b6a95a8cb3
* Dropped unused codekit config * Integrated dynamic and static bindata for public * Ignore public bindata * Add a general generate make task * Integrated flexible public assets into web command * Updated vendoring, added all missiong govendor deps * Made the linter happy with the bindata and dynamic code * Moved public bindata definition to modules directory * Ignoring the new bindata path now * Updated to the new public modules import path * Updated public bindata command and drop the new prefix
93 lines
2.4 KiB
Go
93 lines
2.4 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 kv
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import (
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"github.com/juju/errors"
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)
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// BufferStore wraps a Retriever for read and a MemBuffer for buffered write.
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// Common usage pattern:
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// bs := NewBufferStore(r) // use BufferStore to wrap a Retriever
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// defer bs.Release() // make sure it will be released
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// // ...
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// // read/write on bs
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// // ...
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// bs.SaveTo(m) // save above operations to a Mutator
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type BufferStore struct {
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MemBuffer
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r Retriever
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}
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// NewBufferStore creates a BufferStore using r for read.
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func NewBufferStore(r Retriever) *BufferStore {
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return &BufferStore{
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r: r,
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MemBuffer: &lazyMemBuffer{},
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}
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}
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// Get implements the Retriever interface.
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func (s *BufferStore) Get(k Key) ([]byte, error) {
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val, err := s.MemBuffer.Get(k)
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if IsErrNotFound(err) {
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val, err = s.r.Get(k)
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}
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if err != nil {
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return nil, errors.Trace(err)
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}
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if len(val) == 0 {
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return nil, errors.Trace(ErrNotExist)
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}
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return val, nil
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}
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// Seek implements the Retriever interface.
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func (s *BufferStore) Seek(k Key) (Iterator, error) {
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bufferIt, err := s.MemBuffer.Seek(k)
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if err != nil {
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return nil, errors.Trace(err)
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}
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retrieverIt, err := s.r.Seek(k)
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if err != nil {
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return nil, errors.Trace(err)
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}
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return newUnionIter(bufferIt, retrieverIt), nil
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}
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// WalkBuffer iterates all buffered kv pairs.
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func (s *BufferStore) WalkBuffer(f func(k Key, v []byte) error) error {
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iter, err := s.MemBuffer.Seek(nil)
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if err != nil {
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return errors.Trace(err)
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}
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defer iter.Close()
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for ; iter.Valid(); iter.Next() {
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if err := f(iter.Key(), iter.Value()); err != nil {
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return errors.Trace(err)
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}
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}
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return nil
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}
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// SaveTo saves all buffered kv pairs into a Mutator.
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func (s *BufferStore) SaveTo(m Mutator) error {
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err := s.WalkBuffer(func(k Key, v []byte) error {
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if len(v) == 0 {
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return errors.Trace(m.Delete(k))
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}
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return errors.Trace(m.Set(k, v))
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})
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return errors.Trace(err)
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}
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