60 lines
1.3 KiB
Go
60 lines
1.3 KiB
Go
package azure
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import (
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"encoding/base64"
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"fmt"
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"math/rand"
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"sync"
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"time"
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azure "github.com/MSOpenTech/azure-sdk-for-go/storage"
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)
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type blockIDGenerator struct {
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pool map[string]bool
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r *rand.Rand
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m sync.Mutex
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}
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// Generate returns an unused random block id and adds the generated ID
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// to list of used IDs so that the same block name is not used again.
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func (b *blockIDGenerator) Generate() string {
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b.m.Lock()
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defer b.m.Unlock()
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var id string
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for {
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id = toBlockID(int(b.r.Int()))
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if !b.exists(id) {
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break
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}
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}
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b.pool[id] = true
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return id
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}
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func (b *blockIDGenerator) exists(id string) bool {
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_, used := b.pool[id]
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return used
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}
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func (b *blockIDGenerator) Feed(blocks azure.BlockListResponse) {
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b.m.Lock()
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defer b.m.Unlock()
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for _, bl := range append(blocks.CommittedBlocks, blocks.UncommittedBlocks...) {
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b.pool[bl.Name] = true
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}
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}
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func newBlockIDGenerator() *blockIDGenerator {
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return &blockIDGenerator{
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pool: make(map[string]bool),
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r: rand.New(rand.NewSource(time.Now().UnixNano()))}
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}
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// toBlockId converts given integer to base64-encoded block ID of a fixed length.
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func toBlockID(i int) string {
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s := fmt.Sprintf("%029d", i) // add zero padding for same length-blobs
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return base64.StdEncoding.EncodeToString([]byte(s))
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}
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