In the same way than for the tasks, the applets api was changed to be able
to start a new appctx on a thread subset. For now the feature is
disabled. Only appctx_new_here() is working. But it will be possible to
start an appctx on a specific thread or a subset via a mask.
A .init callback function is defined for the spoe_applet applet. This
function finishes the spoe_appctx initialization. It also finishes the
appctx startup by calling appctx_finalize_startup() and its handles the
stream customization.
The session created for frontend applets is now totally owns by the
corresponding appctx. It means the appctx is now responsible to release
it. This removes the hack in stream_free() about frontend applets to be sure
to release the session.
The two functions became exact copies since there's no more special case
for the appctx owner. Let's merge them into a single one, that simplifies
the code.
This one is the pointer to the conn_stream which is always in the
endpoint that is always present in the appctx, thus it's not needed.
This patch removes it and replaces it with appctx_cs() instead. A
few occurences that were using __cs_strm(appctx->owner) were moved
directly to appctx_strm() which does the equivalent.
Remaining flags and associated functions are move in the conn-stream
scope. These flags are added on the endpoint and not the conn-stream
itself. This way it will be possible to get them from the mux or the
applet. The functions to get or set these flags are renamed accordingly with
the "cs_" prefix and updated to manipualte a conn-stream instead of a
stream-interface.
si_shutr(), si_shutw(), si_chk_rcv() and si_chk_snd() are moved in the
conn-stream scope and renamed, respectively, cs_shutr(), cs_shutw(),
cs_chk_rcv(), cs_chk_snd() and manipulate a conn-stream instead of a
stream-interface.
The stream-interface state (SI_ST_*) is now in the conn-stream. It is a
mechanical replacement for now. Nothing special. SI_ST_* and SI_SB_* were
renamed accordingly. Utils functions to manipulate these infos were moved
under the conn-stream scope.
But it could be good to keep in mind that this part should be
reworked. Indeed, at the CS level, we only need to know if it is ready to
receive or to send. The state of conn-stream from INI to EST is only used on
the server side. The client CS is immediately set to EST. Thus current
SI_ST_* states should probably be moved to the stream to reflect the server
connection state during the establishment stage.
At many places, we now use the new CS functions to get a stream or a channel
from a conn-stream instead of using the stream-interface API. It is the
first step to reduce the scope of the stream-interfaces. The main change
here is about the applet I/O callback functions. Before the refactoring, the
stream-interface was the appctx owner. Thus, it was heavily used. Now, as
far as possible,the conn-stream is used. Of course, it remains many calls to
the stream-interface API.
The conn-stream endpoint is now shared between the conn-stream and the
applet or the multiplexer. If the mux or the applet is created first, it is
responsible to also create the endpoint and share it with the conn-stream.
If the conn-stream is created first, it is the opposite.
When the endpoint is only owned by an applet or a mux, it is called an
orphan endpoint (there is no conn-stream). When it is only owned by a
conn-stream, it is called a detached endpoint (there is no mux/applet).
The last entity that owns an endpoint is responsible to release it. When a
mux or an applet is detached from a conn-stream, the conn-stream
relinquishes the endpoint to recreate a new one. This way, the endpoint
state is never lost for the mux or the applet.
It is a transient commit to prepare next changes. Now, when a conn-stream is
created from an applet or a multiplexer, an endpoint is always provided. In
addition, the API to create a conn-stream was specialized to have one
function per type.
The next step will be to share the endpoint structure.
It is a transient commit to prepare next changes. It is possible to pass a
pre-allocated endpoint to create a new conn-stream. If it is NULL, a new
endpoint is created, otherwise the existing one is used. There no more
change at the conn-stream level.
In the applets, all conn-stream are created with no pre-allocated
endpoint. But for multiplexers, an endpoint is systematically created before
creating the conn-stream.
This change is only significant for the multiplexer part. For the applets,
the context and the endpoint are the same. Thus, there is no much change. For
the multiplexer part, the connection was used to set the conn-stream
endpoint and the mux's stream was the context. But it is a bit strange
because once a mux is installed, it takes over the connection. In a
wonderful world, the connection should be totally hidden behind the mux. The
stream-interface and, in a lesser extent, the stream, still access the
connection because that was inherited from the pre-multiplexer era.
