This patch adds the support of filters in HAProxy. The main idea is to have a
way to "easely" extend HAProxy by adding some "modules", called filters, that
will be able to change HAProxy behavior in a programmatic way.
To do so, many entry points has been added in code to let filters to hook up to
different steps of the processing. A filter must define a flt_ops sutrctures
(see include/types/filters.h for details). This structure contains all available
callbacks that a filter can define:
struct flt_ops {
/*
* Callbacks to manage the filter lifecycle
*/
int (*init) (struct proxy *p);
void (*deinit)(struct proxy *p);
int (*check) (struct proxy *p);
/*
* Stream callbacks
*/
void (*stream_start) (struct stream *s);
void (*stream_accept) (struct stream *s);
void (*session_establish)(struct stream *s);
void (*stream_stop) (struct stream *s);
/*
* HTTP callbacks
*/
int (*http_start) (struct stream *s, struct http_msg *msg);
int (*http_start_body) (struct stream *s, struct http_msg *msg);
int (*http_start_chunk) (struct stream *s, struct http_msg *msg);
int (*http_data) (struct stream *s, struct http_msg *msg);
int (*http_last_chunk) (struct stream *s, struct http_msg *msg);
int (*http_end_chunk) (struct stream *s, struct http_msg *msg);
int (*http_chunk_trailers)(struct stream *s, struct http_msg *msg);
int (*http_end_body) (struct stream *s, struct http_msg *msg);
void (*http_end) (struct stream *s, struct http_msg *msg);
void (*http_reset) (struct stream *s, struct http_msg *msg);
int (*http_pre_process) (struct stream *s, struct http_msg *msg);
int (*http_post_process) (struct stream *s, struct http_msg *msg);
void (*http_reply) (struct stream *s, short status,
const struct chunk *msg);
};
To declare and use a filter, in the configuration, the "filter" keyword must be
used in a listener/frontend section:
frontend test
...
filter <FILTER-NAME> [OPTIONS...]
The filter referenced by the <FILTER-NAME> must declare a configuration parser
on its own name to fill flt_ops and filter_conf field in the proxy's
structure. An exemple will be provided later to make it perfectly clear.
For now, filters cannot be used in backend section. But this is only a matter of
time. Documentation will also be added later. This is the first commit of a long
list about filters.
It is possible to have several filters on the same listener/frontend. These
filters are stored in an array of at most MAX_FILTERS elements (define in
include/types/filters.h). Again, this will be replaced later by a list of
filters.
The filter API has been highly refactored. Main changes are:
* Now, HA supports an infinite number of filters per proxy. To do so, filters
are stored in list.
* Because filters are stored in list, filters state has been moved from the
channel structure to the filter structure. This is cleaner because there is no
more info about filters in channel structure.
* It is possible to defined filters on backends only. For such filters,
stream_start/stream_stop callbacks are not called. Of course, it is possible
to mix frontend and backend filters.
* Now, TCP streams are also filtered. All callbacks without the 'http_' prefix
are called for all kind of streams. In addition, 2 new callbacks were added to
filter data exchanged through a TCP stream:
- tcp_data: it is called when new data are available or when old unprocessed
data are still waiting.
- tcp_forward_data: it is called when some data can be consumed.
* New callbacks attached to channel were added:
- channel_start_analyze: it is called when a filter is ready to process data
exchanged through a channel. 2 new analyzers (a frontend and a backend)
are attached to channels to call this callback. For a frontend filter, it
is called before any other analyzer. For a backend filter, it is called
when a backend is attached to a stream. So some processing cannot be
filtered in that case.
- channel_analyze: it is called before each analyzer attached to a channel,
expects analyzers responsible for data sending.
- channel_end_analyze: it is called when all other analyzers have finished
their processing. A new analyzers is attached to channels to call this
callback. For a TCP stream, this is always the last one called. For a HTTP
one, the callback is called when a request/response ends, so it is called
one time for each request/response.
* 'session_established' callback has been removed. Everything that is done in
this callback can be handled by 'channel_start_analyze' on the response
channel.
* 'http_pre_process' and 'http_post_process' callbacks have been replaced by
'channel_analyze'.
