Channel Check

Channels are a great feature of Golang but have several footguns that can lead to deadlocks. In particular, if the receiving channel stops processing the messages, a non-blocking channel send would fail to continue. In certain mission-critical sections of code, this could lead to a complete deadlock.

This linter currently has three features:

• Non-blocking sends
• Non-buffered channel creation detection
• Buffered channel size exceeds maximum size checks

Many of these will lead to false positives or situations where we want a blocking channel send. In these cases, nolint:channelcheck is easy to add. Regardless, having this issue pointed out automatically is a good way to fix bugs; this doesn't necessarily have to be included in CI.

Golangci-lint Integration

This is the recommended way to use the linter. golangci-lint has a module plugin system that works very well. To install the linter this way, do the following:

1. Download this repo locally.
2. In your target repo, create a .custom-gcl.yml file. Add the following content: NOTE: This can't be directly copied. Use the contents of .example-custom-gcl.yml.

       version: v1.64.5
       plugins:
       # a plugin from local source
       - module: github.com/asymmetric-research/channel_linter/channelcheck
           path: /Path/to/channelcheck_repo
       name: golangci-lint-with-channelcheck

3. In your .golangci.yaml file, add the following and enable the linter. NOTE: This can't be directly copied. Use the contents of .example-golangci.yml.

   linters-settings:
       custom: 
           channelcheck:
           type: "module" 
           description: Static analysis for go channel issues   
           settings: 
               CheckBlockingSends: true
               CheckUnbufferedChannels: false

4. Build the custom version of golangci-lint. This is literally recompiling the linter binary and adding our linter into it.

       golangci-lint custom -v

5. Run the new binary on your repo:

       ./golangci-lint-with-channelcheck run 

6. To remove false positives, add nolint:channelcheck above the line that had the linter error.

Configuration Steps Standalone

The linter can be used by itself. Simply run the following to install the binary:

go install ./cmd/channellint/main.go

Usage:

channellint ./examples

This is NOT recommended because false positives cannot be tuned out via nolint comments.