Add new ReadFileWithVerify storage-layer API (#4349)

This is an enhancement to the XL/distributed-XL mode. FS mode is
unaffected.

The ReadFileWithVerify storage-layer call is similar to ReadFile with
the additional functionality of performing bit-rot checking. It
accepts additional parameters for a hashing algorithm to use and the
expected hex-encoded hash string.

This patch provides significant performance improvement because:

1. combines the step of reading the file (during
erasure-decoding/reconstruction) with bit-rot verification;

2. limits the number of file-reads; and

3. avoids transferring the file over the network for bit-rot
verification.

ReadFile API is implemented as ReadFileWithVerify with empty hashing
arguments.

Credits to AB and Harsha for the algorithmic improvement.

Fixes #4236.
This commit is contained in:
Aditya Manthramurthy
2017-05-16 14:21:52 -07:00
committed by Harshavardhana
parent cae4683971
commit 8975da4e84
20 changed files with 471 additions and 88 deletions

View File

@@ -28,7 +28,9 @@ import (
// erasureCreateFile - writes an entire stream by erasure coding to
// all the disks, writes also calculate individual block's checksum
// for future bit-rot protection.
func erasureCreateFile(disks []StorageAPI, volume, path string, reader io.Reader, allowEmpty bool, blockSize int64, dataBlocks int, parityBlocks int, algo string, writeQuorum int) (bytesWritten int64, checkSums []string, err error) {
func erasureCreateFile(disks []StorageAPI, volume, path string, reader io.Reader, allowEmpty bool, blockSize int64,
dataBlocks, parityBlocks int, algo HashAlgo, writeQuorum int) (bytesWritten int64, checkSums []string, err error) {
// Allocated blockSized buffer for reading from incoming stream.
buf := make([]byte, blockSize)