【原创】libevent使能多线程模式需要做些什么

以下内容基于 libevent-2.0.21 版本

[root@Betty WGET]# tar zxvf libevent-2.0.21-stable.tar.gz

...

[root@Betty WGET]# cd libevent-2.0.21-stable

查看当前 config.* 文件有哪些（对于后面执行 ./configure 后新增文件）

[root@Betty libevent-2.0.21-stable]# ll config*

-rwxr-xr-x 1 sunfei sunfei 44826 11月 19 2012 config.guess

-rw-r--r-- 1 sunfei sunfei 11968 11月 19 2012 config.h.in

-rwxr-xr-x 1 sunfei sunfei 35454 11月 19 2012 config.sub

-rwxr-xr-x 1 sunfei sunfei 504592 11月 19 2012 configure

-rw-r--r-- 1 sunfei sunfei 21849 11月 18 2012 configure.in

[root@Betty libevent-2.0.21-stable]#

从 README 中可以看到简单几步就可以进行编译和安装

[root@Betty libevent-2.0.21-stable]# vi README

0. BUILDING AND INSTALLATION (Briefly)

$ ./configure

$ make

$ make verify # (optional)

$ sudo make install

...

查看 configure 配置选项

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[root@Betty libevent-2.0.21-stable]# ./configure --help

`configure' configures this package to adapt to many kinds of systems.

Usage: ./configure [OPTION]... [VAR=VALUE]...

To assign environment variables (e.g., CC, CFLAGS...), specify them as

VAR=VALUE. See below for descriptions of some of the useful variables.

Defaults for the options are specified in brackets.

Configuration:

-h, --help display this help and exit

--help=short display options specific to this package

--help=recursive display the short help of all the included packages

-V, --version display version information and exit

-q, --quiet, --silent do not print `checking ...' messages

--cache-file=FILE cache test results in FILE [disabled]

-C, --config-cache alias for `--cache-file=config.cache'

-n, --no-create do not create output files

--srcdir=DIR find the sources in DIR [configure dir or `..']

Installation directories:

--prefix=PREFIX install architecture-independent files in PREFIX

[/usr/local]

--exec-prefix=EPREFIX install architecture-dependent files in EPREFIX

[PREFIX]

By default, `make install' will install all the files in

`/usr/local/bin', `/usr/local/lib' etc. You can specify

an installation prefix other than `/usr/local' using `--prefix',

for instance `--prefix=$HOME'.

For better control, use the options below.

Fine tuning of the installation directories:

--bindir=DIR user executables [EPREFIX/bin]

--sbindir=DIR system admin executables [EPREFIX/sbin]

--libexecdir=DIR program executables [EPREFIX/libexec]

--sysconfdir=DIR read-only single-machine data [PREFIX/etc]

--sharedstatedir=DIR modifiable architecture-independent data [PREFIX/com]

--localstatedir=DIR modifiable single-machine data [PREFIX/var]

--libdir=DIR object code libraries [EPREFIX/lib]

--includedir=DIR C header files [PREFIX/include]

--oldincludedir=DIR C header files for non-gcc [/usr/include]

--datarootdir=DIR read-only arch.-independent data root [PREFIX/share]

--datadir=DIR read-only architecture-independent data [DATAROOTDIR]

--infodir=DIR info documentation [DATAROOTDIR/info]

--localedir=DIR locale-dependent data [DATAROOTDIR/locale]

--mandir=DIR man documentation [DATAROOTDIR/man]

--docdir=DIR documentation root [DATAROOTDIR/doc/PACKAGE]

--htmldir=DIR html documentation [DOCDIR]

--dvidir=DIR dvi documentation [DOCDIR]

--pdfdir=DIR pdf documentation [DOCDIR]

--psdir=DIR ps documentation [DOCDIR]

Program names:

--program-prefix=PREFIX prepend PREFIX to installed program names

--program-suffix=SUFFIX append SUFFIX to installed program names

--program-transform-name=PROGRAM run sed PROGRAM on installed program names

System types:

--build=BUILD configure for building on BUILD [guessed]

--host=HOST cross-compile to build programs to run on HOST [BUILD]

Optional Features:

--disable-option-checking ignore unrecognized --enable/--with options

--disable-FEATURE do not include FEATURE (same as --enable-FEATURE=no)

--enable-FEATURE[=ARG] include FEATURE [ARG=yes]

