src/api2/admin/datastore/backup.rs: add speedtest api, improve upload speed

We need to disable tcp Nagle algorythm (set_nodelay), and use larger window size for http2

src/bin/upload-speed.rs

@@ -0,0 +1,43 @@
+use failure::*;
+use futures::*;
+use serde_json::json;
+
+use proxmox_backup::client::*;
+
+fn upload_speed() -> Result<usize, Error> {
+
+    let host = "localhost";
+    let datastore = "store2";
+
+    let username = "root@pam";
+
+    let mut client = HttpClient::new(host, username)?;
+
+    let param = json!({"backup-type": "host", "backup-id": "speedtest" });
+    let upgrade = client.h2upgrade(&format!("/api2/json/admin/datastore/{}/backup", datastore), Some(param));
+
+    let res = upgrade.and_then(|h2| {
+        println!("start upload speed test");
+        h2.upload_speedtest()
+    }).wait()?;
+
+    Ok(res)
+}
+
+fn main()  {
+
+    let mut rt = tokio::runtime::Runtime::new().unwrap();
+
+    // should be rt.block_on_all, but this block forever in release builds
+    let _ = rt.block_on(futures::future::lazy(move || -> Result<(), ()> {
+        match upload_speed() {
+            Ok(mbs) => {
+                println!("average upload speed: {} MB/s", mbs);
+            }
+            Err(err) => {
+                eprintln!("ERROR: {}", err);
+            }
+        }
+        Ok(())
+    }));
+}