From 0b9441e1a49beedca76e9efb4bd372a4a774c6d2 Mon Sep 17 00:00:00 2001
From: Jakob Borg <jakob@nym.se>
Date: Tue, 12 May 2015 17:37:47 +0200
Subject: [PATCH] Reset a namespaced kv-store

---
 internal/db/namespaced.go      | 22 +++++++++++++++++++++
 internal/db/namespaced_test.go | 35 ++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/internal/db/namespaced.go b/internal/db/namespaced.go
index 39b155c2f..9cb14900a 100644
--- a/internal/db/namespaced.go
+++ b/internal/db/namespaced.go
@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/syndtr/goleveldb/leveldb/util"
 )
 
 // NamespacedKV is a simple key-value store using a specific namespace within
@@ -29,6 +30,27 @@ func NewNamespacedKV(db *leveldb.DB, prefix string) *NamespacedKV {
 	}
 }
 
+// Reset removes all entries in this namespace.
+func (n *NamespacedKV) Reset() {
+	it := n.db.NewIterator(util.BytesPrefix(n.prefix), nil)
+	defer it.Release()
+	batch := new(leveldb.Batch)
+	for it.Next() {
+		batch.Delete(it.Key())
+		if batch.Len() > batchFlushSize {
+			if err := n.db.Write(batch, nil); err != nil {
+				panic(err)
+			}
+			batch.Reset()
+		}
+	}
+	if batch.Len() > 0 {
+		if err := n.db.Write(batch, nil); err != nil {
+			panic(err)
+		}
+	}
+}
+
 // PutInt64 stores a new int64. Any existing value (even if of another type)
 // is overwritten.
 func (n *NamespacedKV) PutInt64(key string, val int64) {
diff --git a/internal/db/namespaced_test.go b/internal/db/namespaced_test.go
index 22b274977..b55a21ef0 100644
--- a/internal/db/namespaced_test.go
+++ b/internal/db/namespaced_test.go
@@ -90,3 +90,38 @@ func TestNamespacedString(t *testing.T) {
 		t.Errorf("Incorrect return v %q != \"yo\" || ok %v != true", v, ok)
 	}
 }
+
+func TestNamespacedReset(t *testing.T) {
+	ldb, err := leveldb.Open(storage.NewMemStorage(), nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	n1 := NewNamespacedKV(ldb, "foo")
+
+	n1.PutString("test1", "yo1")
+	n1.PutString("test2", "yo2")
+	n1.PutString("test3", "yo3")
+
+	if v, ok := n1.String("test1"); v != "yo1" || !ok {
+		t.Errorf("Incorrect return v %q != \"yo1\" || ok %v != true", v, ok)
+	}
+	if v, ok := n1.String("test2"); v != "yo2" || !ok {
+		t.Errorf("Incorrect return v %q != \"yo2\" || ok %v != true", v, ok)
+	}
+	if v, ok := n1.String("test3"); v != "yo3" || !ok {
+		t.Errorf("Incorrect return v %q != \"yo3\" || ok %v != true", v, ok)
+	}
+
+	n1.Reset()
+
+	if v, ok := n1.String("test1"); v != "" || ok {
+		t.Errorf("Incorrect return v %q != \"\" || ok %v != false", v, ok)
+	}
+	if v, ok := n1.String("test2"); v != "" || ok {
+		t.Errorf("Incorrect return v %q != \"\" || ok %v != false", v, ok)
+	}
+	if v, ok := n1.String("test3"); v != "" || ok {
+		t.Errorf("Incorrect return v %q != \"\" || ok %v != false", v, ok)
+	}
+}