MyFavMirrors/minio
1
0
Fork 0
mirror of https://github.com/minio/minio.git synced 2025-11-12 14:51:36 -05:00
Code Issues Packages Projects Releases Wiki Activity

XL: Make allocations simpler avoid redundant allocs. (#1961)

Browse Source 
- Reduce 10MiB buffers for loopy calls to use 128KiB.
- start using 128KiB buffer where needed.
This commit is contained in:
Harshavardhana
2016-06-24 02:06:23 -07:00
committed by GitHub
parent ff9fc22c72
commit e8990e42c2
11 changed files with 374 additions and 179 deletions
Download Patch File Download Diff File Expand all files Collapse all files

216
erasure-readfile.go
View File

@@ -17,6 +17,7 @@
package main
import (
"bytes"
"encoding/hex"
"errors"
"io"
@@ -25,6 +26,59 @@ import (
"github.com/klauspost/reedsolomon"
)
// isSuccessDecodeBlocks - do we have all the blocks to be successfully decoded?.
// input disks here are expected to be ordered i.e parityBlocks
// are preceded by dataBlocks. For for information look at getOrderedDisks().
func isSuccessDecodeBlocks(disks []StorageAPI, dataBlocks int) bool {
// Count number of data and parity blocks that were read.
var successDataBlocksCount = 0
var successParityBlocksCount = 0
for index, disk := range disks {
if disk == nil {
continue
}
if index < dataBlocks {
successDataBlocksCount++
continue
}
successParityBlocksCount++
}
// Returns true if we have atleast dataBlocks + 1 parity.
return successDataBlocksCount+successParityBlocksCount >= dataBlocks+1
}
// isSuccessDataBlocks - do we have all the data blocks?
// input disks here are expected to be ordered i.e parityBlocks
// are preceded by dataBlocks. For for information look at getOrderedDisks().
func isSuccessDataBlocks(disks []StorageAPI, dataBlocks int) bool {
// Count number of data blocks that were read.
var successDataBlocksCount = 0
for index, disk := range disks[:dataBlocks] {
if disk == nil {
continue
}
if index < dataBlocks {
successDataBlocksCount++
}
}
// Returns true if we have all the dataBlocks.
return successDataBlocksCount >= dataBlocks
}
// getOrderedDisks - get ordered disks from erasure distribution.
// returns ordered slice of disks from their actual distribution.
func getOrderedDisks(distribution []int, disks []StorageAPI, blockCheckSums []checkSumInfo) (orderedDisks []StorageAPI, orderedBlockCheckSums []checkSumInfo) {
orderedDisks = make([]StorageAPI, len(disks))
orderedBlockCheckSums = make([]checkSumInfo, len(disks))
// From disks gets ordered disks.
for index := range disks {
blockIndex := distribution[index]
orderedDisks[blockIndex-1] = disks[index]
orderedBlockCheckSums[blockIndex-1] = blockCheckSums[index]
}
return orderedDisks, orderedBlockCheckSums
}
// erasureReadFile - read bytes from erasure coded files and writes to given writer.
// Erasure coded files are read block by block as per given erasureInfo and data chunks
// are decoded into a data block. Data block is trimmed for given offset and length,
@@ -36,26 +90,24 @@ func erasureReadFile(writer io.Writer, disks []StorageAPI, volume string, path s
// Gather previously calculated block checksums.
blockCheckSums := metaPartBlockChecksums(disks, eInfos, partName)
orderedBlockCheckSums := make([]checkSumInfo, len(disks))
// []orderedDisks will have first eInfo.DataBlocks disks as data disks and rest will be parity.
orderedDisks := make([]StorageAPI, len(disks))
for index := range disks {
blockIndex := eInfo.Distribution[index]
orderedDisks[blockIndex-1] = disks[index]
orderedBlockCheckSums[blockIndex-1] = blockCheckSums[index]
}
// []orderedDisks will have first eInfo.DataBlocks disks as data
// disks and rest will be parity.
orderedDisks, orderedBlockCheckSums := getOrderedDisks(eInfo.Distribution, disks, blockCheckSums)
// bitrotVerify verifies if the file on a particular disk does not have bitrot by verifying the hash of
// the contents of the file.
// bitrotVerify verifies if the file on a particular disk doesn't have bitrot
// by verifying the hash of the contents of the file.
bitrotVerify := func() func(diskIndex int) bool {
verified := make([]bool, len(orderedDisks))
// Return closure so that we have reference to []verified and not recalculate the hash on it
// everytime the function is called for the same disk.
