go.temporal.io/server@v1.23.0/common/persistence/cassandra/schema_version_reader.go (about)

     1  // The MIT License
     2  //
     3  // Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
     4  //
     5  // Copyright (c) 2020 Uber Technologies, Inc.
     6  //
     7  // Permission is hereby granted, free of charge, to any person obtaining a copy
     8  // of this software and associated documentation files (the "Software"), to deal
     9  // in the Software without restriction, including without limitation the rights
    10  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    11  // copies of the Software, and to permit persons to whom the Software is
    12  // furnished to do so, subject to the following conditions:
    13  //
    14  // The above copyright notice and this permission notice shall be included in
    15  // all copies or substantial portions of the Software.
    16  //
    17  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    18  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    19  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    20  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    21  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    22  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    23  // THE SOFTWARE.
    24  
    25  package cassandra
    26  
    27  import (
    28  	"fmt"
    29  
    30  	"go.temporal.io/server/common/persistence/nosql/nosqlplugin/cassandra/gocql"
    31  )
    32  
    33  const (
    34  	readSchemaVersionCQL = `SELECT curr_version from schema_version where keyspace_name=?`
    35  )
    36  
    37  type (
    38  	SchemaVersionReader struct {
    39  		session gocql.Session
    40  	}
    41  )
    42  
    43  func NewSchemaVersionReader(session gocql.Session) *SchemaVersionReader {
    44  	return &SchemaVersionReader{
    45  		session: session,
    46  	}
    47  }
    48  
    49  // ReadSchemaVersion returns the current schema version for the Keyspace
    50  func (svr *SchemaVersionReader) ReadSchemaVersion(keyspace string) (string, error) {
    51  	query := svr.session.Query(readSchemaVersionCQL, keyspace)
    52  
    53  	iter := query.Iter()
    54  	var version string
    55  	success := iter.Scan(&version)
    56  	err := iter.Close()
    57  	if err == nil && !success {
    58  		err = fmt.Errorf("no schema version found for keyspace %q", keyspace)
    59  	}
    60  	if err != nil {
    61  		return "", fmt.Errorf("unable to get current schema version from Cassandra: %w", err)
    62  	}
    63  
    64  	return version, nil
    65  }