Simplify closeCh mutex

Add test validating safety of DB access after close

Author: willscott

datastore.go

@@ -17,9 +17,8 @@ import (
 
 type Datastore struct {
 	*accessor
-	DB      *leveldb.DB
-	path    string
-	closeLk sync.RWMutex
+	DB   *leveldb.DB
+	path string
 }
 
 var _ ds.Datastore = (*Datastore)(nil)
@@ -54,12 +53,12 @@ func NewDatastore(path string, opts *Options) (*Datastore, error) {
 		return nil, err
 	}
 
+	closeLk := sync.RWMutex{}
 	ds := Datastore{
-		accessor: &accessor{ldb: db, syncWrites: true},
+		accessor: &accessor{ldb: db, syncWrites: true, closeLk: &closeLk},
 		DB:       db,
 		path:     path,
 	}
-	ds.accessor.closeLk = &ds.closeLk
 	return &ds, nil
 }
 
@@ -217,7 +216,7 @@ func (d *Datastore) Batch() (ds.Batch, error) {
 	return &leveldbBatch{
 		b:          new(leveldb.Batch),
 		db:         d.DB,
-		closeLk:    &d.closeLk,
+		closeLk:    d.closeLk,
 		syncWrites: d.syncWrites,
 	}, nil
 }
@@ -263,6 +262,6 @@ func (d *Datastore) NewTransaction(readOnly bool) (ds.Txn, error) {
 	if err != nil {
 		return nil, err
 	}
-	accessor := &accessor{ldb: tx, syncWrites: false, closeLk: &d.closeLk}
+	accessor := &accessor{ldb: tx, syncWrites: false, closeLk: d.closeLk}
 	return &transaction{accessor, tx}, nil
 }

ds_test.go

@@ -149,15 +149,40 @@ func TestQueryRespectsProcess(t *testing.T) {
 
 func TestCloseRace(t *testing.T) {
 	d, close := newDS(t)
-	for n := 0; n < 1000; n++ {
+	for n := 0; n < 100; n++ {
 		d.Put(ds.NewKey(fmt.Sprintf("%d", n)), []byte(fmt.Sprintf("test%d", n)))
 	}
 
 	tx, _ := d.NewTransaction(false)
-	go close()
+	tx.Put(ds.NewKey("txnversion"), []byte("bump"))
+
+	closeCh := make(chan interface{})
+
+	go func() {
+		close()
+		closeCh <- nil
+	}()
 	for k := range testcases {
 		tx.Get(ds.NewKey(k))
 	}
+	tx.Commit()
+	<-closeCh
+}
+
+func TestCloseSafety(t *testing.T) {
+	d, close := newDS(t)
+	addTestCases(t, d, testcases)
+
+	tx, _ := d.NewTransaction(false)
+	err := tx.Put(ds.NewKey("test"), []byte("test"))
+	if err != nil {
+		t.Error("Failed to put in a txn.")
+	}
+	close()
+	err = tx.Commit()
+	if err == nil {
+		t.Error("committing after close should fail.")
+	}
 }
 
 func TestQueryRespectsProcessMem(t *testing.T) {