tracing

Middleware Tracing Example

This example demonstrates the comprehensive middleware tracking capabilities of GoVisual.

Features Demonstrated

• Middleware Chain Tracking: See how requests flow through multiple middleware layers
• SQL Query Tracking: Monitor database queries with timing and results
• HTTP Call Tracking: Track external API calls
• Custom Trace Points: Add custom trace entries for specific operations
• Performance Metrics: View detailed performance data for each request

Running the Example

go run main.go

The server will start on http://localhost:8090

Dashboard

Open http://localhost:8090/__viz to view the dashboard.

Test Endpoints

1. Basic Request: http://localhost:8090/

   • Simple JSON response
   • Shows basic middleware execution

2. Database Query: http://localhost:8090/api/users

   • Executes SQL queries
   • Shows database interaction in traces

3. Slow Operation: http://localhost:8090/api/slow

   • Multi-step operation with timing
   • Shows nested trace entries

4. External API: http://localhost:8090/api/external

   • Simulates external HTTP calls
   • Shows HTTP tracking in traces

Viewing Traces

1. Make some requests to the test endpoints
2. Open the dashboard at http://localhost:8090/__viz
3. Go to the "Trace" tab
4. Select a request to see its detailed execution trace

Trace Information Includes

• Middleware Stack: See each middleware that processed the request
• Execution Timeline: Visual timeline of all operations
• SQL Queries: Full query text, duration, and row counts
• HTTP Calls: External API calls with status and timing
• Custom Events: Application-specific trace points
• Performance Metrics: CPU usage, memory allocation, and bottlenecks

Customizing Traces

You can add custom trace points in your handlers:

tracer := middleware.GetTracer(r.Context())
if tracer != nil {
    tracer.StartTrace("Operation Name", "custom", map[string]interface{}{
        "custom_field": "value",
    })
    // ... your operation ...
    tracer.EndTrace(nil)
}

SQL Query Tracking

SQL queries are automatically tracked when using the profiling-enabled database drivers. The traces show:

• Query text
• Execution duration
• Number of rows affected/returned
• Any errors encountered