* 'http_start' callback has been replaced by 'http_headers'. This new one is
called just before headers sending and parsing of the body.
* 'http_end' callback has been replaced by 'channel_end_analyze'.
* It is possible to set a forwarder for TCP channels. It was already possible to
do it for HTTP ones.
* Forwarders can partially consumed forwardable data. For this reason a new
HTTP message state was added before HTTP_MSG_DONE : HTTP_MSG_ENDING.
Now all filters can define corresponding callbacks (http_forward_data
and tcp_forward_data). Each filter owns 2 offsets relative to buf->p, next and
forward, to track, respectively, input data already parsed but not forwarded yet
by the filter and parsed data considered as forwarded by the filter. A any time,
we have the warranty that a filter cannot parse or forward more input than
previous ones. And, of course, it cannot forward more input than it has
parsed. 2 macros has been added to retrieve these offets: FLT_NXT and FLT_FWD.
In addition, 2 functions has been added to change the 'next size' and the
'forward size' of a filter. When a filter parses input data, it can alter these
data, so the size of these data can vary. This action has an effet on all
previous filters that must be handled. To do so, the function
'filter_change_next_size' must be called, passing the size variation. In the
same spirit, if a filter alter forwarded data, it must call the function
'filter_change_forward_size'. 'filter_change_next_size' can be called in
'http_data' and 'tcp_data' callbacks and only these ones. And
'filter_change_forward_size' can be called in 'http_forward_data' and
'tcp_forward_data' callbacks and only these ones. The data changes are the
filter responsability, but with some limitation. It must not change already
parsed/forwarded data or data that previous filters have not parsed/forwarded
yet.
Because filters can be used on backends, when we the backend is set for a
stream, we add filters defined for this backend in the filter list of the
stream. But we must only do that when the backend and the frontend of the stream
are not the same. Else same filters are added a second time leading to undefined
behavior.
The HTTP compression code had to be moved.
So it simplifies http_response_forward_body function. To do so, the way the data
are forwarded has changed. Now, a filter (and only one) can forward data. In a
commit to come, this limitation will be removed to let all filters take part to
data forwarding. There are 2 new functions that filters should use to deal with
this feature:
* flt_set_http_data_forwarder: This function sets the filter (using its id)
that will forward data for the specified HTTP message. It is possible if it
was not already set by another filter _AND_ if no data was yet forwarded
(msg->msg_state <= HTTP_MSG_BODY). It returns -1 if an error occurs.
* flt_http_data_forwarder: This function returns the filter id that will
forward data for the specified HTTP message. If there is no forwarder set, it
returns -1.
When an HTTP data forwarder is set for the response, the HTTP compression is
disabled. Of course, this is not definitive.
The union name "data" is a little bit heavy while we read the source
code because we can read "data.data.sint". The rename from "data" to "u"
makes the read easiest like "data.u.sint".
This patch remove the struct information stored both in the struct
sample_data and in the striuct sample. Now, only thestruct sample_data
contains data, and the struct sample use the struct sample_data for storing
his own data.
This patch removes the 32 bits unsigned integer and the 32 bit signed
integer. It replaces these types by a unique type 64 bit signed.
This makes easy the usage of integer and clarify signed and unsigned use.
With the previous version, signed and unsigned are used ones in place of
others, and sometimes the converter loose the sign. For example, divisions
are processed with "unsigned", if one entry is negative, the result is
wrong.
Note that the integer pattern matching and dotted version pattern matching
are already working with signed 64 bits integer values.
There is one user-visible change : the "uint()" and "sint()" sample fetch
functions which used to return a constant integer have been replaced with
a new more natural, unified "int()" function. These functions were only
introduced in the latest 1.6-dev2 so there's no impact on regular
deployments.
This patch removes the structs "session", "stream" and "proxy" from
the sample-fetches and converters function prototypes.
This permits to remove some weight in the prototype call.
Many such function need a session, and till now they used to dereference
the stream. Once we remove the stream from the embryonic session, this
will not be possible anymore.
