[VOL-4291] Rw-core updates for gRPC migration
Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
diff --git a/vendor/github.com/coreos/etcd/mvcc/backend/read_tx.go b/vendor/github.com/coreos/etcd/mvcc/backend/read_tx.go
new file mode 100644
index 0000000..0536de7
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/mvcc/backend/read_tx.go
@@ -0,0 +1,120 @@
+// Copyright 2017 The etcd Authors
+//
+// 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 backend
+
+import (
+ "bytes"
+ "math"
+ "sync"
+
+ bolt "github.com/coreos/bbolt"
+)
+
+// safeRangeBucket is a hack to avoid inadvertently reading duplicate keys;
+// overwrites on a bucket should only fetch with limit=1, but safeRangeBucket
+// is known to never overwrite any key so range is safe.
+var safeRangeBucket = []byte("key")
+
+type ReadTx interface {
+ Lock()
+ Unlock()
+
+ UnsafeRange(bucketName []byte, key, endKey []byte, limit int64) (keys [][]byte, vals [][]byte)
+ UnsafeForEach(bucketName []byte, visitor func(k, v []byte) error) error
+}
+
+type readTx struct {
+ // mu protects accesses to the txReadBuffer
+ mu sync.RWMutex
+ buf txReadBuffer
+
+ // txmu protects accesses to buckets and tx on Range requests.
+ txmu sync.RWMutex
+ tx *bolt.Tx
+ buckets map[string]*bolt.Bucket
+}
+
+func (rt *readTx) Lock() { rt.mu.RLock() }
+func (rt *readTx) Unlock() { rt.mu.RUnlock() }
+
+func (rt *readTx) UnsafeRange(bucketName, key, endKey []byte, limit int64) ([][]byte, [][]byte) {
+ if endKey == nil {
+ // forbid duplicates for single keys
+ limit = 1
+ }
+ if limit <= 0 {
+ limit = math.MaxInt64
+ }
+ if limit > 1 && !bytes.Equal(bucketName, safeRangeBucket) {
+ panic("do not use unsafeRange on non-keys bucket")
+ }
+ keys, vals := rt.buf.Range(bucketName, key, endKey, limit)
+ if int64(len(keys)) == limit {
+ return keys, vals
+ }
+
+ // find/cache bucket
+ bn := string(bucketName)
+ rt.txmu.RLock()
+ bucket, ok := rt.buckets[bn]
+ rt.txmu.RUnlock()
+ if !ok {
+ rt.txmu.Lock()
+ bucket = rt.tx.Bucket(bucketName)
+ rt.buckets[bn] = bucket
+ rt.txmu.Unlock()
+ }
+
+ // ignore missing bucket since may have been created in this batch
+ if bucket == nil {
+ return keys, vals
+ }
+ rt.txmu.Lock()
+ c := bucket.Cursor()
+ rt.txmu.Unlock()
+
+ k2, v2 := unsafeRange(c, key, endKey, limit-int64(len(keys)))
+ return append(k2, keys...), append(v2, vals...)
+}
+
+func (rt *readTx) UnsafeForEach(bucketName []byte, visitor func(k, v []byte) error) error {
+ dups := make(map[string]struct{})
+ getDups := func(k, v []byte) error {
+ dups[string(k)] = struct{}{}
+ return nil
+ }
+ visitNoDup := func(k, v []byte) error {
+ if _, ok := dups[string(k)]; ok {
+ return nil
+ }
+ return visitor(k, v)
+ }
+ if err := rt.buf.ForEach(bucketName, getDups); err != nil {
+ return err
+ }
+ rt.txmu.Lock()
+ err := unsafeForEach(rt.tx, bucketName, visitNoDup)
+ rt.txmu.Unlock()
+ if err != nil {
+ return err
+ }
+ return rt.buf.ForEach(bucketName, visitor)
+}
+
+func (rt *readTx) reset() {
+ rt.buf.reset()
+ rt.buckets = make(map[string]*bolt.Bucket)
+ rt.tx = nil
+}