From e1c66c55333956e7c504312ee6fb511ff3cfca50 Mon Sep 17 00:00:00 2001
From: Guillem Jover <gjover@sipwise.com>
Date: Tue, 12 Jan 2021 21:57:31 +0100
Subject: [PATCH] Fix atomic usage on 32-bit systems

The atomic package requires aligned variables (as per the package
documentation), but this is not happening for the variables on the
stack. Instead change the types for these to 32-bit variables as
there should be no need to track 64-bit stats.

This fixes various panics from the unaligned memory accesses.
---
 bigcache_test.go | 14 +++++++-------
 shard.go         | 22 +++++++++++-----------
 stats.go         | 10 +++++-----
 3 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/bigcache_test.go b/bigcache_test.go
index d6249a47..bac2d7ad 100644
--- a/bigcache_test.go
+++ b/bigcache_test.go
@@ -580,10 +580,10 @@ func TestCacheStats(t *testing.T) {
 
 	// then
 	stats := cache.Stats()
-	assertEqual(t, stats.Hits, int64(10))
-	assertEqual(t, stats.Misses, int64(10))
-	assertEqual(t, stats.DelHits, int64(10))
-	assertEqual(t, stats.DelMisses, int64(10))
+	assertEqual(t, stats.Hits, int32(10))
+	assertEqual(t, stats.Misses, int32(10))
+	assertEqual(t, stats.DelHits, int32(10))
+	assertEqual(t, stats.DelMisses, int32(10))
 }
 func TestCacheEntryStats(t *testing.T) {
 	t.Parallel()
@@ -722,7 +722,7 @@ func TestWriteAndReadParallelSameKeyWithStats(t *testing.T) {
 
 	wg.Wait()
 
-	assertEqual(t, Stats{Hits: int64(n * ntest)}, cache.Stats())
+	assertEqual(t, Stats{Hits: int32(n * ntest)}, cache.Stats())
 	assertEqual(t, ntest*n, int(cache.KeyMetadata(key).RequestCount))
 }
 
@@ -946,7 +946,7 @@ func TestHashCollision(t *testing.T) {
 	assertEqual(t, []byte(nil), cachedValue)
 
 	assertEqual(t, "Collision detected. Both %q and %q have the same hash %x", ml.lastFormat)
-	assertEqual(t, cache.Stats().Collisions, int64(1))
+	assertEqual(t, cache.Stats().Collisions, int32(1))
 }
 
 func TestNilValueCaching(t *testing.T) {
@@ -1025,7 +1025,7 @@ func TestEntryNotPresent(t *testing.T) {
 	value, resp, err := cache.GetWithInfo("blah")
 	assertEqual(t, ErrEntryNotFound, err)
 	assertEqual(t, resp.EntryStatus, RemoveReason(0))
-	assertEqual(t, cache.Stats().Misses, int64(1))
+	assertEqual(t, cache.Stats().Misses, int32(1))
 	assertEqual(t, []byte(nil), value)
 }
 
diff --git a/shard.go b/shard.go
index 3f08d5d8..aa8adb9a 100644
--- a/shard.go
+++ b/shard.go
@@ -354,11 +354,11 @@ func (s *cacheShard) capacity() int {
 
 func (s *cacheShard) getStats() Stats {
 	var stats = Stats{
-		Hits:       atomic.LoadInt64(&s.stats.Hits),
-		Misses:     atomic.LoadInt64(&s.stats.Misses),
-		DelHits:    atomic.LoadInt64(&s.stats.DelHits),
-		DelMisses:  atomic.LoadInt64(&s.stats.DelMisses),
-		Collisions: atomic.LoadInt64(&s.stats.Collisions),
+		Hits:       atomic.LoadInt32(&s.stats.Hits),
+		Misses:     atomic.LoadInt32(&s.stats.Misses),
+		DelHits:    atomic.LoadInt32(&s.stats.DelHits),
+		DelMisses:  atomic.LoadInt32(&s.stats.DelMisses),
+		Collisions: atomic.LoadInt32(&s.stats.Collisions),
 	}
 	return stats
 }
@@ -379,7 +379,7 @@ func (s *cacheShard) getKeyMetadata(key uint64) Metadata {
 }
 
 func (s *cacheShard) hit(key uint64) {
-	atomic.AddInt64(&s.stats.Hits, 1)
+	atomic.AddInt32(&s.stats.Hits, 1)
 	if s.statsEnabled {
 		s.lock.Lock()
 		s.hashmapStats[key]++
@@ -388,26 +388,26 @@ func (s *cacheShard) hit(key uint64) {
 }
 
 func (s *cacheShard) hitWithoutLock(key uint64) {
-	atomic.AddInt64(&s.stats.Hits, 1)
+	atomic.AddInt32(&s.stats.Hits, 1)
 	if s.statsEnabled {
 		s.hashmapStats[key]++
 	}
 }
 
 func (s *cacheShard) miss() {
-	atomic.AddInt64(&s.stats.Misses, 1)
+	atomic.AddInt32(&s.stats.Misses, 1)
 }
 
 func (s *cacheShard) delhit() {
-	atomic.AddInt64(&s.stats.DelHits, 1)
+	atomic.AddInt32(&s.stats.DelHits, 1)
 }
 
 func (s *cacheShard) delmiss() {
-	atomic.AddInt64(&s.stats.DelMisses, 1)
+	atomic.AddInt32(&s.stats.DelMisses, 1)
 }
 
 func (s *cacheShard) collision() {
-	atomic.AddInt64(&s.stats.Collisions, 1)
+	atomic.AddInt32(&s.stats.Collisions, 1)
 }
 
 func initNewShard(config Config, callback onRemoveCallback, clock clock) *cacheShard {
diff --git a/stats.go b/stats.go
index 07157132..a961e755 100644
--- a/stats.go
+++ b/stats.go
@@ -3,13 +3,13 @@ package bigcache
 // Stats stores cache statistics
 type Stats struct {
 	// Hits is a number of successfully found keys
-	Hits int64 `json:"hits"`
+	Hits int32 `json:"hits"`
 	// Misses is a number of not found keys
-	Misses int64 `json:"misses"`
+	Misses int32 `json:"misses"`
 	// DelHits is a number of successfully deleted keys
-	DelHits int64 `json:"delete_hits"`
+	DelHits int32 `json:"delete_hits"`
 	// DelMisses is a number of not deleted keys
-	DelMisses int64 `json:"delete_misses"`
+	DelMisses int32 `json:"delete_misses"`
 	// Collisions is a number of happened key-collisions
-	Collisions int64 `json:"collisions"`
+	Collisions int32 `json:"collisions"`
 }