From 17977478e7d017c75433d887292732263ecdf1d5 Mon Sep 17 00:00:00 2001
From: Harry Zhang <resouer@gmail.com>
Date: Fri, 29 Jun 2018 22:19:01 +0800
Subject: [PATCH] RWLock for cache

---
 pkg/scheduler/cache/cache.go | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/pkg/scheduler/cache/cache.go b/pkg/scheduler/cache/cache.go
index fd04a044c6..201b214bee 100644
--- a/pkg/scheduler/cache/cache.go
+++ b/pkg/scheduler/cache/cache.go
@@ -52,7 +52,7 @@ type schedulerCache struct {
 	period time.Duration
 
 	// This mutex guards all fields within this cache struct.
-	mu sync.Mutex
+	mu sync.RWMutex
 	// a set of assumed pod keys.
 	// The key could further be used to get an entry in podStates.
 	assumedPods map[string]bool
@@ -112,8 +112,8 @@ func newSchedulerCache(ttl, period time.Duration, stop <-chan struct{}) *schedul
 // Snapshot takes a snapshot of the current schedulerCache. The method has performance impact,
 // and should be only used in non-critical path.
 func (cache *schedulerCache) Snapshot() *Snapshot {
-	cache.mu.Lock()
-	defer cache.mu.Unlock()
+	cache.mu.RLock()
+	defer cache.mu.RUnlock()
 
 	nodes := make(map[string]*NodeInfo)
 	for k, v := range cache.nodes {
@@ -164,8 +164,8 @@ func (cache *schedulerCache) List(selector labels.Selector) ([]*v1.Pod, error) {
 }
 
 func (cache *schedulerCache) FilteredList(podFilter PodFilter, selector labels.Selector) ([]*v1.Pod, error) {
-	cache.mu.Lock()
-	defer cache.mu.Unlock()
+	cache.mu.RLock()
+	defer cache.mu.RUnlock()
 	// podFilter is expected to return true for most or all of the pods. We
 	// can avoid expensive array growth without wasting too much memory by
 	// pre-allocating capacity.
@@ -216,8 +216,8 @@ func (cache *schedulerCache) finishBinding(pod *v1.Pod, now time.Time) error {
 		return err
 	}
 
-	cache.mu.Lock()
-	defer cache.mu.Unlock()
+	cache.mu.RLock()
+	defer cache.mu.RUnlock()
 
 	glog.V(5).Infof("Finished binding for pod %v. Can be expired.", key)
 	currState, ok := cache.podStates[key]
@@ -387,8 +387,8 @@ func (cache *schedulerCache) IsAssumedPod(pod *v1.Pod) (bool, error) {
 		return false, err
 	}
 
-	cache.mu.Lock()
-	defer cache.mu.Unlock()
+	cache.mu.RLock()
+	defer cache.mu.RUnlock()
 
 	b, found := cache.assumedPods[key]
 	if !found {
@@ -403,8 +403,8 @@ func (cache *schedulerCache) GetPod(pod *v1.Pod) (*v1.Pod, error) {
 		return nil, err
 	}
 
-	cache.mu.Lock()
-	defer cache.mu.Unlock()
+	cache.mu.RLock()
+	defer cache.mu.RUnlock()
 
 	podState, ok := cache.podStates[key]
 	if !ok {
@@ -539,8 +539,8 @@ func (cache *schedulerCache) RemovePDB(pdb *policy.PodDisruptionBudget) error {
 }
 
 func (cache *schedulerCache) ListPDBs(selector labels.Selector) ([]*policy.PodDisruptionBudget, error) {
-	cache.mu.Lock()
-	defer cache.mu.Unlock()
+	cache.mu.RLock()
+	defer cache.mu.RUnlock()
 	var pdbs []*policy.PodDisruptionBudget
 	for _, pdb := range cache.pdbs {
 		if selector.Matches(labels.Set(pdb.Labels)) {
@@ -551,8 +551,8 @@ func (cache *schedulerCache) ListPDBs(selector labels.Selector) ([]*policy.PodDi
 }
 
 func (cache *schedulerCache) IsUpToDate(n *NodeInfo) bool {
-	cache.mu.Lock()
-	defer cache.mu.Unlock()
+	cache.mu.RLock()
+	defer cache.mu.RUnlock()
 	node, ok := cache.nodes[n.Node().Name]
 	return ok && n.generation == node.generation
 }