Commit Graph

343 Commits

Author SHA1 Message Date
Kamil Braun
cb6a97d0dc raft: fsm: add details to on_internal_error_noexcept message
If we receive a message in the same term but from a different leader
than we expect, we print:
```
Got append request/install snapshot/read_quorum from an unexpected leader
```
For some reason the message did not include the details (who the leader
was and who the sender was) which requires almost zero effort and might
be useful for debugging. So let's include them.

Ref: scylladb/scylla-enterprise#4276
(cherry picked from commit 99a0599e1e)

Closes scylladb/scylladb#19265
2024-06-13 11:25:11 +02:00
Kefu Chai
0b0e661a85 build: bring abseil submodule back
because of https://bugzilla.redhat.com/show_bug.cgi?id=2278689,
the rebuilt abseil package provided by fedora has different settings
than the ones if the tree is built with the sanitizer enabled. this
inconsistency leads to a crash.

to address this problem, we have to reinstate the abseil submodule, so
we can built it with the same compiler options with which we build the
tree.

in this change

* Revert "build: drop abseil submodule, replace with distribution abseil"
* update CMake building system with abseil header include settings
* bump up the abseil submodule to the latest LTS branch of abseil:
  lts_2024_01_16
* update scylla-gdb.py to adapt to the new structure of
  flat_hash_map

This reverts commit 8635d24424.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#18511
2024-05-05 23:31:09 +03:00
Kefu Chai
168ade72f8 treewide: replace formatter<std::string_view> with formatter<string_view>
in in {fmt} before v10, it provides the specialization of `fmt::formatter<..>`
for `std::string_view` as well as the specialization of `fmt::formatter<..>`
for `fmt::string_view` which is an implementation builtin in {fmt} for
compatibility of pre-C++17. and this type is used even if the code is
compiled with C++ stadandard greater or equal to C++17. also, before v10,
the `fmt::formatter<std::string_view>::format()` is defined so it accepts
`std::string_view`. after v10, `fmt::formatter<std::string_view>` still
exists, but it is now defined using `format_as()` machinery, so it's
`format()` method does not actually accept `std::string_view`, it
accepts `fmt::string_view`, as the former can be converted to
`fmt::string_view`.

this is why we can inherit from `fmt::formatter<std::string_view>` and
use `formatter<std::string_view>::format(foo, ctx);` to implement the
`format()` method with {fmt} v9, but we cannot do this with {fmt} v10,
and we would have following compilation failure:

```
FAILED: service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o
/home/kefu/.local/bin/clang++ -DFMT_DEPRECATED_OSTREAM -DFMT_SHARED -DSCYLLA_BUILD_MODE=release -DSEASTAR_API_LEVEL=7 -DSEASTAR_LOGGER_COMPILE_TIME_FMT -DSEASTAR_LOGGER_TYPE_STDOUT -DSEASTAR_SCHEDULING_GROUPS_COUNT=16 -DSEASTAR_SSTRING -DXXH_PRIVATE_API -DCMAKE_INTDIR=\"RelWithDebInfo\" -I/home/kefu/dev/scylladb -I/home/kefu/dev/scylladb/build/gen -I/home/kefu/dev/scylladb/seastar/include -I/home/kefu/dev/scylladb/build/seastar/gen/include -I/home/kefu/dev/scylladb/build/seastar/gen/src -ffunction-sections -fdata-sections -O3 -g -gz -std=gnu++20 -fvisibility=hidden -Wall -Werror -Wextra -Wno-error=deprecated-declarations -Wimplicit-fallthrough -Wno-c++11-narrowing -Wno-deprecated-copy -Wno-mismatched-tags -Wno-missing-field-initializers -Wno-overloaded-virtual -Wno-unsupported-friend -Wno-enum-constexpr-conversion -Wno-unused-parameter -ffile-prefix-map=/home/kefu/dev/scylladb=. -march=westmere -mllvm -inline-threshold=2500 -fno-slp-vectorize -U_FORTIFY_SOURCE -Werror=unused-result -MD -MT service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o -MF service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o.d -o service/CMakeFiles/service.dir/RelWithDebInfo/topology_state_machine.cc.o -c /home/kefu/dev/scylladb/service/topology_state_machine.cc
/home/kefu/dev/scylladb/service/topology_state_machine.cc:254:41: error: no matching member function for call to 'format'
  254 |     return formatter<std::string_view>::format(it->second, ctx);
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
/usr/include/fmt/core.h:2759:22: note: candidate function template not viable: no known conversion from 'seastar::basic_sstring<char, unsigned int, 15>' to 'const fmt::basic_string_view<char>' for 1st argument
 2759 |   FMT_CONSTEXPR auto format(const T& val, FormatContext& ctx) const
      |                      ^      ~~~~~~~~~~~~
```

