Add wepoll support to light up the epoll backend on Windows

libevent is lacking a scalable backend on Windows. Let's leverage the wepoll
library until Windows comes up with an epoll/kqueue compete user mode API.

- All regress tests pass for standard wepoll
- These 2 tests fail intermittently for changelist wepoll, so disabling
  changelist wepoll for now
     http/cancel_inactive_server
     http/stream_in
- verify target on Windows runs tests for both wepoll and win32 backends
- wepoll backend preferred over win32 backend
- wepoll version 1.5.6

v2: cleaner backend abstraction. Disallow wepoll on MinGW/Cygwin.
v3: Add wepoll.h to dist
v4: Make sure wepoll source files are excluded from cygwin/mingw builds
v5: Keep win32 as default backend on windows.
v6: Include wepoll in mingw builds. Verified that regress tests pass w/ WEPOLL backend.
v7: Enable wepoll on mingw when building with cmake
v8: Add wepoll testrunner for autotools test target

1 files changed, 15 insertions, 3 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index fd6595a1..9b064944 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -514,6 +514,9 @@ set(EVENT_INCLUDES ${EVENT_INCLUDES} stdio.h)
 CHECK_SYMBOLS_EXIST("${SYMBOLS_TO_CHECK}" "${EVENT_INCLUDES}" "EVENT")
 unset(SYMBOLS_TO_CHECK)
 set(EVENT__HAVE_EPOLL ${EVENT__HAVE_EPOLL_CREATE})
+if(WIN32 AND NOT CYGWIN)
+    set(EVENT__HAVE_WEPOLL 1)
+endif()
 
 # Get the gethostbyname_r prototype.
 if(EVENT__HAVE_GETHOSTBYNAME_R)
@@ -839,6 +842,12 @@ if(EVENT__HAVE_EPOLL)
     list(APPEND SRC_CORE epoll.c)
 endif()
 
+if(EVENT__HAVE_WEPOLL)
+    list(APPEND SRC_CORE
+        epoll.c
+        wepoll.c)
+endif()
+
 if(EVENT__HAVE_EVENT_PORTS)
     list(APPEND SRC_CORE evport.c)
 endif()
@@ -1240,6 +1249,10 @@ if (NOT EVENT__DISABLE_TESTS)
         list(APPEND BACKENDS DEVPOLL)
     endif()
 
+    if (EVENT__HAVE_WEPOLL)
+        list(APPEND BACKENDS WEPOLL)
+    endif()
+
     if (WIN32)
         list(APPEND BACKENDS WIN32)
     endif()
@@ -1382,13 +1395,12 @@ if (NOT EVENT__DISABLE_TESTS)
     #  If they are set in the shell the tests are running using simply "ctest" or "make test" will fail)
     if (WIN32)
         # Windows doesn't have "unset". But you can use "set VAR=" instead.
-        # We need to guard against the possibility taht EVENT_NOWIN32 is set, and all test failing
-        # since no event backend being available.
         file(TO_NATIVE_PATH ${CMAKE_CTEST_COMMAND} WINDOWS_CTEST_COMMAND)
 
         file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/tmp/verify_tests.bat
             "
             set EVENT_NOWIN32=
+            set EVENT_NOWEPOLL=
             \"${WINDOWS_CTEST_COMMAND}\"
             ")
 
@@ -1410,7 +1422,7 @@ if (NOT EVENT__DISABLE_TESTS)
         add_custom_target(verify COMMAND "${VERIFY_PATH}"
                           DEPENDS event ${ALL_TESTPROGS})
     else()
-        # On some platforms doing exec(unset) as CMake does won't work, so make sure
+        # On some platforms doing exec(unset) as CMake doesn't work, so make sure
         # we run the unset command in a shell instead.
         # First we write the script contents.
         file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/tmp/verify_tests.sh