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Willy Tarreau 4256463b5a [BUG] url_param hash may return a down server
Jozef Hovan reported a bug sometimes causing a down server to be
used in url_param hashing mode.

This happens if the following conditions are met :
  - the backend contains more than one server with at least two
    of different weights
  - all servers but one are down
  - the server which is not down has a weight which does not divide
    all the other ones

Example: 3 servers with 20,20,10, the first one remains up.

The problem is caused by an optimisation in recalc_server_map()
which only fills the first map slot when only one server is up,
because all LB algorithms are optimized to use entry zero when
only one server is up... All but url_param. When doing the modulus,
we can return a position which is greater than zero and use an
entry which still refers to a server which has since been stopped.

One solution could be to optimize the url_param algo to proceed
as the other ones, but the fact that was wrong implies that we
can repeat the same bug later. So let's first correctly initialize
the map in order to avoid that trap.
2010-03-12 06:22:16 +01:00
contrib [CONTRIB] add base64rev-gen.c that was used to generate the base64rev table. 2010-01-31 19:14:07 +01:00
doc [MINOR] stats socket: add show sess <id> to dump details about a session 2010-03-05 17:58:04 +01:00
ebtree [MINOR] ebtree: add functions to lookup non-null terminated strings 2009-12-14 12:43:37 +01:00
examples [RELEASE] Released version 1.4.1 2010-03-04 23:39:19 +01:00
include [MINOR] stats socket: add show sess <id> to dump details about a session 2010-03-05 17:58:04 +01:00
src [BUG] url_param hash may return a down server 2010-03-12 06:22:16 +01:00
tests [MINOR] add option "mysql-check" to use MySQL health checks 2010-01-12 10:37:39 +01:00
.gitignore [CLEANUP] update .gitignore to ignore more temporary files 2008-03-07 09:39:37 +01:00
CHANGELOG [RELEASE] Released version 1.4.1 2010-03-04 23:39:19 +01:00
CONTRIB [DOC] Add information about http://haproxy.1wt.eu/contrib.html 2009-10-04 18:31:35 +02:00
LICENSE
Makefile [BUILD] fix platform-dependant build issues related to crypt() 2010-03-04 19:10:14 +01:00
Makefile.bsd [BUILD] fix BSD and OSX makefiles for missing files 2010-02-26 21:36:32 +01:00
Makefile.osx [BUILD] fix BSD and OSX makefiles for missing files 2010-02-26 21:36:32 +01:00
README [DOC] add some build info about the AIX platform 2010-01-29 10:30:19 +01:00
ROADMAP
SUBVERS [BUILD] centralize version and date into one file for each 2007-09-09 23:31:11 +02:00
TODO [MEDIUM] Implement "track [<backend>/]<server>" 2008-02-27 10:39:53 +01:00
VERDATE [RELEASE] Released version 1.4.1 2010-03-04 23:39:19 +01:00
VERSION [RELEASE] Released version 1.4.1 2010-03-04 23:39:19 +01:00

                           -------------------
                             H A - P r o x y
                             How to build it
                           -------------------
                              version 1.3.15
                              willy tarreau
                                2008/05/25


To build haproxy, you will need :
  - GNU make. Neither Solaris nor OpenBSD's make work with this makefile.
    However, specific Makefiles for BSD and OSX are provided.
  - GCC between 2.91 and 4.3. Others may work, but not tested.
  - GNU ld

Also, you might want to build with libpcre support, which will provide a very
efficient regex implementation and will also fix some badness on Solaris's one.

To build haproxy, you have to choose your target OS amongst the following ones
and assign it to the TARGET variable :

  - linux22     for Linux 2.2
  - linux24     for Linux 2.4 and above (default)
  - linux24e    for Linux 2.4 with support for a working epoll (> 0.21)
  - linux26     for Linux 2.6 and above
  - solaris     for Solaris 8 or 10 (others untested)
  - freebsd     for FreeBSD 5 to 6.2 (others untested)
  - openbsd     for OpenBSD 3.1 to 3.7 (others untested)
  - cygwin      for Cygwin
  - generic     for any other OS.
  - custom      to manually adjust every setting

You may also choose your CPU to benefit from some optimizations. This is
particularly important on UltraSparc machines. For this, you can assign
one of the following choices to the CPU variable :

  - i686 for intel PentiumPro, Pentium 2 and above, AMD Athlon
  - i586 for intel Pentium, AMD K6, VIA C3.
  - ultrasparc : Sun UltraSparc I/II/III/IV processor
  - generic : any other processor or no specific optimization. (default)

Alternatively, you may just set the CPU_CFLAGS value to the optimal GCC options
for your platform.

You may want to build specific target binaries which do not match your native
compiler's target. This is particularly true on 64-bit systems when you want
to build a 32-bit binary. Use the ARCH variable for this purpose. Right now
it only knows about a few x86 variants (i386,i486,i586,i686,x86_64) and sets
-m32/-m64 as well as -march=<arch> accordingly.

If your system supports PCRE (Perl Compatible Regular Expressions), then you
really should build with libpcre which is between 2 and 10 times faster than
other libc implementations. Regex are used for header processing (deletion,
rewriting, allow, deny). The only inconvenient of libpcre is that it is not
yet widely spread, so if you build for other systems, you might get into
trouble if they don't have the dynamic library. In this situation, you should
statically link libpcre into haproxy so that it will not be necessary to
install it on target systems. Available build options for PCRE are :

  - USE_PCRE=1 to use libpcre, in whatever form is available on your system
    (shared or static)

  - USE_STATIC_PCRE=1 to use a static version of libpcre even if the dynamic
    one is available. This will enhance portability.

  - with no option, use your OS libc's standard regex implemntation (default).
    Warning! group references on Solaris seem broken. Use static-pcre whenever
    possible.

By default, the DEBUG variable is set to '-g' to enable debug symbols. It is
not wise to disable it on uncommon systems, because it's often the only way to
get a complete core when you need one. Otherwise, you can set DEBUG to '-s' to
strip the binary.

For example, I use this to build for Solaris 8 :

    $ make TARGET=solaris CPU=ultrasparc USE_STATIC_PCRE=1

And I build it this way on OpenBSD or FreeBSD :

    $ make -f Makefile.bsd REGEX=pcre DEBUG= COPTS.generic="-Os -fomit-frame-pointer -mgnu"

In order to build a 32-bit binary on an x86_64 Linux system :

    $ make TARGET=linux26 ARCH=i386

If you need to pass other defines, includes, libraries, etc... then please
check the Makefile to see which ones will be available in your case, and
use the USE_* variables in the GNU Makefile, or ADDINC, ADDLIB, and DEFINE
variables in the BSD makefiles.

AIX 5.3 is known to work with the generic target. However, for the binary to
also run on 5.2 or earlier, you need to build with DEFINE="-D_MSGQSUPPORT",
otherwise __fd_select() will be used while not being present in the libc.

-- end