From fc15e3cfe69eb46d21dfb40753bbcffa0ef81c43 Mon Sep 17 00:00:00 2001
From: Dan Laine <daniel.laine@avalabs.org>
Date: Mon, 22 Jun 2020 16:35:42 -0400
Subject: [PATCH] prevent potential memory leaks

---
 database/encdb/db.go        | 6 +++++-
 database/memdb/db.go        | 9 ++++++---
 database/prefixdb/db.go     | 6 +++++-
 database/rpcdb/db_client.go | 6 +++++-
 4 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/database/encdb/db.go b/database/encdb/db.go
index fe33fa7..ddf47e0 100644
--- a/database/encdb/db.go
+++ b/database/encdb/db.go
@@ -17,6 +17,10 @@ import (
 	"github.com/ava-labs/gecko/utils/hashing"
 )
 
+const (
+	minBatchSize = 32
+)
+
 // Database encrypts all values that are provided
 type Database struct {
 	lock   sync.RWMutex
@@ -201,7 +205,7 @@ func (b *batch) Write() error {
 
 // Reset resets the batch for reuse.
 func (b *batch) Reset() {
-	b.writes = b.writes[:0]
+	b.writes = make([]keyValue, 0, minBatchSize)
 	b.Batch.Reset()
 }
 
diff --git a/database/memdb/db.go b/database/memdb/db.go
index de0cae3..5bbd3a2 100644
--- a/database/memdb/db.go
+++ b/database/memdb/db.go
@@ -13,8 +13,11 @@ import (
 	"github.com/ava-labs/gecko/utils"
 )
 
-// DefaultSize is the default initial size of the memory database
-const DefaultSize = 1 << 10
+const (
+	// DefaultSize is the default initial size of the memory database
+	DefaultSize  = 1 << 10
+	minBatchSize = 32
+)
 
 // Database is an ephemeral key-value store that implements the Database
 // interface.
@@ -191,7 +194,7 @@ func (b *batch) Write() error {
 
 // Reset implements the Batch interface
 func (b *batch) Reset() {
-	b.writes = b.writes[:0]
+	b.writes = make([]keyValue, 0, minBatchSize)
 	b.size = 0
 }
 
diff --git a/database/prefixdb/db.go b/database/prefixdb/db.go
index 34bc50d..a413846 100644
--- a/database/prefixdb/db.go
+++ b/database/prefixdb/db.go
@@ -12,6 +12,10 @@ import (
 	"github.com/ava-labs/gecko/utils/hashing"
 )
 
+const (
+	minBatchSize = 32
+)
+
 // Database partitions a database into a sub-database by prefixing all keys with
 // a unique value.
 type Database struct {
@@ -199,7 +203,7 @@ func (b *batch) Write() error {
 
 // Reset resets the batch for reuse.
 func (b *batch) Reset() {
-	b.writes = b.writes[:0]
+	b.writes = make([]keyValue, 0, minBatchSize)
 	b.Batch.Reset()
 }
 
diff --git a/database/rpcdb/db_client.go b/database/rpcdb/db_client.go
index dc3f60b..f1a3abc 100644
--- a/database/rpcdb/db_client.go
+++ b/database/rpcdb/db_client.go
@@ -14,6 +14,10 @@ import (
 	"github.com/ava-labs/gecko/utils"
 )
 
+const (
+	minBatchSize = 32
+)
+
 var (
 	errClosed   = fmt.Sprintf("rpc error: code = Unknown desc = %s", database.ErrClosed)
 	errNotFound = fmt.Sprintf("rpc error: code = Unknown desc = %s", database.ErrNotFound)
@@ -180,7 +184,7 @@ func (b *batch) Write() error {
 }
 
 func (b *batch) Reset() {
-	b.writes = b.writes[:0]
+	b.writes = make([]keyValue, 0, minBatchSize)
 	b.size = 0
 }