c++ - 编译libfluid示例 Controller 时未定义对 'event_base_del_virtual'的引用

Question

我正在尝试使用libfluid来编码我自己的OpenFlow Controller 。但是首先，我想构建sample controller以了解其工作原理。
编译样本 Controller 时出现以下错误:(这是我尝试make msg_controller时遇到的错误)

c++ msg/MsgController.cc -lfluid_msg -lfluid_base -I. -O3 -std=c++0x -o msg_controller
/usr/lib/gcc/x86_64-linux-gnu/7/../../../../lib/libfluid_base.so: undefined reference to `event_base_del_virtual'
/usr/lib/gcc/x86_64-linux-gnu/7/../../../../lib/libfluid_base.so: undefined reference to `event_base_add_virtual'
collect2: error: ld returned 1 exit status
Makefile:10: recipe for target 'msg_controller' failed
make: *** [msg_controller] Error 1

在构建样本 Controller 之前，我遵循 steps来构建 libfluid_base和 libfluid_msg。构建这两个库时，出现以下提示，我认为这可能有助于解决我的问题

If you ever happen to want to link against installed libraries in a given directory, LIBDIR, you must either use libtool, and specify the full pathname of the library, or use the '-LLIBDIR' flag during linking and do at least one of the following:

• add LIBDIR to the 'LD_LIBRARY_PATH' environment variable during execution
• add LIBDIR to the 'LD_RUN_PATH' environment variable during linking
• use the '-Wl,-rpath -Wl,LIBDIR' linker flag
• have your system administrator add LIBDIR to '/etc/ld.so.conf'

See any operating system documentation about shared libraries for more information, such as the ld(1) and ld.so(8) manual pages.

库未正确链接，是否存在 undefined 的引用错误？
我需要对c++命令进行一些更改吗？

我尝试了命令 grep -rn "event_base_del" /usr/lib和 grep -rn "event_base_add" /usr/lib event_base_del的输出如下( event_base_add相同)

Binary file /usr/lib/libfluid_base.a matches
Binary file /usr/lib/libfluid_base.so.0.0.0 matches
Binary file /usr/lib/x86_64-linux-gnu/libevent.a matches
Binary file /usr/lib/x86_64-linux-gnu/libevent-2.1.so.6.0.2 matches
Binary file /usr/lib/x86_64-linux-gnu/libevent_core.a matches
Binary file /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.6.0.2 matches

这是否意味着链接正确？因为 libfluid_base.so只是 libfluid_base.so.0.0.0的链接

lrwxrwxrwx  1 root root       22 Oct  8 09:36 libfluid_base.so -> libfluid_base.so.0.0.0

那么我该如何解决呢？

在尝试使用-levent_core或-levnet使示例代码链接到libevent之后。该错误继续存在，可能是因为我现在使用的libevent版本与当前版本的libfluid不兼容。通过我使用Ubuntu18.04的方式。

我将尝试使用旧版本的libevent在ubuntu16.04上构建它，以查看它是否有效。

Answer 1

event_base_del_virtual来自libevent library。将其与-levent_core链接。