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b2e4c88b80
The LevelDB storage types return an interface type now that wraps around the underlying iterator. This both enhances testability but improves upon, in my opinion, the interface design for the LevelDB iterator. Secondarily, the resource reaping behaviors for the LevelDB iterators have been improved by dropping the externalized io.Closer object. Finally, the iterator provisioning methods provide the option for indicating whether one wants a snapshotted iterator or not.
42 lines
1.7 KiB
Go
42 lines
1.7 KiB
Go
// Copyright 2013 Prometheus Team
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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 leveldb
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// TODO: Evaluate whether to use coding.Encoder for the key and values instead
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// raw bytes for consistency reasons.
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// Iterator wraps Levigo and LevelDB's iterator behaviors in a manner that is
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// conducive to IO-free testing.
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//
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// It borrows some of the operational assumptions from goskiplist, which
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// functions very similarly, in that it uses no separate Valid method to
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// determine health. All methods that have a return signature of (ok bool)
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// assume in the real LevelDB case that if ok == false that the iterator
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// must be disposed of at this given instance and recreated if future
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// work is desired. This is a quirk of LevelDB itself!
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type Iterator interface {
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// GetError reports low-level errors, if available. This should not indicate
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// that the iterator is necessarily unhealthy but maybe that the underlying
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// table is corrupted itself. See the notes above for (ok bool) return
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// signatures to determine iterator health.
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GetError() error
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Key() []byte
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Next() (ok bool)
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Previous() (ok bool)
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Seek(key []byte) (ok bool)
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SeekToFirst() (ok bool)
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SeekToLast() (ok bool)
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Value() []byte
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}
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