From 0945e2659b4ae9151544c8ed555f3208fc810728 Mon Sep 17 00:00:00 2001
From: Anton Strogonoff <anton@strogonoff.name>
Date: Thu, 2 Dec 2021 14:15:13 +0100
Subject: [PATCH] feat(download): return cached object, if possible

---
 src/download.ts | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/download.ts b/src/download.ts
index 0d9ae34..54af881 100644
--- a/src/download.ts
+++ b/src/download.ts
@@ -24,12 +24,25 @@ function isValidLFSInfoResponseData(val: Record<string, any>): val is LFSInfoRes
 
 /**
  * Downloads, caches and returns a blob corresponding to given LFS pointer.
+ * Uses already cached object, if size matches.
  */
 export default async function downloadBlobFromPointer(
   { http: { request }, headers = {}, url, auth }: HTTPRequest,
   { info, objectPath }: Pointer,
 ): Promise<Buffer> {
 
+  try {
+    const cached = await fsp.readFile(objectPath);
+    if (cached.byteLength === info.size) {
+      return cached;
+    }
+  } catch (e) {
+    // Silence file not found errors (implies cache miss)
+    if ((e as any).code !== 'ENOENT') {
+      throw e;
+    }
+  }
+
   const authHeaders: Record<string, string> = auth
     ? getAuthHeader(auth)
     : {};