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https://github.com/etcd-io/etcd.git
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785deebd62
This pr changes UnsafeForEach to traverse on boltdb before on the buffer. This ordering guarantees that UnsafeForEach traverses in the same order before or after the commit of buffer.
94 lines
2.6 KiB
Go
94 lines
2.6 KiB
Go
// Copyright 2017 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package backend
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import (
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"bytes"
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"math"
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"sync"
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bolt "github.com/coreos/bbolt"
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)
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// safeRangeBucket is a hack to avoid inadvertently reading duplicate keys;
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// overwrites on a bucket should only fetch with limit=1, but safeRangeBucket
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// is known to never overwrite any key so range is safe.
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var safeRangeBucket = []byte("key")
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type ReadTx interface {
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Lock()
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Unlock()
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UnsafeRange(bucketName []byte, key, endKey []byte, limit int64) (keys [][]byte, vals [][]byte)
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UnsafeForEach(bucketName []byte, visitor func(k, v []byte) error) error
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}
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type readTx struct {
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// mu protects accesses to the txReadBuffer
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mu sync.RWMutex
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buf txReadBuffer
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// txmu protects accesses to the Tx on Range requests
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txmu sync.Mutex
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tx *bolt.Tx
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}
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func (rt *readTx) Lock() { rt.mu.RLock() }
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func (rt *readTx) Unlock() { rt.mu.RUnlock() }
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func (rt *readTx) UnsafeRange(bucketName, key, endKey []byte, limit int64) ([][]byte, [][]byte) {
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if endKey == nil {
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// forbid duplicates for single keys
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limit = 1
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}
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if limit <= 0 {
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limit = math.MaxInt64
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}
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if limit > 1 && !bytes.Equal(bucketName, safeRangeBucket) {
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panic("do not use unsafeRange on non-keys bucket")
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}
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keys, vals := rt.buf.Range(bucketName, key, endKey, limit)
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if int64(len(keys)) == limit {
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return keys, vals
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}
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// ignore error since bucket may have been created in this batch
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k2, v2, _ := unsafeRange(rt.tx, bucketName, key, endKey, limit-int64(len(keys)), &rt.txmu)
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return append(k2, keys...), append(v2, vals...)
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}
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func (rt *readTx) UnsafeForEach(bucketName []byte, visitor func(k, v []byte) error) error {
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dups := make(map[string]struct{})
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getDups := func(k, v []byte) error {
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dups[string(k)] = struct{}{}
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return nil
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}
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visitNoDup := func(k, v []byte) error {
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if _, ok := dups[string(k)]; ok {
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return nil
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}
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return visitor(k, v)
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}
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if err := rt.buf.ForEach(bucketName, getDups); err != nil {
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return err
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}
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rt.txmu.Lock()
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err := unsafeForEach(rt.tx, bucketName, visitNoDup)
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rt.txmu.Unlock()
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if err != nil {
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return err
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}
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return rt.buf.ForEach(bucketName, visitor)
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}
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