added exponential backoff

src/main.rs

@@ -1,7 +1,8 @@
-use std::process::ExitCode;
+#![feature(async_closure)]
-
 use regex::Regex;
 use reqwest::Client;
+use std::process::ExitCode;
+use tokio::time::{sleep, Duration};
 
 const USER_AGENT: &str = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36";
 
@@ -17,12 +18,14 @@ async fn main() -> ExitCode {
         .to_string();
 
     let client = Client::builder().user_agent(USER_AGENT).build().unwrap();
-    let mut page = 0;
+    let mut page = 1;
 
     loop {
+
         println!("now scraping page {page}");
 
-        let urls = extract_urls(
+        let post_html = async || {
+            extract_urls(
                 &client
                     .get(format!(
                         "https://rule34.xxx/index.php?page=post&s=list&tags={tags}&pid={}",
@@ -34,14 +37,36 @@ async fn main() -> ExitCode {
                     .text()
                     .await
                     .unwrap(),
-        );
+            )
+        };
+
+        let mut urls = post_html().await;
+
+        let mut wait_time = 5000;
+
         if urls.is_empty() {
-            println!("no urls found, exiting...");
+
+            for reconnection_attempts in 0..4 {
+                println!("no urls found, retrying in {} seconds...", wait_time / 1000);
+                sleep(Duration::from_millis(wait_time)).await;
+                
+                urls = post_html().await;
+
+                if !urls.is_empty() {
+                    println!("urls found! continuing...");
+                    break;
+                }
+
+                if reconnection_attempts == 3 {
+                    println!("no urls found in 4 attempts, exiting...");
                     return ExitCode::FAILURE;
                 }
 
+                wait_time += 5000;
+            }
+        }
+
         for url in urls {
-            println!("found post: {url}");
 
             let img_url =
                 extract_img_url(&client.get(url).send().await.unwrap().text().await.unwrap());
@@ -75,4 +100,3 @@ fn extract_img_url(html: &str) -> String {
         String::new()
     }
 }
-