github.com/slspeek/camlistore_namedsearch@v0.0.0-20140519202248-ed6f70f7721a/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  	if !compiled {
    38  		return nil, ErrNotCompiled
    39  	}
    40  
    41  	file := cfg.RequiredString("file")
    42  	if err := cfg.Validate(); err != nil {
    43  		return nil, err
    44  	}
    45  
    46  	fi, err := os.Stat(file)
    47  	if os.IsNotExist(err) || (err == nil && fi.Size() == 0) {
    48  		if err := initDB(file); err != nil {
    49  			return nil, fmt.Errorf("could not initialize sqlite DB at %s: %v", file, err)
    50  		}
    51  	}
    52  	db, err := sql.Open("sqlite3", file)
    53  	if err != nil {
    54  		return nil, err
    55  	}
    56  	kv := &keyValue{
    57  		file: file,
    58  		db:   db,
    59  		KeyValue: &sqlkv.KeyValue{
    60  			DB:     db,
    61  			Serial: true,
    62  		},
    63  	}
    64  
    65  	version, err := kv.SchemaVersion()
    66  	if err != nil {
    67  		return nil, fmt.Errorf("error getting schema version (need to init database with 'camtool dbinit %s'?): %v", file, err)
    68  	}
    69  
    70  	if err := kv.ping(); err != nil {
    71  		return nil, err
    72  	}
    73  
    74  	if version != requiredSchemaVersion {
    75  		if os.Getenv("CAMLI_DEV_CAMLI_ROOT") != "" {
    76  			// Good signal that we're using the devcam server, so help out
    77  			// the user with a more useful tip:
    78  			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)
    79  		}
    80  		return nil, fmt.Errorf("database schema version is %d; expect %d (need to re-init/upgrade database?)",
    81  			version, requiredSchemaVersion)
    82  	}
    83  
    84  	return kv, nil
    85  
    86  }
    87  
    88  type keyValue struct {
    89  	*sqlkv.KeyValue
    90  
    91  	file string
    92  	db   *sql.DB
    93  }
    94  
    95  var compiled = false
    96  
    97  // CompiledIn returns whether SQLite support is compiled in.
    98  // If it returns false, the build tag "with_sqlite" was not specified.
    99  func CompiledIn() bool {
   100  	return compiled
   101  }
   102  
   103  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())
   104  
   105  func compileHint() string {
   106  	if _, err := os.Stat("/etc/apt"); err == nil {
   107  		return " (Hint: apt-get install libsqlite3-dev)"
   108  	}
   109  	return ""
   110  }
   111  
   112  func (kv *keyValue) ping() error {
   113  	// TODO(bradfitz): something more efficient here?
   114  	_, err := kv.SchemaVersion()
   115  	return err
   116  }
   117  
   118  func (kv *keyValue) SchemaVersion() (version int, err error) {
   119  	err = kv.db.QueryRow("SELECT value FROM meta WHERE metakey='version'").Scan(&version)
   120  	return
   121  }