OPTIM/MEDIUM: epoll: fuse active events into polled ones during polling changes

When trying to speculatively send data to a server being connected to,
we see the following pattern :

    connect() = EINPROGRESS
    send() = EAGAIN
    epoll_ctl(add, W)
    epoll_wait() = EPOLLOUT
    send() = success
  > epoll_ctl(del, W)
  > recv() = EAGAIN
  > epoll_ctl(add, R)
    recv() = success
    epoll_ctl(del, R)

The reason for the failed recv() call is that the reading was marked
as speculative while we already have a polled I/O there. So we already
know when removing send write poll that the read is pending. Thus,
let's improve this by merging speculative I/O into polled I/O when
polled state changes. The result is now the following as expected :

    connect() = EINPROGRESS
    send() = EAGAIN
    epoll_ctl(add, W)
    epoll_wait() = EPOLLOUT
    send() = success
    epoll_ctl(mod, R)
    recv() = success
    epoll_ctl(del, R)

This is specific to epoll(), it doesn't make much sense at the moment
to do so for other pollers, because the cost of updating them is very
small.

The average performance gain on small requests is of 1.6% in TCP mode,
which is easily explained with the syscall stats below for 10000 forwarded
connections :

Before :
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 91.02    0.024608           0     60000         1 epoll_wait
  2.19    0.000593           0     20000           shutdown
  1.52    0.000412           0     10000     10000 connect
  1.36    0.000367           0     29998      9998 sendto
  1.09    0.000294           0     49993           epoll_ctl
  0.93    0.000252           0     50004     20002 recvfrom
  0.79    0.000214           0     20005           close
  0.62    0.000167           0     20001     10001 accept4
  0.25    0.000067           0     20002           setsockopt
  0.13    0.000035           0     10001           socket
  0.10    0.000028           0     10001           fcntl

After:
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 87.59    0.024269           0     50012         1 epoll_wait
  3.19    0.000884           0     20000           shutdown
  2.33    0.000646           0     29996      9996 sendto
  2.02    0.000560           0     10005     10003 connect
  1.40    0.000387           0     40013     10013 recvfrom
  1.35    0.000374           0     40000           epoll_ctl
  0.64    0.000178           0     20001     10001 accept4
  0.55    0.000152           0     20005           close
  0.45    0.000124           0     20002           setsockopt
  0.31    0.000086           0     10001           fcntl
  0.17    0.000047           0     10001           socket

Overall :
   -16.6% epoll_wait
   -20%   recvfrom
   -20%   epoll_ctl

On HTTP, the gain is even better :

% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 80.43    0.015386           0     60006         1 epoll_wait
  4.61    0.000882           0     30000     10000 sendto
  3.74    0.000715           0     20001     10001 accept4
  3.35    0.000640           0     10000     10000 connect
  2.66    0.000508           0     20005           close
  1.34    0.000257           0     30002     10002 recvfrom
  1.27    0.000242           0     30005           epoll_ctl
  1.20    0.000230           0     10000           shutdown
  0.62    0.000119           0     20003           setsockopt
  0.40    0.000077           0     10001           socket
  0.39    0.000074           0     10001           fcntl
willy@wtap:haproxy$ head -15 apres.txt
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 83.47    0.020301           0     50008         1 epoll_wait
  4.26    0.001036           0     20005           close
  3.30    0.000803           0     30000     10000 sendto
  2.55    0.000621           0     20001     10001 accept4
  1.76    0.000428           0     10000     10000 connect
  1.20    0.000292           0     10000           shutdown
  1.14    0.000278           0     20001         1 recvfrom
  0.86    0.000210           0     20003           epoll_ctl
  0.71    0.000173           0     20003           setsockopt
  0.49    0.000120           0     10001           socket
  0.25    0.000060           0     10001           fcntl

Overall :
  -16.6% epoll_wait
  -33%   recvfrom
  -33%   epoll_ctl
OPTIM/MINOR: mark the source address as already known on accept()

Commit 986a9d2d12 moved the source address from the stream interface
to the session, but it did not set the flag on the connection to
report that the source address is known. Thus when logs are enabled,
we had a call to getpeername() which is redundant with the result
from accept(). This patch simply sets the flag.
BUG/MINOR: stats: don't count tarpitted connections twice

When a connection is tarpitted, a denied req is counted once when the
action is applied, and then a failed req is counted when the tarpit
timeout expires. This is completely wrong as the tarpit is exactly
equivalent to a deny since it's a disguised deny.

So let's not increment the failed req anymore.

This fix may be backported to 1.4 which has the same issue.
CLEANUP: http: homogenize processing of denied req counter

The reqdeny/reqideny and reqtarpit/reqitarpit rules used to maintain
the stats counters themselves while http-request deny/tarpit and
rspdeny/rspideny used to centralize them at the point where the
error is processed.