// Return closure so that we have reference to []verified and
// not recalculate the hash on it everytime the function is
// called for the same disk.
return func(diskIndex int) bool {
if verified[diskIndex] {
// Already validated.
return true
}
// Is this a valid block?
isValid := isValidBlock(orderedDisks[diskIndex], volume, path, orderedBlockCheckSums[diskIndex])
verified[diskIndex] = isValid
return isValid
@@ -65,128 +117,166 @@ func erasureReadFile(writer io.Writer, disks []StorageAPI, volume string, path s
// Total bytes written to writer
bytesWritten := int64(0)
// Each element of enBlocks holds curChunkSize'd amount of data read from its corresponding disk.
enBlocks := make([][]byte, len(orderedDisks))
// chunkSize is roughly BlockSize/DataBlocks.
// chunkSize is calculated such that chunkSize*DataBlocks accommodates BlockSize bytes.
// So chunkSize*DataBlocks can be slightly larger than BlockSize if BlockSize is not divisible by
// DataBlocks. The extra space will have 0-padding.
chunkSize := getEncodedBlockLen(eInfo.BlockSize, eInfo.DataBlocks)
// Get start and end block, also bytes to be skipped based on the input offset.
startBlock, endBlock, bytesToSkip := getBlockInfo(offset, totalLength, eInfo.BlockSize)
// For each block, read chunk from each disk. If we are able to read all the data disks then we don't
// need to read parity disks. If one of the data disk is missing we need to read DataBlocks+1 number
// of disks. Once read, we Reconstruct() missing data if needed and write it to the given writer.
for block := startBlock; bytesWritten < length; block++ {
// curChunkSize will be chunkSize except for the last block because the size of the last block
// can be less than BlockSize.
// curChunkSize is chunkSize until end block.
curChunkSize := chunkSize
if block == endBlock && (totalLength%eInfo.BlockSize != 0) {
// If this is the last block and size of the block is < BlockSize.
curChunkSize = getEncodedBlockLen(totalLength%eInfo.BlockSize, eInfo.DataBlocks)
}
// Each element of enBlocks holds curChunkSize'd amount of data read from its corresponding disk.
enBlocks := make([][]byte, len(disks))
// Block offset.
// NOTE: That for the offset calculation we have to use chunkSize and
// not curChunkSize. If we use curChunkSize for offset calculation
// then it can result in wrong offset for the last block.
blockOffset := block * chunkSize
// Figure out the number of disks that are needed for the read.
// We will need DataBlocks number of disks if all the data disks are up.
// We will need DataBlocks+1 number of disks even if one of the data disks is down.
diskCount := 0
readableDiskCount := 0
// Count the number of data disks that are up.
for _, disk := range orderedDisks[:eInfo.DataBlocks] {
if disk == nil {
continue
}
diskCount++
readableDiskCount++
}
if diskCount < eInfo.DataBlocks {
// Not enough data disks up, so we need DataBlocks+1 number of disks for reed-solomon Reconstruct()
diskCount = eInfo.DataBlocks + 1
// Readable disks..
if readableDiskCount < eInfo.DataBlocks {
// Not enough data disks up, so we need DataBlocks+1 number
// of disks for reed-solomon Reconstruct()
readableDiskCount = eInfo.DataBlocks + 1
}
wg := &sync.WaitGroup{}
// Initialize wait group.
var wg = &sync.WaitGroup{}
// current disk index from which to read, this will be used later in case one of the parallel reads fails.
// Current disk index from which to read, this will be used later
// in case one of the parallel reads fails.
index := 0
// Read from the disks in parallel.
for _, disk := range orderedDisks {
if disk == nil {
index++
continue
}
// Increment wait group.
wg.Add(1)
// Start reading from disk in a go-routine.
go func(index int, disk StorageAPI) {
defer wg.Done()
ok := bitrotVerify(index)
if !ok {
// Verify bit rot for this disk slice.
if !bitrotVerify(index) {
// So that we don't read from this disk for the next block.
orderedDisks[index] = nil
return
}
buf := make([]byte, curChunkSize)
// Note that for the offset calculation we have to use chunkSize and not
// curChunkSize. If we use curChunkSize for offset calculation then it
// can result in wrong offset for the last block.
n, err := disk.ReadFile(volume, path, block*chunkSize, buf)
// Chunk writer.
chunkWriter := bytes.NewBuffer(make([]byte, 0, curChunkSize))
// CopyN copies until current chunk size.
err := copyN(chunkWriter, disk, volume, path, blockOffset, curChunkSize)
if err != nil {
// So that we don't read from this disk for the next block.
orderedDisks[index] = nil
return
}
enBlocks[index] = buf[:n]
// Copy the read blocks.
enBlocks[index] = chunkWriter.Bytes()
// Reset the buffer.
chunkWriter.Reset()
// Successfully read.