So as of now, sample fetch functions will be called with this :
- sess = NULL, strm = NULL : never
- sess = valid, strm = NULL : tcp-req connection
- sess = valid, strm = valid, strm->txn = NULL : tcp-req content
- sess = valid, strm = valid, strm->txn = valid : http-req / http-res
All of them can now retrieve the HTTP transaction *if it exists* from
the stream and be sure to get NULL there when called with an embryonic
session.
The patch is a bit large because many locations were touched (all fetch
functions had to have their prototype adjusted). The opportunity was
taken to also uniformize the call names (the stream is now always "strm"
instead of "l4") and to fix indent where it was broken. This way when
we later introduce the session here there will be less confusion.
Now this one is dynamically allocated. It means that 280 bytes of memory
are saved per TCP stream, but more importantly that it will become
possible to remove the l7 pointer from fetches and converters since
it will be deduced from the stream and will support being null.
A lot of care was taken because it's easy to forget a test somewhere,
and the previous code used to always trust s->txn for being valid, but
all places seem to have been visited.
All HTTP fetch functions check the txn first so we shouldn't have any
issue there even when called from TCP. When branching from a TCP frontend
to an HTTP backend, the txn is properly allocated at the same time as the
hdr_idx.
Just like for the listener, the frontend is session-wide so let's move
it to the session. There are a lot of places which were changed but the
changes are minimal in fact.
With HTTP/2, we'll have to support multiplexed streams. A stream is in
fact the largest part of what we currently call a session, it has buffers,
logs, etc.
In order to catch any error, this commit removes any reference to the
struct session and tries to rename most "session" occurrences in function
names to "stream" and "sess" to "strm" when that's related to a session.
The files stream.{c,h} were added and session.{c,h} removed.
The session will be reintroduced later and a few parts of the stream
will progressively be moved overthere. It will more or less contain
only what we need in an embryonic session.
Sample fetch functions and converters will have to change a bit so
that they'll use an L5 (session) instead of what's currently called
"L4" which is in fact L6 for now.
Once all changes are completed, we should see approximately this :
L7 - http_txn
L6 - stream
L5 - session
L4 - connection | applet
There will be at most one http_txn per stream, and a same session will
possibly be referenced by multiple streams. A connection will point to
a session and to a stream. The session will hold all the information
we need to keep even when we don't yet have a stream.
Some more cleanup is needed because some code was already far from
being clean. The server queue management still refers to sessions at
many places while comments talk about connections. This will have to
be cleaned up once we have a server-side connection pool manager.
Stream flags "SN_*" still need to be renamed, it doesn't seem like
any of them will need to move to the session.
This library is designed to emit a zlib-compatible stream with no
memory usage and to favor resource savings over compression ratio.
While zlib requires 256 kB of RAM per compression context (and can only
support 4000 connections per GB of RAM), the stateless compression
offered by libslz does not need to retain buffers between subsequent
calls. In theory this slightly reduces the compression ratio but in
practice it does not have that much of an effect since the zlib
window is limited to 32kB.
Libslz is available at :
http://git.1wt.eu/web?p=libslz.git
It was designed for web compression and provides a lot of savings
over zlib in haproxy. Here are the preliminary results on a single
core of a core2-quad 3.0 GHz in 32-bit for only 300 concurrent
sessions visiting the home page of www.haproxy.org (76 kB) with
the default 16kB buffers :
BW In BW Out BW Saved Ratio memory VSZ/RSS
zlib 237 Mbps 92 Mbps 145 Mbps 2.58 84M / 69M
slz 733 Mbps 380 Mbps 353 Mbps 1.93 5.9M / 4.2M
So while the compression ratio is lower, the bandwidth savings are
much more important due to the significantly lower compression cost
which allows to consume even more data from the servers. In the
example above, zlib became the bottleneck at 24% of the output
bandwidth. Also the difference in memory usage is obvious.
