From 1cb4613b7e6273babcad8696e66505d159abae54 Mon Sep 17 00:00:00 2001
From: bakape <scorpid33@gmail.com>
Date: Fri, 12 May 2017 22:32:24 +0300
Subject: [PATCH] cache: Fix panics

---
 cache/cache.go              |  4 ----
 cache/native/native.go      |  8 ++++----
 cache/native/native_test.go | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 8 deletions(-)
 create mode 100644 cache/native/native_test.go

diff --git a/cache/cache.go b/cache/cache.go
index 98eab0de..c16a16d9 100644
--- a/cache/cache.go
+++ b/cache/cache.go
@@ -7,8 +7,6 @@ import (
 	"github.com/ewhal/nyaa/common"
 	"github.com/ewhal/nyaa/config"
 	"github.com/ewhal/nyaa/model"
-
-	"errors"
 )
 
 // Cache defines interface for caching search results
@@ -17,8 +15,6 @@ type Cache interface {
 	ClearAll()
 }
 
-var ErrInvalidCacheDialect = errors.New("invalid cache dialect")
-
 // Impl cache implementation instance
 var Impl Cache
 
diff --git a/cache/native/native.go b/cache/native/native.go
index c9b3ba36..56c1094c 100644
--- a/cache/native/native.go
+++ b/cache/native/native.go
@@ -111,7 +111,9 @@ func (n *NativeCache) updateUsedSize(delta int) {
 		}
 		s := n.ll.Remove(e).(*store)
 		delete(n.cache, s.key)
+		s.Lock()
 		n.totalUsed -= s.size
+		s.Unlock()
 	}
 }
 
@@ -136,8 +138,6 @@ func (s *store) update(data []model.Torrent, count int) {
 	s.size = newSize
 	s.lastFetched = time.Now()
 
-	// Technically it is possible to update the size even when the store is
-	// already evicted, but that should never happen, unless you have a very
-	// small cache, very large stored datasets and a lot of traffic.
-	s.n.updateUsedSize(delta)
+	// In a separate goroutine, to ensure there is never any lock intersection
+	go s.n.updateUsedSize(delta)
 }
diff --git a/cache/native/native_test.go b/cache/native/native_test.go
new file mode 100644
index 00000000..6c977ed4
--- /dev/null
+++ b/cache/native/native_test.go
@@ -0,0 +1,37 @@
+package native
+
+import (
+	"sync"
+	"testing"
+
+	"github.com/ewhal/nyaa/common"
+	"github.com/ewhal/nyaa/model"
+)
+
+// Basic test for deadlocks and race conditions
+func TestConcurrency(t *testing.T) {
+	c := New(0.000001)
+
+	fn := func() ([]model.Torrent, int, error) {
+		return []model.Torrent{{}, {}, {}}, 10, nil
+	}
+
+	var wg sync.WaitGroup
+	wg.Add(300)
+	for i := 0; i < 3; i++ {
+		go func() {
+			for j := 0; j < 100; j++ {
+				go func(j int) {
+					defer wg.Done()
+					k := common.SearchParam{
+						Page: j,
+					}
+					if _, _, err := c.Get(k, fn); err != nil {
+						t.Fatal(err)
+					}
+				}(j)
+			}
+		}()
+	}
+	wg.Wait()
+}