because the inherited `format()` method actually comes from
`fmt::formatter<fmt::string_view>`. to reduce the confusion, in this
change, we just inherit from `fmt::format<string_view>`, where
`string_view` is actually `fmt::string_view`. this follows
the document at
https://fmt.dev/latest/api.html#formatting-user-defined-types,
and since there is less indirection under the hood -- we do not
use the specialization created by `FMT_FORMAT_AS` which inherit
from `formatter<fmt::string_view>`, hopefully this can improve
the compilation speed a little bit. also, this change addresses
the build failure with {fmt} v10.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#18299
2024-04-19 07:44:07 +03:00
Kefu Chai
e97ae6b0de raft: server: print pointee of server_impl::_fsm
before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.

in this change, instead of printing the `unique_ptr` instance, we
print the pointee of it. since `server_impl` uses pimpl paradigm,
`_fsm` is always valid after `server_impl::start()`, we can always
deference it without checking for null.

Refs #13245

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#17953
2024-03-25 11:20:34 +02:00
Kefu Chai
50637964ed raft: add fmt::formatter for error classes
before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.

in this change, we define formatter for classes derived from
`raft::error`. since {fmt} v10 defines the formatter for all classes
derived from `std::exception`, the definition is provided only when
the tree is compiled with {fmt} < 10.

Refs #13245

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
2024-03-20 21:01:29 +08:00
Kefu Chai
079d70145e raft: add fmt::formatter for raft tracker types
before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.

in this change, we define formatters for

* raft::election_tracker
* raft::votes
* raft::vote_result

and drop their operator<<:s.

Refs #13245

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#17670
2024-03-08 15:19:37 +02:00
Kefu Chai
57ede58a64 raft: add fmt::formatter for raft::fsm
before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.

in this change, we define formatters for `raft::fsm`, and drop its
operator<<.

Refs #13245

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#17414
2024-02-20 09:02:02 +02:00
Kefu Chai
c555af3cd8 raft: add formatter for raft::log
before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.

in this change, we define formatters for `raft::log`, and drop its
operator<<.

Refs #13245

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#17301
2024-02-13 17:17:57 +02:00
Botond Dénes
d202d32f81 Merge 'Add an API to trigger snapshot in Raft servers' from Kamil Braun
This allows the user of `raft::server` to cause it to create a snapshot
and truncate the Raft log (leaving no trailing entries; in the future we
may extend the API to specify number of trailing entries left if
needed). In a later commit we'll add a REST endpoint to Scylla to
trigger group 0 snapshots.

One use case for this API is to create group 0 snapshots in Scylla
deployments which upgraded to Raft in version 5.2 and started with an
empty Raft log with no snapshot at the beginning. This causes problems,
e.g. when a new node bootstraps to the cluster, it will not receive a
snapshot that would contain both schema and group 0 history, which would
then lead to inconsistent schema state and trigger assertion failures as
observed in scylladb/scylladb#16683.

In 5.4 the logic of initial group 0 setup was changed to start the Raft
log with a snapshot at index 1 (ff386e7a44)
but a problem remains with these existing deployments coming from 5.2,
we need a way to trigger a snapshot in them (other than performing 1000
arbitrary schema changes).

Another potential use case in the future would be to trigger snapshots
based on external memory pressure in tablet Raft groups (for strongly
consistent tables).

The PR adds the API to `raft::server` and a HTTP endpoint that uses it.

In a follow-up PR, we plan to modify group 0 server startup logic to automatically
call this API if it sees that no snapshot is present yet (to automatically
fix the aforementioned 5.2 deployments once they upgrade.)

