Add download endpoint to EdenApi trait

Summary:
This adds the plumbing to access download a file using the endpoint from the previous diff via the EdenApi trait, which does the actual http request.

It concats the stream into a Bytes object and returns it.

Reviewed By: StanislavGlebik

Differential Revision: D30582422

fbshipit-source-id: ed0fe5e34e3fecc6c1b26d2dceb322dfcf5f8e37

eden/scm/lib/eagerepo/src/api.rs

@@ -564,6 +564,14 @@ impl EdenApi for EagerRepo {
             .map_err(|e| EdenApiError::Other(e.into()))?;
         Ok(convert_to_response(hashes))
     }
+
+    async fn download_file(
+        &self,
+        _repo: String,
+        _token: UploadToken,
+    ) -> Result<Bytes, EdenApiError> {
+        unimplemented!()
+    }
 }
 
 impl EagerRepo {

eden/scm/lib/edenapi/Cargo.toml

@@ -15,6 +15,7 @@ async-trait = "0.1.51"
 atty = "0.2"
 auth = { path = "../auth" }
 blake2 = "0.8"
+bytes = { version = "1.0", features = ["serde"] }
 chrono = { version = "0.4", features = ["clock", "serde", "std"], default-features = false }
 configmodel = { path = "../configmodel" }
 configparser = { path = "../configparser" }

eden/scm/lib/edenapi/src/client.rs

@@ -5,7 +5,9 @@
  * GNU General Public License version 2.
  */
 
+use bytes::Bytes as RawBytes;
 use std::collections::{HashMap, HashSet};
+use std::convert::TryInto;
 use std::fmt::Debug;
 use std::fs::{create_dir_all, File};
 use std::iter::FromIterator;
@@ -45,8 +47,8 @@ use edenapi_types::{
     HgMutationEntryContent, HistoryEntry, HistoryRequest, LookupRequest, LookupResponse,
     ServerError, ToApi, ToWire, TreeAttributes, TreeEntry, TreeRequest,
     UploadBonsaiChangesetRequest, UploadHgChangeset, UploadHgChangesetsRequest,
-    UploadHgFilenodeRequest, UploadToken, UploadTokensResponse, UploadTreeEntry, UploadTreeRequest,
-    UploadTreeResponse,
+    UploadHgFilenodeRequest, UploadToken, UploadTokenMetadata, UploadTokensResponse,
+    UploadTreeEntry, UploadTreeRequest, UploadTreeResponse,
 };
 use hg_http::http_client;
 use http_client::{AsyncResponse, HttpClient, HttpClientError, Progress, Request};
@@ -97,6 +99,7 @@ mod paths {
     pub const UPLOAD_BONSAI_CHANGESET: &str = "upload/changeset/bonsai";
     pub const EPHEMERAL_PREPARE: &str = "ephemeral/prepare";
     pub const FETCH_SNAPSHOT: &str = "snapshot";
+    pub const DOWNLOAD_FILE: &str = "download/file";
 }
 
 #[derive(Clone)]
@@ -1241,6 +1244,39 @@ impl EdenApi for Client {
 
         Ok(self.fetch::<WireFetchSnapshotResponse>(vec![request], None)?)
     }
+
+    async fn download_file(&self, repo: String, token: UploadToken) -> Result<Bytes, EdenApiError> {
+        let download_file = "Downloading file";
+        tracing::info!("{}", download_file);
+        if self.config().debug {
+            eprintln!("{}", download_file);
+        }
+        let url = self.build_url(paths::DOWNLOAD_FILE, Some(&repo))?;
+        let metadata = token.data.metadata.clone();
+        let req = token.to_wire();
+        let request = self
+            .configure_request(Request::post(url.clone()))?
+            .cbor(&req)
+            .map_err(EdenApiError::RequestSerializationFailed)?;
+
+        use bytes::BytesMut;
+        let buf = if let Some(UploadTokenMetadata::FileContentTokenMetadata(m)) = metadata {
+            BytesMut::with_capacity(m.content_size.try_into().unwrap_or_default())
+        } else {
+            BytesMut::new()
+        };
+
+        Ok(self
+            .fetch::<RawBytes>(vec![request], None)?
+            .entries
+            .try_fold(buf, |mut buf, chunk| async move {
+                buf.extend_from_slice(&chunk);
+                Ok(buf)
+            })
+            .await?
+            .freeze()
+            .into())
+    }
 }
 
 /// Split up a collection of keys into batches of at most `batch_size`.

eden/scm/lib/edenapi/trait/src/api.rs

@@ -203,4 +203,7 @@ pub trait EdenApi: Send + Sync + 'static {
         repo: String,
         request: FetchSnapshotRequest,
     ) -> Result<Response<FetchSnapshotResponse>, EdenApiError>;
+
+    /// Download single file from upload token
+    async fn download_file(&self, repo: String, token: UploadToken) -> Result<Bytes, EdenApiError>;
 }

eden/scm/lib/revisionstore/src/testutil.rs

@@ -523,6 +523,14 @@ impl EdenApi for FakeEdenApi {
     ) -> Result<Response<CommitHashLookupResponse>, EdenApiError> {
         unimplemented!()
     }
+
+    async fn download_file(
+        &self,
+        _repo: String,
+        _token: UploadToken,
+    ) -> Result<Bytes, EdenApiError> {
+        unimplemented!()
+    }
 }
 
 pub fn make_config(dir: impl AsRef<Path>) -> ConfigSet {