Add first version of gemini-grc.

gemini/ip-address-pool.go

@@ -0,0 +1,54 @@
+package gemini
+
+import "sync"
+
+// Used to limit requests per
+// IP address. Maps IP address
+// to number of active connections.
+type IpAddressPool struct {
+	IPs  map[string]int
+	Lock sync.RWMutex
+}
+
+func (p *IpAddressPool) Set(key string, value int) {
+	p.Lock.Lock()         // Lock for writing
+	defer p.Lock.Unlock() // Ensure mutex is unlocked after the write
+	p.IPs[key] = value
+}
+
+func (p *IpAddressPool) Get(key string) int {
+	p.Lock.RLock()         // Lock for reading
+	defer p.Lock.RUnlock() // Ensure mutex is unlocked after reading
+	if value, ok := p.IPs[key]; !ok {
+		return 0
+	} else {
+		return value
+	}
+}
+
+func (p *IpAddressPool) Delete(key string) {
+	p.Lock.Lock()
+	defer p.Lock.Unlock()
+	delete(p.IPs, key)
+}
+
+func (p *IpAddressPool) Incr(key string) {
+	p.Lock.Lock()
+	defer p.Lock.Unlock()
+	if _, ok := p.IPs[key]; !ok {
+		p.IPs[key] = 1
+	} else {
+		p.IPs[key] = p.IPs[key] + 1
+	}
+}
+
+func (p *IpAddressPool) Decr(key string) {
+	p.Lock.Lock()
+	defer p.Lock.Unlock()
+	if val, ok := p.IPs[key]; ok {
+		p.IPs[key] = val - 1
+		if p.IPs[key] == 0 {
+			delete(p.IPs, key)
+		}
+	}
+}