Closes scylladb/scylladb#16816

* github.com:scylladb/scylladb:
  raft: remove `empty()` from `fsm_output`
  test: add test for manual triggering of Raft snapshots
  api: add HTTP endpoint to trigger Raft snapshots
  raft: server: add `trigger_snapshot` API
  raft: server: track last persisted snapshot descriptor index
  raft: server: framework for handling server requests
  raft: server: inline `poll_fsm_output`
  raft: server: fix indentation
  raft: server: move `io_fiber`'s processing of `batch` to a separate function
  raft: move `poll_output()` from `fsm` to `server`
  raft: move `_sm_events` from `fsm` to `server`
  raft: fsm: remove constructor used only in tests
  raft: fsm: move trace message from `poll_output` to `has_output`
  raft: fsm: extract `has_output()`
  raft: pass `max_trailing_entries` through `fsm_output` to `store_snapshot_descriptor`
  raft: server: pass `*_aborted` to `set_exception` call
2024-01-29 15:06:04 +02:00
Kefu Chai
abb12979f8 raft: do not include unused headers
these unused includes were identified by clangd. see
https://clangd.llvm.org/guides/include-cleaner#unused-include-warning
for more details on the "Unused include" warning.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#17011
2024-01-29 10:00:56 +02:00
Kamil Braun
1824c12975 raft: remove empty() from fsm_output
Nobody remembered to keep this function up to date when adding stuff to
`fsm_output`.

Turns out that it's not being used by any Raft logic but only in some
tests. That use case can now be replaced with `fsm::has_output()` which
is also being used by `raft::server` code.
2024-01-23 16:48:28 +01:00
Kamil Braun
0eda7a2619 raft: server: add trigger_snapshot API
This allows the user of `raft::server` to ask it to create a snapshot
and truncate the Raft log. In a later commit we'll add a REST endpoint
to Scylla to trigger group 0 snapshots.

One use case for this API is to create group 0 snapshots in Scylla
deployments which upgraded to Raft in version 5.2 and started with an
empty Raft log with no snapshot at the beginning. This causes problems,
e.g. when a new node bootstraps to the cluster, it will not receive a
snapshot that would contain both schema and group 0 history, which would
then lead to inconsistent schema state and trigger assertion failures as
observed in scylladb/scylladb#16683.

In 5.4 the logic of initial group 0 setup was changed to start the Raft
log with a snapshot at index 1 (ff386e7a44)
but a problem remains with these existing deployments coming from 5.2,
we need a way to trigger a snapshot in them (other than performing 1000
arbitrary schema changes).

Another potential use case in the future would be to trigger snapshots
based on external memory pressure in tablet Raft groups (for strongly
consistent tables).
2024-01-23 16:48:28 +01:00
Kamil Braun
3268be3860 raft: server: track last persisted snapshot descriptor index
Also introduce a condition variable notified whenever this index is
updated.

Will be user in following commits.
2024-01-22 16:48:08 +01:00
Kamil Braun
1e786d9d64 raft: server: framework for handling server requests
Add data structures and modify `io_fiber` code to prepare it for
handling requests generated by the `server`, not just `fsm`.
Used in later commits.
2024-01-22 16:47:34 +01:00
Kamil Braun
8d9b0a6538 raft: server: inline poll_fsm_output 2024-01-18 18:09:13 +01:00
Kamil Braun
754a7b54e4 raft: server: fix indentation 2024-01-18 18:09:11 +01:00
Kamil Braun
527780987b raft: server: move io_fiber's processing of batch to a separate function 2024-01-18 18:09:02 +01:00
Kamil Braun
3e6b4910a6 raft: move poll_output() from fsm to server
`server` was the only user of this function and it can now be
implemented using `fsm`'s public interface.

In later commits we'll extend the logic of `io_fiber` to also subscribe
to other events, triggered by `server` API calls, not only to outputs
from `fsm`.
2024-01-18 18:07:52 +01:00
Kamil Braun
95b6a60428 raft: move _sm_events from fsm to server
In later commits we will use it to wake up `io_fiber` directly from
`raft::server` based on events generated by `raft::server` itself -- not
only from events generated by `raft::fsm`.

