To be able to support endpoint-to-endpoint fast-forwarding (formerly called
mux-to-mux fast-forwarding), we cannot rely on data in the input channel to
compute amount of data the applet has produced.
The applet API is not really designed to know how many bytes are produced or
received at each call. Till now, it was not a problem because data always
passed through the channels. With E2E fast-frowarding, input data may be
immediately consumed. From the caller point of view (task_run_applet), there
is only the total field of the input channel that will change. So let's use
it now.
Till now, it was not possible to notify an producing applet is streaming
data. It means, it was not possible to set CF_STREAMER and CF_STREAMER_FLAGS
on the input channel of an applet streaming data.
While it is not a big deal for most of applets, it is interesting for the
cache. Because there are now dedicated functions to deal with these flags,
we can use them in task_run_applet() to set/unset these flags on the input
channel.
This patch relies on "MINOR: channel: Use dedicated functions to deal with
STREAMER flags".
For applets and connection, when a send attempt is performed, we must be
sure to not report a send activity if there was no output data at all before
the attempt.
It is not important for the <fsb> date itself but for the <lra> date for
non-independent stream.
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.
For now, the appctx is removed from the buffer wait list when it is
freed. However, when it is released, it is not necessarily freed
immediately. But it is detached from the SC. If it is still registered in
the buffer wait list, it could then be woken up to get a buffer. At this
stage it is totally unexpected, especially because we must access the SC.
The fix is obvious, the appctx must be removed from the buffer wait list on
release.
Note this bug exists because the appctx was moved at the mux level.
This patch must be backported as far as 2.6.
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.
The pipes used to put data when the kernel splicing is in used are moved in
the SE descriptors. For now, it is just a simple remplacement but there is a
major difference with the pipes in the channel. The data are pushed in the
consumer's pipe while it was pushed in the producer's pipe. So it means the
request data are now pushed in the pipe of the backend SE descriptor and
response data are pushed in the pipe of the frontend SE descriptor.
The idea is to hide the pipe from the channel/SC side and to be able to
handle fast-forwading in pipe but also in buffer. To do so, the pipe is
inside a new entity, called iobuf. This entity will be extended.
In the same way than for stream-connectors (see "BUG/MEDIUM: stconn: Report
a send activity everytime data were sent" for details), we now report a send
activity everytime something was consumed by an applet, even if some output
data remains blocked into the channel's buffer.
This patch must be backported to 2.8.
It is a revert of following patches:
* d7111e7ac ("MEDIUM: stconn: Don't requeue the stream's task after I/O")
* 3479d99d5 ("BUG/MEDIUM: stconn: Update stream expiration date on blocked sends")
Because the first one is reverted, the second one is useless and can be reverted
too.
The issue here is that I/O may be performed without stream wakeup. So if no
expiration date was set on the last call to process_stream(), the stream is
never rescheduled and no timeout can be detected. This especially happens on
TCP streams because fast-forward is enabled very early.
Instead of tracking all places where the stream's expiration data must be
updated, it is now centralized in sc_notify(), as it was performed before
the timeout refactoring.
This patch must be backported to 2.8.
If an abort was performed and the applet still request more room, it means
the applet has not properly handle the error on its own. At least the CLI
applet is concerned. Instead of reviewing all applets, the error is now
handled in task_run_applet() function.
Because of this bug, a session may be blocked infinitly and may also lead to
a wakup loop.
This patch must only be backported to 2.8 for now. And only to lower
versions if a bug is reported because it is a bit sensitive and the code
older versions are very different.
When outgoing data are blocked, we must update the stream expiration date
and requeue the task. It is important to be sure to properly handle write
timeout, expecially if the stream cannot expire on reads. This bug was
introduced when handling of channel's timeouts was refactored to be managed
by the stream-connectors.
It is an issue if there is no server timeout and the client does not consume
the response (or the opposite but it is less common). It is also possible to
trigger the same scenario with applets on server side because, most of time,
there is no server timeout.
This patch must be backported to 2.8.
The wrong label was used in trace to report expiration dates of the opposite
SC. "sc" was used instead of "sco".
This patch should be backported to 2.8.
During the refactoring on SC/SE flags, it was stated that SE_FL_EOS flag
should not be set without on of SE_FL_EOI or SE_FL_ERROR flags. In fact, it
is a problem for the QUIC/H3 multiplexer. When a RST_STREAM frame is
received, it means no more data will be received from the peer. And this
happens before the end of the message (RST_STREAM frame received after the
end of the message are ignored). At this stage, it is a problem to report an
error because from the QUIC point of view, it is valid. Data may still be
sent to the peer. If an error is reported, this will stop the data sending
too.
In the same idea, the H1 mulitplexer reports an error when the message is
truncated because of a read0. But only an EOS flag should be reported in
this case, not an error. Fundamentally, it is important to distinguish
errors from shuts for reads because some cases are valid. For instance a H1
client can choose to stop uploading data if it received the server response.
So, relax tests on SE flags by removing BUG_ON_HOT() on SE_FL_EOS flag. For
now, the abort will be handled in the HTTP analyzers.
