From 4844c617de86233bb8f438f2d368f463277a6768 Mon Sep 17 00:00:00 2001
From: Jay Chiu <jchiu@dgraph.io>
Date: Tue, 6 Dec 2016 23:25:34 -0800
Subject: [PATCH] Fix some cgo memory leaks

---
 raftwal/wal.go      | 2 ++
 rdb/db.go           | 3 ++-
 worker/predicate.go | 1 +
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/raftwal/wal.go b/raftwal/wal.go
index 61cfffc944f..21a7483c7d3 100644
--- a/raftwal/wal.go
+++ b/raftwal/wal.go
@@ -89,6 +89,7 @@ func (w *Wal) Store(gid uint32, s raftpb.Snapshot, h raftpb.HardState, es []raft
 		start := w.entryKey(gid, t, i+1)
 		prefix := w.prefix(gid)
 		itr := w.wals.NewIterator()
+		defer itr.Close()
 
 		for itr.Seek(start); itr.ValidForPrefix(prefix); itr.Next() {
 			b.Delete(itr.Key().Data())
@@ -123,6 +124,7 @@ func (w *Wal) Entries(gid uint32, fromTerm, fromIndex uint64) (es []raftpb.Entry
 	start := w.entryKey(gid, fromTerm, fromIndex)
 	prefix := w.prefix(gid)
 	itr := w.wals.NewIterator()
+	defer itr.Close()
 
 	for itr.Seek(start); itr.ValidForPrefix(prefix); itr.Next() {
 		data := itr.Value().Data()
diff --git a/rdb/db.go b/rdb/db.go
index 62748319924..08c994e3d12 100644
--- a/rdb/db.go
+++ b/rdb/db.go
@@ -66,7 +66,8 @@ func (db *DB) Close() {
 	C.rdb_close(db.c)
 }
 
-// Get returns the data associated with the key from the database.
+// Get returns the data associated with the key from the database. Remember
+// to deallocate the returned Slice.
 func (db *DB) Get(opts *ReadOptions, key []byte) (*Slice, error) {
 	var (
 		cErr    *C.char
diff --git a/worker/predicate.go b/worker/predicate.go
index 5124ffba19d..35d3f52ed0e 100644
--- a/worker/predicate.go
+++ b/worker/predicate.go
@@ -36,6 +36,7 @@ const (
 // writeBatch performs a batch write of key value pairs to RocksDB.
 func writeBatch(ctx context.Context, kv chan *task.KV, che chan error) {
 	wb := pstore.NewWriteBatch()
+	defer wb.Destroy()
 	batchSize := 0
 	batchWriteNum := 1
 	for i := range kv {