From ab83f51735d21dde77aa5f946cde3b0266997e44 Mon Sep 17 00:00:00 2001
From: Jeff Becker <jeff@i2p.rocks>
Date: Thu, 14 Mar 2019 09:19:30 -0400
Subject: [PATCH 1/2] clear errno

---
 llarp/ev/ev_epoll.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/llarp/ev/ev_epoll.cpp b/llarp/ev/ev_epoll.cpp
index adcabe097..def589aa3 100644
--- a/llarp/ev/ev_epoll.cpp
+++ b/llarp/ev/ev_epoll.cpp
@@ -343,7 +343,6 @@ llarp_epoll_loop::tick(int ms)
         {
           llarp::LogDebug("epoll error");
           ev->error();
-          errno = 0;
         }
         else
         {
@@ -362,12 +361,13 @@ llarp_epoll_loop::tick(int ms)
         }
       }
       ++idx;
+      // clear errno just in case
+      errno = 0;
     }
   }
   if(result != -1)
     tick_listeners();
   /// if we didn't get an io events we sleep to avoid 100% cpu use
-  errno = 0;
   if(!didIO)
     std::this_thread::sleep_for(std::chrono::milliseconds(ms));
   return result;

From 8d078f19eb9527622f5d060c260fba1a42059e2b Mon Sep 17 00:00:00 2001
From: Jeff Becker <jeff@i2p.rocks>
Date: Fri, 15 Mar 2019 10:31:54 -0400
Subject: [PATCH 2/2] wrap epoll with IO checks for resetting errno

---
 llarp/ev/ev.cpp       | 13 ++++++-------
 llarp/ev/ev.hpp       | 21 +++++++++++++++++++++
 llarp/ev/ev_epoll.cpp | 25 ++++++++++++++++---------
 3 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/llarp/ev/ev.cpp b/llarp/ev/ev.cpp
index 556f3b72e..8e51ff213 100644
--- a/llarp/ev/ev.cpp
+++ b/llarp/ev/ev.cpp
@@ -51,8 +51,7 @@ llarp_make_ev_loop()
 #error no event loop subclass
 #endif
   r->init();
-  r->_now = llarp::time_now_ms();
-
+  r->update_time();
   return r;
 }
 
@@ -71,7 +70,7 @@ llarp_ev_loop_run(struct llarp_ev_loop *ev, llarp::Logic *logic)
 {
   while(ev->running())
   {
-    ev->_now = llarp::time_now_ms();
+    ev->update_time();
     ev->tick(EV_TICK_INTERVAL);
     if(ev->running())
       logic->tick(ev->_now);
@@ -92,12 +91,12 @@ llarp_ev_loop_run_single_process(struct llarp_ev_loop *ev,
 {
   while(ev->running())
   {
-    ev->_now = llarp::time_now_ms();
+    ev->update_time();
     ev->tick(EV_TICK_INTERVAL);
     if(ev->running())
     {
-      ev->_now = llarp::time_now_ms();
-      logic->tick_async(ev->_now);
+      ev->update_time();
+      logic->tick_async(ev->time_now());
       llarp_threadpool_tick(tp);
     }
   }
@@ -125,7 +124,7 @@ llarp_time_t
 llarp_ev_loop_time_now_ms(struct llarp_ev_loop *loop)
 {
   if(loop)
-    return loop->_now;
+    return loop->time_now();
   return llarp::time_now_ms();
 }
 
diff --git a/llarp/ev/ev.hpp b/llarp/ev/ev.hpp
index a18cd7801..ff54dd683 100644
--- a/llarp/ev/ev.hpp
+++ b/llarp/ev/ev.hpp
@@ -50,6 +50,15 @@ typedef struct sockaddr_un
 #define EV_WRITE_BUF_SZ (2 * 1024UL)
 #endif
 
+/// do io and reset errno after
+static ssize_t
+IO(std::function< ssize_t(void) > iofunc)
+{
+  ssize_t ret = iofunc();
+  errno       = 0;
+  return ret;
+}
+
 namespace llarp
 {
 #ifdef _WIN32
@@ -697,6 +706,18 @@ struct llarp_ev_loop
   virtual bool
   running() const = 0;
 
+  void
+  update_time()
+  {
+    _now = llarp::time_now_ms();
+  }
+
+  virtual llarp_time_t
+  time_now() const
+  {
+    return _now;
+  }
+
   /// return false on socket error (non blocking)
   virtual bool
   tcp_connect(llarp_tcp_connecter* tcp, const sockaddr* addr) = 0;
diff --git a/llarp/ev/ev_epoll.cpp b/llarp/ev/ev_epoll.cpp
index def589aa3..1b9baaed0 100644
--- a/llarp/ev/ev_epoll.cpp
+++ b/llarp/ev/ev_epoll.cpp
@@ -341,35 +341,42 @@ llarp_epoll_loop::tick(int ms)
                         " events=", std::to_string(events[idx].events));
         if(events[idx].events & EPOLLERR && errno)
         {
-          llarp::LogDebug("epoll error");
-          ev->error();
+          IO([&]() -> ssize_t {
+            llarp::LogDebug("epoll error");
+            ev->error();
+            return 0;
+          });
         }
         else
         {
           // write THEN READ don't revert me
           if(events[idx].events & EPOLLOUT)
           {
-            llarp::LogDebug("epoll out");
-            ev->flush_write();
+            IO([&]() -> ssize_t {
+              llarp::LogDebug("epoll out");
+              ev->flush_write();
+              return 0;
+            });
           }
           if(events[idx].events & EPOLLIN)
           {
-            llarp::LogDebug("epoll in");
-            if(ev->read(readbuf, sizeof(readbuf)) > 0)
+            ssize_t amount = IO([&]() -> ssize_t {
+              llarp::LogDebug("epoll in");
+              return ev->read(readbuf, sizeof(readbuf));
+            });
+            if(amount > 0)
               didIO = true;
           }
         }
       }
       ++idx;
-      // clear errno just in case
-      errno = 0;
     }
   }
   if(result != -1)
     tick_listeners();
   /// if we didn't get an io events we sleep to avoid 100% cpu use
   if(!didIO)
-    std::this_thread::sleep_for(std::chrono::milliseconds(ms));
+    std::this_thread::sleep_for(std::chrono::milliseconds(5));
   return result;
 }