From b687d8ea9589f0ffa54e38df68f19bb8f91f59dc Mon Sep 17 00:00:00 2001
From: Zoe Roux <zoe.roux@zoriya.dev>
Date: Sun, 18 Feb 2024 22:22:18 +0100
Subject: [PATCH] Create a concurrent map

---
 transcoder/src/cmap.go | 56 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 transcoder/src/cmap.go

diff --git a/transcoder/src/cmap.go b/transcoder/src/cmap.go
new file mode 100644
index 00000000..e10447cf
--- /dev/null
+++ b/transcoder/src/cmap.go
@@ -0,0 +1,56 @@
+package src
+
+import "sync"
+
+type CMap[K comparable, V any] struct {
+	data map[K]V
+	lock sync.RWMutex
+}
+
+func NewCMap[K comparable, V any]() CMap[K, V] {
+	return CMap[K, V]{
+		data: make(map[K]V),
+	}
+}
+
+func (m *CMap[K, V]) Get(key K) (V, bool) {
+	m.lock.RLock()
+	defer m.lock.RUnlock()
+	ret, ok := m.data[key]
+	return ret, ok
+}
+
+func (m *CMap[K, V]) GetOrCreate(key K, create func() V) (V, bool) {
+	m.lock.RLock()
+	ret, ok := m.data[key]
+	if ok {
+		m.lock.RUnlock()
+		return ret, false
+	}
+	m.lock.RUnlock()
+
+	// data does not exist, create it
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	// check if another gorountine already created it before we could lock
+	ret, ok = m.data[key]
+	if ok {
+		return ret, false
+	}
+
+	val := create()
+	m.data[key] = val
+	return val, true
+}
+
+func (m *CMap[K, V]) GetOrSet(key K, val V) (V, bool) {
+	return m.GetOrCreate(key, func() V { return val })
+}
+
+func (m *CMap[K, V]) Remove(key K) {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	delete(m.data, key)
+}