diff --git a/internal/vaultik/restore.go b/internal/vaultik/restore.go index 5adaf9e..31e9ae0 100644 --- a/internal/vaultik/restore.go +++ b/internal/vaultik/restore.go @@ -569,14 +569,22 @@ func (v *Vaultik) restoreRegularFile( return fmt.Errorf("getting blob %s: %w", blobChunk.BlobID, err) } - // Download and decrypt blob if not cached + // If the blob isn't on disk yet, download it (one full readout + // of the plaintext into memory), write it to the cache, and + // satisfy THIS chunk from the in-memory copy. Subsequent files + // needing chunks from the same blob hit the ReadAt branch and + // read only the bytes they actually want — never the whole + // blob — which is the difference between sub-millisecond chunk + // extraction and ~1 s per cache hit on a 10 GB blob. blobHashStr := blob.Hash.String() + var chunkData []byte t0 = time.Now() - blobData, ok := blobCache.Get(blobHashStr) + blobInCache := blobCache.Has(blobHashStr) cacheGetDur += time.Since(t0) - if !ok { + + if !blobInCache { t0 = time.Now() - blobData, err = v.downloadBlob(ctx, blobHashStr, blob.CompressedSize, identity) + blobData, err := v.downloadBlob(ctx, blobHashStr, blob.CompressedSize, identity) downloadDur += time.Since(t0) if err != nil { return fmt.Errorf("downloading blob %s: %w", blobHashStr[:16], err) @@ -589,17 +597,22 @@ func (v *Vaultik) restoreRegularFile( downloadCount++ result.BlobsDownloaded++ result.BytesDownloaded += blob.CompressedSize + + if blobChunk.Offset+blobChunk.Length > int64(len(blobData)) { + return fmt.Errorf("chunk %s extends beyond blob data (offset=%d, length=%d, blob_size=%d)", + fc.ChunkHash[:16], blobChunk.Offset, blobChunk.Length, len(blobData)) + } + chunkData = blobData[blobChunk.Offset : blobChunk.Offset+blobChunk.Length] } else { cacheHitCount++ + t0 = time.Now() + chunkData, err = blobCache.ReadAt(blobHashStr, blobChunk.Offset, blobChunk.Length) + cacheGetDur += time.Since(t0) + if err != nil { + return fmt.Errorf("reading chunk %s from cached blob %s: %w", fc.ChunkHash[:16], blobHashStr[:16], err) + } } - // Extract chunk from blob - if blobChunk.Offset+blobChunk.Length > int64(len(blobData)) { - return fmt.Errorf("chunk %s extends beyond blob data (offset=%d, length=%d, blob_size=%d)", - fc.ChunkHash[:16], blobChunk.Offset, blobChunk.Length, len(blobData)) - } - chunkData := blobData[blobChunk.Offset : blobChunk.Offset+blobChunk.Length] - // Write chunk to output file t0 = time.Now() n, err := outFile.Write(chunkData)