`raft::fsm` still obtains a reference to the condition variable so it
can keep signaling it.
2024-01-18 18:07:44 +01:00
Kamil Braun
a83e04279e raft: fsm: remove constructor used only in tests
This constructor does not provide persisted commit index. It was only
used in tests, so move it there, to the helper `fsm_debug` which
inherits from `fsm`.

Test cases which used `fsm` directly instead of `fsm_debug` were
modified to use `fsm_debug` so they can access the constructor.
`fsm_debug` doesn't change the behavior of `fsm`, only adds some helper
members. This will be useful in following commits too.
2024-01-18 18:07:17 +01:00
Kamil Braun
689d59fccd raft: fsm: move trace message from poll_output to has_output
In a later commit we'll move `poll_output` out of `fsm` and it won't
have access to internals logged by this message (`_log.stable_idx()`).

Besides, having it in `has_output` gives a more detailed trace. In
particular we can now see values such as `stable_idx` and `last_idx`
from the moment of returning a new fsm output, not only when poll
started waiting for it (a lot of time can pass between these two
events).
2024-01-18 18:06:55 +01:00
Kamil Braun
f6d43779af raft: fsm: extract has_output()
Also use the more efficient coroutine-specific
`condition_variable::when` instead of `wait`.
2024-01-18 18:06:27 +01:00
Kamil Braun
dccfd09d83 raft: pass max_trailing_entries through fsm_output to store_snapshot_descriptor
This parameter says how many entries at most should be left trailing
before the snapshot index. There are multiple places where this
decision is made:
- in `applier_fiber` when the server locally decides to take a snapshot
  due to log size pressure; this applies to the in-memory log
- in `fsm::step` when the server received an `install_snapshot` message
  from the leader; this also applies to the in-memory log
- and in `io_fiber` when calling `store_snapshot_descriptor`; this
  applies to the on-disk log.

The logic of how many entries should be left trailing is calculated
twice:
- first, in `applier_fiber` or in `fsm::step` when truncating the
  in-memory log
- and then again as the snapshot descriptor is being persisted.

The logic is to take `_config.snapshot_trailing` for locally generated
snapshots (coming from `applier_fiber`) and `0` for remote snapshots
(from `fsm::step`).

But there is already an error injection that changes the behavior of
`applier_fiber` to leave `0` trailing entries. However, this doesn't
affect the following `store_snapshot_descriptor` call which still uses
`_config.snapshot_trailing`. So if the server got restarted, the entries
which were truncated in-memory would get "revived" from disk.
Fortunately, this is test-only code.

However in future commits we'd like to change the logic of
`applier_fiber` even further. So instead of having a separate
calculation of trailing entries inside `io_fiber`, it's better for it to
use the number that was already calculated once. This number is passed to
`fsm::apply_snapshot` (by `applier_fiber` or `fsm::step`) and can then
be received by `io_fiber` from `fsm_output` to use it inside
`store_snapshot_descriptor`.
2024-01-18 18:05:45 +01:00
Kamil Braun
40cd91cff7 raft: server: pass *_aborted to set_exception call
This looks like a minor oversight, in `server_impl::abort` there are
multiple calls to `set_exception` on the different promises, only one of
them would not receive `*_aborted`.
2024-01-18 18:05:18 +01:00
Patryk Jędrzejczak
df2034ebd7 server, raft_group0_client: remove the default nullptr values
The previous commit has fixed 5 bugs of the same type - incorrectly
passing the default nullptr to one of the changed functions. At
least some of these bugs wouldn't appear if there was no default
value. It's much harder to make this kind of a bug if you have to
write "nullptr". It's also much easier to detect it in review.

Moreover, these default values are rarely used outside tests.
Keeping them is just not worth the time spent on debugging.
2024-01-05 18:45:50 +01:00
Botond Dénes
d2a88cd8de Merge 'Typos: fix typos in code' from Yaniv Kaul
Fixes some more typos as found by codespell run on the code. In this commit, there are more user-visible errors.

