github.com/thiagoyeds/go-cloud@v0.26.0/internal/testing/octest/exporter.go (about)

     1  // Copyright 2019 The Go Cloud Development Kit Authors
     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  //     https://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 octest supports testing of OpenCensus integrations.
    16  package octest
    17  
    18  // This code was copied from cloud.google.com/go/internal/testutil/trace.go
    19  
    20  import (
    21  	"log"
    22  	"sync"
    23  	"time"
    24  
    25  	"go.opencensus.io/stats/view"
    26  	"go.opencensus.io/trace"
    27  )
    28  
    29  // TestExporter is an exporter of OpenCensus traces and metrics, for testing.
    30  // It should be created with NewTestExporter.
    31  type TestExporter struct {
    32  	mu    sync.Mutex
    33  	spans []*trace.SpanData
    34  	Stats chan *view.Data
    35  }
    36  
    37  // NewTestExporter creates a TestExporter and registers it with OpenCensus.
    38  func NewTestExporter(views []*view.View) *TestExporter {
    39  	te := &TestExporter{Stats: make(chan *view.Data)}
    40  
    41  	// Register for metrics.
    42  	view.RegisterExporter(te)
    43  	// The reporting period will affect how long it takes to get stats (view.Data).
    44  	// We want it short so tests don't take too long, but long enough so that all
    45  	// the actions in a test complete.
    46  	//   If the period is too short, then some actions may not be finished when the first
    47  	// call to ExportView happens. diffCounts checks for matching counts, so it will
    48  	// fail in that case.
    49  	//   Tests that use the exporter (search for TestOpenCensus) are designed to avoid
    50  	// network traffic or computation, so they finish quickly. But we must account for
    51  	// the race detector, which slows everything down.
    52  	view.SetReportingPeriod(100 * time.Millisecond)
    53  	if err := view.Register(views...); err != nil {
    54  		log.Fatal(err)
    55  	}
    56  
    57  	// Register for traces.
    58  	trace.RegisterExporter(te)
    59  	trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
    60  
    61  	return te
    62  }
    63  
    64  // ExportSpan "exports" a span by remembering it.
    65  func (te *TestExporter) ExportSpan(s *trace.SpanData) {
    66  	te.mu.Lock()
    67  	defer te.mu.Unlock()
    68  	te.spans = append(te.spans, s)
    69  }
    70  
    71  // ExportView exports a view by writing it to the Stats channel.
    72  func (te *TestExporter) ExportView(vd *view.Data) {
    73  	if len(vd.Rows) > 0 {
    74  		select {
    75  		case te.Stats <- vd:
    76  		default:
    77  		}
    78  	}
    79  }
    80  
    81  func (te *TestExporter) Spans() []*trace.SpanData {
    82  	te.mu.Lock()
    83  	defer te.mu.Unlock()
    84  	return te.spans
    85  }
    86  
    87  // Counts returns the first exported data that includes aggregated counts.
    88  func (te *TestExporter) Counts() []*view.Row {
    89  	// Wait for counts. Expect all counts to arrive in the same view.Data.
    90  	for {
    91  		data := <-te.Stats
    92  		if _, ok := data.Rows[0].Data.(*view.CountData); !ok {
    93  			continue
    94  		}
    95  		return data.Rows
    96  	}
    97  }
    98  
    99  // Unregister unregisters the exporter from OpenCensus.
   100  func (te *TestExporter) Unregister() {
   101  	view.UnregisterExporter(te)
   102  	trace.UnregisterExporter(te)
   103  	view.SetReportingPeriod(0) // reset to default value
   104  }