flags

.vscode/launch.json

@@ -6,7 +6,7 @@
             "type": "go",
             "request": "launch",
             "mode": "auto",
-            "program": "${fileDirname}",
+            "program": "${workspaceFolder}",
             "console": "integratedTerminal"
         }
     ]

README.md

@@ -91,6 +91,9 @@ literal --> rparen2
 colSep2 --> rparen2
 ```
 
+## Flags
+Run `cdb -h` for command line flags.
+
 ## Architecture
 ```mermaid
 ---

db/db.go

@@ -22,18 +22,20 @@ type dbCatalog interface {
 }
 
 type DB struct {
-	vm      executor
-	catalog dbCatalog
+	vm        executor
+	catalog   dbCatalog
+	UseMemory bool
 }
 
-func New(useMemory bool) (*DB, error) {
-	kv, err := kv.New(useMemory)
+func New(useMemory bool, filename string) (*DB, error) {
+	kv, err := kv.New(useMemory, filename)
 	if err != nil {
 		return nil, err
 	}
 	return &DB{
-		vm:      vm.New(kv),
-		catalog: kv.GetCatalog(),
+		vm:        vm.New(kv),
+		catalog:   kv.GetCatalog(),
+		UseMemory: useMemory,
 	}, nil
 }
 

db/db_test.go

@@ -7,7 +7,7 @@ import (
 
 func TestExecute(t *testing.T) {
 	t.Run("create, select schema, insert, select", func(t *testing.T) {
-		db, err := New(true)
+		db, err := New(true, "")
 		if err != nil {
 			t.Fatal(err.Error())
 		}
@@ -58,7 +58,7 @@ func TestExecute(t *testing.T) {
 	})
 
 	t.Run("bulk insert", func(t *testing.T) {
-		db, err := New(true)
+		db, err := New(true, "")
 		if err != nil {
 			t.Fatal(err.Error())
 		}

kv/kv.go

@@ -17,8 +17,8 @@ type KV struct {
 	catalog *catalog
 }
 
-func New(useMemory bool) (*KV, error) {
-	pager, err := pager.New(useMemory)
+func New(useMemory bool, filename string) (*KV, error) {
+	pager, err := pager.New(useMemory, filename)
 	if err != nil {
 		return nil, err
 	}

kv/kv_test.go

@@ -7,7 +7,7 @@ import (
 
 func TestKv(t *testing.T) {
 	t.Run("get", func(t *testing.T) {
-		kv, _ := New(true)
+		kv, _ := New(true, "")
 		k := []byte{1}
 		v := []byte{'n', 'e', 'd'}
 		kv.Set(1, k, v)
@@ -24,7 +24,7 @@ func TestKv(t *testing.T) {
 	})
 
 	t.Run("set page split", func(t *testing.T) {
-		kv, _ := New(true)
+		kv, _ := New(true, "")
 		var rk []byte
 		var rv []byte
 		ri := 178
@@ -58,7 +58,7 @@ func TestKv(t *testing.T) {
 	})
 
 	t.Run("test bulk insert and get", func(t *testing.T) {
-		kv, _ := New(true)
+		kv, _ := New(true, "")
 		amount := 500_000
 		kv.BeginWriteTransaction()
 		for i := 1; i <= amount; i += 1 {

main.go

@@ -1,14 +1,22 @@
 package main
 
 import (
+	"flag"
 	"log"
 
 	"github.com/chirst/cdb/db"
+	"github.com/chirst/cdb/pager"
 	"github.com/chirst/cdb/repl"
 )
 
+const fFlagHelp = "Specify the database file name"
+const mFlagHelp = "Run the database in memory with no persistence"
+
 func main() {
-	db, err := db.New(false)
+	dbfName := flag.String("f", pager.DefaultDBFileName, fFlagHelp)
+	isMemory := flag.Bool("m", false, mFlagHelp)
+	flag.Parse()
+	db, err := db.New(*isMemory, *dbfName)
 	if err != nil {
 		log.Fatal(err)
 	}

main_test.go

@@ -7,7 +7,7 @@ import (
 )
 
 func TestBulk(t *testing.T) {
-	d, _ := db.New(true)
+	d, _ := db.New(true, "")
 	r := d.Execute("CREATE TABLE test (id INTEGER, junk TEXT)")
 	if r.Err != nil {
 		t.Fatal(r.Err.Error())

pager/pager.go

@@ -28,10 +28,13 @@ import (
 // +---------+
 
 const (
-	// journalFileName is the name of the file the rollback journal uses.
-	journalFileName = "journal.db"
-	// dbFileName is the name of the file the database uses.
-	dbFileName = "db.db" // TODO make dynamic
+	// journalSuffix is the suffix of the filename the rollback journal uses.
+	// If the database file is called cdb.db a journal will be called
+	// cdb-journal.db
+	journalSuffix = "-journal"
+	// DefaultDBFileName is the default name of the file the database uses. The
+	// file extension is .db.
+	DefaultDBFileName = "cdb"
 	// pageCacheSize is maximum amount of pages that can be cached in memory.
 	pageCacheSize = 1000
 )
@@ -124,13 +127,13 @@ type Pager struct {
 // New creates a new pager. The useMemory flag means the database will not
 // create a file or persist changes to disk. This is useful for testing
 // purposes.
-func New(useMemory bool) (*Pager, error) {
+func New(useMemory bool, filename string) (*Pager, error) {
 	var s storage
 	var err error
 	if useMemory {
 		s = newMemoryStorage()
 	} else {
-		s, err = newFileStorage()
+		s, err = newFileStorage(filename)
 	}
 	if err != nil {
 		return nil, err

pager/pager_test.go

@@ -7,7 +7,7 @@ import (
 )
 
