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97aa335a60
A couple of improvements to prepare for the next patchset. We move `logical_timer` and `ticker` to their own headers due to the generality of these data structures. They are not very specific to the test. `logical_timer` is extended with a `schedule` function, allowing to schedule any given function to be called at the given time point. The interface of `network` in `randomized_nemesis_test` is extended by `add_grudge` and `remove_grudge` functions for implementing network partitioning nemeses. Furthermore `network` can be now constructed with an arbitrary network delay, which was previously hardcoded. `with_env_and_ticker` is now generic w.r.t. return values (previously `future<>` was assumed). `environment` exposes a reference to the `network` through a getter. The `not_a_leader` exception now shows the leader's ID in the exception message. Useful for logging. In `logical_timer::with_timeout`, when we timeout, we don't just return `timed_out_error`. The returned exception now actually contains the original future... well almost; in any case, the user can now do something different to the future other than simply discarding it. We also fix some `broken_promise` exceptions appearing in discarded futures in certain scenarios. See the corresponding commit for detailed explanation. We handle `raft::dropped_entry` in the `call` function. `persistence` is fixed to avoid creating gaps in the log when storing snapshots and to support complex state types. Waiting for leader was refactored into a separate function and generalized (we wait for a set of nodes to elect a leader instead of a single node to elect itself) to be useful in more situations. Finally, we introduce `reconfigure`, a higher-level version of `set_configuration` which performs error handling and supports timeouts. * kbr/raft-nemesis-improvements-v4: test: raft: randomized_nemesis_test: `reconfigure` function test: raft: randomized_nemesis_test: refactor waiting for leader into a separate function test: raft: randomized_nemesis_test: persistence: avoid creating gaps in the log when storing snapshots test: raft: randomized_nemesis_test: persistence: handle complex state types test: raft: randomized_nemesis_test: `call`: handle `raft::dropped_entry` test: raft: randomized_nemesis_test: impure_state_machine/call: handle dropped channels test: raft: randomized_nemesis_test: environment: expose the network test: raft: randomized_nemesis_test: configurable network delay and FD convict threshold test: raft: randomized_nemesis_test: generalize `with_env_and_ticker` test: raft: randomized_nemesis_test: network: `add_grudge`, `remove_grudge` functions test: raft: randomized_nemesis_test: move `ticker` to its own header test: raft: randomized_nemesis_test: ticker: take `logger` as a constructor parameter test: raft: logical_timer: handle immediate timeout test: raft: logical_timer: on timeout, return the original future in the exception test: raft: logical_timer: add `schedule` member function test: raft: randomized_nemesis_test: move `logical_timer` to its own header test: raft: include the leader's ID in the `not_a_leader` exception's message
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.