Now, the conn-stream endpoint is the mux's stream (an opaque entity for the
conn-stream) and the connection is the context. Dedicated functions have
been added to attached an applet or a mux to a conn-stream.
The appctx owner is now always a conn-stream. Thus, it can be set during the
appctx allocation. But, to do so, the conn-stream must be created first. It
is not a problem on the server side because the conn-stream is created with
the stream. On the client side, we must take care to create the conn-stream
first.
This change should ease other changes about the applets bootstrapping.
Thanks to all previous changes, it is now possible to move the
stream-interface into the conn-stream. To do so, some SI functions are
removed and their conn-stream counterparts are added. In addition, the
conn-stream is now responsible to create and release the
stream-interface. While the stream-interfaces were inlined in the stream
structure, there is now a pointer in the conn-stream. stream-interfaces are
now dynamically allocated. Thus a dedicated pool is added. It is a temporary
change because, at the end, the stream-interface structure will most
probably disappear.
In the same way the conn-stream has a pointer to the stream endpoint , this
patch adds a pointer to the application entity in the conn-stream
structure. For now, it is a stream or a health-check. It is mandatory to
merge the stream-interface with the conn-stream.
Because appctx is now an endpoint of the conn-stream, there is no reason to
still have the stream-interface as appctx owner. Thus, the conn-stream is
now the appctx owner.
Thanks to previous changes, it is now possible to set an appctx as endpoint
for a conn-stream. This means the appctx is no longer linked to the
stream-interface but to the conn-stream. Thus, a pointer to the conn-stream
is explicitly stored in the stream-interface. The endpoint (connection or
appctx) can be retrieved via the conn-stream.
There's a bug in spoe_release_appctx() which checks the presence of items
in the wrong list rt[tid].agents to run over rt[tid].waiting_queue and
zero their spoe_appctx. The effect is that these contexts are not zeroed
and if spoe_stop_processing() is called, "sa->cur_fpa--" will be applied
to one of these recently freed contexts and will corrupt random memory
locations, as found at least in bugs #1494 and #1525.
This must be backported to all stable versions.
Many thanks to Christian Ruppert from Babiel for exchanging so many
useful traces over the last two months, testing debugging code and
helping set up a similar environment to reproduce it!
The last 3 fields were 3 list heads that are per-thread, and which are:
- the pool's LRU head
- the buffer_wq
- the streams list head
Moving them into thread_ctx completes the removal of dynamic elements
from the struct thread_info. Now all these dynamic elements are packed
together at a single place for a thread.
We'll need to improve the API to pass other arguments in the future, so
let's start to adapt better to the current use cases. task_new() is used:
- 18 times as task_new(tid_bit)
- 18 times as task_new(MAX_THREADS_MASK)
- 2 times with a single bit (in a loop)
- 1 in the debug code that uses a mask
This patch provides 3 new functions to achieve this:
- task_new_here() to create a task on the calling thread
- task_new_anywhere() to create a task to be run anywhere
- task_new_on() to create a task to run on a specific thread
The change is trivial and will allow us to later concentrate the
required adaptations to these 3 functions only. It's still possible
to call task_new() if needed but a comment was added to encourage the
use of the new ones instead. The debug code was not changed and still
uses it.
appctx_new() is exclusively called with tid_bit and it only uses the
mask to pass it to the accompanying task. There is no point requiring
the caller to know about a mask there, nor is there any point in
creating an applet outside of the context of its own thread anyway.
Let's drop this and pass tid_bit to task_new() directly.
It is the second part of the fix that should solve fairness issues with the
connections management inside the SPOE filter. Indeed, in multithreaded
mode, when the SPOE detects there are some connections in queue on a server,
it closes existing connections by releasing SPOE applets. It is mandatory
when a maxconn is set because few connections on a thread may prenvent new
connections establishment.