If the opposite SC is waiting for a minimum free space to receive more data,
it is only unblock is the condition is respected. 0 is a special cases where
the opposite SC is always unblocked.
Because shutowns for reads are now considered as aborts, the shudowns for
writes can now be considered as shutdowns. Here it is just a flag
renaming. SC_FL_SHUTW_NOW is renamed SC_FL_SHUT_WANTED.
When a trace message for an applet is dumped, if the SC exists, the stream
always exists too. There is no way to attached an applet to a health-check.
So, we can use the unsafe version __sc_strm() to get the stream.
This patch is related to #2106. Not sure it will be enough for
Coverity. However, there is no bug here.
SE_FL_EOS flag must never be set on the SE descriptor without SE_FL_EOI or
SE_FL_ERROR. When a mux or an applet report an end of stream, it must be
able to state if it is the end of input too or if it is an error.
Because all this part was recently refactored, especially the applet part,
it is a bit sensitive. Thus a BUG_ON_HOT() is used and not a BUG_ON().
The purpose of this patch is only a one-to-one replacement, as far as
possible.
CF_SHUTR(_NOW) and CF_SHUTW(_NOW) flags are now carried by the
stream-connecter. CF_ prefix is replaced by SC_FL_ one. Of course, it is not
so simple because at many places, we were testing if a channel was shut for
reads and writes in same time. To do the same, shut for reads must be tested
on one side on the SC and shut for writes on the other side on the opposite
SC. A special care was taken with process_stream(). flags of SCs must be
saved to be able to detect changes, just like for the channels.
Since 465a6c8 ("BUG/MEDIUM: applet: only set appctx->sedesc on
successful allocation"), sedesc is attached to the appctx after the
task is successfully allocated.
If the task fails to allocate: current sedesc cleanup is performed
on appctx->sedesc which still points to NULL so sedesc won't be
freed.
This is fine when sedesc is provided as argument (!=NULL), but leads
to memory leaks if sedesc is allocated locally.
It was shown in GH #2086 that if sedesc != NULL when passed as
argument, it shouldn't be freed on error paths. This is what 465a6c8
was trying to address.
In an attempt to fix both issues at once, we do as Christopher
suggested: that is moving sedesc allocation attempt at the
end of the function, so that we don't have to free it in case
of error, thus removing the ambiguity.
(We won't risk freeing a sedesc that does not belong to us)
If we fail to allocate sedesc, then the task that was previously
created locally is simply destroyed.
This needs to be backported to 2.6 with 465a6c8 ("BUG/MEDIUM: applet:
only set appctx->sedesc on successful allocation")
[Copy pasting the original backport note from Willy:
In 2.6 the function is slightly
different and called appctx_new(), though the issue is exactly the
same.]
If appctx_new_on() fails to allocate a task, it will not remove the
freshly allocated sedesc from the appctx despite freeing it, causing
a UAF. Let's only assign appctx->sedesc upon success.
This needs to be backported to 2.6. In 2.6 the function is slightly
different and called appctx_new(), though the issue is exactly the
same.
Instead of reporting a blocked send if nothing is send, we do it if some
output data remain blocked after a write attempts or after a call the the
applet's I/O handler. It is mandatory to properly handle write timeouts.
Indeed, if an endpoint is blocked for a while but it partially consumed
output data, no timeout is triggered. It is especially true for
connections. But the same may happen for applet, there is no reason.
Of course, if the endpoint decides to partially consume output data because
it must wait to move on for any reason, it should use the se/applet API
(se/applet_will_consume(), se/applet_wont_consume() and
se/applet_need_more_data()).
This bug was introduced during the channels timeouts refactoring. No
backport is needed.
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.
Just like CF_READ_PARTIAL, CF_WRITE_PARTIAL is now merged with
CF_WRITE_EVENT. There a subtlety in sc_notify(). The "connect" event
(formely CF_WRITE_NULL) is now detected with
(CF_WRITE_EVENT + sc->state < SC_ST_EST).
This is very similar to what we did in commit 6c539c4b8 ("BUG/MINOR:
stream: make the call_rate only count the no-progress calls"), it's
better to only count the call rate with no progress than to count all
calls and try to figure if there's no progress, because a fast running
applet might once satisfy the whole condition and trigger the bug. This
typically happens when artificially limiting the number of messages sent
at once by an applet, but could happen with plenty of highly interactive
applets.
This patch could be backported to stable versions if there are any
indications that it might be useful there.
We have quite numerous checks for abnormal applet handler behavior which
are supposed to trigger the loop protection. However, consecutive to
commit 15252cd9c ("MEDIUM: stconn: move the RXBLK flags to the stream
connector") that was merged into 2.6-dev12, one flag was incorrectly
renamed, and the check for an applet waiting for a buffer that is present
mistakenly turned to a check for missing room in the buffer. This erroneous
test could mistakenly trigger on applets that perform intensive I/Os doing
small exchanges each (e.g. cache, peers or HTTP client) if the load would
be sustained (>100k iops). For the cache this could represent higher than
13 Gbps on an object at least 1.6 GB large for example, which is quite
unlikely but theoretically possible.
