Implement InstrumentedCall (#54)

instrument.go

@@ -0,0 +1,60 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package tally
+
+const (
+	_resultType        = "result_type"
+	_resultTypeError   = "error"
+	_resultTypeSuccess = "success"
+	_timingFormat      = "latency"
+)
+
+// NewInstrumentedCall returns an InstrumentedCall with the given name
+func NewInstrumentedCall(scope Scope, name string) InstrumentedCall {
+	return &instrumentedCall{
+		error:   scope.Tagged(map[string]string{_resultType: _resultTypeError}).Counter(name),
+		success: scope.Tagged(map[string]string{_resultType: _resultTypeSuccess}).Counter(name),
+		timing:  scope.SubScope(name).Timer(_timingFormat),
+	}
+}
+
+type instrumentedCall struct {
+	scope   Scope
+	success Counter
+	error   Counter
+	timing  Timer
+}
+
+// Exec executes the given block of code, and records whether it succeeded or
+// failed, and the amount of time that it took
+func (c *instrumentedCall) Exec(f ExecFn) error {
+	sw := c.timing.Start()
+
+	if err := f(); err != nil {
+		c.error.Inc(1.0)
+		return err
+	}
+
+	sw.Stop()
+	c.success.Inc(1.0)
+
+	return nil
+}

scope_test.go

@@ -21,6 +21,7 @@
 package tally
 
 import (
+	"errors"
 	"math"
 	"sync"
 	"sync/atomic"
@@ -313,6 +314,43 @@ func TestWriteReportLoop(t *testing.T) {
 	r.WaitAll()
 }
 
+func TestInstrumentedCallSuccess(t *testing.T) {
+	r := newTestStatsReporter()
+	s, closer := NewRootScope(ScopeOptions{Reporter: r}, 10)
+	defer closer.Close()
+
+	r.cg.Add(1)
+	r.tg.Add(1)
+	err := NewInstrumentedCall(s, "test_instrumented").Exec(func() error {
+		return nil
+	})
+	assert.Nil(t, err)
+
+	r.WaitAll()
+	assert.EqualValues(t, 1, r.counters["test_instrumented"].val)
+	resultType, _ := r.counters["test_instrumented"].tags["result_type"]
+	assert.EqualValues(t, resultType, "success")
+	assert.NotNil(t, r.timers["test_instrumented.latency"].val)
+}
+
+func TestInstrumentedCallFail(t *testing.T) {
+	r := newTestStatsReporter()
+	s, closer := NewRootScope(ScopeOptions{Reporter: r}, 10)
+	defer closer.Close()
+
+	r.cg.Add(1)
+	err := NewInstrumentedCall(s, "test_instrumented").Exec(func() error {
+		return errors.New("failure")
+	})
+	assert.NotNil(t, err)
+
+	r.WaitAll()
+	assert.EqualValues(t, 1, r.counters["test_instrumented"].val)
+	resultType, _ := r.counters["test_instrumented"].tags["result_type"]
+	assert.EqualValues(t, resultType, "error")
+	assert.Nil(t, r.timers["test_instrumented.latency"])
+}
+
 func TestCachedReportLoop(t *testing.T) {
 	r := newTestStatsReporter()
 	s, closer := NewRootScope(ScopeOptions{CachedReporter: r}, 10)

types.go

@@ -150,3 +150,13 @@ type Capabilities interface {
 	// Tagging returns whether the reporter has the capability for tagged metrics.
 	Tagging() bool
 }
+
+// ExecFn will be executed in an InstrumentedCall
+type ExecFn func() error
+
+// An InstrumentedCall allows tracking the success, errors, and timing of blocks of code
+type InstrumentedCall interface {
+	// Exec executes the given block of code, and records whether it succeeded or
+	// failed, and the amount of time that it took
+	Exec(f ExecFn) error
+}