The test cases in sstable_directory_test use a temporary directory that
differs from the one sstables manager starts over. Fix that.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
This adds the test/lib's tmpdir instance _and_ configures the
data_file_directories with this path. This makes sure sstables manager
and the rest of the test use the same directory for sstables. For now
it doesn't change anything, but helps next patching.
(A neat side effect of this change is that sstable_test_env is now
configured the same way as cql_test_env does)
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The goal is to make it possible to make config with custom-initialized
options in test_env::impl's constructor initializer list (next patch).
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Issue #12538 suggested that maybe Alternator shouldn't bother reporting an
invalid table name in item operations like PutItem, and that it's enough
to report that the table doesn't exist. But the test added in this patch
shows that DynamoDB, like Alternator, reports the invalid table name in
this case - not just that the table doesn't exist.
That should make us think twice before acting on issue #12538. If we do
what this issue recommended, this test will need to be fixed (e.g., to
accept as correct both types of errors).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#12608
Don't use a range scan, which is very inefficient, to perform a query for checking CQL availability.
Improve logging when waiting for server startup times out. Provide details about the failure: whether we managed to obtain the Host ID of the server and whether we managed to establish a CQL connection.
Closes#12588
* github.com:scylladb/scylladb:
test/pylib: scylla_cluster: better logging for timeout on server startup
test/pylib: scylla_cluster: use less expensive query to check for CQL availability
Waiting for server startup is a multi-step procedure: after we start the
actual process, we will:
- try to obtain the Host ID (by querying a REST API endpoint)
- then try to connect a CQL session
- then try to perform a CQL query
The steps are repeated every .1 second until we reach a timeout (the
Host ID step is skipped if we previously managed to obtain it).
On timeout we'd only get a generic "failed to start server" message, it
wouldn't say what we managed to do and what not.
For example, on one of the failed jobs on Jenkins I observed this
timeout error. Looking at the logs of the server, it turned out that the
server printed the "initialization completed" message more than 2
minutes before the actual timeout happened. So for 2 minutes, the test
framework either couldn't obtain the Host ID, or couldn't establish a
CQL connection, or couldn't perform a CQL query, but I wasn't able to
determine fully which one of these was the case.
Improve the code by printing whether we managed to get the Host ID of
the server and if so - whether we managed to connect to CQL.
If the after test check fails (is_after_test_ok is False), discard the cluster and raise exception so context manager (pool) does not recycle it.
Ignore exception re-raised by the context manager.
Fixes#12360Closes#12569
* github.com:scylladb/scylladb:
test.py: handle broken clusters for Python suite
test.py: Pool discard method
This test creates random dummy reads and simulates a query with them.
The test works in terms of iteration (tick), advancing each simulating
read in each iteration. To prevent infinite runtime an iteration limit
of 100 was added to detect a non-converging test and kill it. This limit
proved too strict however and in this patch we bump it to 1000 to
prevent some unlucky seed making this test fail, as seen recently in CI.
Closes#12580
We noticed that old branches of Scylla had problems with looking up a
null value in a local secondary index - hanging or crashing. This patch
includes tests to reproduce these bugs. The tests pass on current
master - apparently this bug has already been fixed, but we didn't
have a regression test for it.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#12570
If an endpoint handler throws an exception, the details of the exception
are not returned to the client. Normally this is desirable so that
information is not leaked, but in this test framework we do want to
return the details to the client so it can log a useful error message.
Do it by wrapping every handler into a catch clause that returns
the exception message.
Also modify a bit how HTTPErrors are rendered so it's easier to discern
the actual body of the error from other details (such as the params used
to make the request etc.)
Before:
```
E test.pylib.rest_client.HTTPError: HTTP error 500: 500 Internal Server Error
E
E Server got itself in trouble, params None, json None, uri http+unix://api/cluster/before-test/test_stuff
```
After:
```
E test.pylib.rest_client.HTTPError: HTTP error 500, uri: http+unix://api/cluster/before-test/test_stuff, params: None, json: None, body:
E Failed to start server at host 127.155.129.1.