More tests run on a single core of a core i5-3320M, with 500 concurrent
users and the default 16kB buffers :
At 100% CPU (no limit) :
BW In BW Out BW Saved Ratio memory VSZ/RSS hits/s
zlib 480 Mbps 188 Mbps 292 Mbps 2.55 130M / 101M 744
slz 1700 Mbps 810 Mbps 890 Mbps 2.10 23.7M / 9.7M 2382
At 85% CPU (limited) :
BW In BW Out BW Saved Ratio memory VSZ/RSS hits/s
zlib 1240 Mbps 976 Mbps 264 Mbps 1.27 130M / 100M 1738
slz 1600 Mbps 976 Mbps 624 Mbps 1.64 23.7M / 9.7M 2210
The most important benefit really happens when the CPU usage is
limited by "maxcompcpuusage" or the BW limited by "maxcomprate" :
in order to preserve resources, haproxy throttles the compression
ratio until usage is within limits. Since slz is much cheaper, the
average compression ratio is much higher and the input bandwidth
is quite higher for one Gbps output.
Other tests made with some reference files :
BW In BW Out BW Saved Ratio hits/s
daniels.html zlib 1320 Mbps 163 Mbps 1157 Mbps 8.10 1925
slz 3600 Mbps 580 Mbps 3020 Mbps 6.20 5300
tv.com/listing zlib 980 Mbps 124 Mbps 856 Mbps 7.90 310
slz 3300 Mbps 553 Mbps 2747 Mbps 5.97 1100
jquery.min.js zlib 430 Mbps 180 Mbps 250 Mbps 2.39 547
slz 1470 Mbps 764 Mbps 706 Mbps 1.92 1815
bootstrap.min.css zlib 790 Mbps 165 Mbps 625 Mbps 4.79 777
slz 2450 Mbps 650 Mbps 1800 Mbps 3.77 2400
So on top of saving a lot of memory, slz is constantly 2.5-3.5 times
faster than zlib and results in providing more savings for a fixed CPU
usage. For links smaller than 100 Mbps, zlib still provides a better
compression ratio, at the expense of a much higher CPU usage.
Larger input files provide slightly higher bandwidth for both libs, at
the expense of a bit more memory usage for zlib (it converges to 256kB
per connection).
This function used to take a zlib-specific flag as argument to indicate
whether a buffer flush or end of contents was met, let's split it in two
so that we don't depend on zlib anymore.
This algorithm is exactly the same as "deflate" without the zlib wrapper,
and used as an alternative when the browser wants "deflate". All major
browsers understand it and despite violating the standards, it is known
to work better than "deflate", at least on MSIE and some versions of
Safari. Do not use it in conjunction with "deflate", use either one or
the other since both react to the same Accept-Encoding token. Note that
the lack of Adler32 checksum makes it slightly faster.
Thanks to MSIE/IIS, the "deflate" name is ambigous. According to the RFC
it's a zlib-wrapped deflate stream, but IIS used to send only a raw deflate
stream, which is the only format MSIE understands for "deflate". The other
widely used browsers do support both formats. For this reason some people
prefer to emit a raw deflate stream on "deflate" to serve more users even
it that means violating the standards. Haproxy only follows the standard,
so they cannot do this.
This patch makes it possible to have one algorithm name in the configuration
and another one in the protocol. This will make it possible to have a new
configuration token to add a different algorithm so that users can decide if
they want a raw deflate or the standard one.
There's no reason for exporting identity_* nor deflate_*, they're only
used in the same file. Mark them static, it will make it easier to add
other algorithms.
When checking if the buffer is large enough, we used to rely on a fixed
size that was "apparently" enough. We need to consider the expansion
factor of deflate-encoded streams instead, which is of 5 bytes per 32kB.
The previous value was OK till 128kB buffers but became wrong past that.
It's totally harmless since we always keep the reserve when compressiong,
so there's 1kB or so available, which is enough for buffers as large as
6.5 MB, but better fix the check anyway.
This fix could be backported into 1.5 since compression was added there.
Till now we used to rely on a fixed maximum chunk size. Thanks to last
commit we're now free to adjust the chunk's length before sending the
data, so we don't have to use 6 digits all the time anymore, and if
one wants buffers larger than 16 MB it is now possible.
Till now we used to copy the pending outgoing data into the new buffer,
then compute the chunk size, then compress, then fix the chunk size,
then copy the remaining data into the destination buffer. If the
compression would fail for whatever reason (eg: not enough input bytes
to push an extra block), this work still had to be performed for no
added value. It also presents the disadvantage of having to use a fixed
length to encode the chunk size.
