github.com/slspeek/camlistore_namedsearch@v0.0.0-20140519202248-ed6f70f7721a/pkg/sorted/mysql/mysqlkv.go (about)

     1  /*
     2  Copyright 2011 The Camlistore Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8       http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  // Package mysql provides an implementation of sorted.KeyValue
    18  // on top of MySQL.
    19  package mysql
    20  
    21  import (
    22  	"database/sql"
    23  	"fmt"
    24  	"os"
    25  	"strings"
    26  
    27  	"camlistore.org/pkg/jsonconfig"
    28  	"camlistore.org/pkg/sorted"
    29  	"camlistore.org/pkg/sorted/sqlkv"
    30  
    31  	_ "camlistore.org/third_party/github.com/go-sql-driver/mysql"
    32  )
    33  
    34  func init() {
    35  	sorted.RegisterKeyValue("mysql", newKeyValueFromJSONConfig)
    36  }
    37  
    38  func newKeyValueFromJSONConfig(cfg jsonconfig.Obj) (sorted.KeyValue, error) {
    39  	host := cfg.OptionalString("host", "")
    40  	dsn := fmt.Sprintf("%s:%s@/%s",
    41  		cfg.RequiredString("user"),
    42  		cfg.OptionalString("password", ""),
    43  		cfg.RequiredString("database"),
    44  	)
    45  	if err := cfg.Validate(); err != nil {
    46  		return nil, err
    47  	}
    48  	if host != "" {
    49  		// TODO(mpl): document that somewhere
    50  		if !strings.Contains(host, ":") {
    51  			host = host + ":3306"
    52  		}
    53  		dsn = strings.Replace(dsn, "@", fmt.Sprintf("@tcp(%v)", host), 1)
    54  	}
    55  
    56  	db, err := sql.Open("mysql", dsn)
    57  	if err != nil {
    58  		return nil, err
    59  	}
    60  	for _, tableSql := range SQLCreateTables() {
    61  		if _, err := db.Exec(tableSql); err != nil {
    62  			return nil, fmt.Errorf("error creating table with %q: %v", tableSql, err)
    63  		}
    64  	}
    65  	if _, err := db.Exec(fmt.Sprintf(`REPLACE INTO meta VALUES ('version', '%d')`, SchemaVersion())); err != nil {
    66  		return nil, fmt.Errorf("error setting schema version: %v", err)
    67  	}
    68  
    69  	kv := &keyValue{
    70  		db: db,
    71  		KeyValue: &sqlkv.KeyValue{
    72  			DB: db,
    73  		},
    74  	}
    75  	if err := kv.ping(); err != nil {
    76  		return nil, fmt.Errorf("MySQL db unreachable: %v", err)
    77  	}
    78  	version, err := kv.SchemaVersion()
    79  	if err != nil {
    80  		return nil, fmt.Errorf("error getting schema version (need to init database?): %v", err)
    81  	}
    82  	if version != requiredSchemaVersion {
    83  		if version == 20 && requiredSchemaVersion == 21 {
    84  			fmt.Fprintf(os.Stderr, fixSchema20to21)
    85  		}
    86  		if os.Getenv("CAMLI_DEV_CAMLI_ROOT") != "" {
    87  			// Good signal that we're using the devcam server, so help out
    88  			// the user with a more useful tip:
    89  			return nil, fmt.Errorf("database schema version is %d; expect %d (run \"devcam server --wipe\" to wipe both your blobs and re-populate the database schema)", version, requiredSchemaVersion)
    90  		}
    91  		return nil, fmt.Errorf("database schema version is %d; expect %d (need to re-init/upgrade database?)",
    92  			version, requiredSchemaVersion)
    93  	}
    94  
    95  	return kv, nil
    96  }
    97  
    98  type keyValue struct {
    99  	*sqlkv.KeyValue
   100  
   101  	db *sql.DB
   102  }
   103  
   104  func (kv *keyValue) ping() error {
   105  	// TODO(bradfitz): something more efficient here?
   106  	_, err := kv.SchemaVersion()
   107  	return err
   108  }
   109  
   110  func (kv *keyValue) SchemaVersion() (version int, err error) {
   111  	err = kv.db.QueryRow("SELECT value FROM meta WHERE metakey='version'").Scan(&version)
   112  	return
   113  }
   114  
   115  const fixSchema20to21 = `Character set in tables changed to binary, you can fix your tables with:
   116  ALTER TABLE rows CONVERT TO CHARACTER SET binary;
   117  ALTER TABLE meta CONVERT TO CHARACTER SET binary;
   118  UPDATE meta SET value=21 WHERE metakey='version' AND value=20;
   119  `