,41 @@ 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);
+  }
+}
+
+void service_queue() {
+  u16_t seq = 0;
+  while (1) {
+    event_t e;
+    queue_remove_blocking(&queue, &e);
+    switch (e.type) {
+    case BUTTONPRESS: {
+      event_t send_e;
+      send_e.type = SEND;
+      send_e.send.timestamp = e.buttonpress.timestamp;
+      send_e.send.seq = seq++;
+      send_e.send.send_count = 0;
+      queue_try_add_ignoring_errors(&queue, &send_e);
+    } break;
+    case SEND: {
+      uint32_t now = time_s();
+      uint32_t ago = now - e.send.timestamp;
+      send_report(e.send.seq, ago);
+      e.send.send_count++;
+      if (e.send.send_count < config_resend_count)
+        queue_try_add_ignoring_errors(&queue, &e);
+      /* TODO: Sleep elsewhere. */
+      signal(e.send.send_count == 1 ? 2 : 1, 100);
+      sleep_ms(config_resend_interval_ms);
+    } break;
+    default:
+      signal_error_by_blinking();
+    }
   }
 }
 
@@ -35,21 +95,9 @@ 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();
 }