--disable-dependency-tracking speeds up one-time build

--enable-dependency-tracking do not reject slow dependency extractors

--enable-gcc-warnings enable verbose warnings with GCC

--disable-thread-support

disable support for threading 去使能多线程支持（锁相关）

--disable-malloc-replacement

disable support for replacing the memory mgt

functions

--disable-openssl disable support for openssl encryption

--disable-debug-mode disable support for running in debug mode

--disable-libevent-install, disable installation of libevent

--disable-libevent-regress, skip regress in make check

--enable-function-sections, make static library allow smaller binaries with --gc-sections

--enable-shared[=PKGS] build shared libraries [default=yes]

--enable-static[=PKGS] build static libraries [default=yes]

--enable-fast-install[=PKGS]

optimize for fast installation [default=yes]

--disable-libtool-lock avoid locking (might break parallel builds)

Optional Packages:

--with-PACKAGE[=ARG] use PACKAGE [ARG=yes]

--without-PACKAGE do not use PACKAGE (same as --with-PACKAGE=no)

--with-pic[=PKGS] try to use only PIC/non-PIC objects [default=use

both]

--with-gnu-ld assume the C compiler uses GNU ld [default=no]

--with-sysroot=DIR Search for dependent libraries within DIR

(or the compiler's sysroot if not specified).

Some influential environment variables:

CC C compiler command

CFLAGS C compiler flags

LDFLAGS linker flags, e.g. -L<lib dir> if you have libraries in a

nonstandard directory <lib dir>

LIBS libraries to pass to the linker, e.g. -l<library>

CPPFLAGS (Objective) C/C++ preprocessor flags, e.g. -I<include dir> if

you have headers in a nonstandard directory <include dir>

CPP C preprocessor

Use these variables to override the choices made by `configure' or to help

it to find libraries and programs with nonstandard names/locations.

Report bugs to the package provider.

[root@Betty libevent-2.0.21-stable]#

因为我需要 libevent 支持多线程锁，只需默认配置即可

[root@Betty libevent-2.0.21-stable]# ./configure

...

checking for the pthreads library -lpthreads... no -- 1

checking whether pthreads work without any flags... yes -- 2

checking for joinable pthread attribute... PTHREAD_CREATE_JOINABLE -- 3

checking if more special flags are required for pthreads... no

checking size of pthread_t... 8

...

[root@Betty libevent-2.0.21-stable]#

[root@Betty libevent-2.0.21-stable]# ll config*

-rwxr-xr-x 1 sunfei sunfei 44826 11月 19 2012 config.guess

-rw-r--r-- 1 root root 12603 8月 19 14:25 config.h -- new

-rw-r--r-- 1 sunfei sunfei 11968 11月 19 2012 config.h.in

-rw-r--r-- 1 root root 168882 8月 19 14:25 config.log -- new

-rwxr-xr-x 1 root root 65544 8月 19 14:25 config.status -- new

-rwxr-xr-x 1 sunfei sunfei 35454 11月 19 2012 config.sub

-rwxr-xr-x 1 sunfei sunfei 504592 11月 19 2012 configure

-rw-r--r-- 1 sunfei sunfei 21849 11月 18 2012 configure.in

[root@Betty libevent-2.0.21-stable]#

查看 config.log 的内容（对应 ./configure 输出的详细内容）

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[root@Betty libevent-2.0.21-stable]# vi config.log

This file contains any messages produced by compilers while

running configure, to aid debugging if configure makes a mistake.

It was created by configure, which was

generated by GNU Autoconf 2.68. Invocation command line was

$ ./configure

## --------- ##

## Platform. ##

## --------- ##

hostname = Betty

uname -m = x86_64

uname -r = 2.6.32-358.el6.x86_64

uname -s = Linux

uname -v = #1 SMP Fri Feb 22 00:31:26 UTC 2013

...

## ----------- ##

## Core tests. ##

## ----------- ##

...

configure:3214: checking for gcc

configure:3230: found /usr/bin/gcc

configure:3241: result: gcc

configure:3470: checking for C compiler version

configure:3479: gcc --version >&5

gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-11)

This is free software; see the source for copying conditions. There is NO

warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

configure:3490: $? = 0

configure:3479: gcc -v >&5

Using built-in specs.

