perf: generate block hashes as we parse the stream

lib/integrity.js

@@ -9,6 +9,10 @@ const BLOCK_SIZE = 4 * 1024 * 1024
 
 const pipeline = promisify(stream.pipeline)
 
+function hashBlock (block) {
+  return crypto.createHash(ALGORITHM).update(block).digest('hex')
+}
+
 async function getFileIntegrity (path) {
   const read = fs.createReadStream(path)
   const hash = crypto.createHash(ALGORITHM)
@@ -32,7 +36,7 @@ async function getFileIntegrity (path) {
           currentBlockSize += diffToSlice
           currentBlock.push(chunk.slice(0, diffToSlice))
           if (currentBlockSize === BLOCK_SIZE) {
-            blocks.push(Buffer.concat(currentBlock))
+            blocks.push(hashBlock(Buffer.concat(currentBlock)))
             currentBlock = []
             currentBlockSize = 0
           }
@@ -44,7 +48,7 @@ async function getFileIntegrity (path) {
         callback()
       },
       flush (callback) {
-        blocks.push(Buffer.concat(currentBlock))
+        blocks.push(hashBlock(Buffer.concat(currentBlock)))
         currentBlock = []
         callback()
       }
@@ -55,7 +59,7 @@ async function getFileIntegrity (path) {
     algorithm: ALGORITHM,
     hash: hash.read(),
     blockSize: BLOCK_SIZE,
-    blocks: blocks.map(block => crypto.createHash(ALGORITHM).update(block).digest('hex'))
+    blocks: blocks
   }
 }