reaction/ARCHITECTURE.md

Architecture

Here is a high-level overview of the codebase.

Don't hesitate to create an issue or a merge request if something is unclear, missing or outdated.

Build

• build.rs: permits to create shell completions and man pages on build.
• Cargo.toml, Cargo.lock: manifest and dependencies.
• config/: example / test configuration files. Look at its git history to discover more.
• Makefile: Makefile. Resumes useful commands.
• packaging/: Files useful for .deb and .tar generation.
• release.py: Build process for a release. Handles cross-compilation, .tar and .deb generation.

Main source code

• helpers_c/: C helpers. I wish to have special IP support in reaction and get rid of them. See #79 and #116.
• tests/: Integration tests. For now they test basic reaction runtime behavior, persistance, and client-daemon communication.
• src/: The source code, here we go!

Top-level files

• src/main.rs: Main entrypoint
• src/lib.rs: Second main entrypoint
• src/cli.rs: Command-line arguments
• src/tests.rs: Test utilities

src/concepts/

reaction really is about its configuration, which is at the center of the code.

There is one file for each of its concepts: configuration, streams, filters, actions, patterns.

src/protocol/

Low-level serialization/deserialization and client-daemon protocol messages.

Shared by the client and daemon's socket. Also used by daemon's database.

src/client/

Client code: reaction show, reaction flush, reaction trigger, reaction test-regex.

• request.rs: commands requiring client/server communication: show, flush & trigger.
• test_config.rs: test-config command.
• test_regex.rs: test-regex command.

src/daemon

Daemon runtime structures and logic.

This code has async code, to handle input streams and communication with clients, using the tokio runtime.

• mod.rs: daemon main function. Initializes all tasks, handles synchronization and quitting, etc.
• stream.rs: Stream managers: start the stream cmd and dispatch its stdout lines to its Filter managers.
• filter/: Filter managers: handle lines, persistance, store matches and trigger actions. This is the main piece of runtime logic.
  • mod.rs: High-level logic
  • state.rs: Inner state operations
• socket.rs: The socket task, responsible for communication with clients.
• shutdown.rs: Logic for passing shutdown signal across all tasks

src/tree

Persistence layer.

This is a database highly adapted to reaction workload, making reaction faster than when used with general purpose key-value databases (heed, sled and fjall crates have been tested). Its design is explained in the comments of its files:

• mod.rs: main database code, with its two API structs: Tree and Database.
• raw.rs low-level part, directly interacting with de/serializisation and files.