The first attempt to fix this bug (9e647e5af "BUG/MEDIUM: spoe: Kill applets
if there are pending connections and nbthread > 1") introduced a bug. In
pipelining mode, SPOE applets might be closed while some frames are pending
for the ACK reply. To fix the bug, in the processing stage, if there are
some connections in queue, only truly idle applets may process pending
requests. In this case, only one request at a time is processed. And at the
end of the processing stage, only truly idle applets may be released. It is
an empirical workaround, but it should be good enough to solve contention
issues when a low maxconn is set.
This patch should partely fix the issue #1340. It must be backported as far
as 2.0.
On a thread, when the last SPOE applet is released, if there are still
pending streams, a new one is created. Of course, HAproxy must not be
stopping. It is important to start a new applet in this case to not abort
in-progress jobs, especially when a maxconn is set. Because applets may be
closed to be fair with connections waiting for a free slot.
This patch should partely fix the issue #1340. It depends on the commit
"MINOR: spoe: Create a SPOE applet if necessary when the last one on a
thread is closed". Both must be backported as far as 2.0.
There was no way to access the SPOE filter configuration from the agent
object. However it could be handy to have it. And in fact, this will be
required to fix a bug.
Lots of places iterating over nbproc or comparing with nbproc could be
simplified. Further, "bind-process" and "process" parsing that was
already limited to process 1 or "all" or "odd" resulted in a bind_proc
field that was either 0 or 1 during the init phase and later always 1.
All the checks for compatibilities were removed since it's not possible
anymore to run a frontend and a backend on different processes or to
have peers and stick-tables bound on different ones. This is the largest
part of this patch.
The bind_proc field was removed from both the proxy and the receiver
structs.
Since the "process" and "bind-process" directives are still parsed,
configs making use of correct values allowing process 1 will continue
to work.
The current "ADD" vs "ADDQ" is confusing because when thinking in terms
of appending at the end of a list, "ADD" naturally comes to mind, but
here it does the opposite, it inserts. Several times already it's been
incorrectly used where ADDQ was expected, the latest of which was a
fortunate accident explained in 6fa922562 ("CLEANUP: stream: explain
why we queue the stream at the head of the server list").
Let's use more explicit (but slightly longer) names now:
LIST_ADD -> LIST_INSERT
LIST_ADDQ -> LIST_APPEND
LIST_ADDED -> LIST_INLIST
LIST_DEL -> LIST_DELETE
The same is true for MT_LISTs, including their "TRY" variant.
LIST_DEL_INIT keeps its short name to encourage to use it instead of the
lazier LIST_DELETE which is often less safe.
The change is large (~674 non-comment entries) but is mechanical enough
to remain safe. No permutation was performed, so any out-of-tree code
can easily map older names to new ones.
The list doc was updated.
This patch replaces roughly all occurrences of an HA_ATOMIC_ADD(&foo, 1)
or HA_ATOMIC_SUB(&foo, 1) with the equivalent HA_ATOMIC_INC(&foo) and
HA_ATOMIC_DEC(&foo) respectively. These are 507 changes over 45 files.
This patch registers the parsed file and the line where a log server
is declared to make those information available in configuration
post check.
Those new informations were added on error messages probed resolving
ring names on post configuration check.
The function's purpose used to be to fail a buffer allocation if that
allocation wouldn't result in leaving some buffers available. Thus,
some allocations could succeed and others fail for the sole purpose of
trying to provide 2 buffers at once to process_stream(). But things
have changed a lot with 1.7 breaking the promise that process_stream()
would always succeed with only two buffers, and later the thread-local
pool caches that keep certain buffers available that are not accounted
for in the global pool so that local allocators cannot guess anything
from the number of currently available pools.
Let's just replace all last uses of b_alloc_margin() with b_alloc() once
for all.
pool_alloc_dirty() is the version below pool_alloc() that never performs
the memory poisonning. It should only be called directly for very large
unstructured areas for which enabling memory poisonning would not bring
anything but could significantly hurt performance (e.g. buffers). Using
this function here will not provide any real benefit, it only avoids the
area being poisonned before being zeroed. Ideally a pool_calloc() function
should be provided for this.
It's been too short for quite a while now and is now full. It's still
time to extend it to 32-bits since we have room for this without
wasting any space, so we now gained 16 new bits for future flags.