Refs: https://github.com/scylladb/scylladb/issues/16255

Closes scylladb/scylladb#16289

* github.com:scylladb/scylladb:
  Update unified/build_unified.sh
  Update main.cc
  Update dist/common/scripts/scylla-housekeeping
  Typos: fix typos in code
2023-12-06 07:36:41 +02:00
Yaniv Kaul
ae2ab6000a Typos: fix typos in code
Fixes some more typos as found by codespell run on the code.
In this commit, there are more user-visible errors.

Refs: https://github.com/scylladb/scylladb/issues/16255
2023-12-05 15:18:11 +02:00
Kefu Chai
3a8a3100af raft: add formatter for raft::logical_clock::time_point
before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.

in this change, we

* define a formatter for logical_clock::time_point, as fmt does not
  provide formatter for this time_point, as it is not a part of the
  standard library
* remove operator<<() for logical_clock::time_point, as its soly
  purpose is to generate the corresponding fmt::formatter when
  FMT_DEPRECATED_OSTREAM is defined.
* remove operator<<() for logical_clock::duration, as fmt provides
  a default implementation for formatting
  std::chrono::nanoseconds already, which uses `int64_t` as its rep
  template parameter as well.
* include "fmt/chrono.h" so that the source files including this
  header can have access the formatter without including it by
  themselves, this preserve the existing behavior which we have
  before removal of "operator<<()".

Refs #13245

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#16263
2023-12-04 18:32:03 +02:00
Yaniv Kaul
7c4b742583 Update raft/tracker.hh 2023-12-03 10:07:55 +02:00
Yaniv Kaul
c658bdb150 Typos: fix typos in comments
Fixes some typos as found by codespell run on the code.
In this commit, I was hoping to fix only comments, not user-visible alerts, output, etc.
Follow-up commits will take care of them.

Refs: https://github.com/scylladb/scylladb/issues/16255
Signed-off-by: Yaniv Kaul <yaniv.kaul@scylladb.com>
2023-12-02 22:37:22 +02:00
Piotr Dulikowski
c58ff554d8 raft: rpc: introduce destination_not_alive_error
Add a new destination_not_alive_error, thrown from two-way RPCs in case
when the RPC is not issued because the destination is not reported as
alive by the failure detector.

In snapshot transfer code, lower the verbosity of the message printed in
case it fails on the new error. This is done to prevent flakiness in the
CI - in case of slow runs, nodes might get spuriously marked as dead if
they are busy, and a message with the "error" verbosity can cause some
tests to fail.
2023-11-23 11:14:28 +01:00
Piotr Dulikowski
a1ebfcf006 raft: add server::is_alive
Add a method which reports whether given raft server is running.

In following commits, the information about whether the local raft
group 0 is running or not will be included in the response to the
failure detector ping, and the is_alive method will be used there.
2023-11-23 00:34:22 +01:00
Kefu Chai
efd65aebb2 build: cmake: add check-header target
to have feature parity with `configure.py`. we won't need this
once we migrate to C++20 modules. but before that day comes, we
need to stick with C++ headers.

we generate a rule for each .hh files to create a corresponding
.cc and then compile it, in order to verify the self-containness of
that header. so the number of rule is quite large, to avoid the
unnecessary overhead. the check-header target is enabled only if
`Scylla_CHECK_HEADERS` option is enabled.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#15913
2023-11-13 10:27:06 +02:00
Gleb Natapov
9f6e93c144 raft: make sure that all operation forwarded to a leader are completed before destroying raft server
Hold a gate around all operations that are forwarded to a leader to be
able to wait for them during server::abort() otherwise the abort() may
complete while those operations are still running which may cause use
after free.
2023-10-25 13:29:36 +03:00
Piotr Dulikowski
64668e325e raft: expose current_leader in raft::server
The handler for join_node_request will need to know which node is
considered the group 0 leader right now by the local node.

If the topology coordinator crashes and a new node immediately wants to
replace it with the same IP, the node that handles join_node_request
will attempt to perform a read barrier. If this happens quickly enough,
due to the IP reuse the RPC will be sent to the new node instead of the
(now crashed) topology coordinator; the RPC will get an error and will
fail the barrier.

