93be4c0cb0
Currently he gossiper marks endpoint_state objects as alive/dead. I some cases the endpoint_state::is_alive function is checked but in many other cases gossiper::is_alive(endpoint) is used to determine if the endpoint is alive. This series removed the endpoint_state::is_alive state and moves all the logic to gossiper::is_alive that bases its decision on the endpoint having an endpoint_state and being in the _live_endpoints set. For that, the _live_endpoints is made sure to be replicated to all shards when changed and the endpoint_state changes are serialized under lock_endpoint, and also making sure that the endpoint_state in the _endpoint_states_map is never updated in place, but rather a temporary copy is changed and then safely replicated using gossiper::replicate Refs https://github.com/scylladb/scylladb/issues/14794 Closes #14801 * github.com:scylladb/scylladb: gossiper: mark_alive: remove local_state param endpoint_state: get rid of _is_alive member and methods gossiper: is_alive: use _live_endpoints gossiper: evict_from_membership: erase endpoint from _live_endpoints gossiper: replicate_live_endpoints_on_change: use _live_endpoints_version to detect change gossiper: run: no need to replicate live_endpoints gossiper: fold update_live_endpoints_version into replicate_live_endpoints_on_change gossiper: add mutate_live_and_unreachable_endpoints gossiper: reset_endpoint_state_map: clear also shadow endpoint sets gossiper: reset_endpoint_state_map: clear live/unreachable endpoints on all shards gossiper: functions that change _live_endpoints must be called on shard 0 gossiper: add lock_endpoint_update_semaphore gossiper: make _live_endpoints an unordered_set endpoint_state: use gossiper::is_alive externally
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 community forum 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.