The values were not reassigned just in case there would be a few
hidden u16 or short somewhere in which these flags are placed (as
it used to be the case with stream->pending_events).
The patch is tagged MEDIUM because this required to update the task's
process() prototype to use an int instead of a short, that's quite a
bunch of places.
When the processing stage is finished for a SPOE applet, before returning it
into the idle list, we check if the assigned server appears as full or if
there are some pending connections on the backend or the assigned server. If
yes, it means we reach a maxconn and we close the applet to free a
slot. Otherwise, the applet can be reused. This test is only performed if
there are more than one thread.
It is important to close SPOE applets when there are pending connections for
multithreaded instances because connections with the SPOE agents are
persistent and local to a thread (applets are local to a thread). If a
maxconn is configured, some threads may take all available slots for a
while, leaving remaining threads without any free slot to process SPOE
messages. It is especially true if the maxconn is low.
This patch should fix the issue #705. It must be backported as far as
1.8. However, the code in 1.8 is quite different, a test must be performed
to be sure it works well.
This makes the code more readable and less prone to copy-paste errors.
In addition, it allows to place some __builtin_constant_p() predicates
to trigger a link-time error in case the compiler knows that the freed
area is constant. It will also produce compile-time error if trying to
free something that is not a regular pointer (e.g. a function).
The DEBUG_MEM_STATS macro now also defines an instance for ha_free()
so that all these calls can be checked.
178 occurrences were converted. The vast majority of them were handled
by the following Coccinelle script, some slightly refined to better deal
with "&*x" or with long lines:
@ rule @
expression E;
@@
- free(E);
- E = NULL;
+ ha_free(&E);
It was verified that the resulting code is the same, more or less a
handful of cases where the compiler optimized slightly differently
the temporary variable that holds the copy of the pointer.
A non-negligible amount of {free(str);str=NULL;str_len=0;} are still
present in the config part (mostly header names in proxies). These
ones should also be cleaned for the same reasons, and probably be
turned into ist strings.
Historically this function would try to wake the most accurate number of
process_stream() waiters. But since the introduction of filters which could
also require buffers (e.g. for compression), things started not to be as
accurate anymore. Nowadays muxes and transport layers also use buffers, so
the runqueue size has nothing to do anymore with the number of supposed
users to come.
In addition to this, the threshold was compared to the number of free buffer
calculated as allocated minus used, but this didn't work anymore with local
pools since these counts are not updated upon alloc/free!
Let's clean this up and pass the number of released buffers instead, and
consider that each waiter successfully called counts as one buffer. This
is not rocket science and will not suddenly fix everything, but at least
it cannot be as wrong as it is today.
This could have been marked as a bug given that the current situation is
totally broken regarding this, but this probably doesn't completely fix
it, it only goes in a better direction. It is possible however that it
makes sense in the future to backport this as part of a larger series if
the situation significantly improves.
The buffer wait queue used to be global historically but this doest not
make any sense anymore given that the most common use case is to have
thread-local pools. Thus there's no point waking up waiters of other
threads after releasing an entry, as they won't benefit from it.
Let's move the queue head to the thread_info structure and use
ti->buffer_wq from now on.
If a SPOE filter is configured to send its logs to a ring buffer, the
corresponding sink must be resolved during the configuration post
parsing. Otherwise, the sink is undefined when a log message is emitted,
crashing HAProxy.
This patch must be backported as far as 2.2.
It is now possible to set the buffer used by the channel request buffer when
a stream is created. It may be useful if input data are already received,
instead of waiting the first call to the mux rcv_buf() callback. This change
is mandatory to support H1 connection with no stream attached.
For now, the multiplexers don't pass any buffer. BUF_NULL is thus used to
call stream_create_from_cs().
In sync mode, if an applet receives a ack while the processing delay has already
expired, there is not frame waiting for this ack. But there is no reason to
close the connection in this case. The ack may be ignored and the connection may
be reused to process another frame. The only reason to trigger an error and
close the connection is when the wrong ack is received while there is still a
frame waiting for its ack. In sync mode, this should never happen.
This patch may be backported in all versions supporting the SPOE.