If we detect that the new node wants to replace the current topology
coordinator, the upcoming join_node_request_handler will wait until
there is a leader change.
2023-09-26 15:56:52 +02:00
Gleb Natapov
55f047f33f raft: drop assert in server_impl::apply_snapshot for a condition that may happen
server_impl::apply_snapshot() assumes that it cannot receive a snapshots
from the same host until the previous one is handled and usually this is
true since a leader will not send another snapshot until it gets
response to a previous one. But it may happens that snapshot sending
RPC fails after the snapshot was sent, but before reply is received
because of connection disconnect. In this case the leader may send
another snapshot and there is no guaranty that the previous one was
already handled, so the assumption may break.

Drop the assert that verifies the assumption and return an error in this
case instead.

Fixes: #15222

Message-ID: <ZO9JoEiHg+nIdavS@scylladb.com>
2023-09-01 07:17:49 +03:00
Mikołaj Grzebieluch
dc6017b71b raft topology: make mutation_size_threshold depends on max_command_size
`get_cdc_generation_mutations` splits data to mutations of maximal size
`mutation_size_treshold`. Before this commit it was hardcoded to 2 MB.

Calculate `mutation_size_threshold` to leave space for cdc generation
data and not exceed `max_command_size`.
2023-07-07 13:11:52 +02:00
Kamil Braun
ff386e7a44 service: raft: force initial snapshot transfer in new cluster
When we upgrade a cluster to use Raft, or perform manual Raft recovery
procedure (which also creates a fresh group 0 cluster, using the same
algorithm as during upgrade), we start with a non-empty group 0 state
machine; in particular, the schema tables are non-empty.

In this case we need to ensure that nodes which join group 0 receive the
group 0 state. Right now this is not the case. In previous releases,
where group 0 consisted only of schema, and schema pulls were also done
outside Raft, those nodes received schema through this outside
mechanism. In 91f609d065 we disabled
schema pulls outside Raft; we're also extending group 0 with other
things, like topology-specific state.

To solve this, we force snapshot transfers by setting the initial
snapshot index on the first group 0 server to `1` instead of `0`. During
replication, Raft will see that the joining servers are behind,
triggering snapshot transfer and forcing them to pull group 0 state.

It's unnecessary to do this for cluster which bootstraps with Raft
enabled right away but it also doesn't hurt, so we keep the logic simple
and don't introduce branches based on that.

Extend Raft upgrade tests with a node bootstrap step at the end to
prevent regressions (without this patch, the step would hang - node
would never join, waiting for schema).

Fixes: #14066

Closes #14336
2023-06-29 22:46:42 +02:00
Gleb Natapov
945f476363 test: add test for group0 raft command merging
Add a test that submits 3 large commands each one a little bit larger
than 1/3 of maximum mutation size. Check that in the end 2 command were
executed (first 2 were merged and third was executed separately).
2023-06-27 14:59:55 +03:00
Kamil Braun
5504da3745 raft: server: throw fewer commit_status_unknowns from wait_for_entry
There are some cases where we can deduce that the entry was committed,
but we were throwing `commit_status_unknown`. Handle one more such case.
The added comment explains it in detail.

Also add a FIXME for another case where we throw `commit_status_unknown`
but we could do better.

Fixes: #14029
2023-06-07 14:17:23 +02:00
Kefu Chai
82cac8e7cf treewide: s/std::source_location/seastar::compact::source_location/
CWG 2631 (https://cplusplus.github.io/CWG/issues/2631.html) reports
an issue on how the default argument is evaluated. this problem is
more obvious when it comes to how `std::source_location::current()`
is evaluated as a default argument. but not all compilers have the
same behavior, see https://godbolt.org/z/PK865KdG4.

notebaly, clang-15 evaluates the default argument at the callee
site. so we need to check the capability of compiler and fall back
to the one defined by util/source_location-compat.hh if the compiler
suffers from CWG 2631. and clang-16 implemented CWG2631 in
https://reviews.llvm.org/D136554. But unfortunately, this change
was not backported to clang-15.

before switching over to clang-16, for using std::source_location::current()
as the default parameter and expect the behavior defined by CWG2631,
we have to use the compatible layer provided by Seastar. otherwise
we always end up having the source_location at the callee side, which
is not interesting under most circumstances.

