Commit Graph

22619 Commits

Author SHA1 Message Date
Takuya ASADA
01f9be1ced scylla_setup: improve help message 2020-07-01 11:39:44 +03:00
Avi Kivity
c84217adaa Merge 'Compaction fix stall in perform cleanup' from Asias
"
compaction_manager: Avoid stall in perform_cleanup

The following stall was seen during a cleanup operation:

    scylla: Reactor stalled for 16262 ms on shard 4.

    | std::_MakeUniq<locator::tokens_iterator_impl>::__single_object std::make_unique<locator::tokens_iterator_impl, locator::tokens_iterator_impl&>(locator::tokens_iterator_impl&) at /usr/include/fmt/format.h:1158
    |  (inlined by) locator::token_metadata::tokens_iterator::tokens_iterator(locator::token_metadata::tokens_iterator const&) at ./locator/token_metadata.cc:1602
    | locator::simple_strategy::calculate_natural_endpoints(dht::token const&, locator::token_metadata&) const at simple_strategy.cc:?
    |  (inlined by) locator::simple_strategy::calculate_natural_endpoints(dht::token const&, locator::token_metadata&) const at ./locator/simple_strategy.cc:56
    | locator::abstract_replication_strategy::get_ranges(gms::inet_address, locator::token_metadata&) const at /usr/include/fmt/format.h:1158
    | locator::abstract_replication_strategy::get_ranges(gms::inet_address) const at /usr/include/fmt/format.h:1158
    | service::storage_service::get_ranges_for_endpoint(seastar::basic_sstring<char, unsigned int, 15u, true> const&, gms::inet_address const&) const at /usr/include/fmt/format.h:1158
    | service::storage_service::get_local_ranges(seastar::basic_sstring<char, unsigned int, 15u, true> const&) const at /usr/include/fmt/format.h:1158
    |  (inlined by) operator() at ./sstables/compaction_manager.cc:691
    |  (inlined by) _M_invoke at /usr/include/c++/9/bits/std_function.h:286
    | std::function<std::vector<seastar::lw_shared_ptr<sstables::sstable>, std::allocator<seastar::lw_shared_ptr<sstables::sstable> > > (table const&)>::operator()(table const&) const at /usr/include/fmt/format.h:1158
    |  (inlined by) compaction_manager::rewrite_sstables(table*, sstables::compaction_options, std::function<std::vector<seastar::lw_shared_ptr<sstables::sstable>, std::allocator<seastar::lw_shared_ptr<sstables::sstable> > > (table const&)>) at ./sstables/compaction_manager.cc:604
    | compaction_manager::perform_cleanup(table*) at /usr/include/fmt/format.h:1158

To fix, we furturize the function to get sstables. If get_local_ranges()
is called inside a thread, get_local_ranges will yield automatically.

Fixes #6662
"

* asias-compaction_fix_stall_in_perform_cleanup:
  compaction_manager: Avoid stall in perform_cleanup
  compaction_manager: Return exception future in perform_cleanup
  abstract_replication_strategy: Add get_ranges_in_thread
2020-07-01 11:30:37 +03:00
Avi Kivity
7e9a3b08ac Merge "mutation_reader: shard_reader fix fast-forwarding with read-ahead" from Botond
"
Currently, the fast forwarding implementation of the shard reader is
 broken in some read-ahead related corner cases, namely:
* If the reader was not created yet, but there is an ongoing read-ahead
  (which is going to create it), the function bails out. This will
  result in this shard reader not being fast-forwarded to the new range
  at all.
* If the reader was already created and there is an ongoing read-ahead,
  the function will wait for this to complete, then fast-forward the
  reader, as it should. However, the buffer is cleared *before* the
  read-ahead is waited for. So if the read-ahead brings in new data,
  this will land in the buffer. This data will be outside of the
  fast-forwarded-to range and worse, as we just cleared the buffer, it
  might violate mutation fragment stream monotonicity requirements.

This series fixes these two bugs and adds a unit test which reproduces
both of them.

