feat(evpp): implement LB_IpHash load balance strategy

base/hsocket.c

@@ -67,6 +67,7 @@ int ResolveAddr(const char* host, sockaddr_u* addr) {
 
     if (inet_pton(AF_INET6, host, &addr->sin6.sin6_addr) == 1) {
         addr->sa.sa_family = AF_INET6; // host is ipv6
+        return 0;
     }
 
     struct addrinfo* ais = NULL;
@@ -190,11 +191,35 @@ int sockaddr_compare(const sockaddr_u* addr1, const sockaddr_u* addr2) {
             return addr1->sin6.sin6_family - addr2->sin6.sin6_family;
         if (addr1->sin6.sin6_port != addr2->sin6.sin6_port)
             return addr1->sin6.sin6_port - addr2->sin6.sin6_port;
-        return memcmp(&addr1->sin6.sin6_addr, &addr2->sin6.sin6_addr, sizeof(struct in_addr));
+        return memcmp(&addr1->sin6.sin6_addr, &addr2->sin6.sin6_addr, sizeof(struct in6_addr));
     }
     return memcmp(addr1, addr2, sizeof(sockaddr_u));
 }
 
+uint32_t sockaddr_ip_hash(sockaddr_u* addr) {
+    // FNV-1a hash over the ip bytes only (port excluded).
+    const uint32_t FNV_PRIME = 16777619u;
+    uint32_t hash = 2166136261u;
+    const unsigned char* p = NULL;
+    int len = 0;
+    if (addr->sa.sa_family == AF_INET) {
+        p = (const unsigned char*)&addr->sin.sin_addr;
+        len = sizeof(struct in_addr);
+    }
+    else if (addr->sa.sa_family == AF_INET6) {
+        p = (const unsigned char*)&addr->sin6.sin6_addr;
+        len = sizeof(struct in6_addr);
+    }
+    else {
+        return 0;
+    }
+    for (int i = 0; i < len; ++i) {
+        hash ^= p[i];
+        hash *= FNV_PRIME;
+    }
+    return hash;
+}
+
 static int sockaddr_bind(sockaddr_u* localaddr, int type) {
     // socket -> setsockopt -> bind
 #ifdef SOCK_CLOEXEC

base/hsocket.h

@@ -122,6 +122,8 @@ HV_EXPORT int sockaddr_set_ipport(sockaddr_u* addr, const char* host, int port);
 HV_EXPORT socklen_t sockaddr_len(sockaddr_u* addr);
 HV_EXPORT const char* sockaddr_str(sockaddr_u* addr, char* buf, int len);
 HV_EXPORT int sockaddr_compare(const sockaddr_u* addr1, const sockaddr_u* addr2);
+// hash the ip part only (port ignored), so the same client ip maps to the same value. used by LB_IpHash.
+HV_EXPORT uint32_t sockaddr_ip_hash(sockaddr_u* addr);
 
 //#define INET_ADDRSTRLEN   16
 //#define INET6_ADDRSTRLEN  46

docs/cn/TcpServer.md

@@ -17,6 +17,8 @@ class TcpServer {
     void setMaxConnectionNum(uint32_t num);
 
     // 设置负载均衡策略
+    // 可选: LB_RoundRobin(轮询, 默认) / LB_Random(随机) /
+    //       LB_LeastConnections(最少连接数) / LB_IpHash(按客户端IP哈希, 同一IP固定分配到同一worker)
     void setLoadBalance(load_balance_e lb);
 
     // 设置线程数

evpp/EventLoopThreadPool.h

@@ -28,7 +28,8 @@ class EventLoopThreadPool : public Status {
         thread_num_ = num;
     }
 
-    EventLoopPtr nextLoop(load_balance_e lb = LB_RoundRobin) {
+    // @param hash: used by LB_IpHash (see sockaddr_ip_hash), ignored by other strategies.
+    EventLoopPtr nextLoop(load_balance_e lb = LB_RoundRobin, uint32_t hash = 0) {
         size_t numLoops = loop_threads_.size();
         if (numLoops == 0) return NULL;
         size_t idx = 0;
@@ -43,8 +44,12 @@ class EventLoopThreadPool : public Status {
                     idx = i;
                 }
             }
+        } else if (lb == LB_IpHash) {
+            idx = hash % numLoops;
         } else {
-            // Not Implemented
+            // Not Implemented, fallback to RoundRobin
+            if (++next_loop_idx_ >= numLoops) next_loop_idx_ = 0;
+            idx = next_loop_idx_ % numLoops;
         }
         return loop_threads_[idx]->loop();
     }

evpp/TcpServer.h

@@ -255,7 +255,11 @@ class TcpServerEventLoopTmpl {
         TcpServerEventLoopTmpl* server = (TcpServerEventLoopTmpl*)hevent_userdata(connio);
         // NOTE: detach from acceptor loop
         hio_detach(connio);
-        EventLoopPtr worker_loop = server->worker_threads.nextLoop(server->load_balance);
+        uint32_t hash = 0;
+        if (server->load_balance == LB_IpHash) {
+            hash = sockaddr_ip_hash((sockaddr_u*)hio_peeraddr(connio));
+        }
+        EventLoopPtr worker_loop = server->worker_threads.nextLoop(server->load_balance, hash);
         if (worker_loop == NULL) {
             worker_loop = server->acceptor_loop;
         }