- map_get_server_hash() doesn't need a write lock since it only
reads the array, let's only use a read lock here.
- map_get_server_rr() only needs exclusivity to adjust the rr_idx
while looking for its entry. Since this one is not used by
map_get_server_hash(), let's turn this lock to a seek lock that
doesn't block reads.
With 8 threads, no significant performance difference was noticed
given that lookups are usually instant with this LB algo so the
lock contention is rare.
It was previously a spinlock, and it happens that a number of LB algos
only lock it for lookups, without performing any modification. Let's
first turn it to an rwlock and w-lock it everywhere. This is strictly
identical.
It was carefully checked that every HA_SPIN_LOCK() was turned to
HA_RWLOCK_WRLOCK() and that HA_SPIN_UNLOCK() was turned to
HA_RWLOCK_WRUNLOCK() on this lock. _INIT and _DESTROY were updated too.
Changes performed using the following coccinelle patch:
@@
type T;
expression E;
expression t;
@@
(
t = calloc(E, sizeof(*t))
|
- t = calloc(E, sizeof(T))
+ t = calloc(E, sizeof(*t))
)
Looking through the commit history, grepping for coccinelle shows that the same
replacement with a different patch was already performed in the past in commit
02779b6263.
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.
extern struct dict server_name_dict was moved from the type file to the
main file. A handful of inlined functions were moved at the bottom of
the file. Call places were updated to use server-t.h when relevant, or
to simply drop the entry when not needed.
The files remained mostly unchanged since they were OK. However, half of
the users didn't need to include them, and about as many actually needed
to have it and used to find functions like srv_currently_usable() through
a long chain that broke when moving the file.
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 used to be stored into debug.h but the debug tools got larger
and require a lot of other includes, which can't use BUG_ON() anymore
because of this. It does not make sense and instead this macro should
be placed into the lower includes and given its omnipresence, the best
solution is to create a new bug.h with the few surrounding macros needed
to trigger bugs and place assertions anywhere.
Another benefit is that it won't be required to add include <debug.h>
anymore to use BUG_ON, it will automatically be covered by api.h. No
less than 32 occurrences were dropped.
The FSM_PRINTF macro was dropped since not used at all anymore (probably
since 1.6 or so).
All files that were including one of the following include files have
been updated to only include haproxy/api.h or haproxy/api-t.h once instead:
- common/config.h
- common/compat.h
- common/compiler.h
- common/defaults.h
- common/initcall.h
- common/tools.h
The choice is simple: if the file only requires type definitions, it includes
api-t.h, otherwise it includes the full api.h.
In addition, in these files, explicit includes for inttypes.h and limits.h
were dropped since these are now covered by api.h and api-t.h.
No other change was performed, given that this patch is large and
affects 201 files. At least one (tools.h) was already freestanding and
didn't get the new one added.
This is where other imported components are located. All files which
used to directly include ebtree were touched to update their include
path so that "import/" is now prefixed before the ebtree-related files.
The ebtree.h file was slightly adjusted to read compiler.h from the
common/ subdirectory (this is the only change).
A build issue was encountered when eb32sctree.h is loaded before
eb32tree.h because only the former checks for the latter before
defining type u32. This was addressed by adding the reverse ifdef
in eb32tree.h.
No further cleanup was done yet in order to keep changes minimal.
The loop trying to figure the best server is theorically capable of
finishing the loop with best == NULL, causing the HA_ATOMIC_SUB()
to fail there. However for this to happen the list should be empty,
which is avoided at the beginning of the function. As it is, the
function still remains at risk so better address this now.
This patch should be backported to 1.8.
It's a bit painful to have to deal with HTTP semantics for each protocol
version (H1 and H2), and working on the version-agnostic code further
emphasizes the problem.
This patch creates http.h and http.c which are agnostic to the version
in use, and which borrow a few parts from proto_http and from h1. For
example the once thought h1-specific h1_char_classes array is in fact
dictated by RFC7231 and is used to parse HTTP headers. A few changes
were made to a few files which were including proto_http.h while they
only needed http.h.
