Request Size

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Overview

• Monitor request sizes
• Collect bandwidth metrics
• Analyze traffic patterns

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Installation

import "github.com/go-mizu/mizu/middlewares/requestsize"

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Quick Start

app := mizu.New()

app.Use(requestsize.New())

app.Post("/upload", func(c *mizu.Ctx) error {
    size := requestsize.Get(c)
    log.Printf("Request size: %d bytes", size)
    return c.Text(200, "OK")
})

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Configuration

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Options

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Examples

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Track in Context

app.Use(requestsize.New())

app.Post("/api", func(c *mizu.Ctx) error {
    size := requestsize.Get(c)
    // Use size for logging, metrics, etc.
    return c.JSON(200, map[string]int64{"received": size})
})

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With Callback

app.Use(requestsize.WithHandler(func(c *mizu.Ctx, size int64) {
    metrics.RecordRequestSize(c.Request().URL.Path, size)
}))

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Combined with Response Size

app.Use(requestsize.New())
app.Use(responsesize.New())

app.Post("/api", func(c *mizu.Ctx) error {
    reqSize := requestsize.Get(c)
    // Response size available after response
    return c.JSON(200, data)
})

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API Reference

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Functions

// New creates request size middleware
func New() mizu.Middleware

// WithHandler creates with callback
func WithHandler(handler func(*mizu.Ctx, int64)) mizu.Middleware

// Get returns request size from context
func Get(c *mizu.Ctx) int64

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Technical Details

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Architecture

• Context Storage: Size information is stored in the request context using a private context key
• Body Wrapping: The middleware wraps http.Request.Body with a trackingBody struct that counts bytes as they’re read
• Deferred Callback: Size callbacks are executed via defer to ensure they run after the request body is processed

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Implementation Details

1. Info Structure: Contains two fields:
   • ContentLength: The Content-Length header value (may be -1 if not set)
   • BytesRead: Actual bytes read from the request body during processing
2. Tracking Mechanism: The trackingBody wrapper intercepts all Read() calls and accumulates the byte count
3. Context Integration: Size info is attached to the request context and can be retrieved using the Get(), ContentLength(), or BytesRead() helper functions
4. Callback Execution: If configured, the OnSize callback is invoked after request processing completes, providing access to final byte counts

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Best Practices

• Use for bandwidth monitoring
• Track alongside response sizes
• Set alerts for unusually large requests
• Combine with body limit for enforcement

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Testing

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Related Middlewares

• responsesize - Response size tracking
• bodylimit - Size enforcement
• metrics - Metrics collection