so in this change, all places using the idiom of passing
std::source_location::current() as the default parameter are changed
to use seastar::compat::source_location::current(). despite that
we have `#include "seastarx.h"` for opening the seastar namespace,
to disambiguate the "namespace compat" defined somewhere in scylladb,
the fully qualified name of
`seastar::compat::source_location::current()` is used.

see also 09a3c63345, where we used
std::source_location as an alias of std::experimental::source_location
if it was available. but this does not apply to the settings of our
current toolchain, where we have GCC-12 and Clang-15.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes #14086
2023-05-30 15:10:12 +03:00
Kefu Chai
cb22492379 raft: specialize fmt::formatter<raft::server_address&> and friends
this is a part of a series to migrating from `operator<<(ostream&, ..)`
based formatting to fmtlib based formatting. the goal here is to enable
fmtlib to print

- raft::server_address
- raft::config_member
- raft::configuration

without the help of `operator<<`.

the corresponding `operator<<()` is removed in this change, as all its
callers are now using fmtlib for formatting now.

Refs #13245

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes #13976
2023-05-24 09:11:55 +03:00
Benny Halevy
adfb79ba3e raft, idl: restore internal::tagged_uint64 type
Change f5f566bdd8 introduced
tagged_integer and replaced raft::internal::tagged_uint64
with utils::tagged_integer.

However, the idl type for raft::internal::tagged_uint64
was not marked as final, but utils::tagged_integer is, breaking
the on-the-wire compatibility.

This change defines the different raft tagged_uint64
types in idl/raft_storage.idl.hh as non-final
to restore the way they were serialized prior to
f5f566bdd8

Fixes #13752

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
2023-05-09 12:38:20 +03:00
Benny Halevy
531ac63a8d raft: define term_t as a tagged uint64_t
It was defined as a tagged (signed) int64_t by mistake
in f5f566bdd8.

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
2023-05-09 06:51:26 +03:00
Kefu Chai
f80f638bb9 raft: disambiguate promise name in raft::awaited_conf_changes
otherwise GCC 13 complains that

```
/home/kefu/dev/scylladb/raft/server.cc:42:15: error: declaration of ‘seastar::promise<void> raft::awaited_index::promise’ changes meaning of ‘promise’ [-Wchanges-meaning]
   42 |     promise<> promise;
      |               ^~~~~~~
/home/kefu/dev/scylladb/raft/server.cc:42:5: note: used here to mean ‘class seastar::promise<void>’
   42 |     promise<> promise;
      |     ^~~~~~~~~
```
see also cd4af0c722

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
2023-04-29 17:02:25 +08:00
Harsh Soni
84ea2f5066 raft: fsm: add empty check for max_read_id_with_quorum
Updated the empty() function in the struct fsm_output to include the
max_read_id_with_quorum field when checking whether the fsm output is
empty or not. The change was made in order maintain consistency with the
codebase and adding completeness to the empty check. This change has no
impact on other parts of the codebase.

Closes #13656
2023-04-27 16:04:58 +02:00
Kamil Braun
30cc07b40d Merge 'Introduce tablets' from Tomasz Grabiec
This PR introduces an experimental feature called "tablets". Tablets are
a way to distribute data in the cluster, which is an alternative to the
current vnode-based replication. Vnode-based replication strategy tries
to evenly distribute the global token space shared by all tables among
nodes and shards. With tablets, the aim is to start from a different
side. Divide resources of replica-shard into tablets, with a goal of
having a fixed target tablet size, and then assign those tablets to
serve fragments of tables (also called tablets). This will allow us to
balance the load in a more flexible manner, by moving individual tablets
around. Also, unlike with vnode ranges, tablet replicas live on a
particular shard on a given node, which will allow us to bind raft
groups to tablets. Those goals are not yet achieved with this PR, but it
lays the ground for this.

Things achieved in this PR:

  - You can start a cluster and create a keyspace whose tables will use
    tablet-based replication. This is done by setting `initial_tablets`
    option:

    ```
        CREATE KEYSPACE test WITH replication = {'class': 'NetworkTopologyStrategy',
                        'replication_factor': 3,
                        'initial_tablets': 8};
    ```

    All tables created in such a keyspace will be tablet-based.

