diff --git a/srtcore/api.cpp b/srtcore/api.cpp
index d9875a8f4..65760da61 100644
--- a/srtcore/api.cpp
+++ b/srtcore/api.cpp
@@ -1433,6 +1433,20 @@ int CUDTUnited::epoll_wait(
    return m_EPoll.wait(eid, readfds, writefds, msTimeOut, lrfds, lwfds);
 }
 
+int CUDTUnited::epoll_uwait(
+   const int eid,
+   SRT_EPOLL_EVENT* fdsSet,
+   int fdsSize, 
+   int64_t msTimeOut)
+{
+   return m_EPoll.uwait(eid, fdsSet, fdsSize, msTimeOut);
+}
+
+int32_t CUDTUnited::epoll_set(int eid, int32_t flags)
+{
+    return m_EPoll.setflags(eid, flags);
+}
+
 int CUDTUnited::epoll_release(const int eid)
 {
    return m_EPoll.release(eid);
@@ -2663,6 +2677,52 @@ int CUDT::epoll_wait(
    }
 }
 
+int CUDT::epoll_uwait(
+   const int eid,
+   SRT_EPOLL_EVENT* fdsSet,
+   int fdsSize,
+   int64_t msTimeOut)
+{
+   try
+   {
+      return s_UDTUnited.epoll_uwait(eid, fdsSet, fdsSize, msTimeOut);
+   }
+   catch (CUDTException e)
+   {
+      s_UDTUnited.setError(new CUDTException(e));
+      return ERROR;
+   }
+   catch (std::exception& ee)
+   {
+      LOGC(mglog.Fatal, log << "epoll_uwait: UNEXPECTED EXCEPTION: "
+         << typeid(ee).name() << ": " << ee.what());
+      s_UDTUnited.setError(new CUDTException(MJ_UNKNOWN, MN_NONE, 0));
+      return ERROR;
+   }
+}
+
+int32_t CUDT::epoll_set(
+   const int eid,
+   int32_t flags)
+{
+   try
+   {
+      return s_UDTUnited.epoll_set(eid, flags);
+   }
+   catch (CUDTException e)
+   {
+      s_UDTUnited.setError(new CUDTException(e));
+      return ERROR;
+   }
+   catch (std::exception& ee)
+   {
+      LOGC(mglog.Fatal, log << "epoll_set: UNEXPECTED EXCEPTION: "
+         << typeid(ee).name() << ": " << ee.what());
+      s_UDTUnited.setError(new CUDTException(MJ_UNKNOWN, MN_NONE, 0));
+      return ERROR;
+   }
+}
+
 int CUDT::epoll_release(const int eid)
 {
    try
@@ -3102,6 +3162,11 @@ int epoll_wait2(
    return ret;
 }
 
+int epoll_uwait(int eid, SRT_EPOLL_EVENT* fdsSet, int fdsSize, int64_t msTimeOut)
+{
+   return CUDT::epoll_uwait(eid, fdsSet, fdsSize, msTimeOut);
+}
+
 int epoll_release(int eid)
 {
    return CUDT::epoll_release(eid);
diff --git a/srtcore/api.h b/srtcore/api.h
index 2036d5d7c..54d1713ef 100644
--- a/srtcore/api.h
+++ b/srtcore/api.h
@@ -190,6 +190,8 @@ friend class CRendezvousQueue;
    int epoll_update_usock(const int eid, const SRTSOCKET u, const int* events = NULL);
    int epoll_update_ssock(const int eid, const SYSSOCKET s, const int* events = NULL);
    int epoll_wait(const int eid, std::set<SRTSOCKET>* readfds, std::set<SRTSOCKET>* writefds, int64_t msTimeOut, std::set<SYSSOCKET>* lrfds = NULL, std::set<SYSSOCKET>* lwfds = NULL);
+   int epoll_uwait(const int eid, SRT_EPOLL_EVENT* fdsSet, int fdsSize, int64_t msTimeOut);
+   int32_t epoll_set(const int eid, int32_t flags);
    int epoll_release(const int eid);
 
