[orcaman#136] Add custom shard count value in concurrent map

Author: SeunghoonBaek

concurrent_map.go

@@ -16,8 +16,9 @@ type Stringer interface {
 // A "thread" safe map of type string:Anything.
 // To avoid lock bottlenecks this map is dived to several (SHARD_COUNT) map shards.
 type ConcurrentMap[K comparable, V any] struct {
-	shards   []*ConcurrentMapShared[K, V]
-	sharding func(key K) uint32
+	shards     []*ConcurrentMapShared[K, V]
+	sharding   func(key K) uint32
+	shardCount uint32
 }
 
 // A "thread" safe string to anything map.
@@ -26,35 +27,41 @@ type ConcurrentMapShared[K comparable, V any] struct {
 	sync.RWMutex // Read Write mutex, guards access to internal map.
 }
 
-func create[K comparable, V any](sharding func(key K) uint32) ConcurrentMap[K, V] {
+func create[K comparable, V any](sharding func(key K) uint32, shardCount uint32) ConcurrentMap[K, V] {
 	m := ConcurrentMap[K, V]{
-		sharding: sharding,
-		shards:   make([]*ConcurrentMapShared[K, V], SHARD_COUNT),
+		sharding:   sharding,
+		shards:     make([]*ConcurrentMapShared[K, V], shardCount),
+		shardCount: shardCount,
 	}
-	for i := 0; i < SHARD_COUNT; i++ {
+	for i := 0; i < int(m.shardCount); i++ {
 		m.shards[i] = &ConcurrentMapShared[K, V]{items: make(map[K]V)}
 	}
 	return m
 }
 
 // Creates a new concurrent map.
 func New[V any]() ConcurrentMap[string, V] {
-	return create[string, V](fnv32)
+	return create[string, V](fnv32, uint32(SHARD_COUNT))
 }
 
 // Creates a new concurrent map.
 func NewStringer[K Stringer, V any]() ConcurrentMap[K, V] {
-	return create[K, V](strfnv32[K])
+	return create[K, V](strfnv32[K], uint32(SHARD_COUNT))
 }
 
 // Creates a new concurrent map.
 func NewWithCustomShardingFunction[K comparable, V any](sharding func(key K) uint32) ConcurrentMap[K, V] {
-	return create[K, V](sharding)
+	return create[K, V](sharding, uint32(SHARD_COUNT))
+}
+
+// NewWithCustomShardingCountFunction Create a new concurrent map using the given shardCount
+func NewWithCustomShardingCountFunction[K comparable, V any](sharding func(key K) uint32, shardCount uint32) ConcurrentMap[K, V] {
+	return create[K, V](sharding, shardCount)
 }
 
 // GetShard returns shard under given key
 func (m ConcurrentMap[K, V]) GetShard(key K) *ConcurrentMapShared[K, V] {
-	return m.shards[uint(m.sharding(key))%uint(SHARD_COUNT)]
+	return m.shards[uint(m.sharding(key))%uint(m.shardCount)]
 }
 
 func (m ConcurrentMap[K, V]) MSet(data map[K]V) {
@@ -119,7 +126,7 @@ func (m ConcurrentMap[K, V]) Get(key K) (V, bool) {
 // Count returns the number of elements within the map.
 func (m ConcurrentMap[K, V]) Count() int {
 	count := 0
-	for i := 0; i < SHARD_COUNT; i++ {
+	for i := 0; i < int(m.shardCount); i++ {
 		shard := m.shards[i]
 		shard.RLock()
 		count += len(shard.items)
@@ -228,9 +235,9 @@ func snapshot[K comparable, V any](m ConcurrentMap[K, V]) (chans []chan Tuple[K,
 	if len(m.shards) == 0 {
 		panic(`cmap.ConcurrentMap is not initialized. Should run New() before usage.`)
 	}
-	chans = make([]chan Tuple[K, V], SHARD_COUNT)
+	chans = make([]chan Tuple[K, V], m.shardCount)
 	wg := sync.WaitGroup{}
-	wg.Add(SHARD_COUNT)
+	wg.Add(int(m.shardCount))
 	// Foreach shard.
 	for index, shard := range m.shards {
 		go func(index int, shard *ConcurrentMapShared[K, V]) {
@@ -303,7 +310,7 @@ func (m ConcurrentMap[K, V]) Keys() []K {
 	go func() {
 		// Foreach shard.
 		wg := sync.WaitGroup{}
-		wg.Add(SHARD_COUNT)
+		wg.Add(int(m.shardCount))
 		for _, shard := range m.shards {
 			go func(shard *ConcurrentMapShared[K, V]) {
 				// Foreach key, value pair.