Certain string definitions pre-dated the introduction of indirect
strings (ist) so some were used to simplify the definition of the known
HTTP methods. The current lookup code saves 2 kB of a heavily used table
and is faster than the previous table based lookup (typ. 14 ns vs 16
before).
Since commit 3ff577e ("MAJOR: server: make server state changes
synchronous again"), srv_update_status() calls the various maintenance
operations of the LB algorithms (->set_server_up, ->set_server_down,
->update_server_weight()). These ones are called with a single thread
guaranteed by the rendez-vous point, so the fact that they're lacking
some locks has no effect. However we'll need to remove the rendez-vous
point so we have to take care of properly locking all the LB algos.
The comments have been properly updated on the various functions to
mention their locking expectations. All these functions are called
with the server lock held, and all of them now support concurrent
calls by using the lbprm's lock.
This fix doesn't need to be backported at the moment, though if any
check-specific issue surfaced in 1.8, it could make sense to reuse it.
Adrian Williams reported that several balancing methods were broken and
sent all requests to one backend. This is a regression in haproxy 1.8 where
the server score was not correctly recalculated.
This fix must be backported to the 1.8 branch.
A lock for LB parameters has been added inside the proxy structure and atomic
operations have been used to update server variables releated to lb.
The only significant change is about lb_map. Because the servers status are
updated in the sync-point, we can call recalc_server_map function synchronously
in map_set_server_status_up/down function.
The server state and weight was reworked to handle
"pending" values updated by checks/CLI/LUA/agent.
These values are commited to be propagated to the
LB stack.
In further dev related to multi-thread, the commit
will be handled into a sync point.
Pending values are named using the prefix 'next_'
Current values used by the LB stack are named 'cur_'
In C89, "void *" is automatically promoted to any pointer type. Casting
the result of malloc/calloc to the type of the LHS variable is therefore
unneeded.
Most of this patch was built using this Coccinelle patch:
@@
type T;
@@
- (T *)
(\(lua_touserdata\|malloc\|calloc\|SSL_get_app_data\|hlua_checkudata\|lua_newuserdata\)(...))
@@
type T;
T *x;
void *data;
@@
x =
- (T *)
data
@@
type T;
T *x;
T *data;
@@
x =
- (T *)
data
Unfortunately, either Coccinelle or I is too limited to detect situation
where a complex RHS expression is of type "void *" and therefore casting
is not needed. Those cases were manually examined and corrected.
srv_is_usable() is broader than srv_is_usable() as it not only considers
the weight but the server's state as well. Future changes will allow a
server to be in drain mode with a non-zero weight, so we should migrate
to use that function instead.
Servers used to have 3 flags to store a state, now they have 4 states
instead. This avoids lots of confusion for the 4 remaining undefined
states.
The encoding from the previous to the new states can be represented
this way :
SRV_STF_RUNNING
| SRV_STF_GOINGDOWN
| | SRV_STF_WARMINGUP
| | |
0 x x SRV_ST_STOPPED
1 0 0 SRV_ST_RUNNING
1 0 1 SRV_ST_STARTING
1 1 x SRV_ST_STOPPING
Note that the case where all bits were set used to exist and was randomly
dealt with. For example, the task was not stopped, the throttle value was
still updated and reported in the stats and in the http_server_state header.
It was the same if the server was stopped by the agent or for maintenance.
It's worth noting that the internal function names are still quite confusing.
Till now, the server's state and flags were all saved as a single bit
field. It causes some difficulties because we'd like to have an enum
for the state and separate flags.
This commit starts by splitting them in two distinct fields. The first
one is srv->state (with its counter-part srv->prev_state) which are now
enums, but which still contain bits (SRV_STF_*).
The flags now lie in their own field (srv->flags).
The function srv_is_usable() was updated to use the enum as input, since
it already used to deal only with the state.
Note that currently, the maintenance mode is still in the state for
simplicity, but it must move as well.
