Miroslav reported in issue #1802 a problem that affects atomic map/acl
updates. During an update, incorrect versions are properly skipped, but
in order to do so, we rely on ebmb_next() instead of ebmb_next_dup().
This means that if a new matching entry is in the process of being
added and is the first one to succeed in the lookup, we'll skip it due
to its version and use the next entry regardless of its value provided
that it has the correct version. For IP addresses and string prefixes
it's particularly visible because a lookup may match a new longer prefix
that's not yet committed (e.g. 11.0.0.1 would match 11/8 when 10/7 was
the only committed one), and skipping it could end up on 12/8 for
example. As soon as a commit for the last version happens, the issue
disappears.
This problem only affects tree-based matches: the "str", "ip", and "beg"
matches.
Here we replace the ebmb_next() values with ebmb_next_dup() for exact
string matches, and with ebmb_lookup_shorter() for longest matches,
which will first visit duplicates, then look for shorter prefixes. This
relies on previous commit:
MINOR: ebtree: add ebmb_lookup_shorter() to pursue lookups
Both need to be backported to 2.4, where the generation ID was added.
Note that nowadays a simpler and more efficient approach might be employed,
by having a single version in the current tree, and a list of trees per
version. Manipulations would look up the tree version and work (and lock)
only in the relevant trees, while normal operations would be performed on
the current tree only. Committing would just be a matter of swapping tree
roots and deleting old trees contents.
The output of "show map/acl" now contains the 'entry_cnt' value that
represents the count of all the entries for each map/acl, not just the
active ones, which means that it also includes entries currently being
added.
This function was not used anymore after the atomic updates were
implemented in 2.3, and it must not be used given that it does not
yield and can easily make the process hang for tens of seconds on
large acls/maps. Let's remove it before someone uses it as an
example to implement something else!
Instead of being able to purge only values older than a specific value,
let's support arbitrary ranges and make pat_ref_purge_older() just be
one special case of this one.
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.
Interestingly, all arrays used to declare patterns were read-write while
only hard-coded. Let's mark them const so that they move from data to
rodata and don't risk to experience false sharing.
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.
It's about the third time I get confused by these functions, half of
which manipulate the reference as a whole and those manipulating only
an entry. For me "pat_ref_commit" means committing the pattern reference,
not just an element, so let's rename it. A number of other ones should
really be renamed before 2.4 gets released :-/
This is from the output of codespell. It's done at once over a bunch
of files and only affects comments, so there is nothing user-visible.
No backport needed.
The functions add final 0 to string if the final 0 is not set,
but don't check the flag CONST. This patch duplicates the strings
if the final zero is not set and the string is CONST.
Should be backported until 2.2 (at least)
It does not require heavy deletion from the expr anymore, so we can now
turn this to a single-linked list since most of the time we want to delete
all instances of a given pattern from the head. By doing so we save 32 bytes
of memory per pattern. The pat_unlink_from_head() function was adjusted
accordingly.
Instead of using LIST_DEL() on the pattern itself inside an expression,
we look it up from its head. The goal is to get rid of the double-linked
list while this usage remains exclusively for freeing on startup error!
Instead of scanning all elements from the expression and using the
slow delete path there, let's use the faster way which involves
pat_delete_gen() while the elements are detached from ther reference.
When purging all of a reference, it's much more efficient to scan the
reference patterns from the reference head and delete all derivative
patterns than to scan the expressions. The only thing is that we need
to proceed both for the current and next generations, in case there is
a huge gap between the two. With this, purging 20M IP addresses in small
batches of 100 takes roughly 3 seconds.
This function will be usable to purge at most a specified number of old
entries from a reference. Entries are declared old if their generation
number is in the past compared to the one passed in argument. This will
ease removal of early entries when new ones have been appended.
We also call malloc_trim() when available, at the end of the series,
because this is one place where there is a lot of memory to save. Reloads
of 1M IP addresses used in an ACL made the process grow up to 1.7 GB RSS
after 10 reloads and roughly stabilize there without this call, versus
only 260 MB when the call is present. Sadly there is no direct equivalent
for jemalloc, which stabilizes around 800MB-1GB.
pat_ref_load() basically combines pat_ref_append() and pat_ref_commit().