E Check the log files:
E /home/kbraun/dev/scylladb/testlog/test.py.dev.log
E /home/kbraun/dev/scylladb/testlog/dev/scylla-1.log
```
Closes#12563
When we obtained a new cluster for a test case after the previous test
case left a dirty cluster, we would release the old cluster's used IP
addresses (`_before_test` function). However, we would not release the
last cluster's IP after the last test case. We would run out of IPs with
sufficiently many test files or `--repeat` runs. Fix this.
Also reorder the operations a bit: stop the cluster (and release its
IPs) before freeing up space in the cluster pool (i.e. call
`self.cluster.stop()` before `self.clusters.steal()`). This reduces
concurrency a bit - fewer Scyllas running at the same time, which is
good (the pool size gives a limit on the desired max number of
concurrently running clusters). Killing a cluster is quick so it won't
make a significant difference for the next guy waiting on the pool.
Closes#12564
Recently, commit 0b418fa made the checking for "unset" values more
centralized and more robust, but as the tests added in this patch
show, the situation is good (and in particular, that #10358 is
solved).
The tests in this patch check that the behavior of "unset" values in
the CQL v4 protocol matches Cassandra's behavior and its documentation,
and how it compares to our wishes of how we want unset values to behave.
One of these tests fail on Cassandra (we consider this a Cassandra bug).
One test fails on Scylla because it doesn't yet support arithmetic
expressions (Refs #2693).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#12534
The CQL protocol and specification call for lists with NULLs in
some places. For example, the statement:
```cql
UPDATE tab
SET x = 3
IF y IN (1, 2, NULL)
WHERE pk = 4
```
has a list `(1, 2, NULL)` that contains NULL. Although the syntax is tuple-like, the value is a list;
consider the same statement as a prepared statement:
```cql
UPDATE tab
SET x = :x
IF y IN :y_values
WHERE pk = :pk
```
`:y_values` must have a list type, since the number of elements is unknown.
Currently, this is done with special paths inside LWT that bypass normal
evaluation, but if we want to unify those paths, we must allow NULLs in
lists (except in storage). This series does that.
Closes#12411
* github.com:scylladb/scylladb:
test: materialized view: add test exercising synthetic empty-type columns
cql3: expr: relax evaluate_list() to allow allow NULL elements
types: allow lists with NULL
test: relax NULL check test predicate
cql3, types: validate listlike collections (sets, lists) for storage
types: make empty type deserialize to non-null value
following tests are integrated into scylla executable
- perf_fast_forward
- perf_row_cache_update
- perf_simple_query
- perf_row_cache_update
- perf_sstable
before this change
```console
$ size build/release/scylla
text data bss dec hex filename
82284664 288960 335897 82909521 4f11951 build/release/scylla
$ ls -l build/release/scylla
-rwxrwxr-x 1 kefu kefu 1719672112 Jan 19 17:51 build/release/scylla
```
after this change
```console
$ size build/release/scylla
text data bss dec hex filename
84349449 289424 345257 84984130 510c142 build/release/scylla
$ ls -l build/release/scylla
-rwxrwxr-x 1 kefu kefu 1774204800 Jan 19 17:52 build/release/scylla
```
Fixes#12484Closes#12558
* github.com:scylladb/scylladb:
main: move perf_sstable into scylla
main: move perf_row_cache_update into scylla
test: perf_row_cache_update: add static specifier to local functions
main: move perf_fast_forward into scylla
main: move perf_simple_query into scylla
test: extract debug::the_database out
main: shift the args when checking exec_name
main: extract lookup_main_func() out
If a cluster fails to boot, it saves the exception in
`self.start_exception` variable; the exception will be rethrown when
a test tries to start using this cluster. As explained in `before_test`:
```
def before_test(self, name) -> None:
"""Check that the cluster is ready for a test. If
there was a start error, throw it here - the server is
running when it's added to the pool, which can't be attributed
to any specific test, throwing it here would stop a specific
test."""
```
It's arguable whether we should blame some random test for a failure
that it didn't cause, but nevertheless, there's a problem here: the
`start_exception` will be rethrown and the test will fail, but then the
cluster will be simply returned to the pool and the next test will
attempt to use it... and so on.
