47 lines
1.9 KiB
Markdown
47 lines
1.9 KiB
Markdown
---
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stage: none
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group: unassigned
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info: Any user with at least the Maintainer role can merge updates to this content. For details, see https://docs.gitlab.com/ee/development/development_processes.html#development-guidelines-review.
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---
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# JSON development guidelines
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At GitLab we handle a lot of JSON data. To best ensure we remain performant
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when handling large JSON encodes or decodes, we use our own JSON class
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instead of the default methods.
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## `Gitlab::Json`
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This class should be used in place of any calls to the default `JSON` class,
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`.to_json` calls, and the like. It implements the majority of the public
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methods provided by `JSON`, such as `.parse`, `.generate`, `.dump`, etc, and
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should be entirely identical in its response.
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The difference being that by sending all JSON handling through `Gitlab::Json`
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we can change the gem being used in the background. We use `oj`
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instead of the `json` gem, which uses C extensions and is therefore notably
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faster.
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This class came into existence because, due to the age of the GitLab application,
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it was proving impossible to just replace the `json` gem with `oj` by default because:
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- The number of tests with exact expectations of the responses.
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- The subtle variances between different JSON processors, particularly
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around formatting.
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The `Gitlab::Json` class takes this into account and can
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vary the adapter based on the use case, and account for outdated formatting
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expectations.
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## `Gitlab::Json::PrecompiledJson`
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This class is used by our hooks into the Grape framework to ensure that
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already-generated JSON is not then run through JSON generation
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a second time when returning the response.
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## `Gitlab::Json::LimitedEncoder`
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This class can be used to generate JSON but fail with an error if the
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resulting JSON would be too large. The default limit for the `.encode`
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method is 25 MB, but this can be customized when using the method.
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