From 108a1bfd1b5fbf6d81f66dd4861175d26dbd3f53 Mon Sep 17 00:00:00 2001
From: Kevin Lynx <kevinlynx@gmail.com>
Date: Sun, 21 Jul 2013 21:29:47 +0800
Subject: [PATCH] fix hash_download_cache startup bug

---
 src/hash_reader/hash_download_cache.erl | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/hash_reader/hash_download_cache.erl b/src/hash_reader/hash_download_cache.erl
index 84f6216..bf1cdf5 100644
--- a/src/hash_reader/hash_download_cache.erl
+++ b/src/hash_reader/hash_download_cache.erl
@@ -94,8 +94,12 @@ do_save(DBPool, Docs) ->
 try_load(DBPool, []) ->
 	?T("download_cache empty, load hash from db"),
 	Conn = mongo_pool:get(DBPool),
-	{Doc} = hash_reader_common:load_delete_doc(Conn, ?HASH_DOWNLOAD_COLL),
-	{Doc, []};
+	case hash_reader_common:load_delete_doc(Conn, ?HASH_DOWNLOAD_COLL) of
+		{Doc} ->
+			{Doc, []};
+		{} ->
+			{{}, []}
+	end;
 try_load(_, [First|Rest]) ->
 	{First, Rest}.