Prevent this by marking the cluster as dirty the first time we rethrow
the exception.
Closes#12560
Commitlog O_DSYNC is intended to make Raft and schema writes durable
in the face of power loss. To make O_DSYNC performant, we preallocate
the commitlog segments, so that the commitlog writes only change file
data and not file metadata (which would require the filesystem to commit
its own log).
However, in tests, this causes each ScyllaDB instance to write 384MB
of commitlog segments. This overloads the disks and slows everything
down.
Fix this by disabling O_DSYNC (and therefore preallocation) during
the tests. They can't survive power loss, and run with
--unsafe-bypass-fsync anyway.
Closes#12542
* configure.py:
- include `test/perf/perf_sstable` and its dependencies in scylla_perfs
* test/perf/perf_sstable.cc: change `main()` to
`perf::scylla_sstable_main()`
* test/perf/entry_point.hh: add
`perf::scylla_sstable_main()`
* main.cc:
- dispatch "perf-sstable" subcommand to
`perf::scylla_sstable_main`
before this change, we have a tool at `test/perf/perf_sstable`
for running performance tests by exercising sstable related operations.
after this change, the `test/perf/perf_sstable` is integreated
into `scylla` as a subcommand. so we can run `scylla perf-sstable`
[options, ...]` to perform the same tests previous driven by the tool.
Fixes#12484
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
* configure.py:
- include `test/perf/perf_row_cache_update.cc` in scylla_perfs
* main.cc:
- dispatch "perf-row-cache-update" subcommand to
`perf::scylla_row_cache_update_main`
* test/perf/perf_fast_forward.cc: change `main()` to
`perf::scylla_row_cache_update_main()`
* test/perf/entry_point.hh: add
`perf::scylla_row_cache_update_main()`
before this change, we have a tool at `test/perf/perf_row_cache_update`
for running performance tests by updating row cache.
after this change, the `test/perf/perf_row_cache_update` is integreated
into `scylla` as a subcommand. so we can run `scylla perf-row-cache-update
[options, ...]` to perform the same tests previous driven by the tool.
Fixes#12484
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
now that these functions are only used by the same compiling unit,
they don't need external linkage. so let's hide them using `static`.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
* configure.py:
- include `test/perf/perf_simple_query.cc` in scylla_perfs
* main.cc:
- dispatch "perf-fast-forward" subcommand to
`perf::scylla_fast_forward_main`
* test/perf/perf_fast_forward.cc: change `main()` to
`perf::scylla_simple_query_main()`
* test/perf/entry_point.hh: add
`perf::scylla_simple_query_main()`
before this change, we have a tool at `test/perf/perf_fast_forward`
for running performance tests by fast forwarding the reader.
after this change, the `test/perf/perf_fast_forward` is integreated
into `scylla` as a subcommand. so we can run `scylla perf-fast-forward
[options, ...]` to perform the same tests previous driven by the tool.
Fixes#12484
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
* configure.py:
- include scylla_perfs in scylla
- move 'test/lib/debug.cc' down scylla_perfs, as the latter uses
`debug::the_database`
- link `scylla` against seastar_testing_libs also. because we
use the helpers in `test/lib/random_utils.hh` for generating
random numbers / sequences in `perf_simple_query.cc`, and
`random_utils.hh` references `seastar::testing::local_random_engine`
as a local RNG. but `seastar::testing::local_random_engine`
is included in `libseastar_testing.a` or
`libseastar_perf_testing.a`. since we already have the rules for
linking against `libseastar_testing.a`, let's just reuse them,
and link `scylla` against this new dependency.
* main.cc:
- dispatch "perf-simple-query" subcommand to
`perf::scylla_simple_query_main`
* test/perf/perf_simple_query.cc: change `main()` to
`perf::scylla_simple_query_main()`
* test/perf/entry_point.hh: define the main function entries
so `main.cc` can find them. it's quite like how we collect
the entries in `tools/entry_point.hh`
before this change, we have a tool at `test/perf/perf_simple_query`
for running performance test by sending simple query to a single-node
cluster.
after this change, the `test/perf/perf_simple_query` is integreated
into `scylla` as a subcommand. so we can run `scylla perf-simple-query
[options, ...]` to perform the same tests previous driven by the tool.
