jan/src-tauri/src/core/utils/download.rs
Thien Tran 6415be9c74
feat: Support download resume (#5111)
* initial support

* append instead of replace extension
2025-05-27 10:46:49 +08:00

315 lines
10 KiB
Rust

use crate::core::cmd::get_jan_data_folder_path;
use crate::core::state::AppState;
use crate::core::utils::normalize_path;
use futures_util::StreamExt;
use reqwest::header::{HeaderMap, HeaderName, HeaderValue};
use std::collections::HashMap;
use std::time::Duration;
use tauri::{Emitter, State};
use tokio::fs::File;
use tokio::io::AsyncWriteExt;
use tokio_util::sync::CancellationToken;
#[derive(Default)]
pub struct DownloadManagerState {
pub cancel_tokens: HashMap<String, CancellationToken>,
}
#[derive(serde::Deserialize, Clone, Debug)]
pub struct DownloadItem {
pub url: String,
pub save_path: String,
}
#[derive(serde::Serialize, Clone, Debug)]
pub struct DownloadEvent {
pub transferred: u64,
pub total: u64,
}
fn err_to_string<E: std::fmt::Display>(e: E) -> String {
format!("Error: {}", e)
}
#[tauri::command]
pub async fn download_files(
app: tauri::AppHandle,
state: State<'_, AppState>,
items: Vec<DownloadItem>,
task_id: &str,
headers: HashMap<String, String>,
) -> Result<(), String> {
// insert cancel tokens
let cancel_token = CancellationToken::new();
{
let mut download_manager = state.download_manager.lock().await;
if download_manager.cancel_tokens.contains_key(task_id) {
return Err(format!("task_id {} exists", task_id));
}
download_manager
.cancel_tokens
.insert(task_id.to_string(), cancel_token.clone());
}
let result =
_download_files_internal(app.clone(), &items, &headers, task_id, cancel_token.clone())
.await;
// cleanup
{
let mut download_manager = state.download_manager.lock().await;
download_manager.cancel_tokens.remove(task_id);
}
// delete files if cancelled
if cancel_token.is_cancelled() {
let jan_data_folder = get_jan_data_folder_path(app.clone());
for item in items {
let save_path = jan_data_folder.join(&item.save_path);
let _ = std::fs::remove_file(&save_path); // don't check error
}
}
result.map_err(err_to_string)
}
#[tauri::command]
pub async fn cancel_download_task(state: State<'_, AppState>, task_id: &str) -> Result<(), String> {
// NOTE: might want to add User-Agent header
let mut download_manager = state.download_manager.lock().await;
if let Some(token) = download_manager.cancel_tokens.remove(task_id) {
token.cancel();
log::info!("Cancelled download task: {}", task_id);
Ok(())
} else {
Err(format!("No download task: {}", task_id))
}
}
fn _convert_headers(
headers: &HashMap<String, String>,
) -> Result<HeaderMap, Box<dyn std::error::Error>> {
let mut header_map = HeaderMap::new();
for (k, v) in headers {
let key = HeaderName::from_bytes(k.as_bytes())?;
let value = HeaderValue::from_str(v)?;
header_map.insert(key, value);
}
Ok(header_map)
}
async fn _get_file_size(
client: &reqwest::Client,
url: &str,
) -> Result<u64, Box<dyn std::error::Error>> {
let resp = client.head(url).send().await?;
if !resp.status().is_success() {
return Err(format!("Failed to get file size: HTTP status {}", resp.status()).into());
}
// this is buggy, always return 0 for HEAD request
// Ok(resp.content_length().unwrap_or(0))
match resp.headers().get("content-length") {
Some(value) => {
let value_str = value.to_str()?;
let value_u64: u64 = value_str.parse()?;
Ok(value_u64)
}
None => Ok(0),
}
}
async fn _download_files_internal(
app: tauri::AppHandle,
items: &[DownloadItem],
headers: &HashMap<String, String>,
task_id: &str,
cancel_token: CancellationToken,
) -> Result<(), String> {
log::info!("Start download task: {}", task_id);
let header_map = _convert_headers(headers).map_err(err_to_string)?;
// .read_timeout() and .connect_timeout() requires reqwest 0.12, which is not
// compatible with hyper 0.14
let client = reqwest::Client::builder()
.http2_keep_alive_timeout(Duration::from_secs(15))
// .read_timeout(Duration::from_secs(10)) // timeout between chunks
// .connect_timeout(Duration::from_secs(10)) // timeout for first connection
.default_headers(header_map.clone())
.build()
.map_err(err_to_string)?;
let total_size = {
let mut total_size = 0u64;
