fix bug that server has 1 extra dead conn

change keepalive req interval from 5 to 2 sec. that is if no response in 8 sec, it will reconnect

callbacks/INetConnKeepAlive.h

@@ -32,6 +32,8 @@ class INetConnKeepAlive {
         virtual int SendNetConnRst(const ConnInfo &src, IntKeyType connKey) = 0;
 
         virtual INetConnKeepAlive *GetIKeepAlive() const = 0;
+
+        virtual int RemoveRequest(IntKeyType connKey) = 0;
     };
 
     using IntConnKeyType = uint32_t;

conn/FakeTcp.cpp

@@ -85,8 +85,10 @@ void FakeTcp::SetAckISN(uint32_t isn) {
     mInfo.UpdateAck(isn);
 }
 
+// it is likely that router doesn't send rst/fin even it has no record for this connection
+// Because server will not send request, so it doesn't know if this conn is dead.
 bool FakeTcp::Alive() {
-    return mAlive;
+    return mAlive && IConn::Alive();
 }
 
 ConnInfo *FakeTcp::GetInfo() {

conn/FakeUdp.cpp

@@ -16,7 +16,3 @@ ConnInfo *FakeUdp::GetInfo() {
 bool FakeUdp::IsUdp() {
     return true;
 }
-
-bool FakeUdp::Alive() {
-    return true;
-}

conn/FakeUdp.h

@@ -16,8 +16,6 @@ class FakeUdp : public INetConn {
 
     inline bool IsUdp() override;
 
-    bool Alive() override;
-
 private:
     ConnInfo mInfo;
 };

conn/IAppGroup.cpp

@@ -206,7 +206,7 @@ int IAppGroup::NetConnKeepAliveHelper::OnSendRequest(uint8_t cmd, ssize_t nread,
 }
 
 int IAppGroup::NetConnKeepAliveHelper::OnRecvResponse(INetConn::IntKeyType connKey) {
-    return mReqMap.erase(connKey);
+    return RemoveRequest(connKey);
 }
 
 INetConn *IAppGroup::NetConnKeepAliveHelper::ConnOfIntKey(INetConn::IntKeyType connKey) {
@@ -251,8 +251,9 @@ void IAppGroup::NetConnKeepAliveHelper::onFlush() {
     auto aCopy = mReqMap;
     for (auto &e: aCopy) {
         if (e.second >= MAX_RETRY) {        // keep alive timeout
+            LOGE << "keepalive timeout";
             mAppGroup->onNetconnDead(e.first);
-            mReqMap.erase(e.first);
+            RemoveRequest(e.first);
         }
     }
 }
@@ -261,6 +262,10 @@ INetConnKeepAlive *IAppGroup::NetConnKeepAliveHelper::GetIKeepAlive() const {
     return mKeepAlive;
 }
 
+int IAppGroup::NetConnKeepAliveHelper::RemoveRequest(INetConnKeepAlive::IntKeyType connKey) {
+    return mReqMap.erase(connKey);
+}
+
 IAppGroup::ResetHelper::ResetHelper(IAppGroup *appGroup) {
     mAppGroup = appGroup;
     mReset = new ConnReset(this);

conn/IAppGroup.h

@@ -79,6 +79,8 @@ class IAppGroup : public IGroup, public ITcpObserver {
 
         INetConnKeepAlive *GetIKeepAlive() const override;
 
+        int RemoveRequest(IntKeyType connKey) override;
+
     private:
         void onFlush();
 
@@ -89,7 +91,7 @@ class IAppGroup : public IGroup, public ITcpObserver {
 
     private:
         const int MAX_RETRY = 3;
-        const uint32_t FLUSH_INTERVAL = 5000;  // every 5sec
+        const uint32_t FLUSH_INTERVAL = 2000;  // every 2sec
         const uint32_t FIRST_FLUSH_DELAY = 5000;   // on app start
         IAppGroup *mAppGroup = nullptr;
         uv_timer_t *mFlushTimer = nullptr;