Multiple errors support

[unflxw]

See https://github.com/appsignal/appsignal-agent/pull/1186 for context.

⚠️ The changes in this PR will not work or pass the tests without the changes in the agent PR. You can test these changes as follows:

# Replace this with your target OS+arch
TARGET_OS_ARCH=x86_64-apple-darwin

# Build the agent locally
cd appsignal-agent
git fetch; git checkout extension-transaction-duplication
rake build:target:${TARGET_OS_ARCH}

# Copy the agent build to the integration
for file in appsignal-agent/release/${TARGET_OS_ARCH}/release/*; do
  cp $file appsignal-ruby/ext/
done

# Build the Ruby extension
cd appsignal-ruby/ext
rake extconf.rb && make clean && make

Also see the test setup: appsignal/test-setups#222

A release of the agent containing the changes in the agent PR will be added to this PR before merging.

---

Support multiple errors per transaction

Implement a new add_error method that allows for multiple errors
to be added to a transaction. These additional errors are stored on
the Ruby transaction object. When the transaction is completed,
duplicate the current transaction to report each of the errors
in its own duplicate transaction.

https://appsignal.slack.com/archives/CNPP953E2/p1720083599598159

Add .duplicate transaction method

Implement support for the appsignal_transaction_duplicate method
implemented in the agent side the extension, in both the Ruby C
extension and the JRuby FFI extension.

Implement a duplicate method for the Transaction class that
calls the extension's own duplicate method to duplicate a
transaction.

Always set error causes when setting errors

This fixes a bug where, when overwriting an already set error by
setting an error that has no error causes, the error causes from the
first error would be kept.

Avoid reporting performance and error sample

When a transaction does not have an error, but it does have one or
more additional errors, instead of reporting the error-less
transaction alongside its duplicates, set the last additional error
as the error for this transaction.

Limit additional errors

Report at most ten additional errors per transaction. If more errors
are provided, report only the last ten additional errors.

Pass the extension as an option when initialising the transaction
object.

Use add_error in report_error helper

Within the report_error helper, use add_error instead of the
set_error method, so that multiple errors can be reported from
the same transaction.

[tombruijn]

You can test these changes as follows

You wrote quite a lengthy set of instructions, but you can also run rake integrations:ruby and test it in the integrations/appsignal-ruby agent submodule.

[unflxw]

✅ on all the above -- will amend the PR tomorrow with #1212 and multiple-errors-aliased in it.

[tombruijn]

👏

[tombruijn]

Suggested change

	attr_writer :ext, :is_duplicate
	attr_writer :is_duplicate

I don't see where this is used. Can we remove it?

[backlog-helper]

• This Pull Request needs more reviews. @jeffkreeftmeijer - (More info)

---

This is a message from the daily scheduled checks.

New issue guide | Backlog management | Rules | Feedback

[tombruijn]

For future Tom and Noemi, and other readers, the last commit comes from this internal discussion (and some messages around that specific thread).