From 9a8f4be06cb476b8149ed4f73d2cb62add14873f Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Thu, 22 Jul 2021 17:34:34 +0300
Subject: refactor: use async for "obnam get-chunk"

Sponsored-by: author
---
 src/client.rs        | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/cmd/get_chunk.rs |  13 ++++--
 2 files changed, 123 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/client.rs b/src/client.rs
index f90d377..e9ceea3 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -81,6 +81,120 @@ pub enum ClientError {
     FileWrite(PathBuf, std::io::Error),
 }
 
+pub struct AsyncBackupClient {
+    chunk_client: AsyncChunkClient,
+}
+
+impl AsyncBackupClient {
+    pub fn new(config: &ClientConfig) -> Result<Self, ClientError> {
+        info!("creating backup client with config: {:#?}", config);
+        Ok(Self {
+            chunk_client: AsyncChunkClient::new(config)?,
+        })
+    }
+
+    pub async fn fetch_chunk(&self, chunk_id: &ChunkId) -> Result<DataChunk, ClientError> {
+        self.chunk_client.fetch_chunk(chunk_id).await
+    }
+}
+
+pub struct AsyncChunkClient {
+    client: reqwest::Client,
+    base_url: String,
+    cipher: CipherEngine,
+}
+
+impl AsyncChunkClient {
+    pub fn new(config: &ClientConfig) -> Result<Self, ClientError> {
+        let pass = config.passwords()?;
+
+        let client = reqwest::Client::builder()
+            .danger_accept_invalid_certs(!config.verify_tls_cert)
+            .build()
+            .map_err(ClientError::ReqwestError)?;
+        Ok(Self {
+            client,
+            base_url: config.server_url.to_string(),
+            cipher: CipherEngine::new(&pass),
+        })
+    }
+
+    fn base_url(&self) -> &str {
+        &self.base_url
+    }
+
+    fn chunks_url(&self) -> String {
+        format!("{}/chunks", self.base_url())
+    }
+
+    pub async fn fetch_chunk(&self, chunk_id: &ChunkId) -> Result<DataChunk, ClientError> {
+        let (headers, body) = self.get(&format!("/{}", chunk_id), &[]).await?;
+        let meta = self.get_chunk_meta_header(chunk_id, &headers)?;
+
+        let meta_bytes = meta.to_json_vec();
+        let chunk = self.cipher.decrypt_chunk(&body, &meta_bytes)?;
+
+        Ok(chunk)
+    }
+
+    async fn get(
+        &self,
+        path: &str,
+        query: &[(&str, &str)],
+    ) -> Result<(HeaderMap, Vec<u8>), ClientError> {
+        let url = format!("{}{}", &self.chunks_url(), path);
+        info!("GET {}", url);
+
+        // Build HTTP request structure.
+        let req = self
+            .client
+            .get(&url)
+            .query(query)
+            .build()
+            .map_err(ClientError::ReqwestError)?;
+
+        // Make HTTP request.
+        let res = self
+            .client
+            .execute(req)
+            .await
+            .map_err(ClientError::ReqwestError)?;
+
+        // Did it work?
+        if res.status() != 200 {
+            return Err(ClientError::NotFound(path.to_string()));
+        }
+
+        // Return headers and body.
+        let headers = res.headers().clone();
+        let body = res.bytes().await.map_err(ClientError::ReqwestError)?;
+        let body = body.to_vec();
+        Ok((headers, body))
+    }
+
+    fn get_chunk_meta_header(
+        &self,
+        chunk_id: &ChunkId,
+        headers: &HeaderMap,
+    ) -> Result<ChunkMeta, ClientError> {
+        let meta = headers.get("chunk-meta");
+
+        if meta.is_none() {
+            let err = ClientError::NoChunkMeta(chunk_id.clone());
+            error!("fetching chunk {} failed: {}", chunk_id, err);
+            return Err(err);
+        }
+
+        let meta = meta
+            .unwrap()
+            .to_str()
+            .map_err(ClientError::MetaHeaderToString)?;
+        let meta: ChunkMeta = serde_json::from_str(meta).map_err(ClientError::JsonParse)?;
+
+        Ok(meta)
+    }
+}
+
 pub struct BackupClient {
     chunk_client: ChunkClient,
 }
diff --git a/src/cmd/get_chunk.rs b/src/cmd/get_chunk.rs
index 4ee70fe..f574c99 100644
--- a/src/cmd/get_chunk.rs
+++ b/src/cmd/get_chunk.rs
@@ -1,9 +1,10 @@
 use crate::chunkid::ChunkId;
-use crate::client::BackupClient;
+use crate::client::AsyncBackupClient;
 use crate::config::ClientConfig;
 use crate::error::ObnamError;
 use std::io::{stdout, Write};
 use structopt::StructOpt;
+use tokio::runtime::Runtime;
 
 #[derive(Debug, StructOpt)]
 pub struct GetChunk {
@@ -13,10 +14,14 @@ pub struct GetChunk {
 
 impl GetChunk {
     pub fn run(&self, config: &ClientConfig) -> Result<(), ObnamError> {
-        let client = BackupClient::new(config)?;
-        let chunk_id: ChunkId = self.chunk_id.parse().unwrap();
-        let chunk = client.fetch_chunk(&chunk_id)?;
+        let rt = Runtime::new()?;
+        rt.block_on(self.run_async(config))
+    }
 
+    async fn run_async(&self, config: &ClientConfig) -> Result<(), ObnamError> {
+        let client = AsyncBackupClient::new(config)?;
+        let chunk_id: ChunkId = self.chunk_id.parse().unwrap();
+        let chunk = client.fetch_chunk(&chunk_id).await?;
         let stdout = stdout();
         let mut handle = stdout.lock();
         handle.write_all(chunk.data())?;
-- 
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