Improved error management for wifi failure, including quadratic retry falloff

src/main.rs

@@ -1,5 +1,6 @@
 use core::panic;
-use std::borrow::Cow;
+use std::num::NonZeroU16;
+use std::{borrow::Cow, num::NonZero};
 use std::str::FromStr;
 
 use chrono::{format::Fixed, DateTime, Datelike, Days, FixedOffset, NaiveTime};
@@ -33,6 +34,9 @@ type Timetable = [[Option<Lesson>;8]; 5];
 #[link_section = ".rtc.data"]
 static mut WAKEUP_COUNTER: u64 = 0;
 
+#[link_section = ".rtc.data"]
+static mut WIFI_FAIL_COUNTER: Option<NonZeroU16> = None;
+
 #[link_section = ".rtc.data"]
 static mut ERROR_MSG: Option<[u8; 2048]> = None;
 
@@ -164,14 +168,38 @@ fn main() -> anyhow::Result<()> {
         },
     ))
     .unwrap();
-    wifi.start().unwrap();
-    wifi.connect().unwrap();
-    wifi.wait_netif_up().unwrap();
+    let connected = wifi.start()
+        .and_then(|_| wifi.connect())
+        .and_then(|_| wifi.wait_netif_up())
+        .and_then(|_| loop {if wifi.is_connected().unwrap() {break Ok(());}}).is_ok();
+
+    if !connected{
+        let fail_count: u16 = unsafe {
+            let new_val = match WIFI_FAIL_COUNTER{
+                Some(c) => c.saturating_add(1),
+                None => {
+                    NonZeroU16::new_unchecked(1)
+                }
+            };
+            WIFI_FAIL_COUNTER = Some(new_val);
+            new_val
+        }.into();
+
+        println!("Failed to connect to wifi for the {}th time", fail_count);
+        
+        // Quadratic falloff
+        let sleep_time = u32::min((fail_count as u32).pow(2u32) * 4, 600);
+        println!("Going to sleep for {} seconds", sleep_time);
+        unsafe {
+            esp_deep_sleep(sleep_time as u64 * 1000_000)
+        }
+    }
     
-    while !wifi.is_connected().unwrap() {}
     println!("Connected to wifi");
 
-    let ip_info = wifi.wifi().sta_netif().get_ip_info().unwrap();
+    unsafe {
+        WIFI_FAIL_COUNTER = None;
+    }
 
     let httpconnection = EspHttpConnection::new(&HttpConfig {
         use_global_ca_store: true,