If it is the last patch to introduce dedicated termination events for each
location. In this one, events for the stream location are introcued. The old
enum is also removed because it is now unused.
Here, more accurate evets are added. The "intercepted" event was splitted.
Termination events dedicated to mux connection and stream-endpoint
descriptors are added in this patch. Specific events to these locations are
thus added. Changes for the H1 and H2 multiplexers are reviewed to be more
accurate.
In this patch, events for the stream location are reported. These events are
first reported on the corresponding stream-connector. So front events on scf
and back event on scb. Then all events are both merged in the stream. But
only 4 events are saved on the stream.
Several internal events are for now grouped with the type
"tevt_type_intercepted". More events will be added to have a better
resolution. But at least the place to report these events are identified.
For now, when a event is reported on a SC, it is also reported on the stream
and vice versa.
There is no reason to disable the 0-copy data forwarding if an end-of-stream
was reported on the consumer side. Indeed, the consumer will send data in
this case. So there is no reason to check the read side here.
This patch may be backported as far as 2.9.
se_opposite() function is added to let an endpoint retrieve the opposite
endpoint descriptor. Muxes supportng the zero-copy forwarding can now use
it. The se_shutdown() function too. This will be use by the SPOP multiplexer
to be able to retrieve the SPOE agent configuration attached to the applet
on client side.
The related issue is #2502.
The previous fix (792a645ec2 ["BUG/MEDIUM: mux-quic: Unblock zero-copy
forwarding if the txbuf can be released"]) introduced a regression. The
zero-copy data forwarding must only be unblocked if it was blocked by the
producer, after a successful negotiation.
It is important because during a negotiation, the consumer may be blocked
for another reason. Because of the flow control for instance. In that case,
there is not necessarily a TX buffer. And it unexpected to try to release an
unallocated TX buf.
In addition, the same may happen while a TX buf is still in-use. In that
case, it must also not be released. So testing the TX buffer is not the
right solution.
To fix the issue, a new IOBUF flag was added (IOBUF_FL_FF_WANT_ROOM). It
must be set by the producer if it is blocked after a sucessful negotiation
because it needs more room. In that case, we know a buffer was provided by
the consummer. In done_fastfwd() callback function, it is then possible to
safely unblock the zero-copy data forwarding if this flag is set.
This patch must be backported to 3.0 with the commit above.
We used to have two states for the channel's input buffer used by the SC,
NEED_BUFF or not, flipped by sc_need_buff() and sc_have_buff(). We want to
have a 3rd state, indicating that we've just got a desired buffer. Let's
add an HAVE_BUFF flag that is set by sc_have_buff() and that is cleared by
sc_used_buff(). This way by looking at HAVE_BUFF we know that we're coming
back from the allocation callback and that the offered buffer has not yet
been used.
se_shutdown() function is now used to perform a shutdown on a connection
endpoint and an applet endpoint. The same function is used for
both. sc_conn_shut() function was removed and appctx_shut() function was
updated to only deal with the applet stuff.
The SC API to perform shutdowns on connection endpoints was unified to have
only one function, sc_conn_shut(), with read/write shut modes passed
explicitly. It means sc_conn_shutr() and sc_conn_shutw() were removed. The
next step is to do the same at the mux level.
CO_SHR_* and CO_SHW_* modes are in fact used by the stream-connectors to
instruct the muxes how streams must be shut done. It is then the mux
responsibility to decide if it must be propagated to the connection layer or
not. And in this case, the modes above are only tested to pass a boolean
(clean or not).
So, it is not consistant to still use connection related modes for
information set at an upper layer and never used by the connection layer
itself.
These modes are thus moved at the sedesc level and merged into a single
enum. Idea is to add more modes, not necessarily mutually exclusive, to pass
more info to the muxes. For now, it is a one-for-one renaming.
Since the begining, this function returns a pointer on an appctx while it
should be a void pointer. It is the caller responsibility to cast it to the
right type, the corresponding mux stream in this case.
However, it is not a big deal because this function is unused for now. Only
the unsafe one is used.
This patch must be backported as far as 2.6.
This case does not exist yet with the H1 multiplexer, but applets may decide to
not produce data if there is not enough room in the destination buffer (the
applet's outbuf or the opposite SE buffer). It is true for the stats applets for
instance. However this case is not properly handled when the zero-copy
forwarding is in-use.
