use ncruces recommendations for ensursing this a read only vfs

README.md

@@ -43,33 +43,28 @@ if initErr != nil {
     panic(fmt.Sprintf("Failed to initialize SQLiteZSTD: %s", initErr))
 }
 
-db, err := sql.Open("sqlite3", "<path-to-your-file>?vfs=zstd&mode=ro&immutable=true&synchronous=off")
+db, err := sql.Open("sqlite3", "<path-to-your-file>?vfs=zstd")
 if err != nil {
     panic(fmt.Sprintf("Failed to open database: %s", err))
 }
 ```
 
 In this Go code example:
 
-- The SQLiteZSTD library is initialized first with sqlitezstd.Init().
+- The SQLiteZSTD library is initialized first with `sqlitezstd.Init()`.
 - An SQL connection to a compressed SQLite database is established with
-  sql.Open().
+  `sql.Open()`.
 
-The sql.Open() function takes as a parameter the path to the compressed SQLite
+The `sql.Open()` function takes as a parameter the path to the compressed SQLite
 database, appended with a query string. Key query string parameters include:
 
 - `vfs=zstd`: Ensures the ZSTD VFS is used.
-- `mode=ro`: Opens the database in read-only mode.
-- `immutable=true`: Ensures the database is protected from any accidental write
-  operations.
-- `synchronous=off`: Disables SQLite's disk synchronization for improved
-  performance on read-heavy operations.
 
 ## Performance
 
 Here's a simple benchmark comparing performance between reading from an
 uncompressed vs. a compressed SQLite database, involving the insertion of 10k
-records and retrieval of the MAX value, without an index.
+records and retrieval of the `MAX` value, without an index.
 
 ```
 BenchmarkReadUncompressedSQLite-8           5301            214922 ns/op

benchmark_test.go

@@ -105,7 +105,7 @@ func BenchmarkReadCompressedSQLite(b *testing.B) {
 	_, zstPath, cleanup := setupDB(b)
 	defer cleanup()
 
-	client, err := sql.Open("sqlite3", fmt.Sprintf("%s?vfs=zstd&mode=ro&immutable=true&synchronous=off", zstPath))
+	client, err := sql.Open("sqlite3", fmt.Sprintf("%s?vfs=zstd", zstPath))
 	if err != nil {
 		b.Fatalf("Failed to open database: %v", err)
 	}

file.go

@@ -2,7 +2,6 @@ package sqlitezstd
 
 import (
 	"os"
-	"sync/atomic"
 
 	seekable "github.com/SaveTheRbtz/zstd-seekable-format-go"
 	"github.com/klauspost/compress/zstd"
@@ -14,16 +13,13 @@ type ZstdFile struct {
 	file     *os.File
 	seekable seekable.Reader
 
-	count int64
-	size  int64
+	size int64
 }
 
 var _ sqlite3vfs.File = &ZstdFile{}
 
 func (z *ZstdFile) CheckReservedLock() (bool, error) {
-	count := atomic.LoadInt64(&z.count)
-
-	return count > 0, nil
+	return false, nil
 }
 
 func (z *ZstdFile) Close() error {
@@ -34,20 +30,14 @@ func (z *ZstdFile) Close() error {
 }
 
 func (z *ZstdFile) DeviceCharacteristics() sqlite3vfs.DeviceCharacteristic {
-	return 0
+	return sqlite3vfs.IocapImmutable
 }
 
 func (z *ZstdFile) FileSize() (int64, error) {
 	return z.size, nil
 }
 
 func (z *ZstdFile) Lock(elock sqlite3vfs.LockType) error {
-	if elock == sqlite3vfs.LockNone {
-		return nil
-	}
-
-	atomic.AddInt64(&z.count, 1)
-
 	return nil
 }
 
@@ -68,12 +58,6 @@ func (z *ZstdFile) Truncate(size int64) error {
 }
 
 func (z *ZstdFile) Unlock(elock sqlite3vfs.LockType) error {
-	if elock == sqlite3vfs.LockNone {
-		return nil
-	}
-
-	atomic.AddInt64(&z.count, -1)
-
 	return nil
 }
 

sqlite_zstd_suite_test.go

@@ -65,7 +65,7 @@ var _ = Describe("SqliteZSTD", func() {
 	It("can read from a compressed sqlite db", func() {
 		zstPath := createDatabase()
 
-		client, err := sql.Open("sqlite3", fmt.Sprintf("%s?vfs=zstd&mode=ro&immutable=true&synchronous=off", zstPath))
+		client, err := sql.Open("sqlite3", fmt.Sprintf("%s?vfs=zstd", zstPath))
 		Expect(err).ToNot(HaveOccurred())
 		defer client.Close()
 
@@ -90,7 +90,7 @@ var _ = Describe("SqliteZSTD", func() {
 				defer waiter.Done()
 				defer GinkgoRecover()
 
-				client, err := sql.Open("sqlite3", fmt.Sprintf("%s?vfs=zstd&mode=ro&immutable=true&synchronous=off", zstPath))
+				client, err := sql.Open("sqlite3", fmt.Sprintf("%s?vfs=zstd", zstPath))
 				Expect(err).ToNot(HaveOccurred())
 				defer client.Close()
 

vfs.go

@@ -60,7 +60,7 @@ func (z *ZstdVFS) Open(name string, flags sqlite3vfs.OpenFlag) (sqlite3vfs.File,
 		file:     file,
 		seekable: seekable,
 		size:     size,
-	}, 0, nil
+	}, flags | sqlite3vfs.OpenReadOnly, nil
 }
 
 func Init() error {