Go Channel Bridge Pattern — Complete Guide

In this tutorial, you'll learn about Go Channel Bridge Pattern. We cover key concepts, practical examples, and best practices.

Channel bridge pattern -- Flatten a channel of channels into a single unified channel for sequential processing.

The Problem

Bridge pattern reads from a channel that yields other channels, merging all values into a single output stream. Useful for handling pagination or fragmented data sources.

Wrong

ch := make(chan <-chan int) // Channel of channels
// How to read all values sequentially?

Output:

// Manual reading is complex and error-prone

Right

func bridge(ctx context.Context, ch <-chan <-chan int) <-chan int {
    out := make(chan int)
    go func() {
        defer close(out)
        for {
            var stream <-chan int
            select {
            case <-ctx.Done():
                return
            case stream, ok := <-ch:
                if !ok { return }
            }
            for val := range stream {
                select {
                case out <- val:
                case <-ctx.Done():
                    return
                }
            }
        }
    }()
    return out
}

Output:

// All values from all sub-channels streamed through out

Prevention

• Bridge pattern = channel of channels to single stream
• Internal channels are consumed sequentially
• External channel close signals end of all data
• Use context for cancellation throughout
• Useful for paginated API results, fragmented data

Common Mistakes with channel bridge

1. Non-exhaustive pattern matches that compile with warnings then crash at runtime
2. Misunderstanding that String is [Char] with poor performance for large text operations
3. Using foldl instead of foldl' causing stack overflow on large lists

These mistakes appear frequently in real-world GO code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

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