Fixes#12484
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
we want to integrate some perf test into scylla executable, so we
can run them on a regular basis. but `test/lib/cql_test_env.cc`
shares `debug::the_database` with `main.cc`, so we cannot just
compile them into a single binary without changing them.
before this change, both `test/lib/cql_test_env.cc`
and `main.cc` define `debug::the_database`.
after this change, `debug::the_database` is extracted into
`debug.cc`, so it compiles into a separate compiling unit.
and scylla and tests using seastar testing framework are linked
against `debug.cc` via `scylla_core` respectively. this paves the road to
integrating scylla with the tests linking aginst
`test/lib/cql_test_env.cc`.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Commit 0b418fa improved the error detection of unset values in
inappropriate CQL statements, and some of the unit tests translated
from Cassandra started to pass, so this patch removes their "xfail"
mark.
In a couple of places Scylla's error message is worded differently
from Cassandra, so the test was modified to look for a shorter
string common to both implementations.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#12553
The reader concurrency semaphore has no mechanism to limit the memory consumption of already admitted read. Once memory collective memory consumption of all the admitted reads is above the limit, all it can do is to not admit any more. Sometimes this is not enough and the memory consumption of the already admitted reads balloons to the point of OOMing the node. This pull-request offers a solution to this: it introduces two more layers of defense above this: a soft and a hard limit. Both are multipliers applied on the semaphores normal memory limit.
When the soft limit threshold is surpassed, all readers but one are blocked via a new blocking `request_memory()` call which is used by the `tracking_file_impl`. The reader to be allowed to proceed is chosen at random, it is the first reader which happens to request memory after the limit is surpassed. This is both very simple and should avoid situations where the algorithm choosing the reader to be allowed to proceed chooses a reader which will then always time out.
When the hard limit threshold is surpassed, `reader_concurrency_semaphore::consume()` starts throwing `std::bad_alloc`. This again will result in eliminating whichever reader was unlucky enough to request memory at the right moment.
With this, the semaphore is now effectively enforcing an upper bound for memory consumption, defined by the hard limit.
Refs: https://github.com/scylladb/scylladb/issues/11927Closes#11955
* github.com:scylladb/scylladb:
test: reader_concurrency_semaphore_test: add tests for semaphore memory limits
reader_permit: expose operator<<(reader_permit::state)
reader_permit: add id() accessor
reader_concurrency_semaphore: add foreach_permit()
reader_concurrency_semaphore: document the new memory limits
reader_concurrency_semaphore: add OOM killer
reader_concurrency_semaphore: make consume() and signal() private
test: stop using reader_concurrency_semaphore::{consume,signal}() directly
reader_concurrency_semaphore: move consume() out-of-line
reader_permit: consume(): make it exception-safe
reader_permit: resource_units::reset(): only call consume() if needed
reader_concurrency_semaphore: tracked_file_impl: use request_memory()
reader_concurrency_semaphore: add request_memory()
reader_concurrency_semaphore: wrap wait list
reader_concurrency_semaphore: add {serialize,kill}_limit_multiplier parameters
test/boost/reader_concurrency_semaphore_test: dummy_file_impl: don't use hardoced buffer size
reader_permit: add make_new_tracked_temporary_buffer()
reader_permit: add get_state() accessor
reader_permit: resource_units: add constructor for already consumed res
reader_permit: resource_units: remove noexcept qualifier from constructor
db/config: introduce reader_concurrency_semaphore_{serialize,kill}_limit_multiplier
scylla-gdb.py: scylla-memory: extract semaphore stats formatting code
scylla-gdb.py: fix spelling of "graphviz"
`prepare_expression` takes an unprepared CQL expression straight from the parser output and prepares it. Preparation consists of various type checks that are needed to ensure that the expression is correct and to reason about it.
While `prepare_expression` supports a number of different types of expressions, until now it was impossible to prepare a `binary_operator`. Eventually we would like to be able to prepare all kinds of expressions, so this PR adds the missing support for `binary_operator`.
