11a44a94b1
The etcd cursor Delete stepped to the next item in the range before Delete to not invalidate the iteation. This is unnecessary and not compatible with bbolt, resulting in an extra fetch too.
127 lines
3.0 KiB
Go
127 lines
3.0 KiB
Go
// +build kvdb_etcd
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package etcd
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// readWriteCursor holds a reference to the cursors bucket, the value
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// prefix and the current key used while iterating.
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type readWriteCursor struct {
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// bucket holds the reference to the parent bucket.
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bucket *readWriteBucket
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// prefix holds the value prefix which is in front of each
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// value key in the bucket.
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prefix string
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// currKey holds the current key of the cursor.
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currKey string
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}
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func newReadWriteCursor(bucket *readWriteBucket) *readWriteCursor {
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return &readWriteCursor{
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bucket: bucket,
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prefix: string(bucket.id),
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}
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}
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// First positions the cursor at the first key/value pair and returns
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// the pair.
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func (c *readWriteCursor) First() (key, value []byte) {
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// Get the first key with the value prefix.
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kv, err := c.bucket.tx.stm.First(c.prefix)
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if err != nil {
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// TODO: revise this once kvdb interface supports errors
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return nil, nil
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}
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if kv != nil {
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c.currKey = kv.key
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return getKeyVal(kv)
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}
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return nil, nil
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}
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// Last positions the cursor at the last key/value pair and returns the
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// pair.
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func (c *readWriteCursor) Last() (key, value []byte) {
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kv, err := c.bucket.tx.stm.Last(c.prefix)
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if err != nil {
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// TODO: revise this once kvdb interface supports errors
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return nil, nil
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}
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if kv != nil {
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c.currKey = kv.key
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return getKeyVal(kv)
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}
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return nil, nil
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}
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// Next moves the cursor one key/value pair forward and returns the new
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// pair.
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func (c *readWriteCursor) Next() (key, value []byte) {
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kv, err := c.bucket.tx.stm.Next(c.prefix, c.currKey)
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if err != nil {
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// TODO: revise this once kvdb interface supports errors
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return nil, nil
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}
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if kv != nil {
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c.currKey = kv.key
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return getKeyVal(kv)
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}
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return nil, nil
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}
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// Prev moves the cursor one key/value pair backward and returns the new
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// pair.
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func (c *readWriteCursor) Prev() (key, value []byte) {
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kv, err := c.bucket.tx.stm.Prev(c.prefix, c.currKey)
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if err != nil {
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// TODO: revise this once kvdb interface supports errors
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return nil, nil
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}
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if kv != nil {
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c.currKey = kv.key
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return getKeyVal(kv)
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}
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return nil, nil
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}
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// Seek positions the cursor at the passed seek key. If the key does
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// not exist, the cursor is moved to the next key after seek. Returns
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// the new pair.
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func (c *readWriteCursor) Seek(seek []byte) (key, value []byte) {
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// Seek to the first key with prefix + seek. If that key is not present
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// STM will seek to the next matching key with prefix.
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kv, err := c.bucket.tx.stm.Seek(c.prefix, c.prefix+string(seek))
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if err != nil {
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// TODO: revise this once kvdb interface supports errors
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return nil, nil
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}
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if kv != nil {
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c.currKey = kv.key
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return getKeyVal(kv)
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}
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return nil, nil
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}
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// Delete removes the current key/value pair the cursor is at without
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// invalidating the cursor. Returns ErrIncompatibleValue if attempted
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// when the cursor points to a nested bucket.
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func (c *readWriteCursor) Delete() error {
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if isBucketKey(c.currKey) {
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c.bucket.DeleteNestedBucket(getKey(c.currKey))
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} else {
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c.bucket.Delete(getKey(c.currKey))
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}
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return nil
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}
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