Thus, let's do the same for reqdeny/reqtarpit so that the functions
which iterate over the rules do not have to deal with these counters
anymore.
CLEANUP: http: merge error handling for req* and http-request *

The reqdeny/reqtarpit and http-request deny/tarpit were using
a copy-paste of the error handling code because originally the
req* actions used to maintain their own stats. This is not the
case anymore so we can use the same error blocks for both.

The http-request rulesets still has precedence over req* so no
functionality was changed.
url32+src - like base32+src but whole url including parameters

I have a need to limit traffic to each url from each source address. much
like base32+src but the whole url including parameters (this came from
looking at the recent 'Haproxy rate limit per matching request' thread)

attached is patch that seems to do the job, its a copy and paste job of the
base32 functions

the url32 function seems to work too and using 2 machines to request the
same url locks me out of both if I abuse from either with the url32 key
function and only the one if I use url32_src.

Neil
BUG/MEDIUM: http: fix possible parser crash when parsing erroneous "http-request redirect" rules

Baptiste Assmann reported a bug affecting the "http-request redirect"
parser. It may randomly crash when reporting an error message if the
syntax is not OK. It happens that this is caused by the output error
message pointer which was not initialized to NULL.

This bug is 1.5-specific (introduced in dev17), no backport is needed.
BUG/MINOR: http: fix build warning introduced with url32/url32_src

commit 39c63c5 "url32+src - like base32+src but whole url including parameters"
was missing the last argument "const char *kw", resulting in the build warning
below :

src/proto_http.c:10351:2: warning: initialization from incompatible pointer type [enabled by default]
src/proto_http.c:10351:2: warning: (near initialization for 'sample_fetch_keywords.kw[50].process') [enabled by default]
src/proto_http.c:10352:2: warning: initialization from incompatible pointer type [enabled by default]
src/proto_http.c:10352:2: warning: (near initialization for 'sample_fetch_keywords.kw[51].process') [enabled by default]

It's harmless since it's not needed there anyway.
CLEANUP: Make parameters of srv_downtime and srv_getinter const

The parameters of srv_downtime and srv_getinter are not modified
and thus may be const.

Signed-off-by: Simon Horman <horms@verge.net.au>
CLEANUP: Remove unused 'last_slowstart_change' field from struct peer

This was inadvertently added by "MEDIUM: checks: Add agent health check".
It appears to have never been used.

Signed-off-by: Simon Horman <horms@verge.net.au>
MEDIUM: Split up struct server's check element

This is in preparation for associating a agent check
with a server which runs as well as the server's existing check.

The split has been made by:
* Moving elements of struct server's check element that will
  be shared by both checks into a new check_common element
  of struct server.
* Moving the remaining elements to a new struct check and
  making struct server's check element a struct check.
* Adding a server element to struct check, a back-pointer
  to the server element it is a member of.
  - At this time the server could be obtained using
    container_of, however, this will not be so easy
    once a second struct check element is added to struct server
    to accommodate an agent health check.

Signed-off-by: Simon Horman <horms@verge.net.au>
MEDIUM: Move result element to struct check

Move result element from struct server to struct check
This allows check results to be independent of the check's server.

This is in preparation for associating a agent check
with a server which runs as well as the server's existing check.

Signed-off-by: Simon Horman <horms@verge.net.au>
MEDIUM: Paramatise functions over the check of a server

Paramatise the following functions over the check of a server

* set_server_down
* set_server_up
* srv_getinter
* server_status_printf
* set_server_check_status
* set_server_disabled
* set_server_enabled

Generally the server parameter of these functions has been removed.
Where it is still needed it is obtained using check->server.

This is in preparation for associating a agent check
with a server which runs as well as the server's existing check.
By paramatising these functions they may act on each of the checks
without further significant modification.

Explanation of the SSP_O_HCHK portion of this change:

* Prior to this patch SSP_O_HCHK serves a single purpose which
  is to tell server_status_printf() weather it should print
  the details of the check of a server or not.

  With the paramatisation that this patch adds there are two cases.
  1) Printing the details of the check in which case a
     valid check parameter is needed.
  2) Not printing the details of the check in which case
     the contents check parameter are unused.

  In case 1) we could pass SSP_O_HCHK and a valid check and;
  In case 2) we could pass !SSP_O_HCHK and any value for check
  including NULL.

  If NULL is used for case 2) then SSP_O_HCHK becomes supurfulous
  and as NULL is used for case 2) SSP_O_HCHK has been removed.

Signed-off-by: Simon Horman <horms@verge.net.au>
MEDIUM: cfgparse: Factor out check initialisation

This is in preparation for struct server having two elements
of type struct check.

Signed-off-by: Simon Horman <horms@verge.net.au>
MEDIUM: Add state to struct check

Add state to struct check. This is currently used to store one bit,
CHK_RUNNING, which is set if a check is running and clear otherwise.
This bit was previously SRV_CHK_RUNNING of the state element of struct
server.

This is in preparation for associating a agent check
with a server which runs as well as the server's existing check.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
MEDIUM: Move health element to struct check

This is in preparation for associating a agent check
with a server which runs as well as the server's existing check.

Signed-off-by: Simon Horman <horms@verge.net.au>