It's very similar to pat_ref_add() except that it also allows to set the
generation ID and the line number. pat_ref_add() was modified to directly
rely on it to avoid code duplication. Note that a previous declaration
of pat_ref_load() was removed as it was just a leftover of an earlier
incarnation of something possibly similar, so no existing functionality
was changed here.
This function will be used after a successful pat_ref_append() to propagate
the pattern to all use places (including parsing and indexing). On failure,
it will entirely roll back all insertions and free the pattern itself. It
also preserves the generation number so that it is convenient for use in
association with pat_ref_append(). pat_ref_add() was modified to rely on
it instead of open-coding the insertion and roll-back.
Instead of matching any pattern found in the tree, only match those
matching the current generation of entries. This will make sure that
reloads are atomic, regardless of the time they take to complete, and
that newly added data are not matched until the whole reference is
committed. For consistency we proceed the same way on "show map" and
"show acl".
This will have no impact for now since generations are not used.
Right now it's not possible to perform a safe reload because we don't
know what patterns were recently added or were already present. This
patch adds a generation counter to the reference patterns so that it
is possible to know what generation of the reference they were loaded
with. A reference now has two generations, the current one, used for
all additions, and the next one, allocated to those wishing to update
the contents. The generation wraps at 2^32 so comparisons must be made
relative to the current position.
The idea will be that upon full reload, the caller will first get a new
generation ID, will insert all new patterns using it, will then switch
the current ID to the new one, and will delete all entries older than
the current ID. This has the benefit of supporting chunked updates that
remain consistent and that won't block the whole process for ages like
pat_ref_reload() currently does.
Till now the only way to remove a known reference was via
pat_ref_delete_by_id() which scans the whole list to find a matching pointer.
Let's add pat_ref_delete_by_ptr() which takes a valid pointer. It can be
called by the function above after the pointer is found, and can also be
used to roll back a failed insertion much more efficiently.
These ones are not used anymore, so let's remove them to remove a bit
of the complexity. The ACL keyword's delete() function could be removed
as well, though most keyword declarations are positional and we have a
high risk of introducing a mistake here, so let's not touch the ACL part.
When we're removing an element under the expression lock, we don't need
anymore to run over all ->delete() functions via the expressions, since
we know that the single function does it fine now. Note that at this
point, pattern->delete() is not used at all through out the code anymore.
pat_del_tree_gen() was already chained onto pat_del_list_gen() to deal
with remaining cases, so let's complete the merge and have a generic
pattern deletion function acting on the reference and taking care of
reliably removing all elements.
This is the next step in speeding up entry removal. Now we don't scan
the whole lists or trees for elements pointing to the target reference,
instead we start from the reference and delete all linked patterns.
This simplifies some delete functions since we don't need anymore to
delete multiple times from an expression since all nodes appear after
the reference element. We can now have one generic list and one generic
tree deletion function.
This required the replacement of pattern_delete() with an open-coded
version since we now need to lock all expressions first before proceeding.
This means there is a high risk of lock inversion here but given that the
expressions are always scanned in the same order from the same head, this
must not happen.
Now deleting first entries is instantaneous, and it's still slow to
delete the last ones when looking up their ID since it still requires
to look them up by a full scan, but it's already way faster than
previously. Typically removing the last 10 IP from a 20M entries ACL
with a full-scan each took less than 2 seconds.
It would be technically possible to make use of indexed entries to
speed up most lookups for removal by value (e.g. IP addresses) but
that's for later.
There is a data model issue in the current pattern design that makes
pattern deletion extremely expensive: there's no direct way from a
reference to access all indexed occurrences. As such, the only way
to remove all indexed entries corresponding to a reference update
is to scan all expressions's lists and trees to find a link to the
reference. While this was possibly OK when map removal was not
common and most maps were small, this is not conceivable anymore
with GeoIP maps containing 10M+ entries and del-map operations that
are triggered from http-request rulesets.
This patch introduces two list heads from the pattern reference, one
for the objects linked by lists and one for those linked by tree node.