There are no known field issues related to these bugs. Only row-level
repair ever fast-forwards the multishard reader, but it only uses it in
heterogenous clusters. Even so, in theory none of these bugs affect
repair as it doesn't ever fast-forward the multishard reader before all
shards arrive at EOS.
The bugs were found while auditing the code, looking for the possible
cause of #6613.

Fixes: #6715

Tests: unit(dev)
"

* 'multishard-combining-reader-fast-forward-to-fixes/v1.1' of https://github.com/denesb/scylla:
  test/boost/mutation_reader_test: multishard reader: add tests for fast-forwarding with read-ahead
  test/boost/mutation_reader_test: extract multishard read-ahead test setup
  test/boost/mutation_reader_test: puppet_reader: fast-forward-support
  mutation_reader_test: puppet_reader: make interface more predictable
  dht::sharder: add virtual destructor
  mutation_reader: shard_reader: fix fast-forwarding with read-ahead
2020-07-01 11:22:41 +03:00
Botond Dénes
cb69406f6c test/boost/mutation_reader_test: multishard reader: add tests for fast-forwarding with read-ahead 2020-07-01 10:15:49 +03:00
Botond Dénes
d6e2033d8a test/boost/mutation_reader_test: extract multishard read-ahead test setup
Testing the multishard reader's various read-ahead related corner cases
requires a non-trivial setup. Currently there is just one such test,
but we plan to add more so in this patch we extract this setup code to a
free function to allow reuse across multiple tests.
2020-07-01 10:15:49 +03:00
Botond Dénes
851ae8c650 test/boost/mutation_reader_test: puppet_reader: fast-forward-support
A fast-forwarded puppet reader goes immediately to EOS. A counter is
added to the remote control to allow tests to check which readers were
actually fast forwarded.
2020-07-01 10:15:49 +03:00
Botond Dénes
741f0c276d mutation_reader_test: puppet_reader: make interface more predictable
Currently the puppet reader will do an automatic (half) buffer-fill in
the constructor. This makes it very hard to reason about when and how
the action that was passed to it will be executed. Refactor it to take a
list of actions and only execute those, no hidden buffer-fill anymore.
No better proof is needed for this than the fact that the test which is
supposed to test the multishard reader being destroyed with a pending
read-ahead was silently broken (not testing what it should).
This patch fixes this test too.

Also fixed in this patch is the `pending` and `destroyed` fields of the
remote control, tests can now rely on these to be correct and add
additional checkpoints to ensure the test is indeed doing what it was
intended to do.
2020-07-01 10:15:49 +03:00
Botond Dénes
6ae8e0bc7d dht::sharder: add virtual destructor
This is a class with virtual methods, it should have a virtual
destructor too.
2020-07-01 10:15:49 +03:00
Asias He
07e253542d compaction_manager: Avoid stall in perform_cleanup
The following stall was seen during a cleanup operation:

scylla: Reactor stalled for 16262 ms on shard 4.

| std::_MakeUniq<locator::tokens_iterator_impl>::__single_object std::make_unique<locator::tokens_iterator_impl, locator::tokens_iterator_impl&>(locator::tokens_iterator_impl&) at /usr/include/fmt/format.h:1158
|  (inlined by) locator::token_metadata::tokens_iterator::tokens_iterator(locator::token_metadata::tokens_iterator const&) at ./locator/token_metadata.cc:1602
| locator::simple_strategy::calculate_natural_endpoints(dht::token const&, locator::token_metadata&) const at simple_strategy.cc:?
|  (inlined by) locator::simple_strategy::calculate_natural_endpoints(dht::token const&, locator::token_metadata&) const at ./locator/simple_strategy.cc:56
| locator::abstract_replication_strategy::get_ranges(gms::inet_address, locator::token_metadata&) const at /usr/include/fmt/format.h:1158
| locator::abstract_replication_strategy::get_ranges(gms::inet_address) const at /usr/include/fmt/format.h:1158
| service::storage_service::get_ranges_for_endpoint(seastar::basic_sstring<char, unsigned int, 15u, true> const&, gms::inet_address const&) const at /usr/include/fmt/format.h:1158
| service::storage_service::get_local_ranges(seastar::basic_sstring<char, unsigned int, 15u, true> const&) const at /usr/include/fmt/format.h:1158
|  (inlined by) operator() at ./sstables/compaction_manager.cc:691
|  (inlined by) _M_invoke at /usr/include/c++/9/bits/std_function.h:286
| std::function<std::vector<seastar::lw_shared_ptr<sstables::sstable>, std::allocator<seastar::lw_shared_ptr<sstables::sstable> > > (table const&)>::operator()(table const&) const at /usr/include/fmt/format.h:1158
|  (inlined by) compaction_manager::rewrite_sstables(table*, sstables::compaction_options, std::function<std::vector<seastar::lw_shared_ptr<sstables::sstable>, std::allocator<seastar::lw_shared_ptr<sstables::sstable> > > (table const&)>) at ./sstables/compaction_manager.cc:604
| compaction_manager::perform_cleanup(table*) at /usr/include/fmt/format.h:1158

