X neo/storage: Open backends by raw string, not URL

For both current backends (SQLite and fs1) there is currently a problem
of working with UTF-8 filenames if opening is handled via urls. For
example if backend string is

	sqlite://neo.sqlite·P1-1

after parsing as URL and further reassembled as string it will be

	neo.sqlite%C2%B7P1-1

with then errors like

	neo.sqlite%C2%B7P1-1: open: unable to open database file

showing.

Since storage backends primarily work with local files it makes sense
not to play raw url reassembly games and just pass raw strings to
backends for open.

SQLite uri processing is still possible, via e.g.

	sqlite://file:filepath?param=value,...

See

	https://www.sqlite.org/c3ref/open.html	and
	https://www.sqlite.org/uri.html

for details.

go/neo/storage/fs1/fs1.go

@@ -22,7 +22,6 @@ package fs1
 
 import (
 	"context"
-	"net/url"
 
 	"lab.nexedi.com/kirr/neo/go/neo/internal/xsha1"
 	"lab.nexedi.com/kirr/neo/go/neo/proto"
@@ -93,15 +92,17 @@ func (f *Backend) Load(ctx context.Context, xid zodb.Xid) (*proto.AnswerObject,
 }
 
 
-// ---- open by URL ----
+// ---- open ----
 
-func openURL(ctx context.Context, u *url.URL) (storage.Backend, error) {
-	// TODO handle query
-	// XXX u.Path is not always raw path - recheck and fix
-	path := u.Host + u.Path
-	return Open(ctx, path)
+func openBackend(ctx context.Context, path string) (storage.Backend, error) {
+	b, err := Open(ctx, path)
+	if err == nil {
+		return b, nil
+	} else {
+		return nil, err	// XXX don't return just b -> will be !nil interface
+	}
 }
 
 func init() {
-	storage.RegisterBackend("fs1", openURL)
+	storage.RegisterBackend("fs1", openBackend)
 }

go/neo/storage/sqlite/sqlite.go

@@ -25,7 +25,6 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"net/url"
 	"strings"
 	//"reflect"
 
@@ -416,6 +415,7 @@ func (b *Backend) Close() error {
 func openConn(dburl string) (*sqlite3.Conn, error) {
 	conn, err := sqlite3.Open(dburl,
 		sqlite3.OpenNoMutex,	// we use connections only from 1 goroutine simultaneously
+		sqlite3.OpenUri,	// handle file:... URIs
 		sqlite3.OpenReadWrite)	//, sqlite3.OpenSharedCache)
 
 	if err != nil {
@@ -540,7 +540,7 @@ func Open(dburl string) (_ *Backend, err error) {
 
 	err = errv.Err()
 	if err != nil {
-		return nil, fmt.Errorf("NEO/go POC: not ready to handle: %s", err)
+		return nil, fmt.Errorf("%s: NEO/go POC: not ready to handle: %s", dburl, err)
 	}
 
 	// config("version")
@@ -562,11 +562,11 @@ func Open(dburl string) (_ *Backend, err error) {
 
 	err = errv.Err()
 	if err != nil {
-		return nil, fmt.Errorf("NEO/go POC: checking ttrans/tobj: %s", err)
+		return nil, fmt.Errorf("%s: NEO/go POC: checking ttrans/tobj: %s", dburl, err)
 	}
 
 	if !(nttrans==0 && ntobj==0) {
-		return nil, fmt.Errorf("NEO/go POC: not ready to handle: !empty ttrans/tobj")
+		return nil, fmt.Errorf("%s: NEO/go POC: not ready to handle: !empty ttrans/tobj", dburl)
 	}
 
 	// TODO lock db by path so other process cannot start working with it
@@ -575,10 +575,7 @@ func Open(dburl string) (_ *Backend, err error) {
 }
 
 
-func openURL(ctx context.Context, u *url.URL) (storage.Backend, error) {
-	url := u.String()
-	dburl := strings.TrimPrefix(url, u.Scheme+"://") // url with stripped sqlite://
-
+func openBackend(ctx context.Context, dburl string) (storage.Backend, error) {
 	b, err := Open(dburl)
 	if err == nil {
 		return b, nil
@@ -588,5 +585,5 @@ func openURL(ctx context.Context, u *url.URL) (storage.Backend, error) {
 }
 
 func init() {
-	storage.RegisterBackend("sqlite", openURL)
+	storage.RegisterBackend("sqlite", openBackend)
 }

go/neo/storage/storage.go

@@ -25,6 +25,7 @@ import (
 	"fmt"
 	"net/url"
 	"sort"
+	"strings"
 	"sync"
 
 	"lab.nexedi.com/kirr/neo/go/neo/proto"
@@ -49,7 +50,7 @@ type Backend interface {
 }
 
 // BackendOpener is a function to open a NEO storage backend
-type BackendOpener func (ctx context.Context, u *url.URL) (Backend, error)
+type BackendOpener func (ctx context.Context, path string) (Backend, error)
 
 // {} scheme -> BackendOpener
 var backMu sync.Mutex
@@ -99,5 +100,7 @@ func OpenBackend(ctx context.Context, backendURL string) (Backend, error) {
 		return nil, fmt.Errorf("neo: backend: open %q: URL scheme \"%s://\" not supported", backendURL, u.Scheme)
 	}
 
-	return opener(ctx, u)
+	// open via raw path with only scheme:// stripped
+	path := strings.TrimPrefix(backendURL, u.Scheme+"://")
+	return opener(ctx, path)
 }

go/neo/t/tzodb.go

@@ -292,7 +292,7 @@ func zwrkMain(argv []string) {
 // zwrk simulates database load from multiple clients.
 //
 // It first serially reads all objects and remember theirs per-object crc32
-// checksum. If h/check were provided this phase, similarly to zhash, also
+// checksum. If h/check were provided, this phase, similarly to zhash, also
 // checks that the whole database content is as expected.
 //
 // Then parallel phase starts where nwrk separate connections to database are
@@ -414,7 +414,7 @@ func zwrkPreconnect(ctx context.Context, url string, at zodb.Tid, nwrk int) (_ [
 
 			// load several first objects to warm up storages connection
 			// we need to load several objects so that in case of
-			// NEO cluster with several storage nodes we warm-up
+			// NEO cluster with several storage nodes, we warm-up
 			// connections to them all.
 			//
 			// FIXME 16 hardcoded