feat(upload): Add transfer_speed for downloading and uploading files

.changes/add-transfer-speed.md

@@ -0,0 +1,6 @@
+---
+"upload": "minor"
+"upload-js": "minor"
+---
+
+Added feature for calculating `transfer_speed` during file uploads and downloads

plugins/upload/guest-js/index.ts

@@ -7,6 +7,7 @@ import { invoke, Channel } from '@tauri-apps/api/core'
 interface ProgressPayload {
   progress: number
   total: number
+  transferSpeed: number
 }
 
 type ProgressHandler = (progress: ProgressPayload) => void

plugins/upload/src/lib.rs

@@ -13,6 +13,9 @@
     html_favicon_url = "https://github.com/tauri-apps/tauri/raw/dev/app-icon.png"
 )]
 
+mod transfer_stats;
+use transfer_stats::TransferStats;
+
 use futures_util::TryStreamExt;
 use serde::{ser::Serializer, Serialize};
 use tauri::{
@@ -55,9 +58,11 @@ impl Serialize for Error {
 }
 
 #[derive(Clone, Serialize)]
+#[serde(rename_all = "camelCase")]
 struct ProgressPayload {
     progress: u64,
     total: u64,
+    transfer_speed: u64,
 }
 
 #[command]
@@ -88,11 +93,14 @@ async fn download(
     let mut file = BufWriter::new(File::create(file_path).await?);
     let mut stream = response.bytes_stream();
 
+    let mut stats = TransferStats::default();
     while let Some(chunk) = stream.try_next().await? {
         file.write_all(&chunk).await?;
+        stats.record_chunk_transfer(chunk.len());
         let _ = on_progress.send(ProgressPayload {
             progress: chunk.len() as u64,
             total,
+            transfer_speed: stats.transfer_speed,
         });
     }
     file.flush().await?;
@@ -138,10 +146,16 @@ async fn upload(
 fn file_to_body(channel: Channel<ProgressPayload>, file: File) -> reqwest::Body {
     let stream = FramedRead::new(file, BytesCodec::new()).map_ok(|r| r.freeze());
 
+    let mut stats = TransferStats::default();
     reqwest::Body::wrap_stream(ReadProgressStream::new(
         stream,
         Box::new(move |progress, total| {
-            let _ = channel.send(ProgressPayload { progress, total });
+            stats.record_chunk_transfer(progress as usize);
+            let _ = channel.send(ProgressPayload {
+                progress,
+                total,
+                transfer_speed: stats.transfer_speed,
+            });
         }),
     ))
 }

plugins/upload/src/transfer_stats.rs

@@ -0,0 +1,52 @@
+// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: MIT
+
+use std::time::Instant;
+
+// The TransferStats struct is used to track and calculate the transfer speed of data chunks over time.
+pub struct TransferStats {
+    accumulated_chunk_len: usize, // Total length of chunks transferred in the current period
+    accumulated_time: u128,       // Total time taken for the transfers in the current period
+    pub transfer_speed: u64,      // Calculated transfer speed in bytes per second
+    start_time: Instant,          // Time when the current period started
+    granularity: u32, // Time period (in milliseconds) over which the transfer speed is calculated
+}
+
+impl TransferStats {
+    // Initializes a new TransferStats instance with the specified granularity.
+    pub fn start(granularity: u32) -> Self {
+        Self {
+            accumulated_chunk_len: 0,
+            accumulated_time: 0,
+            transfer_speed: 0,
+            start_time: Instant::now(),
+            granularity,
+        }
+    }
+    // Records the transfer of a data chunk and updates the transfer speed if the granularity period has elapsed.
+    pub fn record_chunk_transfer(&mut self, chunk_len: usize) {
+        let now = Instant::now();
+        let it_took = now.duration_since(self.start_time).as_millis();
+        self.accumulated_chunk_len += chunk_len;
+        self.accumulated_time += it_took;
+
+        // If the accumulated time exceeds the granularity, calculate the transfer speed.
+        if self.accumulated_time >= self.granularity as u128 {
+            self.transfer_speed =
+                (self.accumulated_chunk_len as u128 / self.accumulated_time * 1024) as u64;
+            self.accumulated_chunk_len = 0;
+            self.accumulated_time = 0;
+        }
+
+        // Reset the start time for the next period.
+        self.start_time = now;
+    }
+}
+
+// Provides a default implementation for TransferStats with a granularity of 500 milliseconds.
+impl Default for TransferStats {
+    fn default() -> Self {
+        Self::start(500) // Default granularity is 500
+    }
+}