To fix, we furturize the function to get local ranges and sstables.

In addition, this patch removes the dependency to global storage_service object.

Fixes #6662
2020-07-01 15:03:50 +08:00
Asias He
868e2da1c4 compaction_manager: Return exception future in perform_cleanup
We should return the exception future instead of throw a plain
exception.

Refs #6662
2020-07-01 15:00:01 +08:00
Asias He
94995acedb abstract_replication_strategy: Add get_ranges_in_thread
Add a version that runs inside a seastar thread. The benefit is that
get_ranges can yield to avoid stalls.

Refs #6662
2020-07-01 15:00:01 +08:00
Botond Dénes
627054c3d7 mutation_reader: shard_reader: fix fast-forwarding with read-ahead
The current `fast_forward_to(const dht::partition_range&)`
implementation has two problems:
* If the reader was not created yet, but there is an ongoing read-ahead
  (which is going to create it), the function bails out. This will
  result in this shard reader not being fast-forwarded to the new range
  at all.
* If the reader was already created and there is an ongoing read-ahead,
  the function will wait for this to complete, then fast-forward the
  reader, as it should. However, the buffer is cleared *before* the
  read-ahead is waited for. So if the read-ahead brings in new data,
  this will land in the buffer. This data will be outside of the
  fast-forwarded-to range and worse, as we just cleared the buffer, it
  might violate mutation fragment stream monotonicity requirements.

This patch fixes both of these bugs. Targeted reproducer unit tests are
coming in the next patches.
2020-07-01 09:51:02 +03:00
Takuya ASADA
bbd3ed9d47 scylla_util.py: switch to subprocess.run()
When we started to porting bash script to python script, we are not able to use
subprocess.run() since EPEL only provides python 3.4, but now we have
relocatable python, so we can switch to it.
2020-06-30 20:13:30 +03:00
Takuya ASADA
a9de438b1f scylla_swap_setup: handle <1GB environment
Show better error message and exit with non-zero status when memory size <1GB.

Fixes #6659
2020-06-30 20:12:32 +03:00
Avi Kivity
5bcef44935 Update seastar submodule
* seastar 5db34ea8d3...dbecfff5a4 (3):
  > sharded: Do not hang on never set freed promise
Fixes #6606.
  > foreign_ptr: make constructors and methods conditionally noexcept
  > foreign_ptr: specify methods as noexcept
2020-06-30 19:27:21 +03:00
Botond Dénes
27a0772d71 docs/debugging.md: extend section on relocatable binaries
Currently the section on "Debugging coredumps" only briefly mentions
relocatable binaries, then starts with an extensive subsection on how to
open cores generated by non-relocatable binaries. There is a subsection
about relocatable binaries, but it just contains some out-of-date
workaround without any context.
In this patch we completely replace this outdated and not very useful
subsection on relocatable binaries, with a much more extensive one,
documenting step-by-step a procedure that is known to work. Also, this
subsection is moved above the non-relocatable one. All our current
releases except for 2019.1 use relocatable binaries, so the subsection
about these should be the more prominent one.

Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20200630145655.159926-1-bdenes@scylladb.com>
2020-06-30 18:35:36 +03:00
Avi Kivity
40f722f4c7 Update seastar submodule
* seastar 11e86172ba...5db34ea8d3 (7):
  > scollectd: Avoid a deprecated warning
  > prometheus: Avoid protobuf deprecated warning
  > Merge "Avoid abandoned futures in tests" from Rafael
  > Merge "make circular_buffer methods noexcept" from Benny
  > futures_test: Wait for future in test
  > iotune: Report disk IOPS instead of kernel IOPS
  > io_tester: Ability to add dsync option to open_file_dma
2020-06-30 17:23:11 +03:00
Takuya ASADA
5e207696d9 scylla_ntp_setup: switch to distro package
Use distro API to simplify distribution detection.
2020-06-30 13:57:08 +03:00
Raphael S. Carvalho
cf352e7c14 sstables: optimize procedure that checks if a sstable needs cleanup
needs_cleanup() returns true if a sstable needs cleanup.

Turns out it's very slow because it iterates through all the local
ranges for all sstables in the set, making its complexity:
	O(num_sstables * local_ranges)

We can optimize it by taking into account that abstract_replication_strategy
documents that get_ranges() will return a list of ranges that is sorted
and non-overlapping. Compaction for cleanup already takes advantage of that
when checking if a given partition can be actually purged.

So needs_cleanup() can be optimized into O(num_sstables * log(local_ranges)).

With num_sstables=1000, RF=3, then local_ranges=256(num_tokens)*3, it means
the max # of checks performed will go from 768000 to ~9584.

Fixes #6730.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20200629171355.45118-2-raphaelsc@scylladb.com>
2020-06-30 12:58:43 +03:00
Raphael S. Carvalho
a9eebdc778 sstables: export needs_cleanup()
May be needed elsewhere, like in an unit test.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20200629171355.45118-1-raphaelsc@scylladb.com>
2020-06-30 12:58:43 +03:00
Avi Kivity
08d41ee841 Merge "Fix API snapshot details getter" from Pavel E
"
Recent branch introduced uncaught by regular snapshot tests issue
with snapshots listing via API, this set fixes it (patch #1),
cleans the indentation after the fix (#2) and polishes the way
stuff is captured nearby (#3)

Tests: dtest(nodetool_additional_tests)
"

* 'br-fix-snap-get-details' of https://github.com/xemul/scylla:
  api: Remove excessive capture
  api: Fix indentation after previous patch
  api: Fix wrongly captured map of snapshots
2020-06-30 12:56:00 +03:00
Botond Dénes
effa632743 scylla-gdb.py: scylla_find: use ptr to start of object to lookup vptr
And not the pointer to the offset where the searched-for value was found
in the object.

Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20200625081242.486929-1-bdenes@scylladb.com>
2020-06-30 12:54:18 +03:00
Raphael S. Carvalho
68e12bd17e sstables: sstable_directory: place debug message in logger
this message, intended for debugging purposes, is not going through
the logger.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20200629184642.53348-1-raphaelsc@scylladb.com>
2020-06-30 12:47:17 +03:00
Benny Halevy
7dc3ce4994 init: init_ms_fd_gossiper: use logger for error message
Currently fmt::print is used to print an error message
if (broadcast_address != listen && seeds.count(listen))
and the logger should be used instead.

While at it, the information printed in this message is valueable
also in the error-free case, so this change logs it at `info`
level and then logs an error without repeating the said info.

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>

Test: bootstrap_test.py:TestBootstrap.start_stop_test_node(dev)
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Message-Id: <20200630083826.153326-1-bhalevy@scylladb.com>
2020-06-30 12:46:44 +03:00
Avi Kivity
5125e9b51d Merge "Avoid varidic futures" from Rafael
"
These patches removes the last few uses of variadic futures in scylla.
"

