refactored database package structure

database/database.go

@@ -0,0 +1,38 @@
+package database
+
+import (
+	"goposm/mapping"
+)
+
+type Config struct {
+	Type             string
+	ConnectionParams string
+	Srid             int
+}
+
+type DB interface {
+	Init(*mapping.Mapping) error
+	InsertBatch(string, [][]interface{}) error
+}
+
+var databases map[string]func(Config) (DB, error)
+
+func Register(name string, f func(Config) (DB, error)) {
+	if databases == nil {
+		databases = make(map[string]func(Config) (DB, error))
+	}
+	databases[name] = f
+}
+
+func Open(conf Config) (DB, error) {
+	newFunc, ok := databases[conf.Type]
+	if !ok {
+		panic("unsupported database type: " + conf.Type)
+	}
+
+	db, err := newFunc(conf)
+	if err != nil {
+		return nil, err
+	}
+	return db, nil
+}

database/postgis/fields.go

@@ -1,4 +1,4 @@
-package db
+package postgis
 
 import (
 	"fmt"

database/postgis/postgis.go

@@ -1,27 +1,16 @@
-package db
+package postgis
 
 import (
 	"database/sql"
 	"errors"
 	"fmt"
 	"github.com/bmizerany/pq"
+	"goposm/database"
 	"goposm/mapping"
 	"log"
 	"strings"
 )
 
-type Config struct {
-	Type             string
-	ConnectionParams string
-	Srid             int
-	Schema           string
-}
-
-type DB interface {
-	Init(*mapping.Mapping) error
-	InsertBatch(string, [][]interface{}) error
-}
-
 type ColumnSpec struct {
 	Name string
 	Type ColumnType
@@ -78,7 +67,7 @@ func (spec *TableSpec) InsertSQL() string {
 	)
 }
 
-func NewTableSpec(conf *Config, t *mapping.Table, schema string) *TableSpec {
+func NewTableSpec(conf *database.Config, t *mapping.Table, schema string) *TableSpec {
 	spec := TableSpec{
 		Name:         t.Name,
 		Schema:       schema,
@@ -145,12 +134,12 @@ func (pg *PostGIS) createSchema() error {
 	var sql string
 	var err error
 
-	if pg.Config.Schema == "public" {
+	if pg.Schema == "public" {
 		return nil
 	}
 
 	sql = fmt.Sprintf("SELECT EXISTS(SELECT schema_name FROM information_schema.schemata WHERE schema_name = '%s');",
-		pg.Config.Schema)
+		pg.Schema)
 	row := pg.Db.QueryRow(sql)
 	var exists bool
 	err = row.Scan(&exists)
@@ -161,7 +150,7 @@ func (pg *PostGIS) createSchema() error {
 		return nil
 	}
 
-	sql = fmt.Sprintf("CREATE SCHEMA \"%s\"", pg.Config.Schema)
+	sql = fmt.Sprintf("CREATE SCHEMA \"%s\"", pg.Schema)
 	_, err = pg.Db.Exec(sql)
 	if err != nil {
 		return &SQLError{sql, err}
@@ -172,7 +161,7 @@ func (pg *PostGIS) createSchema() error {
 type PostGIS struct {
 	Db     *sql.DB
 	Schema string
-	Config Config
+	Config database.Config
 	Tables map[string]*TableSpec
 }
 
@@ -271,10 +260,7 @@ func (pg *PostGIS) Init(m *mapping.Mapping) error {
 	return nil
 }
 
-func Open(conf Config) (DB, error) {
-	if conf.Type != "postgres" {
-		panic("unsupported database type: " + conf.Type)
-	}
+func New(conf database.Config) (database.DB, error) {
 	db := &PostGIS{}
 	db.Tables = make(map[string]*TableSpec)
 	db.Config = conf
@@ -284,3 +270,8 @@ func Open(conf Config) (DB, error) {
 	}
 	return db, nil
 }
+
+func init() {
+	database.Register("postgres", New)
+	database.Register("postgis", New)
+}

goposm.go

@@ -3,7 +3,8 @@ package main
 import (
 	"flag"
 	"goposm/cache"
-	"goposm/db"
+	"goposm/database"
+	_ "goposm/database/postgis"
 	"goposm/element"
 	"goposm/geom"
 	"goposm/geom/geos"
@@ -249,13 +250,12 @@ func main() {
 		waitFill := sync.WaitGroup{}
 		wayChan := make(chan []element.Way)
 		waitDb := &sync.WaitGroup{}
-		conf := db.Config{
-			Type:             "postgres",
+		conf := database.Config{
+			Type:             "postgis",
 			ConnectionParams: *connection,
 			Srid:             3857,
-			Schema:           "public",
 		}
-		pg, err := db.Open(conf)
+		pg, err := database.Open(conf)
 		if err != nil {
 			log.Fatal(err)
 		}

writer/writer.go

@@ -1,13 +1,13 @@
 package writer
 
 import (
-	"goposm/db"
+	"goposm/database"
 	"log"
 )
 
 const batchSize = 1024
 
-func DBWriter(db db.DB, in chan InsertBatch) {
+func DBWriter(db database.DB, in chan InsertBatch) {
 	for batch := range in {
 		err := db.InsertBatch(batch.Table, batch.Rows)
 		if err != nil {