Ideally a single list would be enough but the linked elements are too
much unrelated to be distinguished at the moment, so we'll need two
lists. However for the long term a single-linked list will suffice but
for now it's not possible due to the way elements are removed from
expressions. As such this patch adds 32 bytes of memory usage per
reference plus 16 per indexed entry, but both will be cut in half
later.
The links are not yet used for deletion, this patch only ensures the
list is always consistent.
Now we have a single prune() function to act on an expression, and one
delete function for the lists and one for the trees. The presence of a
pointer in the lists is enough to warrant a free, and we rely on the
PAT_SF_REGFREE flag to decide whether to free using free() or regfree().
Currently we have no way to know how to delete/prune a pattern in a
generic way. A pattern doesn't contain its own type so we don't know
what function to call. Tree nodes are roughly OK but not lists where
regex are possible. Let's add one new bit for sflags at index time to
indicate that regex_free() will be needed upon deletion. It's not used
for now.
It's pointless to delete a backref and relink it to the next entry since
the next entry is going to do the exact same and so on until all of them
are deleted. Let's simply delete backrefs on reload.
It's not possible to uniquely update a single expression without updating
the pattern reference, I don't know why we've put the revision in the
expression back then, given that it in fact provides an update for a
full pattern. Let's move the revision into the reference's head instead.
This is one case where we may release large amounts of data at once. Tests
show that without this, after 10 full reloads of an ACL containing 1M IP
addresses, the memory usage grew and stabilized around 1.7 GB of RSS. With
this change, it stays around 260 MB and is stable across reloads.
The code is horrible to work with because most functions are documented
with misleading comments resulting from many spelling and grammatical
mistakes, and plenty of remains of copy-paste mentioning arguments that
do not exist and return values that are never set. Too many hours wasted
writing non-working code because of assumptions resulting from this,
let's fix this once for all now!
It's particularly difficult to make sure that the various pattern
structures are properly initialized given that they can be allocated
at multiple places and systematically via malloc() instead of calloc(),
thus not even leaving the possibility of default values. Let's adjust
a few of them.
It's more convenient to return the element than to return just 0 or 1,
as the next thing we'll want to do is to act on this element! In addition
it was using variable arguments instead of consts, causing some reuse
constraints which were also addressed. This doesn't change its use as
a boolean, hence why call places were not modified.
It must be done to expire patterns cached in the LRU cache. Otherwise it is
possible to retrieve an already freed pattern, attached to a released pattern
expression.
When a specific pattern is deleted (->delete() callback), the pattern expression
revision is already renewed. Thus it is not affected by this bug. Only prune
action on the pattern expression is concerned.
In addition, for a pattern expression, in ->prune() callbacks when the pattern
list is released, a missing LIST_DEL() has been added. It is not a real issue
because the list is reinitialized at the end and all elements are released and
should never be reused. But it is less confusing this way.
This bug may be triggered when a map is cleared from the cli socket. A
workaround is to set the pattern cache size (tune.pattern.cache-size) to 0 to
disable it.
This patch should fix the issue #844. It must be backported to all supported
versions.
NetBSD apparently uses macros for tolower/toupper and complains about
the use of char for array subscripts. Let's properly cast all of them
to unsigned char where they are used.
This is needed to fix issue #729.
In pat_match_str() and pat_math_beg() functions, a trailing zero is
systematically added at the end of the string, even if the buffer is not large
enough to accommodate it. It is a possible buffer overflow. For instance, when
the alpn is matched against a list of strings, the sample fetch is filled with a
non-null terminated string returned by the SSL library. No trailing zero must be
added at the end of this string, because it is outside the buffer.
So, to fix the bug, a trailing zero is added only if the buffer is large enough
to accommodate it. Otherwise, the sample fetch is duplicated. smp_dup() function
adds a trailing zero to the duplicated string, truncating it if it is too long.
This patch should fix the issue #718. It must be backported to all supported
versions.
As reported in issue #419, a "clear map" operation on a very large map
can take a lot of time and freeze the entire process for several seconds.
This patch makes sure that pat_ref_prune() can regularly yield after
clearing some entries so that the rest of the process continues to work.