Thanks to the body parser changes that went late into 1.5, the buffers
are not modified anymore during these operations. So this patch rearranges
operations so that they're more optimal :
1) init() prepares a new buffer and reserves space in it for pending
outgoing data (no copy) and for chunk size
2) data are compressed
3) only if data were added to the buffer, then the old data are copied
and the chunk size is set.
A few optimisations are still possible to go further :
- decide whether we prefer to copy pending outgoing data from the
old buffer to the new one, or pending incoming compressed data
from the new one to the old one, based on the amount of outgoing
data available. Given that pending outgoing data are rare and the
operation could be complex in the presence of extra input data,
it's probably better to ignore this one ;
- compute the needed length for the chunk size. This would avoid
sending lots of leading zeroes when not needed.
b_alloc() now allocates a buffer and initializes it to the size specified
in the pool minus the size of the struct buffer itself. This ensures that
callers do not need to care about buffer details anymore. Also this never
applies memory poisonning, which is slow and useless on buffers.
We'll soon need to be able to switch buffers without touching the
channel, so let's move buffer initialization out of channel_init().
We had the same in compressoin.c.
In zlib we track memory usage. The problem is that the way alloc_zlib()
and free_zlib() account for memory is different, resulting in variations
that can lead to negative zlib_mem being reported. The alloc() function
uses the requested size while the free() function uses the pool size. The
difference can happen when pools are shared with other pools of similar
size. The net effect is that zlib_mem can be reported negative with a
slowly decreasing count, and over the long term the limit will not be
enforced anymore.
The fix is simple : let's use the pool size in both cases, which is also
the exact value when it comes to memory usage.
This fix must be backported to 1.5.
Now we have valid buffer offsets, we can use them to safely parse the
input and only forward when needed. Thus we can get rid of the
consumed_data accumulator, and the code now works both for chunked and
content-length, even with a server feeding one byte at a time (which
systematically broke the previous one).
It's worth noting that 0<CRLF> must always be sent after end of data
(ie: chunk_len==0), and that the trailing CRLF is sent only content
length mode, because in chunked we'll have to pass trailers.
We used to have msg->sov updated for every chunk that was parsed. The issue
is that we want to be able to rewind after chunks were parsed in case we need
to redispatch a request and perform a new hash on the request or insert a
different server header name.
Currently, msg->sov and msg->next make parallel progress. We reached a point
where they're always equal because msg->next is initialized from msg->sov,
and is subtracted msg->sov's value each time msg->sov bytes are forwarded.
So we can now ensure that msg->sov can always be replaced by msg->next for
every state after HTTP_MSG_BODY where it is used as a position counter.
This allows us to keep msg->sov untouched whatever the number of chunks that
are parsed, as is needed to extract data from POST request (eg: url_param).
However, we still need to know the starting position of the data relative to
the body, which differs by the chunk size length. We use msg->sol for this
since it's now always zero and unused in the body.
So with this patch, we have the following situation :
- msg->sov = msg->eoh + msg->eol = size of the headers including last CRLF
- msg->sol = length of the chunk size if any. So msg->sov + msg->sol = DATA.
- msg->next corresponds to the byte being inspected based on the current
state and is always >= msg->sov before starting to forward anything.
Since sov and next are updated in case of header rewriting, a rewind will
fix them both when needed. Of course, ->sol has no reason for changing in
such conditions, so it's fine to keep it relative to msg->sov.
In theory, even if a redispatch has to be performed, a transformation
occurring on the request would still work because the data moved would
still appear at the same place relative to bug->p.
There are still some pending issues in the gzip compressor, and fixing
them requires a better handling of intermediate parsing states.
Another issue to deal with is the rewinding of a buffer during a redispatch
when a load balancing algorithm involves L7 data because the exact amount of
data to rewind is not clear. At the moment, this is handled by unwinding all
pending data, which cannot work in responses due to pipelining.
