Retry network related stuff if failing

src/main.rs

@@ -14,7 +14,7 @@ use std::collections::HashMap;
 use std::time::{Instant, Duration};
 
 use json::JsonValue;
-use reqwest::{Client, Response, RedirectPolicy};
+use reqwest::{Client, Response, RedirectPolicy, RequestBuilder};
 use reqwest::header::{Cookie, Charset, SetCookie};
 use reqwest::header::{ContentDisposition, DispositionType, DispositionParam};
 use zip::ZipArchive;
@@ -34,7 +34,8 @@ mod catalogs {
 
 // TODO: use clap for proper CLI
 // TODO: replace unwraps with descriptive expects
-// TODO: retry some things if sensible
+
+const MAX_RETRIES: u8 = 10;
 
 lazy_static! {
     static ref CLIENT: Client = {
@@ -107,10 +108,10 @@ fn get_auth(username: &str, password: &str) -> String {
     form_data.insert("UserName", username);
     form_data.insert("Password", password);
 
-    let res = CLIENT.post("https://streams.tum.de/Mediasite/Login")
+    let res = try_to_get_response(|client| {
+        client.post("https://streams.tum.de/Mediasite/Login")
             .form(&form_data)
-        .send()
+    });
-        .unwrap();
 
     let set_cookie: &SetCookie = res.headers().get().unwrap();
     let cookie = cookie::Cookie::parse(set_cookie.0[0].to_string()).unwrap();
@@ -139,11 +140,9 @@ fn get_catalog_id(name: &str, auth: &str) -> String {
     println!("Fetching catalog id!");
 
     let url = format!("https://streams.tum.de/Mediasite/Catalog/catalogs/{}", name);
-    let res = CLIENT.get(&url)
+    let mut res = try_to_get_response(|client| client.get(&url).header(construct_cookie(auth)));
-        .header(construct_cookie(auth))
-        .send();
     let mut string = String::new();
-    res.unwrap().read_to_string(&mut string).unwrap();
+    res.read_to_string(&mut string).unwrap();
 
     let prefix = "CatalogId: '";
     let idx = string.find(prefix).unwrap();
@@ -155,14 +154,15 @@ fn get_catalog_id(name: &str, auth: &str) -> String {
 }
 
 fn download_presentation(presentation: &Presentation, out_dir: &Path, auth: &str) {
-    fn try_download(presentation: &Presentation, auth: &str) -> Option<(Response, String)> {
+    let response =
-        let response = CLIENT.get(&presentation.download_url)
+        try_to_get_valid_response(|client| {
+                                      client.get(&presentation.download_url)
                                           .header(construct_cookie(auth))
-            .send()
+                                  },
-            .unwrap();
+                                  |resp| resp.headers().get::<ContentDisposition>().is_some());
 
-        let filename = if let Some(content_disposition) =
+    let filename = {
-            response.headers().get::<ContentDisposition>() {
+        let content_disposition = response.headers().get::<ContentDisposition>().unwrap();
         assert_eq!(content_disposition.disposition, DispositionType::Attachment);
         let mut name = None;
         for param in &content_disposition.parameters {
@@ -175,31 +175,8 @@ fn download_presentation(presentation: &Presentation, out_dir: &Path, auth: &str
             }
         }
         name.expect("Missing filename in ContentDisposition!")
-        } else {
-            return None;
     };
 
-        Some((response, filename))
-    }
-
-    let mut tries = 0;
-    let mut tuple = None;
-    while tries < 8 {
-        if tries > 0 {
-            println!("Failed to start download! Retrying!");
-        }
-        let try = try_download(presentation, auth);
-        if try.is_some() {
-            tuple = try;
-            break;
-        }
-        tries += 1;
-    }
-    if tuple.is_none() {
-        panic!("Failed to get a proper response while trying to download presentation!");
-    }
-    let (response, filename) = tuple.unwrap();
-
     let mut path = PathBuf::from(out_dir);
     path.push(fix_filename(&filename));
     println!("Output file: {:?}", path);
@@ -274,12 +251,13 @@ fn get_json(catalog_id: &str, auth: &str) -> String {
     data.insert("CurrentFolderId", catalog_id);
     data.insert("ItemsPerPage", "500");
 
-    let res = CLIENT.post("https://streams.tum.de/Mediasite/Catalog/Data/GetPresentationsForFolder")
+    let mut res = try_to_get_response(|client| {
+        client.post("https://streams.tum.de/Mediasite/Catalog/Data/GetPresentationsForFolder")
             .header(construct_cookie(auth))
             .json(&data)
-        .send();
+    });
     let mut string = String::new();
-    res.unwrap().read_to_string(&mut string).unwrap();
+    res.read_to_string(&mut string).unwrap();
     string
 }
 
@@ -293,3 +271,29 @@ fn zip_is_valid(path: &Path) -> bool {
     let file = File::open(path).unwrap();
     ZipArchive::new(file).is_ok()
 }
+
+fn try_to_get_response<F>(f: F) -> Response
+    where F: Fn(&Client) -> RequestBuilder
+{
+    try_to_get_valid_response(f, |_| true)
+}
+
+fn try_to_get_valid_response<F1, F2>(f1: F1, f2: F2) -> Response
+    where F1: Fn(&Client) -> RequestBuilder,
+          F2: Fn(&Response) -> bool
+{
+    let mut retries = 0;
+    while retries <= MAX_RETRIES {
+        if retries > 0 {
+            println!("Retrying request!");
+        }
+        let response = f1(&*CLIENT).send();
+        if let Ok(response) = response {
+            if f2(&response) {
+                return response;
+            }
+        }
+        retries += 1;
+    }
+    panic!("Reached maximum amout of retries!")
+}