82 lines
2.1 KiB
Go
82 lines
2.1 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 meta
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import (
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"fmt"
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"github.com/juju/errors"
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"github.com/ngaut/log"
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"github.com/pingcap/tidb/kv"
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)
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const (
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// SchemaMetaPrefix is the prefix for database meta key prefix.
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SchemaMetaPrefix = "mDB:"
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// TableMetaPrefix is the prefix for table meta key prefix.
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TableMetaPrefix = "mTable:"
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)
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var (
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nextGlobalIDPrefix = []byte("mNextGlobalID")
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// SchemaMetaVersionKey is used as lock for changing schema
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SchemaMetaVersionKey = []byte("mSchemaVersion")
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)
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// GenID adds step to the value for key and returns the sum.
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func GenID(txn kv.Transaction, key []byte, step int) (int64, error) {
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if len(key) == 0 {
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return 0, errors.New("Invalid key")
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}
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err := txn.LockKeys(key)
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if err != nil {
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return 0, err
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}
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id, err := txn.Inc(key, int64(step))
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if err != nil {
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return 0, errors.Trace(err)
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}
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return id, errors.Trace(err)
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}
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// DBMetaKey generates database meta key according to databaseID.
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func DBMetaKey(databaseID int64) string {
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return fmt.Sprintf("%s:%d", SchemaMetaPrefix, databaseID)
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}
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// AutoIDKey generates table autoID meta key according to tableID.
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func AutoIDKey(tableID int64) string {
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if tableID == 0 {
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log.Error("Invalid tableID")
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}
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return fmt.Sprintf("%s:%d_autoID", TableMetaPrefix, tableID)
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}
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// GenGlobalID generates the next id in the store scope.
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func GenGlobalID(store kv.Storage) (ID int64, err error) {
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err = kv.RunInNewTxn(store, true, func(txn kv.Transaction) error {
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ID, err = GenID(txn, []byte(nextGlobalIDPrefix), 1)
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if err != nil {
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return errors.Trace(err)
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}
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log.Info("Generate global id", ID)
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return nil
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})
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return
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}
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