Last, having a first analysis which parses the body and another one which
restarts from where the parsing was left is wrong. Right now it only works
because we never both parse and transform in the same direction. But that
is wrong anyway.
In order to address the first issue, we'll have to use msg->eoh + msg->eol
to find the end of headers, and we still need to store the information about
the forwarded header length somewhere (msg->sol might be reused for this).
msg->sov may only be used for the start of data and not for subsequent chunks
if possible. This first implies that we stop sharing it with header length,
and stop using msg->sol there. In fact we don't need it already as it is
always zero when reaching the HTTP_MSG_BODY state. It was only updated to
reflect a copy of msg->sov.
So now as a first step into that direction, this patch ensure that msg->sol
is never re-assigned after being set to zero and is not used anymore when
we're dealing with HTTP processing and forwarding. We'll later reuse it
differently but for now it's secured.
The patch does nothing magic, it only removes msg->sol everywhere it was
already zero and avoids setting it. In order to keep the sov-sol difference,
it now resets sov after forwarding data. In theory there's no problem here,
but the patch is still tagged major because that code is complex.
The operations applied on types SMP_T_CSTR and SMP_T_STR are the same,
but the check code and the declarations are double, because it must
declare action for SMP_T_C* and SMP_T_*. The declared actions and checks
are the same. this complexify the code. Only the "conv" functions can
change from "C*" to "*"
Now, if a function needs to modify input string, it can call the new
function smp_dup(). This one duplicate data in a trash buffer.
smp_fetch_res_comp_algo() returns the name of the compression algorithm
in use. The output type is set to SMP_T_STR instead of SMP_T_CSTR, which
causes any transformation to be operated without a cast. Fortunately,
the current converters do not overwrite a zero-sized area, so the result
is an empty string. Fix this to have SMP_T_CSTR instead so that the cast
is always performed using a copy before any transformation is done.
We're having a lot of duplicate code just because of minor variants between
fetch functions that could be dealt with if the functions had the pointer to
the original keyword, so let's pass it as the last argument. An earlier
version used to pass a pointer to the sample_fetch element, but this is not
the best solution for two reasons :
- fetch functions will solely rely on the keyword string
- some other smp_fetch_* users do not have the pointer to the original
keyword and were forced to pass NULL.
So finally we're passing a pointer to the keyword as a const char *, which
perfectly fits the original purpose.
Benoit Dolez reported a failure to start haproxy 1.5-dev19. The
process would immediately report an internal error with missing
fetches from some crap instead of ACL names.
The cause is that some versions of gcc seem to trim static structs
containing a variable array when moving them to BSS, and only keep
the fixed size, which is just a list head for all ACL and sample
fetch keywords. This was confirmed at least with gcc 3.4.6. And we
can't move these structs to const because they contain a list element
which is needed to link all of them together during the parsing.
The bug indeed appeared with 1.5-dev19 because it's the first one
to have some empty ACL keyword lists.
One solution is to impose -fno-zero-initialized-in-bss to everyone
but this is not really nice. Another solution consists in ensuring
the struct is never empty so that it does not move there. The easy
solution consists in having a non-null list head since it's not yet
initialized.
A new "ILH" list head type was thus created for this purpose : create
an Initialized List Head so that gcc cannot move the struct to BSS.
This fixes the issue for this version of gcc and does not create any
burden for the declarations.
Global compression settings (windowsize and memlevel) were only considered
for the gzip algorithm but not the deflate algorithm. Since a single allocator
is used for both algos, if gzip was first initialized the memory with parameters
smaller than default, then initializing deflate after with default settings
would result in overusing the small allocated areas.
To fix this, we make use of deflateInit2() for deflate_init() as well.
Thanks to Godbach for reporting this bug, introduced by in 1.5-dev13 by commit
8b52bb38. No backport is needed.
Implements the "res.comp" ACL which is a boolean returning 1 when a
response has been compressed by HAProxy or 0 otherwise.
Implements the "res.comp_algo" fetch which contains the name of the
algorithm HAProxy used to compress the response.
It was a bit frustrating to have no idea about the bandwidth saved by
HTTP compression. Now we have per-frontend and per-backend stats. The
stats on the HTTP interface are shown in a hover title in the "bytes out"
column if at least something was fed to the compressor. 3 new columns
appeared in the CSV stats output.