 func TestPageHelpers(t *testing.T) {
-	pager, err := New(true)
+	pager, err := New(true, "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -88,7 +88,7 @@ func TestPageHelpers(t *testing.T) {
 
 func TestPageSet(t *testing.T) {
 	t.Run("set", func(t *testing.T) {
-		pager, err := New(true)
+		pager, err := New(true, "")
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -115,7 +115,7 @@ func TestPageSet(t *testing.T) {
 	})
 
 	t.Run("set update", func(t *testing.T) {
-		pager, err := New(true)
+		pager, err := New(true, "")
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -136,7 +136,7 @@ func TestPageSet(t *testing.T) {
 func TestGet(t *testing.T) {
 
 	t.Run("get", func(t *testing.T) {
-		pager, err := New(true)
+		pager, err := New(true, "")
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -157,7 +157,7 @@ func TestGet(t *testing.T) {
 	})
 
 	t.Run("get not found", func(t *testing.T) {
-		pager, err := New(true)
+		pager, err := New(true, "")
 		if err != nil {
 			t.Fatal(err)
 		}

pager/storage.go

@@ -53,40 +53,62 @@ func (mf *memoryStorage) DeleteJournal() error {
 }
 
 type fileStorage struct {
-	file *os.File
+	file        *os.File
+	journalName string
+	dbFileName  string
 }
 
-func newFileStorage() (storage, error) {
-	jfl, err := os.OpenFile(journalFileName, os.O_RDWR, 0644)
+func newFileStorage(filename string) (storage, error) {
+	dName := getFileName(filename)
+	jName := getJournalName(filename)
+	jfl, err := os.OpenFile(jName, os.O_RDWR, 0644)
 	// if journal file doesn't exist open normal db file
 	if err != nil && os.IsNotExist(err) {
-		fl, err := os.OpenFile(dbFileName, os.O_RDWR|os.O_CREATE, 0644)
+		fl, err := os.OpenFile(dName, os.O_RDWR|os.O_CREATE, 0644)
 		if err != nil {
 			return nil, fmt.Errorf("error opening db file: %w", err)
 		}
 		return &fileStorage{
-			file: fl,
+			file:        fl,
+			dbFileName:  dName,
+			journalName: jName,
 		}, nil
 	}
 	// if journal file has an error
 	if err != nil {
 		return nil, fmt.Errorf("error opening journal: %w", err)
 	}
 	// if no error opening journal use journal as main file
-	fl, err := os.OpenFile(dbFileName, os.O_RDWR|os.O_CREATE, 0644)
+	fl, err := os.OpenFile(dName, os.O_RDWR|os.O_CREATE, 0644)
 	if err != nil {
 		return nil, fmt.Errorf("error opening db file to restore journal: %w", err)
 	}
 	_, err = io.Copy(fl, jfl)
 	if err != nil {
 		return nil, fmt.Errorf("error copying journal to db file: %w", err)
 	}
-	os.Remove(journalFileName)
+	os.Remove(jName)
 	return &fileStorage{
-		file: fl,
+		file:        fl,
+		dbFileName:  dName,
+		journalName: jName,
 	}, nil
 }
 
+func getFileName(filename string) string {
+	if filename == "" {
+		return fmt.Sprintf("%s.db", DefaultDBFileName)
+	}
+	return fmt.Sprintf("%s.db", filename)
+}
+
+func getJournalName(filename string) string {
+	if filename == "" {
+		return fmt.Sprintf("%s%s.db", DefaultDBFileName, journalSuffix)
+	}
+	return fmt.Sprintf("%s%s.db", filename, journalSuffix)
+}
+
 func (s *fileStorage) WriteAt(p []byte, off int64) (n int, err error) {
 	return s.file.WriteAt(p, off)
 }
@@ -96,20 +118,20 @@ func (s *fileStorage) ReadAt(p []byte, off int64) (n int, err error) {
 }
 
 func (s *fileStorage) CreateJournal() error {
-	f, err := os.OpenFile(journalFileName, os.O_RDWR|os.O_CREATE, 0644)
+	f, err := os.OpenFile(s.journalName, os.O_RDWR|os.O_CREATE, 0644)
 	if err != nil {
-		return err
+		return fmt.Errorf("error creating journal %w", err)
 	}
 	if f.Close() != nil {
-		return err
+		return fmt.Errorf("error closing journal %w", err)
 	}
 	return nil
 }
 
 func (s *fileStorage) DeleteJournal() error {
-	err := os.Remove(journalFileName)
+	err := os.Remove(s.journalName)
 	if err != nil {
-		return err
+		return fmt.Errorf("error deleting journal %w", err)
 	}
 	return nil
 }

repl/repl.go

@@ -17,6 +17,12 @@ const (
 	emptyHeaderValue = "<anonymous>"
 )
 
+// ansi are codes that will color terminal output
+const (
+	ansiWarn  = "\033[33m"
+	ansiReset = "\033[0m"
+)
+
 type repl struct {
 	db *db.DB
 }
@@ -27,6 +33,9 @@ func New(db *db.DB) *repl {
 
 func (r *repl) Run() {
 	fmt.Println("Welcome to cdb. Type .exit to exit")
+	if r.db.UseMemory {
+		fmt.Println(ansiWarn + "WARN database is running in memory and will not persist changes" + ansiReset)
+	}
 	reader := bufio.NewScanner(os.Stdin)
 	for r.getInput(reader) {
 		input := reader.Text()

vm/vm_test.go

@@ -8,7 +8,7 @@ import (
 )
 
 func TestExec(t *testing.T) {
-	kv, err := kv.New(true)
+	kv, err := kv.New(true, "")
 	if err != nil {
 		log.Fatal(err.Error())
 	}