Implement poll() on systems which support it properly.

This eliminates the restriction on maximum socket descriptor number.

1 files changed, 49 insertions, 0 deletions

diff --git a/src/net.cpp b/src/net.cpp
index 2664828034..7b8b6e5ea2 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -26,6 +26,10 @@
 #include <fcntl.h>
 #endif
 
+#ifdef USE_POLL
+#include <poll.h>
+#endif
+
 #ifdef USE_UPNP
 #include <miniupnpc/miniupnpc.h>
 #include <miniupnpc/miniwget.h>
@@ -33,6 +37,7 @@
 #include <miniupnpc/upnperrors.h>
 #endif
 
+#include <unordered_map>
 
 #include <math.h>
 
@@ -1307,6 +1312,49 @@ bool CConnman::GenerateSelectSet(std::set<SOCKET> &recv_set, std::set<SOCKET> &s
     return !recv_set.empty() || !send_set.empty() || !error_set.empty();
 }
 
+#ifdef USE_POLL
+void CConnman::SocketEvents(std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set)
+{
+    std::set<SOCKET> recv_select_set, send_select_set, error_select_set;
+    if (!GenerateSelectSet(recv_select_set, send_select_set, error_select_set)) {
+        interruptNet.sleep_for(std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS));
+        return;
+    }
+
+    std::unordered_map<SOCKET, struct pollfd> pollfds;
+    for (SOCKET socket_id : recv_select_set) {
+        pollfds[socket_id].fd = socket_id;
+        pollfds[socket_id].events |= POLLIN;
+    }
+
+    for (SOCKET socket_id : send_select_set) {
+        pollfds[socket_id].fd = socket_id;
+        pollfds[socket_id].events |= POLLOUT;
+    }
+
+    for (SOCKET socket_id : error_select_set) {
+        pollfds[socket_id].fd = socket_id;
+        // These flags are ignored, but we set them for clarity
+        pollfds[socket_id].events |= POLLERR|POLLHUP;
+    }
+
+    std::vector<struct pollfd> vpollfds;
+    vpollfds.reserve(pollfds.size());
+    for (auto it : pollfds) {
+        vpollfds.push_back(std::move(it.second));
+    }
+
+    if (poll(vpollfds.data(), vpollfds.size(), SELECT_TIMEOUT_MILLISECONDS) < 0) return;
+
+    if (interruptNet) return;
+
+    for (struct pollfd pollfd_entry : vpollfds) {
+        if (pollfd_entry.revents & POLLIN)            recv_set.insert(pollfd_entry.fd);
+        if (pollfd_entry.revents & POLLOUT)           send_set.insert(pollfd_entry.fd);
+        if (pollfd_entry.revents & (POLLERR|POLLHUP)) error_set.insert(pollfd_entry.fd);
+    }
+}
+#else
 void CConnman::SocketEvents(std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set)
 {
     std::set<SOCKET> recv_select_set, send_select_set, error_select_set;
@@ -1380,6 +1428,7 @@ void CConnman::SocketEvents(std::set<SOCKET> &recv_set, std::set<SOCKET> &send_s
         }
     }
 }
+#endif
 
 void CConnman::SocketHandler()
 {