New option 'maxcompcpuusage' in global section.
Sets the maximum CPU usage HAProxy can reach before stopping the
compression for new requests or decreasing the compression level of
current requests. It works like 'maxcomprate' but with the Idle.
Using compression rate limit, the compression level wasn't taking care
of the max compression level during a session because the test was done
on the wrong variable.
This patch makes changes in the http_response_forward_body state
machine. It checks if the compress algorithm had consumed data before
swapping the temporary and the input buffer. So it prevents null sized
zlib chunks.
Zlib (at least 1.2 and 1.3) aborts when it fails to allocate the state, so we
must not count a round on this event. If the state succeeds, then it allocates
all the 4 remaining counters at once.
Compression algorithms are not always supported depending on build options.
"haproxy -vv" now reports if zlib is supported and lists compression algorithms
also supported.
gcc emits this warning while building free_zlib() :
src/compression.c: In function `free_zlib':
src/compression.c:403: warning: 'pool' might be used uninitialized in this function
This is not a bug as the pool cannot take other values, but let's
pre-initialize is to null to fix the warning.
This patch adds input and output rate calcutation on the HTTP compresion
feature.
Compression can be limited with a maximum rate value in kilobytes per
second. The rate is set with the global 'maxcomprate' option. You can
change this value dynamicaly with 'set rate-limit http-compression
global' on the UNIX socket.
With the global maxzlibmem option, you are able ton control the maximum
amount of RAM usable for HTTP compression.
A test is done before each zlib allocation, if the there isn't available
memory, the test fail and so the zlib initialization, so data won't be
compressed.
Don't use the zlib allocator anymore, 5 pools are used for the zlib
compression. Their sizes depends of the window size and the memLevel in
deflateInit2.
The window size and the memlevel of the zlib are now configurable using
global options tune.zlib.memlevel and tune.zlib.windowsize.
It affects the memory consumption of the zlib.
The build was dependent of the zlib.h header, regardless of the USE_ZLIB
option. The fix consists of several #ifdef in the source code.
It removes the overhead of the zstream structure in the session when you
don't use the option.
The crappy zlib and openssl libs both define a free_func as a different typedef.
That's a very clever idea to use such a generic name in general purpose libraries,
really... The zlib one is easier to redefine than openssl's, so let's only fix this
one.
Decreasing the deflateInit2's memLevel parameter from 9 to 8 does not
affect the compression ratio and increases the compression speed by 12%.
Lower values do not increase transfer speed but decrease the compression
ratio so it looks like 8 is optimal.
This commit introduces HTTP compression using the zlib library.
http_response_forward_body has been modified to call the compression
functions.
This feature includes 3 algorithms: identity, gzip and deflate:
* identity: this is mostly for debugging, and it was useful for
developping the compression feature. With Content-Length in input, it
is making each chunk with the data available in the current buffer.
With chunks in input, it is rechunking, the output chunks will be
bigger or smaller depending of the size of the input chunk and the
size of the buffer. Identity does not apply any change on data.
* gzip: same as identity, but applying a gzip compression. The data
are deflated using the Z_NO_FLUSH flag in zlib. When there is no more
data in the input buffer, it flushes the data in the output buffer
(Z_SYNC_FLUSH). At the end of data, when it receives the last chunk in
input, or when there is no more data to read, it writes the end of
data with Z_FINISH and the ending chunk.
* deflate: same as gzip, but with deflate algorithm and zlib format.
Note that this algorithm has ambiguous support on many browsers and
no support at all from recent ones. It is strongly recommended not
to use it for anything else than experimentation.
You can't choose the compression ratio at the moment, it will be set to
Z_BEST_SPEED (1), as tests have shown very little benefit in terms of
compression ration when going above for HTML contents, at the cost of
a massive CPU impact.
Compression will be activated depending of the Accept-Encoding request
header. With identity, it does not take care of that header.
To build HAProxy with zlib support, use USE_ZLIB=1 in the make
parameters.
This work was initially started by David Du Colombier at Exceliance.
