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// Package memdb implements the "memdb" SQLite VFS.
//
// The "memdb" [vfs.VFS] allows the same in-memory database to be shared
// among multiple database connections in the same process,
// as long as the database name begins with "/".
//
// Importing package memdb registers the VFS:
//
// import _ "github.com/ncruces/go-sqlite3/vfs/memdb"
package memdb
import (
"fmt"
"net/url"
"sync"
"testing"
"github.com/ncruces/go-sqlite3/vfs"
)
func init() {
vfs.Register("memdb", memVFS{})
}
var (
memoryMtx sync.Mutex
// +checklocks:memoryMtx
memoryDBs = map[string]*memDB{}
)
// Create creates a shared memory database,
// using data as its initial contents.
// The new database takes ownership of data,
// and the caller should not use data after this call.
func Create(name string, data []byte) {
memoryMtx.Lock()
defer memoryMtx.Unlock()
db := &memDB{
refs: 1,
name: name,
size: int64(len(data)),
}
// Convert data from WAL/2 to rollback journal.
if len(data) >= 20 && (data[18] == 2 && data[19] == 2 ||
data[18] == 3 && data[19] == 3) {
data[18] = 1
data[19] = 1
}
sectors := divRoundUp(db.size, sectorSize)
db.data = make([]*[sectorSize]byte, sectors)
for i := range db.data {
sector := data[i*sectorSize:]
if len(sector) >= sectorSize {
db.data[i] = (*[sectorSize]byte)(sector)
} else {
db.data[i] = new([sectorSize]byte)
copy((*db.data[i])[:], sector)
}
}
memoryDBs[name] = db
}
// Delete deletes a shared memory database.
func Delete(name string) {
memoryMtx.Lock()
defer memoryMtx.Unlock()
delete(memoryDBs, name)
}
// TestDB creates an empty shared memory database for the test to use.
// The database is automatically deleted when the test and all its subtests complete.
// Each subsequent call to TestDB returns a unique database.
func TestDB(tb testing.TB, params ...url.Values) string {
tb.Helper()
name := fmt.Sprintf("%s_%p", tb.Name(), tb)
tb.Cleanup(func() { Delete(name) })
Create(name, nil)
p := url.Values{"vfs": {"memdb"}}
for _, v := range params {
for k, v := range v {
for _, v := range v {
p.Add(k, v)
}
}
}
return (&url.URL{
Scheme: "file",
OmitHost: true,
Path: "/" + name,
RawQuery: p.Encode(),
}).String()
}
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