Target: x86_64-redhat-linux

Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --ena

ble-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-

dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --wi

th-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux

Thread model: posix

gcc version 4.4.7 20120313 (Red Hat 4.4.7-11) (GCC)

configure:3490: $? = 0

...

configure:14625: checking for the pthreads library -lpthreads -- 检测能否以 -lpthreads 引用 libpthreads.so 库

configure:14658: gcc -o conftest -g -O2 -Wall -fno-strict-aliasing conftest.c -lpthreads -lrt >&5

conftest.c: In function 'main':

conftest.c:121: warning: null argument where non-null required (argument 1)

conftest.c:122: warning: null argument where non-null required (argument 1)

conftest.c:122: warning: null argument where non-null required (argument 3)

conftest.c:120: warning: 'th' is used uninitialized in this function

/usr/bin/ld: cannot find -lpthreads -- 结果发现不能

collect2: ld returned 1 exit status

configure:14658: $? = 1

configure: failed program was:

| /* confdefs.h */

| #define PACKAGE_NAME ""

| #define PACKAGE_TARNAME ""

| #define PACKAGE_VERSION ""

| #define PACKAGE_STRING ""

| #define PACKAGE_BUGREPORT ""

| #define PACKAGE_URL ""

| #define PACKAGE "libevent"

| #define VERSION "2.0.21-stable"

| #define NUMERIC_VERSION 0x02001500

| #define STDC_HEADERS 1

| #define HAVE_SYS_TYPES_H 1

| #define HAVE_SYS_STAT_H 1

| #define HAVE_STDLIB_H 1

| #define HAVE_STRING_H 1

| #define HAVE_MEMORY_H 1

| #define HAVE_STRINGS_H 1

| #define HAVE_INTTYPES_H 1

| #define HAVE_STDINT_H 1

| #define HAVE_UNISTD_H 1

| #define HAVE_DLFCN_H 1

| #define LT_OBJDIR ".libs/"