* 'espindola/no-variadic-future' of https://github.com/espindola/scylla:
  row level repair: Don't return a variadic future from get_sink_source
  row level repair: Don't return a variadic future from read_rows_from_disk
  messaging_service: Don't return variadic futures from make_sink_and_source_for_*
  cql3: Don't use variadic futures in select_statement
2020-06-30 12:45:37 +03:00
Avi Kivity
293d4117c1 Merge "Initial cleanup work post off-strategy" from Raphael
"
Offstrategy work, on boot and refresh, guarantees that a shared SSTable
will not reach the table whatsoever. We have lots of extra code in
table to make it able to live with those shared SSTables.
Now we can fortunately get rid of all that code.

tests: mode(dev).
also manually tested it by triggering resharding both on boot/refresh.
"

* 'cleanup_post_offstrategy_v2' of https://github.com/raphaelsc/scylla:
  distributed_loader: kill unused invoke_shards_with_ptr()
  sstables:: kill unused sstables::sstable_open_info
  sstables: kill unused sstable::load_shared_components()
  distributed_loader: remove declaration of inexistent do_populate_column_family()
  table: simplify table::discard_sstables()
  table: simplify add_sstable()
  table: simplify update_stats_for_new_sstable()
  table: remove unused open_sstable function
  distributed_loader: remove unused code
  table: no longer keep track of sstables that need resharding
  table: Remove unused functions no longer used by resharding
  table: remove sstable::shared() condition from backlog tracker add/remove functions
  table: No longer accept a shared SSTable
2020-06-30 12:42:34 +03:00
Tomasz Grabiec
8bd7359d93 Merge "lwt: introduce LWT flag in prepared statement metadata" from Pavel
This patch set adds a few new features in order to fix issue

The list of changes is briefly as follows:
 - Add a new `LWT` flag to `cql3::prepared_metadata`,
   which allows clients to clearly distinguish betwen lwt and
   non-lwt statements without need to execute some custom parsing
   logic (e.g. parsing the prepared query with regular expressions),
   which is obviously quite fragile.
 - Introduce the negotiation procedure for cql protocol extensions.
   This is done via `cql_protocol_extension` enum and is expected
   to have an appropriate mirroring implementation on the client
   driver side in order to work properly.
 - Implmenent a `LWT_ADD_METADATA_MARK` cql feature on top of the
   aforementioned algorithm to make the feature negotiable and use
   it conditionally (iff both server and client agrees with each
   other on the set of cql extensions).

The feature is meant to be further utilized by client drivers
to use primary replicas consistently when dealing with conditional
statements.

* git@github.com:ManManson/scylla feature/lwt_prepared_meta_flag_2:
  lwt: introduce "LWT" flag in prepared statement metadata
  transport: introduce `cql_protocol_extension` enum and cql protocol extensions negotiation
2020-06-30 12:40:19 +03:00
Takuya ASADA
eb405f0908 scylla_util.py: stop using /etc/os-release, use distro
Currently we we mistakenly made two different way to detect distribution,
directly reading /etc/os-release and use distro package.

distro package provides well abstracted APIs and still have full access to
os-release informations, we should switch to it.

Fixes #6691
2020-06-30 12:40:19 +03:00
Asias He
9abaf9bc2e boot_strapper: Ignore node to be replaced explicitly as stream source
After commit 7d86a3b208 (storage_service:
Make replacing node take writes), during replace operation, tokens in
_token_metadata for node being replaced are updated only after the replace
operation is finished. As a result, in range_streamer::add_ranges, the
node being replaced will be considered as a source to stream data from.

Before commit 7d86a3b208, the node being
replaced will not be considered as a source node because it is already
replaced by the replacing node before the replace operation is finished.
This is the reason why it works in the past.

To fix, filter out the node being replaced as a source node explicitly.