       /// record the UDT exception.
diff --git a/srtcore/core.h b/srtcore/core.h
index 183c0a253..043a438a0 100644
--- a/srtcore/core.h
+++ b/srtcore/core.h
@@ -200,6 +200,8 @@ class CUDT
     static int epoll_update_usock(const int eid, const SRTSOCKET u, const int* events = NULL);
     static int epoll_update_ssock(const int eid, const SYSSOCKET s, const int* events = NULL);
     static int epoll_wait(const int eid, std::set<SRTSOCKET>* readfds, std::set<SRTSOCKET>* writefds, int64_t msTimeOut, std::set<SYSSOCKET>* lrfds = NULL, std::set<SYSSOCKET>* wrfds = NULL);
+    static int epoll_uwait(const int eid, SRT_EPOLL_EVENT* fdsSet, int fdsSize, int64_t msTimeOut);
+    static int32_t epoll_set(const int eid, int32_t flags);
     static int epoll_release(const int eid);
     static CUDTException& getlasterror();
     static int perfmon(SRTSOCKET u, CPerfMon* perf, bool clear = true);
diff --git a/srtcore/epoll.cpp b/srtcore/epoll.cpp
index a2b8d51d3..99f75fb44 100644
--- a/srtcore/epoll.cpp
+++ b/srtcore/epoll.cpp
@@ -326,6 +326,95 @@ int CEPoll::update_ssock(const int eid, const SYSSOCKET& s, const int* events)
    return 0;
 }
 
+int CEPoll::setflags(const int eid, int32_t flags)
+{
+    CGuard pg(m_EPollLock);
+    map<int, CEPollDesc>::iterator p = m_mPolls.find(eid);
+    if (p == m_mPolls.end())
+        throw CUDTException(MJ_NOTSUP, MN_EIDINVAL);
+    CEPollDesc& ed = p->second;
+
+    int32_t oflags = ed.flags();
+
+    if (flags == -1)
+        return oflags;
+
+    if (flags == 0)
+    {
+        ed.clr_flags(~int32_t());
+    }
+    else
+    {
+        ed.set_flags(flags);
+    }
+
+    return oflags;
+}
+
+int CEPoll::uwait(const int eid, SRT_EPOLL_EVENT* fdsSet, int fdsSize, int64_t msTimeOut)
+{
+    // It is allowed to call this function witn fdsSize == 0
+    // and therefore also NULL fdsSet. This will then only report
+    // the number of ready sockets, just without information which.
+    if (fdsSize < 0 || (fdsSize > 0 && !fdsSet))
+        throw CUDTException(MJ_NOTSUP, MN_INVAL);
+
+    int64_t entertime = CTimer::getTime();
+
+    while (true)
+    {
+        {
+            CGuard pg(m_EPollLock);
+            map<int, CEPollDesc>::iterator p = m_mPolls.find(eid);
+            if (p == m_mPolls.end())
+                throw CUDTException(MJ_NOTSUP, MN_EIDINVAL);
+            CEPollDesc& ed = p->second;
+
+            if (!ed.flags(SRT_EPOLL_ENABLE_EMPTY) && ed.watch_empty())
+            {
+                // Empty EID is not allowed, report error.
+                throw CUDTException(MJ_NOTSUP, MN_INVAL);
+            }
+
+            if (ed.flags(SRT_EPOLL_ENABLE_OUTPUTCHECK) && (fdsSet == NULL || fdsSize == 0))
+            {
+                // Empty EID is not allowed, report error.
+                throw CUDTException(MJ_NOTSUP, MN_INVAL);
+            }
+
+            if (!ed.m_sLocals.empty())
+            {
+                // XXX Add error log
+                // uwait should not be used with EIDs subscribed to system sockets
+                throw CUDTException(MJ_NOTSUP, MN_INVAL);
+            }
+
+            int total = 0; // This is a list, so count it during iteration
+            CEPollDesc::enotice_t::iterator i = ed.enotice_begin();
+            while (i != ed.enotice_end())
+            {
+                int pos = total; // previous past-the-end position
+                ++total;
+
+                if (total > fdsSize)
+                    break;
+
+                fdsSet[pos] = *i;
+
+                ed.checkEdge(i++); // NOTE: potentially deletes `i`
+            }
+            if (total)
+                return total;
+        }
+
+        if ((msTimeOut >= 0) && (int64_t(CTimer::getTime() - entertime) >= msTimeOut * int64_t(1000)))
+            break; // official wait does: throw CUDTException(MJ_AGAIN, MN_XMTIMEOUT, 0);
+
+        CTimer::waitForEvent();
+    }
+
+    return 0;
+}
 
 int CEPoll::wait(const int eid, set<SRTSOCKET>* readfds, set<SRTSOCKET>* writefds, int64_t msTimeOut, set<SYSSOCKET>* lrfds, set<SYSSOCKET>* lwfds)
 {
diff --git a/srtcore/epoll.h b/srtcore/epoll.h
old mode 100644
new mode 100755
index 527fa956a..014323df8
--- a/srtcore/epoll.h
+++ b/srtcore/epoll.h
@@ -341,6 +341,15 @@ friend class CRendezvousQueue;
 
    int wait(const int eid, std::set<SRTSOCKET>* readfds, std::set<SRTSOCKET>* writefds, int64_t msTimeOut, std::set<SYSSOCKET>* lrfds, std::set<SYSSOCKET>* lwfds);
 
