github.com/olivere/camlistore@v0.0.0-20140121221811-1b7ac2da0199/pkg/sorted/sqlite/sqlitekv.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 sqlite provides an implementation of sorted.KeyValue
    18  // using an SQLite database file.
    19  package sqlite
    20  
    21  import (
    22  	"database/sql"
    23  	"errors"
    24  	"fmt"
    25  	"os"
    26  
    27  	"camlistore.org/pkg/jsonconfig"
    28  	"camlistore.org/pkg/sorted"
    29  	"camlistore.org/pkg/sorted/sqlkv"
    30  )
    31  
    32  func init() {
    33  	sorted.RegisterKeyValue("sqlite", newKeyValueFromConfig)
    34  }
    35  
    36  func newKeyValueFromConfig(cfg jsonconfig.Obj) (sorted.KeyValue, error) {
    37  	file := cfg.RequiredString("file")
    38  	if err := cfg.Validate(); err != nil {
    39  		return nil, err
    40  	}
    41  	return NewKeyValue(file)
    42  }
    43  
    44  // NewKeyValue returns a KeyValue implementation on top of
    45  // an SQLite database file.
    46  func NewKeyValue(file string) (sorted.KeyValue, error) {
    47  	if !compiled {
    48  		return nil, ErrNotCompiled
    49  	}
    50  
    51  	fi, err := os.Stat(file)
    52  	if os.IsNotExist(err) || (err == nil && fi.Size() == 0) {
    53  		return nil, fmt.Errorf(`You need to initialize your SQLite database with: camtool dbinit --dbname=%s --dbtype=sqlite`, file)
    54  	}
    55  	db, err := sql.Open("sqlite3", file)
    56  	if err != nil {
    57  		return nil, err
    58  	}
    59  	kv := &keyValue{
    60  		file: file,
    61  		db:   db,
    62  		KeyValue: &sqlkv.KeyValue{
    63  			DB:     db,
    64  			Serial: true,
    65  		},
    66  	}
    67  
    68  	version, err := kv.SchemaVersion()
    69  	if err != nil {
    70  		return nil, fmt.Errorf("error getting schema version (need to init database with 'camtool dbinit %s'?): %v", file, err)
    71  	}
    72  
    73  	if err := kv.ping(); err != nil {
    74  		return nil, err
    75  	}
    76  
    77  	if version != requiredSchemaVersion {
    78  		if os.Getenv("CAMLI_DEV_CAMLI_ROOT") != "" {
    79  			// Good signal that we're using the devcam server, so help out
    80  			// the user with a more useful tip:
    81  			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)
    82  		}
    83  		return nil, fmt.Errorf("database schema version is %d; expect %d (need to re-init/upgrade database?)",
    84  			version, requiredSchemaVersion)
    85  	}
    86  
    87  	return kv, nil
    88  
    89  }
    90  
    91  type keyValue struct {
    92  	*sqlkv.KeyValue
    93  
    94  	file string
    95  	db   *sql.DB
    96  }
    97  
    98  var compiled = false
    99  
   100  // CompiledIn returns whether SQLite support is compiled in.
   101  // If it returns false, the build tag "with_sqlite" was not specified.
   102  func CompiledIn() bool {
   103  	return compiled
   104  }
   105  
   106  var ErrNotCompiled = errors.New("camlistored was not built with SQLite support. If you built with make.go, use go run make.go --sqlite=true. If you used go get or get install, use go {get,install} --tags=with_sqlite" + compileHint())
   107  
   108  func compileHint() string {
   109  	if _, err := os.Stat("/etc/apt"); err == nil {
   110  		return " (Hint: apt-get install libsqlite3-dev)"
   111  	}
   112  	return ""
   113  }
   114  
   115  func (kv *keyValue) ping() error {
   116  	// TODO(bradfitz): something more efficient here?
   117  	_, err := kv.SchemaVersion()
   118  	return err
   119  }
   120  
   121  func (kv *keyValue) SchemaVersion() (version int, err error) {
   122  	err = kv.db.QueryRow("SELECT value FROM meta WHERE metakey='version'").Scan(&version)
   123  	return
   124  }