github.com/lulzWill/go-agent@v2.1.2+incompatible/_integrations/nrgin/v1/nrgin.go (about)

     1  // Package nrgin introduces middleware to support the Gin framework.
     2  //
     3  //	router := gin.Default()
     4  //	router.Use(nrgin.Middleware(app))
     5  //
     6  package nrgin
     7  
     8  import (
     9  	"net/http"
    10  
    11  	"github.com/gin-gonic/gin"
    12  	"github.com/lulzWill/go-agent"
    13  	"github.com/lulzWill/go-agent/internal"
    14  )
    15  
    16  func init() { internal.TrackUsage("integration", "framework", "gin", "v1") }
    17  
    18  // headerResponseWriter exists to give the transaction access to response
    19  // headers.
    20  type headerResponseWriter struct{ w gin.ResponseWriter }
    21  
    22  func (w *headerResponseWriter) Header() http.Header       { return w.w.Header() }
    23  func (w *headerResponseWriter) Write([]byte) (int, error) { return 0, nil }
    24  func (w *headerResponseWriter) WriteHeader(int)           {}
    25  
    26  var _ http.ResponseWriter = &headerResponseWriter{}
    27  
    28  type replacementResponseWriter struct {
    29  	gin.ResponseWriter
    30  	txn     newrelic.Transaction
    31  	code    int
    32  	written bool
    33  }
    34  
    35  var _ gin.ResponseWriter = &replacementResponseWriter{}
    36  
    37  func (w *replacementResponseWriter) flushHeader() {
    38  	if !w.written {
    39  		w.txn.WriteHeader(w.code)
    40  		w.written = true
    41  	}
    42  }
    43  
    44  func (w *replacementResponseWriter) WriteHeader(code int) {
    45  	w.code = code
    46  	w.ResponseWriter.WriteHeader(code)
    47  }
    48  
    49  func (w *replacementResponseWriter) Write(data []byte) (int, error) {
    50  	w.flushHeader()
    51  	return w.ResponseWriter.Write(data)
    52  }
    53  
    54  func (w *replacementResponseWriter) WriteString(s string) (int, error) {
    55  	w.flushHeader()
    56  	return w.ResponseWriter.WriteString(s)
    57  }
    58  
    59  func (w *replacementResponseWriter) WriteHeaderNow() {
    60  	w.flushHeader()
    61  	w.ResponseWriter.WriteHeaderNow()
    62  }
    63  
    64  var (
    65  	ctxKey = "newRelicTransaction"
    66  )
    67  
    68  // Transaction returns the transaction stored inside the context, or nil if not
    69  // found.
    70  func Transaction(c *gin.Context) newrelic.Transaction {
    71  	if v, exists := c.Get(ctxKey); exists {
    72  		if txn, ok := v.(newrelic.Transaction); ok {
    73  			return txn
    74  		}
    75  	}
    76  	return nil
    77  }
    78  
    79  // Middleware creates Gin middleware that instruments requests.
    80  //
    81  //	router := gin.Default()
    82  //	router.Use(nrgin.Middleware(app))
    83  //
    84  func Middleware(app newrelic.Application) gin.HandlerFunc {
    85  	return func(c *gin.Context) {
    86  		name := c.HandlerName()
    87  		w := &headerResponseWriter{w: c.Writer}
    88  		txn := app.StartTransaction(name, w, c.Request)
    89  		defer txn.End()
    90  
    91  		c.Writer = &replacementResponseWriter{
    92  			ResponseWriter: c.Writer,
    93  			txn:            txn,
    94  			code:           http.StatusOK,
    95  		}
    96  		c.Set(ctxKey, txn)
    97  		c.Next()
    98  	}
    99  }