}(index, disk)
index++
diskCount--
if diskCount == 0 {
readableDiskCount--
// We have read all the readable disks.
if readableDiskCount == 0 {
break
}
}
// Wait for all the reads to finish.
wg.Wait()
// Count number of data and parity blocks that were read.
var successDataBlocksCount = 0
var successParityBlocksCount = 0
for bufidx, buf := range enBlocks {
if buf == nil {
continue
}
if bufidx < eInfo.DataBlocks {
successDataBlocksCount++
continue
}
successParityBlocksCount++
}
// FIXME: make this parallel.
if successDataBlocksCount < eInfo.DataBlocks {
// If we don't have DataBlocks number of data blocks we will have to read enough
// parity blocks such that we have DataBlocks+1 number for blocks for reedsolomon.Reconstruct()
// If we have all the data blocks no need to decode.
if !isSuccessDataBlocks(orderedDisks, eInfo.DataBlocks) {
// If we don't have DataBlocks number of data blocks we
// will have to read enough parity blocks such that we
// have DataBlocks+1 number for blocks for rs.Reconstruct().
// index is either dataBlocks or dataBlocks + 1.
for ; index < len(orderedDisks); index++ {
if (successDataBlocksCount + successParityBlocksCount) == (eInfo.DataBlocks + 1) {
// We have DataBlocks+1 blocks, enough for reedsolomon.Reconstruct()
// We have enough blocks to decode, break out.
if isSuccessDecodeBlocks(orderedDisks, eInfo.DataBlocks) {
// We have DataBlocks+1 blocks, enough for rs.Reconstruct()
break
}
ok := bitrotVerify(index)
if !ok {
// This disk was previously set to nil and ignored, do not read again.
if orderedDisks[index] == nil {
continue
}
// Verify bit-rot for this index.
if !bitrotVerify(index) {
// Mark nil so that we don't read from this disk for the next block.
orderedDisks[index] = nil
continue
}
buf := make([]byte, curChunkSize)
n, err := orderedDisks[index].ReadFile(volume, path, block*chunkSize, buf)
// Chunk writer.
chunkWriter := bytes.NewBuffer(make([]byte, 0, curChunkSize))
// CopyN copies until current chunk size.
err := copyN(chunkWriter, orderedDisks[index], volume, path, blockOffset, curChunkSize)
if err != nil {
// Mark nil so that we don't read from this disk for the next block.
// ERROR: Mark nil so that we don't read from
// this disk for the next block.
orderedDisks[index] = nil
continue
}
successParityBlocksCount++
enBlocks[index] = buf[:n]
// Copy the read blocks.
chunkWriter.Read(enBlocks[index])
// Reset the buffer.
chunkWriter.Reset()
}
// Reconstruct the missing data blocks.
err := decodeData(enBlocks, eInfo.DataBlocks, eInfo.ParityBlocks)
if err != nil {
return bytesWritten, err
}
// Success.
}
var outSize, outOffset int64
@@ -209,14 +299,18 @@ func erasureReadFile(writer io.Writer, disks []StorageAPI, volume string, path s
// We should not send more data than what was requested.
outSize = length - bytesWritten
}
// Write data blocks.
n, err := writeDataBlocks(writer, enBlocks, eInfo.DataBlocks, outOffset, outSize)
if err != nil {
return bytesWritten, err
}
// Update total bytes written.
bytesWritten += n
}
// Success.
return bytesWritten, nil
}
@@ -273,14 +367,18 @@ func isValidBlock(disk StorageAPI, volume, path string, blockCheckSum checkSumIn
// decodeData - decode encoded blocks.
func decodeData(enBlocks [][]byte, dataBlocks, parityBlocks int) error {
// Initialized reedsolomon.
rs, err := reedsolomon.New(dataBlocks, parityBlocks)
if err != nil {
return err
}
// Reconstruct encoded blocks.
err = rs.Reconstruct(enBlocks)
if err != nil {
return err
}
// Verify reconstructed blocks (parity).
ok, err := rs.Verify(enBlocks)
if err != nil {
@@ -291,5 +389,7 @@ func decodeData(enBlocks [][]byte, dataBlocks, parityBlocks int) error {
err = errors.New("Verification failed after reconstruction, data likely corrupted.")
return err
}
// Success.
return nil
}