To fix the issue, the se_done_ff() function was modified to return the number of
bytes really forwarded and to subs for sends if nothing was forwarded while the
zero-copy forwarding was blocked by the producer. On the applet side, we take
care to block the zero-copy forwarding if the applet requests more room. At the
end, zero-copy forwarding is unblocked if something was forwarded.
This way, it is now possible for the stats applet to report a full buffer and
block the zero-copy forwarding, even if the buffer is not really full, by
requesting more room.
No backport needed.
During zero-copy forwarding negotiation, a pseudo flag was already used to
notify the consummer if the producer is able to use kernel splicing or not. But
this was not extensible. So, now we use a true bitfield to be able to pass flags
during the negotiation. NEGO_FF_FL_* flags may be used now.
Of course, for now, there is only one flags, the kernel splicing support on
producer side (NEGO_FF_FL_MAY_SPLICE).
IS_HXT_SC() macro is only usable if the stream-connector is attached to a
connection. It is a bit restrictive because this cannot work if the SC is
attached to an applet. So let's fix that be adding the support of applets
too.
During the zero-copy forwarding, if the consumer side reports it is blocked,
it means it is blocked on send. At the stream-connector level, the event
must be reported to be sure to set/update the fsb date. Otherwise, write
timeouts cannot be properly reported. If this happens when no other timeout
is armed, this freezes the stream.
This patch must be backported to 2.9.
A regression was introduced by commit 2421c6fa7d ("BUG/MEDIUM: stconn: Block
zero-copy forwarding if EOS/ERROR on consumer side"). When zero-copy
forwarding is inuse and the consumer side is shut or in error, we declare it
as blocked and it is woken up. The idea is to handle this state at the
stream-connector level. However this definitly blocks receives on the
producer side. So if the mux is unable to close by itself, but instead wait
the peer to shut, this can lead to a wake up loop. And indeed, with the
passthrough multiplexer this may happen.
To fix the issue and prevent any loop, instead of blocking the zero-copy
forwarding, we now disable it. This way, the stream-connector on producer
side will fallback on classical receives and will be able to handle peer
shutdown properly. In addition, the wakeup of the consumer side was
removed. This will be handled, if necessary, by sc_notify().
This patch should fix the issue #2395. It must be backported to 2.9.
When the producer side (h1 for now) negociates with the consumer side to
perform a zero-copy forwarding, we now consider the consumer side as blocked
if it is closed and this was reported to the SE via a end-of-stream or a
(pending) error.
It is performed before calling ->nego_ff callback function, in se_nego_ff().
This way, all consumer are concerned automatically. The aim of this patch is
to fix an issue with the QUIC mux. Indeed, it is unexpected to send a frame
on an closed stream. This triggers a BUG_ON(). Other muxes are not affected
but it remains useless to try to send data if the stream is closed.
This patch should fix the issue #2372. It must be backported to 2.9.
Partial sends is an activity, not a full blocking. Thus a read activity must
be reported for non-independent stream. It is especially important for very
congested stream where full sends are uncommon.
This patch must be backported to 2.8.
The first-send-blocked date was originally designed to save the date of the
first send of a series where some data remain blocked. It was relaxed
recently (3083fd90e "BUG/MEDIUM: stconn: Report a send activity everytime
data were sent") to save the date of the first full blocked send. However,
it is not accurrate.
When all data are sent, the fsb value must be reset to TICK_ETERNITY. When
nothing is sent and if it is not already set, it must be set. But when data
are partially sent, the value must be updated and not reset. Otherwise the
write timeout may be ignored because fsb date is never set.
So, changes brought by the patch above are reverted and
sc_ep_report_blocked_send() was changed to know if some data were sent or
not. This way we are able to update fsb value.
l
This patch must be backported to 2.8.
In sc_need_room(), we compute the maximum room that can be requested to
restarted reading to be sure to be able to unblock the SC. At worst when the
buffer is emptied. Here, the buffer reserve is considered but it is an issue.
Counting the reserve can lead to a wicked bug with the H1 multiplexer, when
small amount of data are found at the end of the HTX buffer. In this case,
to not wrap, the H1 mux requests more room. It is an optim to be able to
resync the buffer with the consumer side and to be able to perform zero-copy
transfers. However, if this amount of data is smaller than the reserve and
if the consumer is congested, we fall in a loop because the wrong value is
used to request more room. The H1 mux continues to pretend there is not
enough space in the buffer, while the effective requested value is lower
than the free space in the buffer. While the consumer is congested and does
not consume these data, the is no way to stop the loop.