| #define HAVE_ZLIB_H 1

| #define HAVE_LIBZ 1

| #define HAVE_OPENSSL_BIO_H 1

| #define HAVE_OPENSSL 1

| #define STDC_HEADERS 1

| #define HAVE_FCNTL_H 1

| #define HAVE_STDARG_H 1

| #define HAVE_INTTYPES_H 1

| #define HAVE_STDINT_H 1

| #define HAVE_STDDEF_H 1

| #define HAVE_POLL_H 1

| #define HAVE_UNISTD_H 1

| #define HAVE_SYS_EPOLL_H 1

| #define HAVE_SYS_TIME_H 1

| #define HAVE_SYS_QUEUE_H 1

| #define HAVE_SYS_PARAM_H 1

| #define HAVE_SYS_IOCTL_H 1

| #define HAVE_SYS_SELECT_H 1

| #define HAVE_NETINET_IN_H 1

| #define HAVE_SYS_SOCKET_H 1

| #define HAVE_SYS_UIO_H 1

| #define HAVE_ARPA_INET_H 1

| #define HAVE_SYS_EVENTFD_H 1

| #define HAVE_SYS_MMAN_H 1

| #define HAVE_SYS_SENDFILE_H 1

| #define HAVE_SYS_WAIT_H 1

| #define HAVE_NETDB_H 1

| #define HAVE_SYS_STAT_H 1

| #define HAVE_SYS_SYSCTL_H 1

| #define HAVE_TAILQFOREACH 1

| #define HAVE_TIMERADD 1

| #define HAVE_TIMERCMP 1

| #define HAVE_TIMERCLEAR 1

| #define HAVE_TIMERISSET 1

| #define HAVE_DECL_CTL_KERN 1

| #define HAVE_DECL_KERN_RANDOM 1

| #define HAVE_DECL_RANDOM_UUID 1

| #define HAVE_DECL_KERN_ARND 0

| #define TIME_WITH_SYS_TIME 1

| #define HAVE_GETTIMEOFDAY 1

| #define HAVE_VASPRINTF 1

| #define HAVE_FCNTL 1

| #define HAVE_CLOCK_GETTIME 1

| #define HAVE_STRTOK_R 1

| #define HAVE_STRSEP 1

| #define HAVE_GETNAMEINFO 1

| #define HAVE_INET_NTOP 1

| #define HAVE_INET_PTON 1

| #define HAVE_SIGNAL 1

| #define HAVE_SIGACTION 1

| #define HAVE_STRTOLL 1

| #define HAVE_INET_ATON 1

| #define HAVE_PIPE 1

| #define HAVE_EVENTFD 1

| #define HAVE_SENDFILE 1

| #define HAVE_MMAP 1

| #define HAVE_SPLICE 1

| #define HAVE_GETEUID 1

| #define HAVE_GETEGID 1

| #define HAVE_GETPROTOBYNUMBER 1

| #define HAVE_SETENV 1

| #define HAVE_UNSETENV 1

| #define HAVE_PUTENV 1

| #define HAVE_SYSCTL 1

| #define HAVE_UMASK 1

| #define HAVE_GETADDRINFO 1

| #define SIZEOF_LONG 8

| #define HAVE_SETFD 1

| #define HAVE_SELECT 1

| #define HAVE_POLL 1

| #define HAVE_EPOLL_CTL 1

| #define HAVE_EPOLL 1

| #define HAVE_UINT64_T 1

| #define HAVE_UINT32_T 1

| #define HAVE_UINT16_T 1

| #define HAVE_UINT8_T 1

| #define HAVE_UINTPTR_T 1

| #define HAVE_FD_MASK 1

| #define SIZEOF_LONG_LONG 8

| #define SIZEOF_LONG 8

| #define SIZEOF_INT 4

| #define SIZEOF_SHORT 2

| #define SIZEOF_SIZE_T 8

| #define SIZEOF_VOID_P 8

| #define HAVE_STRUCT_IN6_ADDR 1

| #define HAVE_STRUCT_SOCKADDR_IN6 1

| #define HAVE_SA_FAMILY_T 1

| #define HAVE_STRUCT_ADDRINFO 1

| #define HAVE_STRUCT_SOCKADDR_STORAGE 1

| #define HAVE_STRUCT_IN6_ADDR_S6_ADDR32 1

| #define HAVE_STRUCT_IN6_ADDR_S6_ADDR16 1

| #define HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY 1

| /* end confdefs.h. */

| #include <pthread.h>

| int

| main ()

| {

| pthread_t th; pthread_join(th, 0);

| pthread_attr_init(0); pthread_cleanup_push(0, 0);

| pthread_create(0,0,0,0); pthread_cleanup_pop(0);

| ;

| return 0;

| }

configure:14667: result: no

configure:14570: checking whether pthreads work without any flags -- 检查能否无任何 flag 使用 pthreads （这里的用意不太明白）

configure:14658: gcc -o conftest -g -O2 -Wall -fno-strict-aliasing conftest.c -lrt >&5

conftest.c: In function 'main':

conftest.c:121: warning: null argument where non-null required (argument 1)

conftest.c:122: warning: null argument where non-null required (argument 1)

conftest.c:122: warning: null argument where non-null required (argument 3)

conftest.c:120: warning: 'th' is used uninitialized in this function

configure:14658: $? = 0

configure:14667: result: yes

configure:14686: checking for joinable pthread attribute -- 检查 pthread 特性是否支持 joinable（注意，这里就变成了 pthread 而不再是 pthreads）

configure:14701: gcc -o conftest -g -O2 -Wall -fno-strict-aliasing conftest.c -lrt >&5

configure:14701: $? = 0

configure:14707: result: PTHREAD_CREATE_JOINABLE

configure:14717: checking if more special flags are required for pthreads

configure:14724: result: no

configure:14813: checking size of pthread_t

configure:14818: gcc -o conftest -g -O2 -Wall -fno-strict-aliasing conftest.c -lrt >&5

configure:14818: $? = 0

configure:14818: ./conftest

configure:14818: $? = 0

configure:14835: result: 8

configure:15289: creating ./config.status

...

查看生成的 config.h 文件（只列出和 thread 相关内容）

[root@Betty libevent-2.0.21-stable]# vi config.h

/* config.h. Generated from config.h.in by configure. */

/* config.h.in. Generated from configure.in by autoheader. */

...

/* Define if libevent should not be compiled with thread support */

/* #undef DISABLE_THREAD_SUPPORT */

...

/* Define if you have POSIX threads libraries and header files. */

/* #undef HAVE_PTHREAD */

/* Define if we have pthreads on this system */

#define HAVE_PTHREADS 1 -- 和 thread 有关的宏，只定义了这个

...

