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

     1  /*
     2  Copyright 2012 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 postgres provides an implementation of sorted.KeyValue
    18  // on top of PostgreSQL.
    19  package postgres
    20  
    21  import (
    22  	"database/sql"
    23  	"fmt"
    24  	"os"
    25  	"regexp"
    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/lib/pq"
    32  )
    33  
    34  func init() {
    35  	sorted.RegisterKeyValue("postgres", newKeyValueFromJSONConfig)
    36  }
    37  
    38  func newKeyValueFromJSONConfig(cfg jsonconfig.Obj) (sorted.KeyValue, error) {
    39  	conninfo := fmt.Sprintf("user=%s dbname=%s host=%s password=%s sslmode=%s",
    40  		cfg.RequiredString("user"),
    41  		cfg.RequiredString("database"),
    42  		cfg.OptionalString("host", "localhost"),
    43  		cfg.OptionalString("password", ""),
    44  		cfg.OptionalString("sslmode", "require"),
    45  	)
    46  	if err := cfg.Validate(); err != nil {
    47  		return nil, err
    48  	}
    49  	db, err := sql.Open("postgres", conninfo)
    50  	if err != nil {
    51  		return nil, err
    52  	}
    53  	for _, tableSql := range SQLCreateTables() {
    54  		if _, err := db.Exec(tableSql); err != nil {
    55  			return nil, fmt.Errorf("error creating table with %q: %v", tableSql, err)
    56  		}
    57  	}
    58  	for _, statement := range SQLDefineReplace() {
    59  		if _, err := db.Exec(statement); err != nil {
    60  			return nil, fmt.Errorf("error setting up replace statement with %q: %v", statement, err)
    61  		}
    62  	}
    63  	r, err := db.Query(fmt.Sprintf(`SELECT replaceintometa('version', '%d')`, SchemaVersion()))
    64  	if err != nil {
    65  		return nil, fmt.Errorf("error setting schema version: %v", err)
    66  	}
    67  	r.Close()
    68  
    69  	kv := &keyValue{
    70  		db: db,
    71  		KeyValue: &sqlkv.KeyValue{
    72  			DB:              db,
    73  			SetFunc:         altSet,
    74  			BatchSetFunc:    altBatchSet,
    75  			PlaceHolderFunc: replacePlaceHolders,
    76  		},
    77  	}
    78  	if err := kv.ping(); err != nil {
    79  		return nil, fmt.Errorf("PostgreSQL db unreachable: %v", err)
    80  	}
    81  	version, err := kv.SchemaVersion()
    82  	if err != nil {
    83  		return nil, fmt.Errorf("error getting schema version (need to init database?): %v", err)
    84  	}
    85  	if version != requiredSchemaVersion {
    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  	db *sql.DB
   101  }
   102  
   103  // postgres does not have REPLACE INTO (upsert), so we use that custom
   104  // one for Set operations instead
   105  func altSet(db *sql.DB, key, value string) error {
   106  	r, err := db.Query("SELECT replaceinto($1, $2)", key, value)
   107  	if err != nil {
   108  		return err
   109  	}
   110  	return r.Close()
   111  }
   112  
   113  // postgres does not have REPLACE INTO (upsert), so we use that custom
   114  // one for Set operations in batch instead
   115  func altBatchSet(tx *sql.Tx, key, value string) error {
   116  	r, err := tx.Query("SELECT replaceinto($1, $2)", key, value)
   117  	if err != nil {
   118  		return err
   119  	}
   120  	return r.Close()
   121  }
   122  
   123  var qmark = regexp.MustCompile(`\?`)
   124  
   125  // replace all ? placeholders into the corresponding $n in queries
   126  var replacePlaceHolders = func(query string) string {
   127  	i := 0
   128  	dollarInc := func(b []byte) []byte {
   129  		i++
   130  		return []byte(fmt.Sprintf("$%d", i))
   131  	}
   132  	return string(qmark.ReplaceAllFunc([]byte(query), dollarInc))
   133  }
   134  
   135  func (kv *keyValue) ping() error {
   136  	_, err := kv.SchemaVersion()
   137  	return err
   138  }
   139  
   140  func (kv *keyValue) SchemaVersion() (version int, err error) {
   141  	err = kv.db.QueryRow("SELECT value FROM meta WHERE metakey='version'").Scan(&version)
   142  	return
   143  }