+      /// wait for EPoll events or timeout optimized with explicit EPOLL_ERR event and the edge mode option.
+      /// @param [in] eid EPoll ID.
+      /// @param [out] fdsSet array of user socket events (SRT_EPOLL_IN | SRT_EPOLL_OUT | SRT_EPOLL_ERR).
+      /// @param [int] fdsSize of fds array
+      /// @param [in] msTimeOut timeout threshold, in milliseconds.
+      /// @return total of available events in the epoll system (can be greater than fdsSize)
+
+   int uwait(const int eid, SRT_EPOLL_EVENT* fdsSet, int fdsSize, int64_t msTimeOut);
+ 
       /// close and release an EPoll.
       /// @param [in] eid EPoll ID.
       /// @return 0 if success, otherwise an error number.
@@ -358,6 +367,8 @@ friend class CRendezvousQueue;
 
    int update_events(const SRTSOCKET& uid, std::set<int>& eids, int events, bool enable);
 
+   int setflags(const int eid, int32_t flags);
+
 private:
    int m_iIDSeed;                            // seed to generate a new ID
    pthread_mutex_t m_SeedLock;
diff --git a/srtcore/srt.h b/srtcore/srt.h
index 91ab48f66..65fd2c7de 100644
--- a/srtcore/srt.h
+++ b/srtcore/srt.h
@@ -685,6 +685,9 @@ typedef struct SRT_EPOLL_EVENT_
     SRTSOCKET fd;
     int       events; // SRT_EPOLL_IN | SRT_EPOLL_OUT | SRT_EPOLL_ERR
 } SRT_EPOLL_EVENT;
+SRT_API int srt_epoll_uwait(int eid, SRT_EPOLL_EVENT* fdsSet, int fdsSize, int64_t msTimeOut);
+
+SRT_API int32_t srt_epoll_set(int eid, int32_t flags);
 SRT_API int srt_epoll_release(int eid);
 
 // Logging control
diff --git a/srtcore/srt_c_api.cpp b/srtcore/srt_c_api.cpp
index 67244ff08..56d875f7b 100644
--- a/srtcore/srt_c_api.cpp
+++ b/srtcore/srt_c_api.cpp
@@ -251,6 +251,20 @@ int srt_epoll_wait(
         lrfds, lrnum, lwfds, lwnum);
 }
 
+int srt_epoll_uwait(int eid, SRT_EPOLL_EVENT* fdsSet, int fdsSize, int64_t msTimeOut)
+{
+    return UDT::epoll_uwait(
+        eid,
+        fdsSet,
+        fdsSize,
+        msTimeOut);
+}
+
+// use this function to set flags. Default flags are always "everything unset".
+// Pass 0 here to clear everything, or nonzero to set a desired flag.
+// Pass -1 to not change anything (but still get the current flag value).
+int32_t srt_epoll_set(int eid, int32_t flags) { return CUDT::epoll_set(eid, flags); }
+
 int srt_epoll_release(int eid) { return CUDT::epoll_release(eid); }
 
 void srt_setloglevel(int ll)
diff --git a/srtcore/udt.h b/srtcore/udt.h
index 1aab44623..77f903bd5 100644
--- a/srtcore/udt.h
+++ b/srtcore/udt.h
@@ -376,6 +376,7 @@ UDT_API int epoll_wait(int eid, std::set<UDTSOCKET>* readfds, std::set<UDTSOCKET
                        std::set<SYSSOCKET>* lrfds = NULL, std::set<SYSSOCKET>* wrfds = NULL);
 UDT_API int epoll_wait2(int eid, UDTSOCKET* readfds, int* rnum, UDTSOCKET* writefds, int* wnum, int64_t msTimeOut,
                         SYSSOCKET* lrfds = NULL, int* lrnum = NULL, SYSSOCKET* lwfds = NULL, int* lwnum = NULL);
+UDT_API int epoll_uwait(const int eid, SRT_EPOLL_EVENT* fdsSet, int fdsSize, int64_t msTimeOut);
 UDT_API int epoll_release(int eid);
 UDT_API ERRORINFO& getlasterror();
 UDT_API int getlasterror_code();