Fix freelist rollback.

bucket_test.go

@@ -190,9 +190,9 @@ func TestBucket_Delete_Large(t *testing.T) {
 	})
 }
 
-// Ensure that deleting a large set of keys will work correctly.
-// Reported by Jordan Sherer: https://github.com/boltdb/bolt/issues/184
-func TestBucket_Delete_Large2(t *testing.T) {
+// Deleting a very large list of keys will overflow the freelist.
+// https://github.com/boltdb/bolt/issues/192
+func TestBucket_Delete_ErrFreelistOverflow(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
@@ -223,7 +223,7 @@ func TestBucket_Delete_Large2(t *testing.T) {
 		}
 
 		// Delete all of them in one large transaction
-		db.Update(func(tx *Tx) error {
+		err := db.Update(func(tx *Tx) error {
 			b := tx.Bucket([]byte("0"))
 			c := b.Cursor()
 			for k, _ := c.First(); k != nil; k, _ = c.Next() {
@@ -231,6 +231,9 @@ func TestBucket_Delete_Large2(t *testing.T) {
 			}
 			return nil
 		})
+
+		// Check that a freelist overflow occurred.
+		assert.Equal(t, ErrFreelistOverflow, err)
 	})
 }
 

freelist.go

@@ -113,6 +113,11 @@ func (f *freelist) release(txid txid) {
 	sort.Sort(pgids(f.ids))
 }
 
+// rollback removes the pages from a given pending tx.
+func (f *freelist) rollback(txid txid) {
+	delete(f.pending, txid)
+}
+
 // isFree returns whether a given page is in the free list.
 func (f *freelist) isFree(pgid pgid) bool {
 	for _, id := range f.ids {
@@ -146,7 +151,7 @@ func (f *freelist) write(p *page) error {
 	ids := f.all()
 
 	// Make sure that the sum of all free pages is less than the max uint16 size.
-	if len(ids) > (1 << 16) {
+	if len(ids) >= 65565 {
 		return ErrFreelistOverflow
 	}
 
@@ -157,3 +162,20 @@ func (f *freelist) write(p *page) error {
 
 	return nil
 }
+
+// reload reads the freelist from a page and filters out pending items.
+func (f *freelist) reload(p *page) {
+	f.read(p)
+
+	// Filter out pending free pages.
+	ids := f.ids
+	f.ids = nil
+
+	var a []pgid
+	for _, id := range ids {
+		if !f.isFree(id) {
+			a = append(a, id)
+		}
+	}
+	f.ids = a
+}

tx.go

@@ -157,7 +157,7 @@ func (tx *Tx) Commit() error {
 	// spill data onto dirty pages.
 	startTime = time.Now()
 	if err := tx.root.spill(); err != nil {
-		tx.close()
+		tx.rollback()
 		return err
 	}
 	tx.stats.SpillTime += time.Since(startTime)
@@ -170,10 +170,11 @@ func (tx *Tx) Commit() error {
 	tx.db.freelist.free(tx.id(), tx.db.page(tx.meta.freelist))
 	p, err := tx.allocate((tx.db.freelist.size() / tx.db.pageSize) + 1)
 	if err != nil {
-		tx.close()
+		tx.rollback()
 		return err
 	}
 	if err := tx.db.freelist.write(p); err != nil {
+		tx.rollback()
 		return err
 	}
 	tx.meta.freelist = p.id
@@ -181,7 +182,7 @@ func (tx *Tx) Commit() error {
 	// Write dirty pages to disk.
 	startTime = time.Now()
 	if err := tx.write(); err != nil {
-		tx.close()
+		tx.rollback()
 		return err
 	}
 
@@ -195,7 +196,7 @@ func (tx *Tx) Commit() error {
 
 	// Write meta to disk.
 	if err := tx.writeMeta(); err != nil {
-		tx.close()
+		tx.rollback()
 		return err
 	}
 	tx.stats.WriteTime += time.Since(startTime)
@@ -217,10 +218,18 @@ func (tx *Tx) Rollback() error {
 	if tx.db == nil {
 		return ErrTxClosed
 	}
-	tx.close()
+	tx.rollback()
 	return nil
 }
 
+func (tx *Tx) rollback() {
+	if tx.writable {
+		tx.db.freelist.rollback(tx.id())
+		tx.db.freelist.reload(tx.db.page(tx.db.meta().freelist))
+	}
+	tx.close()
+}
+
 func (tx *Tx) close() {
 	if tx.writable {
 		// Remove writer lock.