From: nsz <nsz@port70.net>
Date: Wed, 16 Nov 2011 11:36:33 +0000 (+0100)
Subject: store simplification (use name,key->value so we can manage many k-v stores)
X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=c89b19c863fc41c0312358a866aebd425f498c76;hp=20fddcfb4f87e47d9e49eef6ed32cd3c181d6d2b;p=epoint

store simplification (use name,key->value so we can manage many k-v stores)
---

diff --git a/store/Makefile b/store/Makefile
new file mode 100644
index 0000000..23c7767
--- /dev/null
+++ b/store/Makefile
@@ -0,0 +1,6 @@
+include $(GOROOT)/src/Make.inc
+
+TARG=epoint/store
+GOFILES=store.go
+
+include $(GOROOT)/src/Make.pkg
diff --git a/store/store.go b/store/store.go
index 48614f2..2595f88 100644
--- a/store/store.go
+++ b/store/store.go
@@ -1,29 +1,26 @@
 package store
 
 // persistent key-value store
-// TODO: thread safety, persistence, efficient update and query, incremental backup
+// multiple key-value store can be managed by a single db connection
+// each store has a name, before usage the name of the store must be
+// ensured to exist
+//
+// TODO: this is a toy implementation
 
 import (
-	"fmt"
 	"os"
 	"path/filepath"
 	"io/ioutil"
-	"sync"
 )
 
 
 type Conn struct {
-	name string
 	path string
-	mutex sync.RWMutex
-	memstore map[string][]byte
 }
 
-func Open(name string) (c *Conn, err error) {
+func Open(root string) (c *Conn, err error) {
 	c = new(Conn)
-	c.memstore = make(map[string][]byte)
-	c.name = name
-	c.path, err = filepath.Abs(name)
+	c.path, err = filepath.Abs(root)
 	if err != nil {
 		return
 	}
@@ -31,49 +28,30 @@ func Open(name string) (c *Conn, err error) {
 	if err != nil {
 		return
 	}
-	err = filepath.Walk(c.path, func(path string, info *os.FileInfo, err error) error {
-		if info.IsDirectory() {
-			if info.Name == c.name {
-				return nil
-			}
-			return filepath.SkipDir
-		}
-		if err != nil {
-			return err
-		}
-		k := info.Name
-		v, err := ioutil.ReadFile(filepath.Join(c.path, k))
-		if err != nil {
-			return err
-		}
-		c.memstore[k] = v
-		return nil
-	})
 	return
 }
 
-func (c *Conn) Get(k string) (v []byte, err error) {
-	c.mutex.RLock()
-	defer c.mutex.RUnlock()
-	v, ok := c.memstore[k]
-	if !ok {
-		err = fmt.Errorf("key not found")
-	}
-	return
+func (c *Conn) Get(name, k string) (v []byte, err error) {
+	return ioutil.ReadFile(filepath.Join(c.path, name, k))
+}
+
+func (c *Conn) Ensure(name string) (err error) {
+	return os.MkdirAll(filepath.Join(c.path, name), 0755)
 }
 
-func (c *Conn) Set(k string, v []byte) (err error) {
-	c.mutex.Lock()
-	defer c.mutex.Unlock()
-	f, err := os.Create(filepath.Join(c.path, k))
+func (c *Conn) Set(name, k string, v []byte) (err error) {
+	fn := filepath.Join(c.path, name, k)
+	// os.O_SYNC
+	f, err := os.Create(fn+".tmp")
 	if err != nil {
 		return
 	}
+	defer f.Close()
 	_, err = f.Write(v)
 	if err != nil {
 		return
 	}
-	c.memstore[k] = v
+	err = os.Rename(fn+".tmp", fn)
 	return
 }
 
diff --git a/store/store_test.go b/store/store_test.go
new file mode 100644
index 0000000..f36fcbb
--- /dev/null
+++ b/store/store_test.go
@@ -0,0 +1,79 @@
+package store
+
+import (
+	"testing"
+)
+
+var testData = map[string]string {
+	"A" : "a",
+	"B" : "b",
+	"C" : "c",
+	"D" : "d",
+	"foo_bar-baz" : "a\nb\nc\nd\n",
+}
+
+func TestStore(t *testing.T) {
+	c, err := Open("teststore")
+	defer c.Close()
+	if err != nil {
+		t.Errorf("open failed: %s", err)
+		return
+	}
+	err = c.Ensure("abc")
+	if err != nil {
+		t.Errorf("ensure failed: %s", err)
+		return
+	}
+	for k, v := range testData {
+		err = c.Set("abc", k, []byte(v))
+		if err != nil {
+			t.Errorf("Set failed: %s", err)
+		}
+	}
+	for k, v := range testData {
+		d, err := c.Get("abc", k)
+		if err != nil {
+			t.Errorf("Get failed: %s", err)
+			continue
+		}
+		if string(d) != v {
+			t.Errorf("expected %s; got %s", v, string(d))
+		}
+	}
+}
+
+func TestPersist(t *testing.T) {
+	c, err := Open("teststore")
+	if err != nil {
+		t.Errorf("open failed: %s", err)
+		return
+	}
+	err = c.Ensure("abc")
+	if err != nil {
+		t.Errorf("ensure failed: %s", err)
+		return
+	}
+	for k, v := range testData {
+		err = c.Set("abc", k, []byte(v))
+		if err != nil {
+			t.Errorf("Set failed: %s", err)
+		}
+	}
+	c.Close()
+
+	c, err = Open("teststore")
+	if err != nil {
+		t.Errorf("open failed: %s", err)
+		return
+	}
+	for k, v := range testData {
+		d, err := c.Get("abc", k)
+		if err != nil {
+			t.Errorf("Get failed: %s", err)
+			continue
+		}
+		if string(d) != v {
+			t.Errorf("expected %s; got %s", v, string(d))
+		}
+	}
+}