We can fix the function by removing the buffer reserve from the
computation. But it remains a dangerous decision to apply a max value on
room_needed. It is safer to require the caller must set a correct value. For
now, it is true. But at the end, it is totally unexepected to wait for more
room than an empty buffer can contain.
This patch must be backported to 2.8.
When receive or send expiration date of a stream-connector is retrieved, we
now automatically check if it may expire. If not, TICK_ETERNITY is returned.
The expiration dates of the frontend and backend stream-connectors are used
to compute the stream expiration date. This operation is performed at 2
places: at the end of process_stream() and in sc_notify() if the stream is
not woken up.
With this patch, there is no special changes for process_stream() because it
was already handled. It make thing a little simpler. However, it fixes
sc_notify() by avoiding to erroneously compute an expiration date in
past. This highly reduce the stream wakeups when there is contention on the
consumer side.
The bug was introduced with the commit 8073094bf ("NUG/MEDIUM: stconn:
Always update stream's expiration date after I/O"). It was an error to
unconditionnaly set the stream expiration data, without testing blocking
conditions on both SC.
This patch must be backported to 2.8.
When data are directly forwarded from a mux to the opposite one, we must not
forget to report send activity when data are successfully sent or report a
blocked send with data are blocked. It is important because otherwise, if
the transfer is quite long, longer than the client or server timeout, an
error may be triggered because the write timeout is reached.
H1, H2 and PT muxes are concerned. To fix the issue, The done_fastword()
callback now returns the amount of data consummed. This way it is possible
to update/reset the FSB data accordingly.
No backport needed.
Instead of speaking of an initialisation stage for each data
fast-forwarding, we now use the negociate term. Thus init_ff/init_fastfwd
functions were renamed nego_ff/nego_fastfwd.
To perform the mux-to-mux data fast-forwarding, 4 new callbacks were added
into the mux_ops structure. 2 callbacks will be used from the stconn for
fast-forward data. The 2 other callbacks will be used by the endpoint to
request an iobuf to the opposite endpoint.
* fastfwd() callback function is used by a producer to forward data
* resume_fastfwd() callback function is used by a consumer if some data are
blocked in the iobuf, to resume the data forwarding.
* init_fastfwd() must be used by an endpoint (the producer one), inside the
fastfwd() callback to request an iobuf to the opposite side (the consumer
one).
* done_fastfwd() must be used by an endpoint (the producer one) at the end
of fastfwd() to notify the opposite endpoint (the consumer one) if data
were forwarded or not.
This API is still under development, so it may evolved. Especially when the
fast-forward will be extended to applets.
2 helper functions were also added into the SE api to wrap init_fastfwd()
and done_fastfwd() callback function of the underlying endpoint.
For now, this API is unsed and not implemented at all in muxes.
It is unused for now, but the iobuf structure now owns a pointer to a
buffer. This buffer will be used to perform mux-to-mux fast-forwarding when
splicing is not supported or unusable. This pointer should be filled by an
endpoint to let the opposite one forward data.
Extra fields, in addition to the buffer, are mandatory because the buffer
may already contains some data. the ".offset" field may be used may be used
as the position to start to copy data. Finally, the amount of data copied in
this buffer must be saved in ".data" field.
Some flags are also added to prepare next changes. And helper stconn
fnuctions are updated to also count data in the buffer. For a first
implementation, it is not planned to handle data in the buffer and in the
pipe in same time. But it will be possible to do so.
Instead of talking about kernel splicing at stconn/sedesc level, we now try
to talk about mux-to-mux fast-forwarding. To do so, 2 functions were added
to know if there are fast-forwarded data and to retrieve this amount of
data. Of course, for now, there is only data in a pipe.
In addition, some flags were renamed to reflect this notion. Note the
channel's documentation was not updated yet.
sc_need_room() function may be called with a negative value. In this case,
the intent is to be notified if any space was made in the channel buffer. In
the function, we get the min between the requested room and the maximum
possible room in the buffer, considering it may be an HTX buffer.
However this max value is unsigned and leads to an unsigned comparison,
casting the negative value to an unsigned value. Of course, in this case,
this always leads to the wrong result. This bug seems to have no effect but
it is hard to be sure.
