client: next_scheduled_send()

[tattlekey] / client / tattlekey.c

diff --git a/client/tattlekey.c b/client/tattlekey.c
index 30f92a4d4e3cb804a86af133a4c058a3908acfd7..f5306c28b8130dffceeef916951202f7d71b5b8f 100644 (file)
--- a/client/tattlekey.c
+++ b/client/tattlekey.c
@@ -1,32 +1,113 @@
 #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"
 
-static u16_t seq = 0;
+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() {
-  /* TODO: This is interrupt context.  We need to get out of interrupt context
-   * quickly; we should not be doing significant work here, & definitely
-   * shouldn't be sleeping here.  We signal errors with blinking the LED, which
-   * involves sleeping, so this all has to move. */
-  send_report(seq++, 0);
-  signal(4, 200);
+  /* This runs in interrupt context; don't linger.  */
+  static uint64_t last_button_press_time = 0;
+  uint32_t now = time_s();
+  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;
+    event_t e;
+    e.type = BUTTONPRESS;
+    e.buttonpress.timestamp = now;
+    queue_try_add_ignoring_errors(&queue, &e);
+  }
 }
 
-static void wait_forever() {
-  /* pico-examples/gpio/hello_gpio_irq/hello_gpio_irq.c implements wait-forever
-   * as "while (1);", but
-   * https://www.raspberrypi.com/documentation/pico-sdk/high_level.html#gaf469c6d691230e9d1008
-   * says sleeping uses less power, so we sleep.  */
+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) {
-    /* https://www.raspberrypi.com/documentation/pico-sdk/hardware.html#rpip7ce2cdc1662dce59296b
-     * says the maximum sleep is 2^32 - 1 microseconds (~71.58 minutes), so we
-     * sleep in chunks. */
-    sleep_ms(1 << 31); /* 35.79 minutes */
+    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();
+    }
   }
 }
 
@@ -34,14 +115,16 @@ int main() {
   stdio_init_all();
   if (cyw43_arch_init_with_country(CYW43_COUNTRY_USA))
     signal_error_by_blinking();
-  signal(1, 200);
   cyw43_arch_enable_sta_mode();
-  signal(2, 200);
-  if (cyw43_arch_wifi_connect_timeout_ms(wifi_ssid, wifi_pass,
-                                         CYW43_AUTH_WPA2_AES_PSK, 10000))
+  signal(3, 100);
+  if (cyw43_arch_wifi_connect_timeout_ms(config_wifi_ssid, config_wifi_pass,
+                                         CYW43_AUTH_WPA2_AES_PSK, 90000))
     signal_error_by_blinking();
-  signal(3, 200);
+  signal(2, 300);
+
+  queue_init(&queue, sizeof(event_t), 99);
+
   begin_listening_for_button_press(button_pressed);
 
-  wait_forever();
+  service_queue();
 }