Closes#12550
* github.com:scylladb/scylladb:
expr_test: test preparing binary_operator with NULL RHS
expr_test: test preparing IS NOT NULL binary_operator
expr_test: test preparing binary_operator with LIKE
expr_test: test preparing binary_operator with CONTAINS KEY
expr_test: test preparing binary_operator with CONTAINS
expr_test: test preparing binary_operator with IN
expr_test: test preparing binary_operator with =, !=, <, <=, >, >=
expr_test: use make_*_untyped function in existing tests
expr_test_utils: add utilities to create untyped_constant
expr_test_utils: add make_float_* and make_double_*
cql3: expr: make it possible to prepare binary_operator using prepare_expression
cql3/expr: check that RHS of IS NOT NULL is a null value when preparing binary operators
cql3: expr: pass non-empty keyspace name in prepare_binary_operator
cql3: expr: take reference to schema in prepare_binary_operator
Add unit test which check that preparing binary_operators
which represent IS NOT NULL works as expected
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add unit test which check that preparing binary_operators
with the LIKE operation works as expected.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com
Add unit test which check that preparing binary_operators
with the CONTAINS KEY operation works as expected.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add unit test which check that preparing binary_operators
with the CONTAINS operation works as expected.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Add unit test which check that preparing binary_operators
with basic comparison operations works as expected.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Use the newly introduced convenience methods that create
untyped_constant in existing tests.
This will make the code more readable by removing
visual clutter that came with the previous overly
verbose code.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
expression tests often need to create instances of untyped_constant.
Creating them by hand is tedious because the required code is overly verbose.
Having convenience functions for it speeds up test writing.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Several cases where fixed in this patches, all are related to processing of malformed base64 data. Main purpose was to bring alternator implementation closer to what DynamoDB does. We now:
- Throw error when padding is missing during base64 decoding
- Throw error when base64 data is malformed
- In alternator when invalid base64 data is fetched from DB (as opposed to being part of user's request) we now exclude such row during filtering
Additionally some small code quality improvements:
- avoid unnecessary type conversions in calls to rjson:from_strings functions
- avoid some copy constructions in calls to rjson:from_strings functions
Fixes https://github.com/scylladb/scylladb/issues/6487Closes#11944
* github.com:scylladb/scylladb:
alternator: evaluate expressions as false for stored malformed binary data
rjson: avoid copy constructors in from_string calls when possible
alternator: remove unused parameters from describe_items func
utils: throw error on malformed input in base64 decode
utils: throw error on missing padding in base64 decode
Materialized views inject synthetic empty-type columns in some conditions.
Since we just touched empty-type serialization/deserialization, add a
test to exercise it and make sure it still works.
Tests are similarly relaxed. A test is added in lwt_test to show
that insertion of a list with NULL is still rejected, though we
allow NULLs in IF conditions.
One test is changed from a list of longs to a list of ints, to
prevent churn in the test helper library.
Allow transient lists that contain NULL throughout the
evaluation machinery. This makes is possible to evalute things
like `IF col IN (1, 2, NULL)` without hacks, once LWT conditions
are converted to expressions.
A few tests are relaxed to accommodate the new behavior:
- cql_query_test's test_null_and_unset_in_collections is relaxed
to allow `WHERE col IN ?`, with the variable bound to a list
containing NULL; now it's explicitly allowed
- expr_test's evaluate_bind_variable_validates_no_null_in_list was
checking generic lists for NULLs, and was similary relaxed (and
renamed)
- expr_Test's evaluate_bind_variable_validates_null_in_lists_recursively
was similarly relaxed to allow NULLs.
When we start allowing NULL in lists in some contexts, the exact
location where an error is raised (when it's disallowed) will
change. To prepare for that, relax the exception check to just
ensure the word NULL is there, without caring about the exact
wording.
The empty type is used internally to implement CQL sets on top
of multi-cell maps. The map's key (an atomic cell) represents the
set value, and the map's value is discarded. Since it's unneeded
we use an internal "empty" type.
Currently, it is deserialized into a `data_value` object representing
a NULL. Since it's discarded, it really doesn't matter.
