Ava Affine
1ef8ff042f
In order to provide persistence of runtime state across the application
the documentbuffer provides a simple cache interface that balances cached
internal state events between an in memory cache and an on disk storage.
From a feature development perspective the DocumentBuffer provides a simple
cache interface:
- Push() and Pop() individual items
- Remove() and Read() bulk items
- Peek() at the most recent item
- Flush() items in memory to the disk
as well as some control features:
- Close(), which calls flush and then returns
index of the last byte of useful data in the
backing store.
- Cached(), which returns the number of items
cached in memory.
Underneath the hood, documentbuffer balances the cache (memory) and store
(disk) by "promoting" the most recent documents in store to cache and by
"demoting" the least recent documents in cache to store. Thus, the cache
is always ordered by most recent, and so is the store.
Documentbuffer takes any implementation of readwriteseeker as an interface
for a backing store. Theoretically this means that documentbuffer can leverage
more than just a standard os.File. Possible implementations could include
transactions over the network or device drivers for long term cold storage devices.
In fact, documentbuffer comes with an in memory test implementation of the
readwriteseeker interface called ReadWriteSeekString. This emulates the functions
of Read(), Write(), and Seek() to operate on an internal string buffer.
This facility is only provided for testing and mock up purposes.
One note about Close(): Since the documentbuffer has no way of truncating the
underlying store an edge case can present itself that necessitates Close() and
specifically Close()'s return type. If the documentbuffer has Remove()ed or
promote()ed more bytes of data from store than it will subsequently Flush() or
demote() to disk one or more bytes of junk data may be left over from the
overwriting of the previously Remove()/promote()ed data. In this case, or
more specifically in all cases Close() wil return the last usable index
of the underlying store. It is up to the caller to then truncate it.
Regretably there is no reasonable truncate interface that applies polymorphicly
to any underlying data stream. Thus the quirk around Close() remains a design
challenge.
This commit provides comprehensive unit tests for both DocumentBuffer and
ReadWriteSeekString.
Not implemented in this commit is the whole design for runtime data persistence.
It is intended that internal modules for bingobot that provide functionality
directly to the user leverage the event pub/sub system as their sole authoritative
source for state management. As long as these modules provide the same output
for the same input sequence of events consistently than all parts of the application
will recover from error status or crashes by re-ingesting the on disk storage
of events provided by the documentbuffer. This way the application will always
come back up with minimal data loss and potentially the exact same state as
before it went down.
Signed-off-by: Ava Affine <ava@sunnypup.io>
|
||
|---|---|---|
| internal | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| config.yaml | ||
| go.mod | ||
| go.sum | ||
| main.go | ||
| README.md | ||
| start.sh | ||
bingobot
Getting started
To make it easy for you to get started with GitLab, here's a list of recommended next steps.
Already a pro? Just edit this README.md and make it your own. Want to make it easy? Use the template at the bottom!
Add your files
- Create or upload files
- Add files using the command line or push an existing Git repository with the following command:
cd existing_repo
git remote add origin https://gitlab.com/whom/bingobot.git
git branch -M main
git push -uf origin main
Integrate with your tools
Collaborate with your team
- Invite team members and collaborators
- Create a new merge request
- Automatically close issues from merge requests
- Enable merge request approvals
- Set auto-merge
Test and Deploy
Use the built-in continuous integration in GitLab.
- Get started with GitLab CI/CD
- Analyze your code for known vulnerabilities with Static Application Security Testing (SAST)
- Deploy to Kubernetes, Amazon EC2, or Amazon ECS using Auto Deploy
- Use pull-based deployments for improved Kubernetes management
- Set up protected environments
Editing this README
When you're ready to make this README your own, just edit this file and use the handy template below (or feel free to structure it however you want - this is just a starting point!). Thanks to makeareadme.com for this template.
Suggestions for a good README
Every project is different, so consider which of these sections apply to yours. The sections used in the template are suggestions for most open source projects. Also keep in mind that while a README can be too long and detailed, too long is better than too short. If you think your README is too long, consider utilizing another form of documentation rather than cutting out information.
Name
Choose a self-explaining name for your project.
Description
Let people know what your project can do specifically. Provide context and add a link to any reference visitors might be unfamiliar with. A list of Features or a Background subsection can also be added here. If there are alternatives to your project, this is a good place to list differentiating factors.
Badges
On some READMEs, you may see small images that convey metadata, such as whether or not all the tests are passing for the project. You can use Shields to add some to your README. Many services also have instructions for adding a badge.
Visuals
Depending on what you are making, it can be a good idea to include screenshots or even a video (you'll frequently see GIFs rather than actual videos). Tools like ttygif can help, but check out Asciinema for a more sophisticated method.
Installation
Within a particular ecosystem, there may be a common way of installing things, such as using Yarn, NuGet, or Homebrew. However, consider the possibility that whoever is reading your README is a novice and would like more guidance. Listing specific steps helps remove ambiguity and gets people to using your project as quickly as possible. If it only runs in a specific context like a particular programming language version or operating system or has dependencies that have to be installed manually, also add a Requirements subsection.
Usage
Use examples liberally, and show the expected output if you can. It's helpful to have inline the smallest example of usage that you can demonstrate, while providing links to more sophisticated examples if they are too long to reasonably include in the README.
Support
Tell people where they can go to for help. It can be any combination of an issue tracker, a chat room, an email address, etc.
Roadmap
If you have ideas for releases in the future, it is a good idea to list them in the README.
Contributing
State if you are open to contributions and what your requirements are for accepting them.
For people who want to make changes to your project, it's helpful to have some documentation on how to get started. Perhaps there is a script that they should run or some environment variables that they need to set. Make these steps explicit. These instructions could also be useful to your future self.
You can also document commands to lint the code or run tests. These steps help to ensure high code quality and reduce the likelihood that the changes inadvertently break something. Having instructions for running tests is especially helpful if it requires external setup, such as starting a Selenium server for testing in a browser.
Authors and acknowledgment
Show your appreciation to those who have contributed to the project.
License
For open source projects, say how it is licensed.
Project status
If you have run out of energy or time for your project, put a note at the top of the README saying that development has slowed down or stopped completely. Someone may choose to fork your project or volunteer to step in as a maintainer or owner, allowing your project to keep going. You can also make an explicit request for maintainers.