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minio/xl-v1-utils.go

111 lines
2.7 KiB

/*
* Minio Cloud Storage, (C) 2016 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package main
import (
"bytes"
"io"
"math/rand"
"path"
"time"
)
// Validates if we have quorum based on the errors with errDiskNotFound.
func isQuorum(errs []error, minQuorumCount int) bool {
var diskFoundCount int
for _, err := range errs {
if err == errDiskNotFound {
continue
}
diskFoundCount++
}
return diskFoundCount >= minQuorumCount
}
// Similar to 'len(slice)' but returns the actual elements count
// skipping the unallocated elements.
func diskCount(disks []StorageAPI) int {
diskCount := 0
for _, disk := range disks {
if disk == nil {
continue
}
diskCount++
}
return diskCount
}
// randInts - uses Knuth Fisher-Yates shuffle algorithm for generating uniform shuffling.
func randInts(count int) []int {
rand.Seed(time.Now().UTC().UnixNano()) // Seed with current time.
ints := make([]int, count)
for i := 0; i < count; i++ {
ints[i] = i + 1
}
for i := 0; i < count; i++ {
// Choose index uniformly in [i, count-1]
r := i + rand.Intn(count-i)
ints[r], ints[i] = ints[i], ints[r]
}
return ints
}
// readAll - returns contents from volume/path as byte array.
func readAll(disk StorageAPI, volume string, path string) ([]byte, error) {
var writer = new(bytes.Buffer)
startOffset := int64(0)
// Allocate 10MiB buffer.
buf := make([]byte, blockSizeV1)
// Read until io.EOF.
for {
n, err := disk.ReadFile(volume, path, startOffset, buf)
if err == io.EOF {
break
}
if err != nil && err != io.EOF {
return nil, err
}
writer.Write(buf[:n])
startOffset += n
}
return writer.Bytes(), nil
}
// readXLMeta reads `xl.json` returns contents as byte array.
func readXLMeta(disk StorageAPI, bucket string, object string) ([]byte, error) {
var writer = new(bytes.Buffer)
startOffset := int64(0)
// Allocate 2MiB buffer, this is sufficient for the most of `xl.json`.
buf := make([]byte, 2*1024*1024)
// Read until io.EOF.
for {
n, err := disk.ReadFile(bucket, path.Join(object, xlMetaJSONFile), startOffset, buf)
if err == io.EOF {
break
}
if err != nil && err != io.EOF {
return nil, err
}
writer.Write(buf[:n])
startOffset += n
}
return writer.Bytes(), nil
}