61 lines
2.0 KiB
Go
61 lines
2.0 KiB
Go
// Copyright 2015 PingCAP, Inc.
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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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// See the License for the specific language governing permissions and
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// limitations under the License.
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package engine
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import "github.com/juju/errors"
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// ErrNotFound indicates no key is found when trying Get or Seek an entry from DB.
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var ErrNotFound = errors.New("local engine: key not found")
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// Driver is the interface that must be implemented by a local storage db engine.
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type Driver interface {
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// Open opens or creates a local storage DB.
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// The schema is a string for a local storage DB specific format.
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Open(schema string) (DB, error)
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}
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// MSeekResult is used to get multiple seek results.
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type MSeekResult struct {
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Key []byte
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Value []byte
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Err error
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}
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// DB is the interface for local storage.
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type DB interface {
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// Get gets the associated value with key, returns (nil, ErrNotFound) if no value found.
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Get(key []byte) ([]byte, error)
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// Seek searches for the first key in the engine which is >= key in byte order, returns (nil, nil, ErrNotFound)
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// if such key is not found.
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Seek(key []byte) ([]byte, []byte, error)
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// MultiSeek seeks multiple keys from the engine.
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MultiSeek(keys [][]byte) []*MSeekResult
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// NewBatch creates a Batch for writing.
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NewBatch() Batch
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// Commit writes the changed data in Batch.
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Commit(b Batch) error
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// Close closes database.
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Close() error
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}
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// Batch is the interface for local storage.
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type Batch interface {
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// Put appends 'put operation' of the key/value to the batch.
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Put(key []byte, value []byte)
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// Delete appends 'delete operation' of the key/value to the batch.
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Delete(key []byte)
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// Len return length of the batch
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Len() int
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}
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