6035fd05b3
The start-stop code is drifting towards a straightforward
scheme of a bunch of
service foo;
foo.start();
auto stop_foo = defer([&foo] { foo.stop(); });
blocks. The drain_on_shutdown() and its relation to drain()
and decommission() is a big hurdle on the way of this effort.
This set unifies drain() and drain_on_shutdown() so that drain
really becomes just some first steps of the regular shutdown,
i.e. -- what it should be. Some synchronisation bits around it
are still needed, though.
This unification also closes a bunch not-yet-caught bugs when
parts of the system remained running in case shutdown happens
after nodetool drain. In this case the whole drain_on_sutdown()
becomes a noop (just returns drain()'s future) and what's
missing in drain() becomes missing on shutdown.
tests: unit(dev), dtest(simple_boot_shutdown : dev),
manual(start+stop, start+drain+stop : dev)
refs: #2737
* xemul/br-drain-on-shutdown:
drain_on_shutdown: Simplify
drain: Fix indentation
storage_service: Unify drain and drain_on_shutdown
storage_proxy: Drain and unsubscribe in main.cc
migration_manager: Stop it in two phases
stream_manager: Stop instances on drain
batchlog_manager: Stop its instances on shutdown
tracing: Shutdown tracing in drain
tracing: Stop it in main.cc
system_distributed_keyspace: Stop it in main.cc
storage_service: Move (un)subscription to migration events
Scylla
What is Scylla?
Scylla is the real-time big data database that is API-compatible with Apache Cassandra and Amazon DynamoDB. Scylla embraces a shared-nothing approach that increases throughput and storage capacity to realize order-of-magnitude performance improvements and reduce hardware costs.
For more information, please see the ScyllaDB web site.
Build Prerequisites
Scylla is fairly fussy about its build environment, requiring very recent versions of the C++20 compiler and of many libraries to build. The document HACKING.md includes detailed information on building and developing Scylla, but to get Scylla building quickly on (almost) any build machine, Scylla offers a frozen toolchain, This is a pre-configured Docker image which includes recent versions of all the required compilers, libraries and build tools. Using the frozen toolchain allows you to avoid changing anything in your build machine to meet Scylla's requirements - you just need to meet the frozen toolchain's prerequisites (mostly, Docker or Podman being available).
Building Scylla
Building Scylla with the frozen toolchain dbuild is as easy as:
$ git submodule update --init --force --recursive
$ ./tools/toolchain/dbuild ./configure.py
$ ./tools/toolchain/dbuild ninja build/release/scylla
For further information, please see:
- Developer documentation for more information on building Scylla.
- Build documentation on how to build Scylla binaries, tests, and packages.
- Docker image build documentation for information on how to build Docker images.
Running Scylla
To start Scylla server, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --workdir tmp --smp 1 --developer-mode 1
This will start a Scylla node with one CPU core allocated to it and data files stored in the tmp directory.
The --developer-mode is needed to disable the various checks Scylla performs at startup to ensure the machine is configured for maximum performance (not relevant on development workstations).
Please note that you need to run Scylla with dbuild if you built it with the frozen toolchain.
For more run options, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --help
Testing
See test.py manual.
Scylla APIs and compatibility
By default, Scylla is compatible with Apache Cassandra and its APIs - CQL and Thrift. There is also support for the API of Amazon DynamoDB™, which needs to be enabled and configured in order to be used. For more information on how to enable the DynamoDB™ API in Scylla, and the current compatibility of this feature as well as Scylla-specific extensions, see Alternator and Getting started with Alternator.
Documentation
Documentation can be found here. Seastar documentation can be found here. User documentation can be found here.
Training
Training material and online courses can be found at Scylla University. The courses are free, self-paced and include hands-on examples. They cover a variety of topics including Scylla data modeling, administration, architecture, basic NoSQL concepts, using drivers for application development, Scylla setup, failover, compactions, multi-datacenters and how Scylla integrates with third-party applications.
Contributing to Scylla
If you want to report a bug or submit a pull request or a patch, please read the contribution guidelines.
If you are a developer working on Scylla, please read the developer guidelines.
Contact
- The users mailing list and Slack channel are for users to discuss configuration, management, and operations of the ScyllaDB open source.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.