for item in items.iter() {
total_size += _get_file_size(&client, &item.url)
.await
.map_err(err_to_string)?;
}
total_size
};
log::info!("Total download size: {}", total_size);
let mut evt = DownloadEvent {
transferred: 0,
total: total_size,
};
let evt_name = format!("download-{}", task_id);
// save file under Jan data folder
let jan_data_folder = get_jan_data_folder_path(app.clone());
for item in items.iter() {
let save_path = jan_data_folder.join(&item.save_path);
let save_path = normalize_path(&save_path);
// enforce scope
if !save_path.starts_with(&jan_data_folder) {
return Err(format!(
"Path {} is outside of Jan data folder {}",
save_path.display(),
jan_data_folder.display()
));
}
// Create parent directories if they don't exist
if let Some(parent) = save_path.parent() {
if !parent.exists() {
tokio::fs::create_dir_all(parent)
.await
.map_err(err_to_string)?;
}
}
let current_extension = save_path.extension().unwrap_or_default().to_string_lossy();
let append_extension = |ext: &str| {
if current_extension.is_empty() {
ext.to_string()
} else {
format!("{}.{}", current_extension, ext)
}
};
let tmp_save_path = save_path.with_extension(append_extension("tmp"));
let url_save_path = save_path.with_extension(append_extension("url"));
let mut resume = tmp_save_path.exists()
&& tokio::fs::read_to_string(&url_save_path)
.await
.map(|url| url == item.url) // check if we resume the same URL
.unwrap_or(false);
tokio::fs::write(&url_save_path, item.url.clone())
.await
.map_err(err_to_string)?;
log::info!("Started downloading: {}", item.url);
let mut download_delta = 0u64;
let resp = if resume {
let downloaded_size = tmp_save_path.metadata().map_err(err_to_string)?.len();
match _get_maybe_resume(&client, &item.url, downloaded_size).await {
Ok(resp) => {
log::info!(
"Resume download: {}, already downloaded {} bytes",
item.url,
downloaded_size
);
download_delta += downloaded_size;
resp
}
Err(e) => {
// fallback to normal download
log::warn!("Failed to resume download: {}", e);
resume = false;
_get_maybe_resume(&client, &item.url, 0).await?
}
}
} else {
_get_maybe_resume(&client, &item.url, 0).await?
};
let mut stream = resp.bytes_stream();
let file = if resume {
// resume download, append to existing file
tokio::fs::OpenOptions::new()
.write(true)
.append(true)
.open(&tmp_save_path)
.await
.map_err(err_to_string)?
} else {
// start new download, create a new file
File::create(&tmp_save_path).await.map_err(err_to_string)?
};
let mut writer = tokio::io::BufWriter::new(file);
// write chunk to file
while let Some(chunk) = stream.next().await {
if cancel_token.is_cancelled() {
log::info!("Download cancelled for task: {}", task_id);
app.emit(&evt_name, evt.clone()).unwrap();
return Ok(());
}
let chunk = chunk.map_err(err_to_string)?;
writer.write_all(&chunk).await.map_err(err_to_string)?;
download_delta += chunk.len() as u64;
// only update every 10 MB
if download_delta >= 10 * 1024 * 1024 {
evt.transferred += download_delta;
app.emit(&evt_name, evt.clone()).unwrap();
download_delta = 0u64;
}
}
writer.flush().await.map_err(err_to_string)?;
evt.transferred += download_delta;
// rename tmp file to final file
tokio::fs::rename(&tmp_save_path, &save_path)
.await
.map_err(err_to_string)?;
tokio::fs::remove_file(&url_save_path)
.await
.map_err(err_to_string)?;
log::info!("Finished downloading: {}", item.url);
}
app.emit(&evt_name, evt.clone()).unwrap();
Ok(())
}
async fn _get_maybe_resume(
client: &reqwest::Client,
url: &str,
start_bytes: u64,
) -> Result<reqwest::Response, String> {
if start_bytes > 0 {
let resp = client
.get(url)
.header("Range", format!("bytes={}-", start_bytes))
.send()
.await
.map_err(err_to_string)?;
if resp.status() != reqwest::StatusCode::PARTIAL_CONTENT {
return Err(format!(
"Failed to resume download: HTTP status {}, {}",
resp.status(),
resp.text().await.unwrap_or_default()
));
}
Ok(resp)
} else {
let resp = client.get(url).send().await.map_err(err_to_string)?;
if !resp.status().is_success() {
return Err(format!(
"Failed to download: HTTP status {}, {}",
resp.status(),
resp.text().await.unwrap_or_default()
));
}
Ok(resp)
}
}