/* Define to necessary symbol if this constant uses a non-standard name on

your system. */

/* #undef PTHREAD_CREATE_JOINABLE */

...

/* The size of `pthread_t', as computed by sizeof. */

#define SIZEOF_PTHREAD_T 8

在 libevent 源码中搜索 HAVE_PTHREADS ，结果只能找到 _EVENT_HAVE_PTHREADS 。那么两者是什么关系呢？

要回答中问题，需要执行 make

[root@Betty libevent-2.0.21-stable]# make

test -d include/event2 || /bin/mkdir -p include/event2

/bin/sed -f ./make-event-config.sed < config.h > include/event2/event-config.hT

mv -f include/event2/event-config.hT include/event2/event-config.h

...

从前几行的输出中，可以看到如何从 config.h 得到 event2/event-config.h 这个头文件的。

基于 make-event-config.sed 文件，对 config.h 进行 sed 替换处理后，得到 event2/event-config.hT 文件；
再将 event2/event-config.hT 强制变更为（覆盖） event2/event-config.h 。

文件 make-event-config.sed 内容如下

[root@Betty libevent-2.0.21-stable]# vi make-event-config.sed

# Sed script to postprocess config.h into event-config.h. -- 这里说的很清楚了，用于将 config.h 处理为 event-config.h

1i\ --指定 event-config.h 开始内容

/* event2/event-config.h\

*\

* This file was generated by autoconf when libevent was built, and post-\

* processed by Libevent so that its macros would have a uniform prefix.\

*\

* DO NOT EDIT THIS FILE.\

*\

* Do not rely on macros in this file existing in later versions.\

*/\

\

#ifndef _EVENT2_EVENT_CONFIG_H_\

#define _EVENT2_EVENT_CONFIG_H_\

$a\

\

#endif /* event2/event-config.h */ -- 指定 event-config.h 最后内容

s/#define /#define _EVENT_/ -- 这里完成了 XXX 到 _EVENT_XXX 的替换

s/#undef /#undef _EVENT_/

s/#ifndef /#ifndef _EVENT_/

所以 make 之后，我们得到了如下的 event-config.h 文件

[root@Betty libevent-2.0.21-stable]# vi include/event2/event-config.h

/* event2/event-config.h

*

* This file was generated by autoconf when libevent was built, and post-

* processed by Libevent so that its macros would have a uniform prefix.

*

* DO NOT EDIT THIS FILE.

*

* Do not rely on macros in this file existing in later versions.

*/

#ifndef _EVENT2_EVENT_CONFIG_H_

#define _EVENT2_EVENT_CONFIG_H_

/* config.h. Generated from config.h.in by configure. */

/* config.h.in. Generated from configure.in by autoheader. */

...

/* Define if libevent should not be compiled with thread support */

/* #undef _EVENT_DISABLE_THREAD_SUPPORT */

...

/* Define if you have POSIX threads libraries and header files. */

/* #undef _EVENT_HAVE_PTHREAD */

/* Define if we have pthreads on this system */

#define _EVENT_HAVE_PTHREADS 1

...

/* Define to necessary symbol if this constant uses a non-standard name on

your system. */

/* #undef _EVENT_PTHREAD_CREATE_JOINABLE */

...

/* The size of `pthread_t', as computed by sizeof. */

#define _EVENT_SIZEOF_PTHREAD_T 8

...

这里留个疑问：
_EVENT_HAVE_PTHREAD 和 _EVENT_HAVE_PTHREADS 的区别是什么？

从源码 thread.h 中可以看到，此时可以使用 evthread_use_pthreads() 函数了。

#if defined(_EVENT_HAVE_PTHREADS) || defined(_EVENT_IN_DOXYGEN)

/** Sets up Libevent for use with Pthreads locking and thread ID functions.

Unavailable if Libevent is not build for use with pthreads. Requires

libraries to link against Libevent_pthreads as well as Libevent.

@return 0 on success, -1 on failure. */

int evthread_use_pthreads(void);

/** Defined if Libevent was built with support for evthread_use_pthreads() */

#define EVTHREAD_USE_PTHREADS_IMPLEMENTED 1

#endif

至于 evthread_use_pthreads() 函数是做什么的，如何使用，已经不是本文要说明的内容了，网上可以找到相关文章。

时间： 2024-11-05 06:30:22

【原创】libevent使能多线程模式需要做些什么

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