Tests: replace_first_boot_test and replace_stopped_node_test
Backports: 4.1
Fixes: #6728
2020-06-30 12:40:19 +03:00
Rafael Ávila de Espíndola
3964b1a551 row level repair: Don't return a variadic future from get_sink_source 2020-06-29 16:51:41 -07:00
Rafael Ávila de Espíndola
eeee63a9a3 row level repair: Don't return a variadic future from read_rows_from_disk 2020-06-29 16:51:10 -07:00
Rafael Ávila de Espíndola
af44684418 messaging_service: Don't return variadic futures from make_sink_and_source_for_* 2020-06-29 16:50:45 -07:00
Rafael Ávila de Espíndola
abb36cc7d1 cql3: Don't use variadic futures in select_statement 2020-06-29 16:49:41 -07:00
Raphael S. Carvalho
18880af9ad distributed_loader: kill unused invoke_shards_with_ptr()
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:23:50 -03:00
Raphael S. Carvalho
593c1e00c8 sstables:: kill unused sstables::sstable_open_info
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:23:48 -03:00
Raphael S. Carvalho
c7ba495691 sstables: kill unused sstable::load_shared_components()
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:23:45 -03:00
Raphael S. Carvalho
4683cb06c2 distributed_loader: remove declaration of inexistent do_populate_column_family()
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:23:42 -03:00
Raphael S. Carvalho
1e9c5b5295 table: simplify table::discard_sstables()
no longer need to have any special code for shared SSTables.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:23:40 -03:00
Raphael S. Carvalho
ce210a4420 table: simplify add_sstable()
get_shards_for_this_sstable() can be called inside table::add_sstable()
because the shards for a sstable is precomputed and so completely
exception safe. We want a central point for checking that table will
no longer added shared SSTables to its sstable set.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:23:32 -03:00
Raphael S. Carvalho
68b527f100 table: simplify update_stats_for_new_sstable()
no longer need to conditionally track the SSTable metadata,
as table will no longer accept shared SSTables.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:22:04 -03:00
Raphael S. Carvalho
607c74dc95 table: remove unused open_sstable function
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:22:00 -03:00
Raphael S. Carvalho
6dfeb107ae distributed_loader: remove unused code
Remove code no longer used by population procedure.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:21:40 -03:00
Raphael S. Carvalho
60467a7e36 table: no longer keep track of sstables that need resharding
Now that table will no longer accept shared SSTables, it no longer
needs to keep track of them.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:21:38 -03:00
Raphael S. Carvalho
cd548c6304 table: Remove unused functions no longer used by resharding
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:21:36 -03:00
Raphael S. Carvalho
68a4739a42 table: remove sstable::shared() condition from backlog tracker add/remove functions
Now that table no longer accept shared SSTables, those two functions can
be simplified by removing the shared condition.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:21:34 -03:00
Raphael S. Carvalho
343efe797d table: No longer accept a shared SSTable
With off-strategy work on reshard on boot and refresh, table no
longer needs to work with Shared SSTables. That will unlock
a host of cleanups.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
2020-06-29 14:21:04 -03:00
Pavel Emelyanov
d0d2da6ccb api: Remove excessive capture
The "result" in this lambda is already not used and can be removed

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
2020-06-29 19:08:59 +03:00
Pavel Emelyanov
4f5ffa980d api: Fix indentation after previous patch
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
2020-06-29 19:08:59 +03:00
Pavel Emelyanov
d99969e0e0 api: Fix wrongly captured map of snapshots
The results of get_snapshot_details() is saved in do_with, then is
captured on the json callback by reference, then the do_with's
future returns, so by the time callback is called the map is already
free and empty.

Fix by capturing the result directly on the callback.
Fixes recently merged b6086526.

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
2020-06-29 19:08:21 +03:00
Pavel Solodovnikov
6c6f3dbe42 lwt: introduce "LWT" flag in prepared statement metadata
This patch adds a new `LWT` flag to `cql3::prepared_metadata`.

That allows clients to clearly distinguish betwen lwt and
non-lwt statements without need to execute some custom parsing
logic (e.g. parsing the prepared query with regular expressions),
which is obviously quite fragile.

The feature is meant to be further utilized by client drivers
to use primary replicas consistently when dealing with conditional
statements.

Whether to use lwt optimization flag or not is handled by negotiation
procedure between scylla server and client library via SUPPORTED/STARTUP
messages (`LWT_ADD_METADATA_MARK` extension).

Tests: unit(dev, debug), manual testing with modified scylla/gocql driver

Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
2020-06-29 12:30:37 +03:00