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state_delta_iterator.go
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/
state_delta_iterator.go
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/*
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you 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 statemgmt
// StateDeltaIterator - An iterator implementation over state-delta
type StateDeltaIterator struct {
updates map[string]*UpdatedValue
relevantKeys []string
currentKeyIndex int
done bool
}
// NewStateDeltaRangeScanIterator - return an iterator for performing a range scan over a state-delta object
func NewStateDeltaRangeScanIterator(delta *StateDelta, chaincodeID string, startKey string, endKey string) *StateDeltaIterator {
updates := delta.GetUpdates(chaincodeID)
return &StateDeltaIterator{updates, retrieveRelevantKeys(updates, startKey, endKey), -1, false}
}
func retrieveRelevantKeys(updates map[string]*UpdatedValue, startKey string, endKey string) []string {
relevantKeys := []string{}
if updates == nil {
return relevantKeys
}
for k, v := range updates {
if k >= startKey && (endKey == "" || k <= endKey) && !v.IsDelete() {
relevantKeys = append(relevantKeys, k)
}
}
return relevantKeys
}
// Next - see interface 'RangeScanIterator' for details
func (itr *StateDeltaIterator) Next() bool {
itr.currentKeyIndex++
if itr.currentKeyIndex < len(itr.relevantKeys) {
return true
}
itr.currentKeyIndex--
itr.done = true
return false
}
// GetKeyValue - see interface 'RangeScanIterator' for details
func (itr *StateDeltaIterator) GetKeyValue() (string, []byte) {
if itr.done {
logger.Warning("Iterator used after it has been exhausted. Last retrieved value will be returned")
}
key := itr.relevantKeys[itr.currentKeyIndex]
value := itr.updates[key].GetValue()
return key, value
}
// Close - see interface 'RangeScanIterator' for details
func (itr *StateDeltaIterator) Close() {
}
// ContainsKey - checks wether the given key is present in the state-delta
func (itr *StateDeltaIterator) ContainsKey(key string) bool {
_, ok := itr.updates[key]
return ok
}