build: Fix features and make pthread an explicit dependency

Includes:
- Include threads sources even when NS3_PTHREAD=OFF
- Do not include realtime sources if NS3_REALTIME=OFF
- Disable tap-bridge if emulation or realtime features are disabled
- Build tap examples when tap-netdevice is enabled
- Remove NS3_PTHREAD option and make it an explicit requirement

CMakeLists.txt

@@ -80,7 +80,6 @@ set(NS3_OUTPUT_DIRECTORY "" CACHE STRING "Directory to store built artifacts")
 option(NS3_PRECOMPILE_HEADERS
        "Precompile module headers to speed up compilation" ON
 )
-option(NS3_PTHREAD "Build with pthread support" ON)
 option(NS3_PYTHON_BINDINGS "Build ns-3 python bindings" OFF)
 option(NS3_REALTIME "Build with realtime support" ON)
 option(NS3_SQLITE "Build with SQLite support" ON)

build-support/custom-modules/ns3-configtable.cmake

@@ -178,9 +178,6 @@ macro(write_configtable)
   string(APPEND out "Tests                         : ")
   check_on_or_off("${ENABLE_TESTS}" "${ENABLE_TESTS}")
 
-  string(APPEND out "Threading Primitives          : ")
-  check_on_or_off("${NS3_PTHREAD}" "${THREADS_ENABLED}")
-
   # string(APPEND out "Use sudo to set suid bit      : not enabled (option
   # --enable-sudo not selected) string(APPEND out "XmlIo : enabled
   string(APPEND out "\n\n")

build-support/custom-modules/ns3-lock.cmake

@@ -62,7 +62,6 @@ function(write_lock)
   )
 
   cache_cmake_flag(ENABLE_REALTIME "ENABLE_REAL_TIME" lock_contents)
-  cache_cmake_flag(NS3_PTHREAD "ENABLE_THREADING" lock_contents)
   cache_cmake_flag(ENABLE_EXAMPLES "ENABLE_EXAMPLES" lock_contents)
   cache_cmake_flag(ENABLE_TESTS "ENABLE_TESTS" lock_contents)
   cache_cmake_flag(NS3_OPENFLOW "ENABLE_OPENFLOW" lock_contents)

build-support/macros-and-definitions.cmake

@@ -683,6 +683,7 @@ macro(process_options)
 
     # LibRT
     mark_as_advanced(LIBRT)
+    set(ENABLE_REALTIME FALSE)
     if(${NS3_REALTIME})
       if(APPLE)
         message(
@@ -692,7 +693,6 @@ macro(process_options)
         find_library(LIBRT rt QUIET)
         if(NOT ${LIBRT_FOUND})
           message(FATAL_ERROR "LibRT was not found.")
-          set(ENABLE_REALTIME FALSE)
         else()
           message(STATUS "LibRT was found.")
           set(ENABLE_REALTIME TRUE)
@@ -702,17 +702,15 @@ macro(process_options)
     endif()
   endif()
 
-  set(THREADS_ENABLED FALSE)
-  set(PTHREADS_FOUND FALSE)
-  if(${NS3_PTHREAD})
   set(THREADS_PREFER_PTHREAD_FLAG)
   find_package(Threads QUIET)
   if(${CMAKE_USE_PTHREADS_INIT})
     include_directories(${THREADS_PTHREADS_INCLUDE_DIR})
-      set(PTHREADS_FOUND TRUE)
     set(HAVE_PTHREAD_H TRUE) # for core-config.h
     set(THREADS_ENABLED TRUE)
-    endif()
+    set(THREADS_FOUND TRUE)
+  else()
+    message(FATAL_ERROR Pthreads are required by ns-3)
   endif()
 
   set(Python3_LIBRARIES)

src/core/CMakeLists.txt

@@ -63,15 +63,17 @@ else()
   )
 endif()
 
-set(rt_sources
+set(rt_sources)
+set(rt_headers)
+if(${ENABLE_REALTIME})
+  set(rt_sources
       model/realtime-simulator-impl.cc
       model/wall-clock-synchronizer.cc
-)
-set(rt_headers
+  )
+  set(rt_headers
       model/realtime-simulator-impl.h
       model/wall-clock-synchronizer.h
-)
-if(${ENABLE_REALTIME})
+  )
   set(libraries_to_link
       ${libraries_to_link}
       ${LIBRT}
@@ -118,40 +120,25 @@ elseif(
   )
 endif()
 
-set(thread_sources)
-set(thread_headers)
-set(thread_test_sources)
-
-if(${NS3_PTHREAD})
-  if(${THREADS_FOUND})
-    set(thread_sources
-        model/unix-fd-reader.cc
-    )
-    set(thread_headers
-        model/unix-fd-reader.h
-    )
-    set(thread_sources
-        ${thread_sources}
+set(thread_sources
     model/system-thread.cc
-        model/unix-system-mutex.cc
+    model/unix-fd-reader.cc
     model/unix-system-condition.cc
-    )
-
-    set(thread_headers
-        ${thread_headers}
+    model/unix-system-mutex.cc
+)
+set(thread_headers
+    model/system-condition.h
     model/system-mutex.h
     model/system-thread.h
-        model/system-condition.h
-    )
-    set(libraries_to_link
+    model/unix-fd-reader.h
+)
+set(libraries_to_link
     ${libraries_to_link}
     pthread
-    )
-    set(thread_test_sources
+)
+set(thread_test_sources
     test/threaded-test-suite.cc
-    )
-  endif()
-endif()
+)
 
 if(${ENABLE_EXAMPLES})
   set(example_as_test_sources

src/fd-net-device/CMakeLists.txt

@@ -77,9 +77,7 @@ set(ENABLE_NETMAP_EMU
           ""
 )
 
-if(${THREADS_ENABLED}
-   AND HAVE_NET_ETHERNET_H
-)
+if(HAVE_NET_ETHERNET_H)
   set(ENABLE_FDNETDEV
       True
       CACHE INTERNAL
@@ -107,6 +105,8 @@ if(${THREADS_ENABLED}
      AND HAVE_IF_TUN_H
      AND HAVE_SYS_IOCTL_H
      AND ${ENABLE_TAP}
+     AND ${ENABLE_REALTIME}
+     AND ${ENABLE_EMU}
   )
     set(ENABLE_TAPNETDEV
         True

src/fd-net-device/examples/CMakeLists.txt

@@ -90,7 +90,7 @@ if(${ENABLE_EMU})
   )
 endif()
 
-if(${ENABLE_TAP})
+if(${ENABLE_TAPNETDEV})
   build_lib_example(
     NAME fd-tap-ping
     SOURCE_FILES fd-tap-ping.cc

src/tap-bridge/CMakeLists.txt

@@ -1,3 +1,25 @@
+if((NOT
+    ${ENABLE_REALTIME})
+   OR (NOT
+       ${ENABLE_EMU})
+)
+  message(
+    ${HIGHLIGHTED_STATUS}
+    "tap-bridge requires emulation and realtime features"
+  )
+  message(
+    ${HIGHLIGHTED_STATUS}
+    "Skipping src/tap-bridge"
+  )
+  list(
+    REMOVE_ITEM
+    libs_to_build
+    tap-bridge
+    PARENT_SCOPE
+  )
+  return()
+endif()
+
 build_lib(
   LIBNAME tap-bridge
   SOURCE_FILES