However, with the impending change to change lists to allow NULLs,
it does matter:
1. the coordinator sets the 'collections_as_maps' flag for LWT
requests since it wants list indexes (this affects sets too).
2. the replica responds by serializing a set as a map.
3. since we start allow NULL collection values, we now serialize
those NULLs as NULLs.
4. the coordinator deserializes the map, and complains about NULL
values, since those are not supported.
The solution is simple, deserialize the empty value as a non-NULL
object. We create an empty empty_type_representation and add the
scaffolding needed. Serialization and deserialization is already
coded, it was just never called for NULL values (which were serialized
with size 0, in collections, rather than size -1, luckily).
A unit test is added.
Make it so that failures in `removenode`/`decommission` don't lead to reduced availability, and any leftovers in group 0 can be removed by `removenode`:
- In `removenode`, make the node a non-voter before removing it from the token ring. This removes the possibility of having a group 0 voting member which doesn't correspond to a token ring member. We can still be left with a non-voter, but that's doesn't reduce the availability of group 0.
- As above but for `decommission`.
- Make it possible to remove group 0 members that don't correspond to token ring members from group 0 using `removenode`.
- Add an API to query the current group 0 configuration.
Fixes#11723.
Closes#12502
* github.com:scylladb/scylladb:
test: test_topology: test for removing garbage group 0 members
test/pylib: move some utility functions to util.py
db: system_keyspace: add a virtual table with raft configuration
db: system_keyspace: improve system.raft_snapshot_config schema
service: storage_service: better error handling in `decommission`
service: storage_service: fix indentation in removenode
service: storage_service: make `removenode` work for group 0 members which are not token ring members
service/raft: raft_group0: perform read_barrier in wait_for_raft
service: storage_service: make leaving node a non-voter before removing it from group 0 in decommission/removenode
test: test_raft_upgrade: remove test_raft_upgrade_with_node_remove
service/raft: raft_group0: link to Raft docs where appropriate
service/raft: raft_group0: more logging
service/raft: raft_group0: separate function for checking and waiting for Raft
This test is frequently failing due to a timeout when we try to restart
one of the nodes. The shutdown procedure apparently hangs when we try to
stop the `hints_manager` service, e.g.:
```
INFO 2023-01-13 03:18:02,946 [shard 0] hints_manager - Asked to stop
INFO 2023-01-13 03:18:02,946 [shard 0] hints_manager - Stopped
INFO 2023-01-13 03:18:02,946 [shard 0] hints_manager - Asked to stop
INFO 2023-01-13 03:18:02,946 [shard 1] hints_manager - Asked to stop
INFO 2023-01-13 03:18:02,946 [shard 1] hints_manager - Stopped
INFO 2023-01-13 03:18:02,946 [shard 1] hints_manager - Asked to stop
INFO 2023-01-13 03:18:02,946 [shard 1] hints_manager - Stopped
INFO 2023-01-13 03:22:56,997 [shard 0] hints_manager - Stopped
```
observe the 5 minute delay at the end.
There is a known issue about `hints_manager` stop hanging: #8079.
Now, for some reason, this is the only test case that is hitting this
issue. We don't completely understand why. There is one significant
difference between this test case and others: this is the only test case
which kills 2 (out of 3) servers in the cluster and then tries to
gracefully shutdown the last server. There's a hypothesis that the last
server gets stuck trying to send hints to the killed servers. We weren't
able to prove/falsify it yet. But if it's true, then this patch will:
- unblock next promotions,
- give us some important information when we see that the issue stops
appearing.
In the patch we shutdown all servers gracefully instead of killing them,
like we do in the other test cases.
Closes#12548
Add a new virtual table `system.raft_state` that shows the currently
operating Raft configuration for each present group. The schema is the
same as `system.raft_snapshot_config` (the latter shows the config from
the last snapshot). In the future we plan to add more columns to this
table, showing more information (like the current leader and term),
hence the generic name.
Adding the table requires some plumbing of
`sharded<raft_group_registry>&` through function parameters to make it
accessible from `register_virtual_tables`, but it's mostly
straightforward.
Also added some APIs to `raft_group_registry` to list all groups and
find a given group (returning `nullptr` if one isn't found, not throwing
an exception).
