incr insdie lcache to avoid race condition, pl being evicted before c…

…alling incr. Fixes #1171
hypermodeinc · Jul 11, 2017 · 2e48afc · 2e48afc
1 parent 686d8f8
commit 2e48afc
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Showing 3 changed files with 6 additions and 7 deletions.
diff --git a/posting/lists.go b/posting/lists.go
@@ -265,7 +265,6 @@ func GetOrCreate(key []byte, group uint32) (rlist *List, decr func()) {
 	lp := lcache.Get(fp)
 	if lp != nil {
 		x.CacheHit.Add(1)
-		lp.incr()
 		return lp, lp.decr
 	}
 	x.CacheMiss.Add(1)
@@ -275,12 +274,10 @@ func GetOrCreate(key []byte, group uint32) (rlist *List, decr func()) {
 	l := getNew(key, pstore) // This retrieves a new *List and sets refcount to 1.
 	l.water = marks.Get(group)
 
+	// We are always going to return lp to caller, whether it is l or not
+	// lcache increments the ref counter
 	lp = lcache.PutIfMissing(fp, l)
 
-	// We are always going to return lp to caller, whether it is l or not. So, let's
-	// increment its reference counter.
-	lp.incr()
-
 	if lp != l {
 		x.CacheRace.Add(1)
 		// Undo the increment in getNew() call above.
@@ -303,7 +300,6 @@ func Get(key []byte, gid uint32) (rlist *List, decr func()) {
 	lp := lcache.Get(fp)
 
 	if lp != nil {
-		lp.incr()
 		return lp, lp.decr
 	}
 

diff --git a/posting/lru.go b/posting/lru.go
@@ -76,6 +76,7 @@ func (c *listCache) PutIfMissing(key uint64, pl *List) (res *List) {
 	if ee, ok := c.cache[key]; ok {
 		c.ll.MoveToFront(ee)
 		res = ee.Value.(*entry).pl
+		res.incr()
 		return res
 	}
 
@@ -92,6 +93,7 @@ func (c *listCache) PutIfMissing(key uint64, pl *List) (res *List) {
 	c.cache[key] = ele
 	c.removeOldest()
 
+	e.pl.incr()
 	return e.pl
 }
 
@@ -127,6 +129,7 @@ func (c *listCache) Get(key uint64) (pl *List) {
 		est := uint64(e.pl.EstimatedSize())
 		c.curSize += est - e.size
 		e.size = est
+		e.pl.incr()
 		return e.pl
 	}
 	return nil

diff --git a/x/metrics.go b/x/metrics.go
@@ -71,7 +71,7 @@ func init() {
 	DirtyMapSize = expvar.NewInt("dirtyMapSize")
 	LCacheSize = expvar.NewInt("lcacheSize")
 	LCacheLen = expvar.NewInt("lcacheLen")
-	lCacheCapacity = expvar.NewInt("lCacheCapacity")
+	LCacheCapacity = expvar.NewInt("lCacheCapacity")
 	NumGoRoutines = expvar.NewInt("numGoRoutines")
 	MemoryInUse = expvar.NewInt("memoryInUse")
 	HeapIdle = expvar.NewInt("heapIdle")