The first part, the removal of the patterns, can take quite some time
by itself in one run but it's still relatively fast. It may block for
up to 100ms for 16M IP addresses in a tree typically. This change needed
to declare an I/O handler for the clear operation so that we can get
back to it after yielding.
The second part can be much slower because it deconstructs the elements
and its users, but it iterates progressively so we can yield less often
here.
The patch was tested with traffic in parallel sollicitating the map being
released and showed no problem. Some traffic will definitely notice an
incomplete map but the filling is already not atomic anyway thus this is
not different.
It may be backported to stable versions once sufficiently tested for side
effects, at least as far as 2.0 in order to avoid the watchdog triggering
when the process is frozen there. For a better behaviour, all these
prune_* functions should support yielding so that the callers have a
chance to continue also yield in turn.
Commit b5997f740 ("MAJOR: threads/map: Make acls/maps thread safe")
introduced a subtle bug in the pattern matching code. In order to cope
with the possibility that another thread might be modifying the pattern's
sample_data while it's being used, we return a thread-local static
sample_data which is a copy of the one found in the matched pattern. The
copy is performed depending on the sample_data's type. But the switch
statement misses some breaks and doesn't set the new sample_data pointer
at the right place, resulting in the original sample_data being restored
at the end before returning.
The net effect overall is that the correct sample_data is returned (hence
functionally speaking the matching works fine) but it's not thread-safe
so any del_map() or set_map() action could modify the pattern on one
thread while it's being used on another one. It doesn't seem likely to
cause a crash but could result in corrupted data appearing where the
value is consumed (e.g. when appended in a header or when logged) or an
ACL occasionally not matching after a map lookup.
This fix should be backported as far as 1.8.
Thanks to Tim for reporting it and to Emeric for the analysis.
This patch fixes all the leftovers from the include cleanup campaign. There
were not that many (~400 entries in ~150 files) but it was definitely worth
doing it as it revealed a few duplicates.
The current state of the logging is a real mess. The main problem is
that almost all files include log.h just in order to have access to
the alert/warning functions like ha_alert() etc, and don't care about
logs. But log.h also deals with real logging as well as log-format and
depends on stream.h and various other things. As such it forces a few
heavy files like stream.h to be loaded early and to hide missing
dependencies depending where it's loaded. Among the missing ones is
syslog.h which was often automatically included resulting in no less
than 3 users missing it.
Among 76 users, only 5 could be removed, and probably 70 don't need the
full set of dependencies.
A good approach would consist in splitting that file in 3 parts:
- one for error output ("errors" ?).
- one for log_format processing
- and one for actual logging.
global.h was one of the messiest files, it has accumulated tons of
implicit dependencies and declares many globals that make almost all
other file include it. It managed to silence a dependency loop between
server.h and proxy.h by being well placed to pre-define the required
structs, forcing struct proxy and struct server to be forward-declared
in a significant number of files.
It was split in to, one which is the global struct definition and the
few macros and flags, and the rest containing the functions prototypes.
The UNIX_MAX_PATH definition was moved to compat.h.
This one is particularly tricky to move because everyone uses it
and it depends on a lot of other types. For example it cannot include
arg-t.h and must absolutely only rely on forward declarations to avoid
dependency loops between vars -> sample_data -> arg. In order to address
this one, it would be nice to split the sample_data part out of sample.h.
It was moved as-is, except for extern declaration of pattern_reference.
A few C files used to include it but didn't need it anymore after having
been split apart so this was cleaned.
And also rename standard.c to tools.c. The original split between
tools.h and standard.h dates from version 1.3-dev and was mostly an
accident. This patch moves the files back to what they were expected
to be, and takes care of not changing anything else. However this
time tools.h was split between functions and types, because it contains
a small number of commonly used macros and structures (e.g. name_desc)
which in turn cause the massive list of includes of tools.h to conflict
with the callers.
They remain the ugliest files of the whole project and definitely need
to be cleaned and split apart. A few types are defined there only for
functions provided there, and some parts are even OS-specific and should
move somewhere else, such as the symbol resolution code.
