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73 lines
1.3 KiB
73 lines
1.3 KiB
package nodb
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import (
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"errors"
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"fmt"
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)
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var (
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ErrNestMulti = errors.New("nest multi not supported")
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ErrMultiDone = errors.New("multi has been closed")
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)
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type Multi struct {
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*DB
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}
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func (db *DB) IsInMulti() bool {
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return db.status == DBInMulti
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}
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// begin a mutli to execute commands,
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// it will block any other write operations before you close the multi, unlike transaction, mutli can not rollback
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func (db *DB) Multi() (*Multi, error) {
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if db.IsInMulti() {
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return nil, ErrNestMulti
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}
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m := new(Multi)
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m.DB = new(DB)
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m.DB.status = DBInMulti
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m.DB.l = db.l
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m.l.wLock.Lock()
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m.DB.sdb = db.sdb
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m.DB.bucket = db.sdb
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m.DB.index = db.index
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m.DB.kvBatch = m.newBatch()
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m.DB.listBatch = m.newBatch()
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m.DB.hashBatch = m.newBatch()
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m.DB.zsetBatch = m.newBatch()
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m.DB.binBatch = m.newBatch()
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m.DB.setBatch = m.newBatch()
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return m, nil
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}
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func (m *Multi) newBatch() *batch {
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return m.l.newBatch(m.bucket.NewWriteBatch(), &multiBatchLocker{}, nil)
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}
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func (m *Multi) Close() error {
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if m.bucket == nil {
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return ErrMultiDone
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}
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m.l.wLock.Unlock()
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m.bucket = nil
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return nil
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}
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func (m *Multi) Select(index int) error {
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if index < 0 || index >= int(MaxDBNumber) {
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return fmt.Errorf("invalid db index %d", index)
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}
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m.DB.index = uint8(index)
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return nil
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}
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