To fix the issue, we take care to respect the requested room sign by casting
the max value to a signed integer.
This patch must be backported to 2.8.
During a code audit of the various situations that promote ERR_PENDING to
ERROR, it appeared that:
- all muxes use se_fl_set_error() to set it, which chooses either based
on EOI/EOS presence ;
- EOI/EOS that arrive late after ERR_PENDING were not systematically
upgraded to ERROR
This results in confusion about how such ERROR or ERR_PENDING ought to
be handled, which is not quite desirable.
This patch adds a test to se_fl_set() to detect if we're setting EOI or
EOS while ERR_PENDING is present, or the other way around so that any
sequence of EOI/EOS <-> ERR_PENDING results in ERROR being set. This
way there will no longer be possible situations where ERROR is missing
while the other ones are set.
When sc_need_room() is called, the caller cannot request more free space
than a minimum value to be sure it is always possible to unblock it. it is a
safety guard to not freeze any SC on NEED_ROOM condition. At worse it will
lead to some wakeups un excess at the edge.
To keep things simple, the following minimum is used:
(global.tune.bufsize - global.tune.maxrewrite - sizeof(struct htx))
sc_need_room() now takes the required free space to receive more data as
parameter. All calls to this function are updated accordingly. For now, this
value is set but not used. When we are waiting for a buffer, 0 is used. So
we expect to be unblocked ASAP. However this must be reviewed because
SC_FL_NEED_BUF is probably enough in this case and this flag is already set
if the input buffer allocation fails.
When the endpoint (applet or mux) is now willing to consume data while it
said it wouldn't, a send activity is reported. Indeed, the writes was
blocked because of the endpoint. It is now ready to consume outgoing
data. So an send activity must be reported to reset corresponding timers.
Concretly, when the flag SE_FL_WONT_CONSULE is removed, a send activity is
reported.
The stream endpoint descriptor now owns two date, lra (last read activity) and
fsb (first send blocked).
The first one is updated every time a read activity is reported, including data
received from the endpoint, successful connect, end of input and shutdown for
reads. A read activity is also reported when receives are unblocked. It will be
used to detect read timeouts.
The other one is updated when no data can be sent to the endpoint and reset
when some data are sent. It is the date of the first send blocked by the
endpoint. It will be used to detect write timeouts.
Helper functions are added to report read/send activity and to retrieve lra/fsb
date.
These timers are related to the I/O. Thus it is logical to move them into
the SE descriptor. The patch is a bit huge but it is just a
replacement. However it is error-prone.
From the stconn or the stream, helper functions are used to get, set or
reset these timers. This simplify the timers manipulations.
In se_fl_set_error() we used to switch to SE_FL_ERROR only when there
is already SE_FL_EOS indicating that the read side is closed. But that
is not sufficient, we need to consider all cases where no more reads
will be performed on the connection, and as such also include SE_FL_EOI.
Without this, some aborted connections during a transfer sometimes only
stop after the timeout, because the ERR_PENDING is never promoted to
ERROR.
This must be backported to 2.7 and requires previous patch "CLEANUP:
stconn: always use se_fl_set_error() to set the pending error".
When the protocol is changed for a client connection at the stream level
(from TCP to H1/H2), there are two cases. The stream may be reused or
not. The first case, when the stream is reused is working. The second one is
buggy since the conn-stream refactoring and leads to a crash.
In this case, the new mux don't reuse the stream. It must be silently
aborted. However, its front stream connector is still referencing the
connection. So it must be detached. But it must be performed in two stages,
to be sure to not loose the context for the upgrade and to be able to
rollback on error. So now, before the upgrade, we prepare to detach the
stconn and it is finally detached if the upgrade succeeds. There is a trick
here. Because we pretend the stconn is detached but its state is preserved.
This patch must be backported to 2.6.
This flag was the only remaining one that was inverted as a blocking
condition, requiring special handling to preset it on sedesc allocation.
Let's flip it in its definition and accessors.
Function arguments and local variables called "cs" were renamed to "sc"
to avoid future confusion. The change is huge (~580 lines), so extreme
care was given not to change anything else.
There's no more reason for keepin the code and definitions in conn_stream,
let's move all that to stconn. The alphabetical ordering of include files
was adjusted.