This fix needs to be backported to 2.6.
The CLI needs to reset the svcctx between commands, and there was nothing
done to handle this. Let's add appctx_reset_svcctx() to do that, it's the
closing equivalent of appctx_reserve_svcctx().
This will have to be backported to 2.6 as it will be used by a subsequent
patch to fix a bug.
This removes the mask-based variant so that from now on the low-level
function becomes appctx_new_on() and it takes either a thread number or
a negative value for "any thread". This way we can use task_new_on() and
task_new_anywhere() instead of task_new() which will soon disappear.
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.
This file contains all the stream-connector functions that are specific
to application layers of type stream. So let's name it accordingly so
that it's easier to figure what's located there.
The alphabetical ordering of include files was preserved.
An equivalent applet_need_more_data() was added as well since that function
is mostly used from applet code. It makes it much clearer that the applet
is waiting for data from the stream layer.
The following flags are not at all related to the endpoint but to the
connector itself:
- SE_FL_RXBLK_ROOM
- SE_FL_RXBLK_BUFF
- SE_FL_RXBLK_CHAN
As such they have no business staying in the endpoint descriptor and
they must move to the stream connector. They've also been renamed
accordingly to better match what they correspond to (the same name
as the function that sets them).
The rare occurrences of cs_rx_blocked() were replaced by an explicit
test on the list of flags. The reason is that cs_rx_blocked() used to
preserve some tests that are not needed at certain places since already
known. For the same reason SE_FL_RXBLK_ANY wasn't converted. As such it
will later be possible to carefully review these few locations and
eliminate the unneeded flags from the tests. No particular function
was made to test them since they're explicit enough.
It now looks like ci_putchk() and friends could very well place the flag
themselves on the connector when they detect a buffer full condition, as
this would significantly simplify the high-level API. But all usages must
first be reviewed before this simplification can be done. For now it
remains done by applet_put*() instead.
The analysis of cs_rx_endp_more() showed that the purpose is for a stream
endpoint to inform the connector that it's ready to deliver more data to
that one, and conversely cs_rx_endp_done() that it's done delivering data
so it should not be bothered again for this.
This was modified two ways:
- the operation is no longer performed on the connector but on the
endpoint so that there is no more doubt when reading applet code
about what this rx refers to; it's the endpoint that has more or
no more data.
- an applet implementation is also provided and mostly used from
applet code since it saves the caller from having to access the
endpoint descriptor.
It's visible that the flag ought to be inverted because some places
have to set it by default for no reason.
These functions are used by the application layer to disable or enable
reading at the stream connector's level when the input buffer failed to
be allocated (or was finally allocated). The new names makes things
clearer.
The new name mor eclearly indicates that a stream connector cannot make
any more progress because it needs room in the channel buffer, or that
it may be unblocked because the buffer now has more room available. The
testing function is sc_waiting_room(). This is mostly used by applets.
Note that the flags will change soon.
sc_is_send_allowed() is now used everywhere instead of the combination
of cs_tx_endp_ready() && !cs_tx_blocked(). There's no place where we
need them individually thus it's simpler. The test was placed in cs_util
as we'll complete it later.
We're starting to propagate the stream connector's new name through the
API. Most call places of these functions that retrieve the channel or its
buffer are in applets. The local variable names are not changed in order
to keep the changes small and reviewable. There were ~92 uses of cs_ic(),
~96 of cs_oc() (due to co_get*() being less factorizable than ci_put*),
and ~5 accesses to the buffer itself.
For historical reasons (stream-interface and connections), we used to
require two independent fields for the application level callbacks and
the transport-level functions. Over time the distinction faded away so
much that the low-level functions became specific to the application
and conversely. For example, applets may only work with streams on top
since they rely on the channels, and the stream-level functions differ
between applets and connections. Right now the application level only
contains a wake() callback and the low-level ones contain the functions
that act at the lower level to perform the shutr/shutw and at the upper
level to notify about readability and writability. Let's just merge them
together into a single set and get rid of this confusing distinction.
Note that the check ops do not define any app-level function since these
are only called by streams.
This renames the "struct conn_stream" to "struct stconn" and updates
the descriptions in all comments (and the rare help descriptions) to
"stream connector" or "connector". This touches a lot of files but
the change is minimal. The local variables were not even renamed, so
there's still a lot of "cs" everywhere.
Now at least it makes it obvious that it's the stream endpoint descriptor
and not an endpoint. There were few changes thanks to the previous refactor
of the flags.
After some discussion we found that the cs_endpoint was precisely the
descriptor for a stream endpoint, hence the naturally coming name,
stream endpoint constructor.
This patch renames only the type everywhere and the new/init/free functions
to remain consistent with it. Future patches will address field names and
argument names in various code areas.
That's the "stream endpoint" pointer. Let's change it now while it's
not much spread. The function __cs_endp_target() wasn't yet renamed
because that will change more globally soon.