    Tablet-based replication is a trait, not a separate replication
    strategy. Tablets don't change the spirit of replication strategy, it
    just alters the way in which data ownership is managed. In theory, we
    could use it for other strategies as well like
    EverywhereReplicationStrategy. Currently, only NetworkTopologyStrategy
    is augmented to support tablets.

  - You can create and drop tablet-based tables (no DDL language changes)

  - DML / DQL work with tablet-based tables

    Replicas for tablet-based tables are chosen from tablet metadata
    instead of token metadata

Things which are not yet implemented:

  - handling of views, indexes, CDC created on tablet-based tables
  - sharding is done using the old method, it ignores the shard allocated in tablet metadata
  - node operations (topology changes, repair, rebuild) are not handling tablet-based tables
  - not integrated with compaction groups
  - tablet allocator piggy-backs on tokens to choose replicas.
    Eventually we want to allocate based on current load, not statically

Closes #13387

* github.com:scylladb/scylladb:
  test: topology: Introduce test_tablets.py
  raft: Introduce 'raft_server_force_snapshot' error injection
  locator: network_topology_strategy: Support tablet replication
  service: Introduce tablet_allocator
  locator: Introduce tablet_aware_replication_strategy
  locator: Extract maybe_remove_node_being_replaced()
  dht: token_metadata: Introduce get_my_id()
  migration_manager: Send tablet metadata as part of schema pull
  storage_service: Load tablet metadata when reloading topology state
  storage_service: Load tablet metadata on boot and from group0 changes
  db, migration_manager: Notify about tablet metadata changes via migration_listener::on_update_tablet_metadata()
  migration_notifier: Introduce before_drop_keyspace()
  migration_manager: Make prepare_keyspace_drop_announcement() return a future<>
  test: perf: Introduce perf-tablets
  test: Introduce tablets_test
  test: lib: Do not override table id in create_table()
  utils, tablets: Introduce external_memory_usage()
  db: tablets: Add printers
  db: tablets: Add persistence layer
  dht: Use last_token_of_compaction_group() in split_token_range_msb()
  locator: Introduce tablet_metadata
  dht: Introduce first_token()
  dht: Introduce next_token()
  storage_proxy: Improve trace-level logging
  locator: token_metadata: Fix confusing comment on ring_range()
  dht, storage_proxy: Abstract token space splitting
  Revert "query_ranges_to_vnodes_generator: fix for exclusive boundaries"
  db: Exclude keyspace with per-table replication in get_non_local_strategy_keyspaces_erms()
  db: Introduce get_non_local_vnode_based_strategy_keyspaces()
  service: storage_proxy: Avoid copying keyspace name in write handler
  locator: Introduce per-table replication strategy
  treewide: Use replication_strategy_ptr as a shorter name for abstract_replication_strategy::ptr_type
  locator: Introduce effective_replication_map
  locator: Rename effective_replication_map to vnode_effective_replication_map
  locator: effective_replication_map: Abstract get_pending_endpoints()
  db: Propagate feature_service to abstract_replication_strategy::validate_options()
  db: config: Introduce experimental "TABLETS" feature
  db: Log replication strategy for debugging purposes
  db: Log full exception on error in do_parse_schema_tables()
  db: keyspace: Remove non-const replication strategy getter
  config: Reformat
2023-04-27 09:40:18 +02:00
Tomasz Grabiec
c1fdbe79b7 raft: Introduce 'raft_server_force_snapshot' error injection
Will be used by tests to force followers to catch up from the snapshot.
2023-04-24 10:49:37 +02:00
Benny Halevy
f5f566bdd8 utils: add tagged_integer
A generic template for defining strongly typed
integer types.

Use it here to replace raft::internal::tagged_uint64.
Will be used for defining gms generation and version
as strong and distinguishable types in following patches.

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
2023-04-23 08:37:32 +03:00
Kefu Chai
3425184b2a raft: include boost header using <path/to/header> not "path/to/header"
for more consistency with the rest of the source tree.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
2023-03-26 14:07:50 +08:00