metrics.go

Documentation: github.com/palantir/go-baseapp/baseapp

     1  // Copyright 2018 Palantir Technologies, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package baseapp
    16  
    17  import (
    18  	"context"
    19  	"net/http"
    20  	"runtime"
    21  	"time"
    22  
    23  	"github.com/rcrowley/go-metrics"
    24  )
    25  
    26  const (
    27  	MetricsKeyRequests    = "server.requests"
    28  	MetricsKeyRequests2xx = "server.requests.2xx"
    29  	MetricsKeyRequests3xx = "server.requests.3xx"
    30  	MetricsKeyRequests4xx = "server.requests.4xx"
    31  	MetricsKeyRequests5xx = "server.requests.5xx"
    32  
    33  	MetricsKeyNumGoroutines = "server.goroutines"
    34  	MetricsKeyMemoryUsed    = "server.mem.used"
    35  )
    36  
    37  type metricsCtxKey struct{}
    38  
    39  // MetricsCtx gets a metrics registry from the context. It returns the default
    40  // registry from the go-metrics package if none exists in the context.
    41  func MetricsCtx(ctx context.Context) metrics.Registry {
    42  	if r, ok := ctx.Value(metricsCtxKey{}).(metrics.Registry); ok {
    43  		return r
    44  	}
    45  	return metrics.DefaultRegistry
    46  }
    47  
    48  // WithMetricsCtx stores a metrics registry in a context.
    49  func WithMetricsCtx(ctx context.Context, registry metrics.Registry) context.Context {
    50  	return context.WithValue(ctx, metricsCtxKey{}, registry)
    51  }
    52  
    53  // RegisterDefaultMetrics adds the default metrics provided by this package to
    54  // the registry. This should be called before any functions emit metrics to
    55  // ensure that no events are lost.
    56  func RegisterDefaultMetrics(registry metrics.Registry) {
    57  	for _, key := range []string{
    58  		MetricsKeyRequests,
    59  		MetricsKeyRequests2xx,
    60  		MetricsKeyRequests3xx,
    61  		MetricsKeyRequests4xx,
    62  		MetricsKeyRequests5xx,
    63  	} {
    64  		metrics.GetOrRegisterCounter(key, registry)
    65  	}
    66  
    67  	registry.GetOrRegister(MetricsKeyNumGoroutines, func() metrics.Gauge {
    68  		return metrics.NewFunctionalGauge(func() int64 {
    69  			return int64(runtime.NumGoroutine())
    70  		})
    71  	})
    72  
    73  	registry.GetOrRegister(MetricsKeyMemoryUsed, func() metrics.Gauge {
    74  		return metrics.NewFunctionalGauge(func() int64 {
    75  			var m runtime.MemStats
    76  			runtime.ReadMemStats(&m)
    77  			return int64(m.Alloc)
    78  		})
    79  	})
    80  }
    81  
    82  // CountRequest is an AccessCallback that records metrics about the request.
    83  func CountRequest(r *http.Request, status int, _ int64, _ time.Duration) {
    84  	registry := MetricsCtx(r.Context())
    85  
    86  	if c := registry.Get(MetricsKeyRequests); c != nil {
    87  		c.(metrics.Counter).Inc(1)
    88  	}
    89  
    90  	if key := bucketStatus(status); key != "" {
    91  		if c := registry.Get(key); c != nil {
    92  			c.(metrics.Counter).Inc(1)
    93  		}
    94  	}
    95  }
    96  
    97  func bucketStatus(status int) string {
    98  	switch {
    99  	case status >= 200 && status < 300:
   100  		return MetricsKeyRequests2xx
   101  	case status >= 300 && status < 400:
   102  		return MetricsKeyRequests3xx
   103  	case status >= 400 && status < 500:
   104  		return MetricsKeyRequests4xx
   105  	case status >= 500 && status < 600:
   106  		return MetricsKeyRequests5xx
   107  	}
   108  	return ""
   109  }
   110
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