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Contributing to sqlite3-ruby

This document is a work-in-progress.

This doc is a short introduction on how to modify and maintain the sqlite3-ruby gem.

Architecture notes

Decision record

As of 2024-09, we're starting to keep some architecture decisions in the subdirectory /adr, so please look there for additional information.

Garbage collection

All statements keep pointers back to their respective database connections. The @connection instance variable on the Statement handle keeps the database connection alive.

We use sqlite3_close_v2 in Database#close since v2.1.0 which defers actually closing the connection and freeing the underlying memory until all open statements are closed; though the Database object will immediately behave as though it's been fully closed. If a Database is not explicitly closed, it will be closed when it is GCed.

Statement#close finalizes the underlying statement. If a Statement is not explicitly closed, it will be closed/finalized when it is GCed.

Debugging memory issues

Please install valgrind and gdb before you use the tools in this section.

Run the test suite under valgrind and ruby_memcheck to look for memory leaks and other memory errors:

bundle exec rake compile test:valgrind

If you can't install valgrind on your system, use the sqlite3-dev docker image, which contains valgrind:

# build the image
bundle exec rake docker:dev:build

# run the test suite in a container
bundle exec rake docker:dev:test

# run the test suite under valgrind in a container
bundle exec rake docker:dev:test:valgrind

Each docker:dev:test task builds the image first, then mounts your working copy at /sqlite3 in the container. Note that the container compiles into the mounted working copy, so please re-run rake compile on your machine afterwards.

Run the test suite in the debugger:

bundle exec rake compile test:gdb

You can also run the test suite with a variety of GC behaviors, which is useful to localize some classes of memory bugs. Set the SQLITE3_TEST_GC_LEVEL environment variable (see test/helper.rb for more info). A more stressful level finds more bugs, but makes the suite slower:

# ordinary GC behavior (the default)
SQLITE3_TEST_GC_LEVEL=normal bundle exec rake compile test

# minor GC after each test
SQLITE3_TEST_GC_LEVEL=minor bundle exec rake compile test

# major GC after each test
SQLITE3_TEST_GC_LEVEL=major bundle exec rake compile test

# major GC after each test, and GC compaction after every 20 tests
SQLITE3_TEST_GC_LEVEL=compact bundle exec rake compile test

# verify references after compaction, after every 20 tests
# (see https://alanwu.space/post/check-compaction/)
SQLITE3_TEST_GC_LEVEL=verify bundle exec rake compile test

# run each test with GC "stress mode" on
SQLITE3_TEST_GC_LEVEL=stress bundle exec rake compile test

The compact and verify levels fall back to normal on a platform that does not support GC compaction. The stress level makes the suite about 150 times slower, and it makes timing-sensitive tests unreliable.

Building gems

As a prerequisite please make sure you have docker correctly installed, so that you're able to cross-compile the native gems.

Run bin/build-gems which will package gems for all supported platforms, and run some basic sanity tests on those packages using bin/test-gem-set and bin/test-gem-file-contents.

Updating the version of libsqlite3

Update /dependencies.yml to reflect:

  • the version of libsqlite3
  • the URL from which to download
  • the checksum of the file, which will need to be verified manually (see comments in that file)

Making a release

A quick checklist to cutting a release of the sqlite3 gem:

Prep

  • Make sure CI is green!
  • Update CHANGELOG.md and lib/sqlite3/version.rb
  • Create a git tag using a format that matches the pattern v\d+\.\d+\.\d+, e.g. v1.3.13
  • git push && git push --tags

Automated build and release

Manual build and release

  • Run bin/build-gems and make sure it completes and all the tests pass
  • for g in gems/*.gem ; do gem push $g ; done

Post-release