mirror of
https://github.com/matrix-org/dendrite
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90 lines
3.1 KiB
Markdown
90 lines
3.1 KiB
Markdown
# Code Style
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We follow the standard Go style using gofmt, but with a few extra
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considerations.
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## Linters
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We use `gometalinter` to run a number of linters, the exact list can be found
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in [linter.json](linter.json). Some of these are slow and expensive to run, but
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a subset can be found in [linter-fast.json](linter-fast.json) that run quickly
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enough to be run as part of an IDE.
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For rare cases where a linter is giving a spurious warning, it can be disabled
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for that line or statement using a [comment directive](https://github.com/alecthomas/gometalinter#comment-directives), e.g.
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`// nolint: gocyclo`. This should be used sparingly and only when its clear
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that the lint warning is spurious.
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The linters are vendored, and can be run using [scripts/find-lint.sh](scripts/find-lint.sh)
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(see file for docs) or as part of a build/test/lint cycle using
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[scripts/build-test-lint.sh](scripts/build-test-lint.sh).
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## HTTP Error Handling
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Unfortunately, converting errors into HTTP responses with the correct status
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code and message can be done in a number of ways in golang:
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1. Having functions return `JSONResponse` directly, which can then either set
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it to an error response or a `200 OK`.
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2. Have the HTTP handler try and cast error values to types that are handled
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differently.
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3. Have the HTTP handler call functions whose errors can only be interpreted
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one way, for example if a `validate(...)` call returns an error then handler
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knows to respond with a `400 Bad Request`.
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We attempt to always use option #3, as it more naturally fits with the way that
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golang generally does error handling. In particular, option #1 effectively
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requires reinventing a new error handling scheme just for HTTP handlers.
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## Line length
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We strive for a line length of roughly 80 characters, though less than 100 is
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acceptable if necessary. Longer lines are fine if there is nothing of interest
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after the first 80-100 characters (e.g. long string literals).
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## TODOs and FIXMEs
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The majority of TODOs and FIXMEs should have an associated tracking issue on
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github. These can be added just before merging of the PR to master, and the
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issue number should be added to the comment, e.g. `// TODO(#324): ...`
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## Logging
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We generally prefer to log with static log messages and include any dynamic
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information in fields.
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```golang
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logger := util.GetLogger(ctx)
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// Not recommended
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logger.Infof("Finished processing keys for %s, number of keys %d", name, numKeys)
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// Recommended
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logger.WithFields(logrus.Fields{
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"numberOfKeys": numKeys,
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"entityName": name,
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}).Info("Finished processing keys")
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```
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This is useful when logging to systems that natively understand log fields, as
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it allows people to search and process the fields without having to parse the
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log message.
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## Visual Studio Code
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If you use VSCode then the following is an example of a workspace setting that
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sets up linting correctly:
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```json
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{
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"go.gopath": "${workspaceRoot}:${workspaceRoot}/vendor",
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"go.lintOnSave": "workspace",
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"go.lintTool": "gometalinter",
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"go.lintFlags": ["--config=linter-fast.json", "--concurrency=5"]
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}
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```
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