We used to call srv_is_usable() with either the current state and weights
or the previous ones. This causes trouble for future changes, so let's first
split it in two variants :
- srv_is_usable(srv) considers the current status
- srv_was_usable(srv) considers the previous status
Detecting that a server's status has changed is a bit messy, as well
as it is to commit the status changes. We'll have to add new conditions
soon and we'd better avoid to multiply the number of touched locations
with the high risk of forgetting them.
This commit introduces :
- srv_lb_status_changed() to report if the status changed from the
previously committed one ;
- svr_lb_commit_status() to commit the current status
The function is now used by all load-balancing algorithms.
A crash was reported by Igor at owind when changing a server's weight
on the CLI. Lukas Tribus could reproduce a related bug where setting
a server's weight would result in the new weight being multiplied by
the initial one. The two bugs are the same.
The incorrect weight calculation results in the total farm weight being
larger than what was initially allocated, causing the map index to be out
of bounds on some hashes. It's easy to reproduce using "balance url_param"
with a variable param, or with "balance static-rr".
It appears that the calculation is made at many places and is not always
right and not always wrong the same way. Thus, this patch introduces a
new function "server_recalc_eweight()" which is dedicated to this task
of computing ->eweight from many other elements including uweight and
current time (for slowstart), and all users now switch to use this
function.
The patch is a bit large but the code was not trivially fixable in a way
that could guarantee this situation would not occur anymore. The fix is
much more readable and has been verified to work with all algorithms,
with both consistent and map-based hashes, and even with static-rr.
Slowstart was tested as well, just like enable/disable server.
The same bug is very likely present in 1.4 as well, so the patch will
probably need to be backported eventhough it will not apply as-is.
Thanks to Lukas and Igor for the information they provided to reproduce it.
Such load balance algorithms as roundrobin, leastconn and first will check the
server after being selected with the following condition:
if (!s->maxconn || (!s->nbpend && s->served < srv_dynamic_maxconn(s)))
But static-rr uses the different one in map_get_server_rr() as below:
if (!srv->maxconn || srv->cur_sess < srv_dynamic_maxconn(srv))
After viewing this difference, it is a better choice for static-rr to use the
same check condition as other algorithms.
This change will only affect static-rr. Though all hash algorithms with type
map-based will use the same server map as static-rr, they call another function
map_get_server_hash() to get server.
Signed-off-by: Godbach <nylzhaowei@gmail.com>
Jozef Hovan reported a bug sometimes causing a down server to be
used in url_param hashing mode.
This happens if the following conditions are met :
- the backend contains more than one server with at least two
of different weights
- all servers but one are down
- the server which is not down has a weight which does not divide
all the other ones
Example: 3 servers with 20,20,10, the first one remains up.
The problem is caused by an optimisation in recalc_server_map()
which only fills the first map slot when only one server is up,
because all LB algorithms are optimized to use entry zero when
only one server is up... All but url_param. When doing the modulus,
we can return a position which is greater than zero and use an
entry which still refers to a server which has since been stopped.
One solution could be to optimize the url_param algo to proceed
as the other ones, but the fact that was wrong implies that we
can repeat the same bug later. So let's first correctly initialize
the map in order to avoid that trap.
All files referencing the previous ebtree code were changed to point
to the new one in the ebtree directory. A makefile variable (EBTREE_DIR)
is also available to use files from another directory.
The ability to build the libebtree library temporarily remains disabled
because it can have an impact on some existing toolchains and does not
appear worth it in the medium term if we add support for multi-criteria
stickiness for instance.
The lbprm structure has moved to backend.h, where it should be, and
all algo-specific types and declarations have moved to their specific
files. The proxy struct is now much more readable.
We need to remove hash map accesses out of backend.c if we want to
later support new hash methods. This patch separates the hash computation
method from the server lookup. It leaves the lookup function to lb_map.c
and calls it with the result of the hash.
It was becoming painful to have all the LB algos in backend.c.
Let's move them to their own files. A few hashing functions still
need be broken in two parts, one for the contents and one for the
map position.
