copy errgroup code to bench and remove giant blob of dependencies

bench/LICENSE

@@ -0,0 +1,30 @@
+The following applies to the files errgroup.go and errgroup_test.go
+in the same directory this file resides:
+
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

bench/bench.go

@@ -2,7 +2,6 @@ package bench
 
 import (
 	"fmt"
-	"golang.org/x/sync/errgroup"
 	"strconv"
 	"sync"
 	"time"
@@ -51,7 +50,7 @@ type parallelBenchmark struct {
 // Init calls Init for each benchmark. If there are any errors, it will return a
 // non-nil error value.
 func (pb *parallelBenchmark) Init(hosts []string, agentNum int) error {
-	var g errgroup.Group
+	var g ErrGroup
 	for i, _ := range pb.benchmarkers {
 		b := pb.benchmarkers[i]
 		g.Go(func() error {

bench/errgroup.go

@@ -0,0 +1,67 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package errgroup provides synchronization, error propagation, and Context
+// cancelation for groups of goroutines working on subtasks of a common task.
+package bench
+
+import (
+	"sync"
+
+	"context"
+)
+
+// An ErrGroup is a collection of goroutines working on subtasks that are part of
+// the same overall task.
+//
+// A zero ErrGroup is valid and does not cancel on error.
+type ErrGroup struct {
+	cancel func()
+
+	wg sync.WaitGroup
+
+	errOnce sync.Once
+	err     error
+}
+
+// WithContext returns a new ErrGroup and an associated Context derived from ctx.
+//
+// The derived Context is canceled the first time a function passed to Go
+// returns a non-nil error or the first time Wait returns, whichever occurs
+// first.
+func WithContext(ctx context.Context) (*ErrGroup, context.Context) {
+	ctx, cancel := context.WithCancel(ctx)
+	return &ErrGroup{cancel: cancel}, ctx
+}
+
+// Wait blocks until all function calls from the Go method have returned, then
+// returns the first non-nil error (if any) from them.
+func (g *ErrGroup) Wait() error {
+	g.wg.Wait()
+	if g.cancel != nil {
+		g.cancel()
+	}
+	return g.err
+}
+
+// Go calls the given function in a new goroutine.
+//
+// The first call to return a non-nil error cancels the group; its error will be
+// returned by Wait.
+func (g *ErrGroup) Go(f func() error) {
+	g.wg.Add(1)
+
+	go func() {
+		defer g.wg.Done()
+
+		if err := f(); err != nil {
+			g.errOnce.Do(func() {
+				g.err = err
+				if g.cancel != nil {
+					g.cancel()
+				}
+			})
+		}
+	}()
+}

bench/errgroup_test.go

@@ -0,0 +1,176 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bench_test
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"os"
+	"testing"
+
+	"context"
+	"github.com/pilosa/pilosa/bench"
+)
+
+var (
+	Web   = fakeSearch("web")
+	Image = fakeSearch("image")
+	Video = fakeSearch("video")
+)
+
+type Result string
+type Search func(ctx context.Context, query string) (Result, error)
+
+func fakeSearch(kind string) Search {
+	return func(_ context.Context, query string) (Result, error) {
+		return Result(fmt.Sprintf("%s result for %q", kind, query)), nil
+	}
+}
+
+// JustErrors illustrates the use of a ErrGroup in place of a sync.WaitGroup to
+// simplify goroutine counting and error handling. This example is derived from
+// the sync.WaitGroup example at https://golang.org/pkg/sync/#example_WaitGroup.
+func ExampleGroup_justErrors() {
+	var g bench.ErrGroup
+	var urls = []string{
+		"http://www.golang.org/",
+		"http://www.google.com/",
+		"http://www.somestupidname.com/",
+	}
+	for _, url := range urls {
+		// Launch a goroutine to fetch the URL.
+		url := url // https://golang.org/doc/faq#closures_and_goroutines
+		g.Go(func() error {
+			// Fetch the URL.
+			resp, err := http.Get(url)
+			if err == nil {
+				resp.Body.Close()
+			}
+			return err
+		})
+	}
+	// Wait for all HTTP fetches to complete.
+	if err := g.Wait(); err == nil {
+		fmt.Println("Successfully fetched all URLs.")
+	}
+}
+
+// Parallel illustrates the use of a ErrGroup for synchronizing a simple parallel
+// task: the "Google Search 2.0" function from
+// https://talks.golang.org/2012/concurrency.slide#46, augmented with a Context
+// and error-handling.
+func ExampleGroup_parallel() {
+	Google := func(ctx context.Context, query string) ([]Result, error) {
+		g, ctx := bench.WithContext(ctx)
+
+		searches := []Search{Web, Image, Video}
+		results := make([]Result, len(searches))
+		for i, search := range searches {
+			i, search := i, search // https://golang.org/doc/faq#closures_and_goroutines
+			g.Go(func() error {
+				result, err := search(ctx, query)
+				if err == nil {
+					results[i] = result
+				}
+				return err
+			})
+		}
+		if err := g.Wait(); err != nil {
+			return nil, err
+		}
+		return results, nil
+	}
+
+	results, err := Google(context.Background(), "golang")
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		return
+	}
+	for _, result := range results {
+		fmt.Println(result)
+	}
+
+	// Output:
+	// web result for "golang"
+	// image result for "golang"
+	// video result for "golang"
+}
+
+func TestZeroGroup(t *testing.T) {
+	err1 := errors.New("errgroup_test: 1")
+	err2 := errors.New("errgroup_test: 2")
+
+	cases := []struct {
+		errs []error
+	}{
+		{errs: []error{}},
+		{errs: []error{nil}},
+		{errs: []error{err1}},
+		{errs: []error{err1, nil}},
+		{errs: []error{err1, nil, err2}},
+	}
+
+	for _, tc := range cases {
+		var g bench.ErrGroup
+
+		var firstErr error
+		for i, err := range tc.errs {
+			err := err
+			g.Go(func() error { return err })
+
+			if firstErr == nil && err != nil {
+				firstErr = err
+			}
+
+			if gErr := g.Wait(); gErr != firstErr {
+				t.Errorf("after %T.Go(func() error { return err }) for err in %v\n"+
+					"g.Wait() = %v; want %v",
+					g, tc.errs[:i+1], err, firstErr)
+			}
+		}
+	}
+}
+
+func TestWithContext(t *testing.T) {
+	errDoom := errors.New("group_test: doomed")
+
+	cases := []struct {
+		errs []error
+		want error
+	}{
+		{want: nil},
+		{errs: []error{nil}, want: nil},
+		{errs: []error{errDoom}, want: errDoom},
+		{errs: []error{errDoom, nil}, want: errDoom},
+	}
+
+	for _, tc := range cases {
+		g, ctx := bench.WithContext(context.Background())
+
+		for _, err := range tc.errs {
+			err := err
+			g.Go(func() error { return err })
+		}
+
+		if err := g.Wait(); err != tc.want {
+			t.Errorf("after %T.Go(func() error { return err }) for err in %v\n"+
+				"g.Wait() = %v; want %v",
+				g, tc.errs, err, tc.want)
+		}
+
+		canceled := false
+		select {
+		case <-ctx.Done():
+			canceled = true
+		default:
+		}
+		if !canceled {
+			t.Errorf("after %T.Go(func() error { return err }) for err in %v\n"+
+				"ctx.Done() was not closed",
+				g, tc.errs)
+		}
+	}
+}

cmd/pilosa/main_test.go

@@ -16,7 +16,6 @@ import (
 	"testing"
 	"testing/quick"
 
-	"context"
 	"github.com/BurntSushi/toml"
 	"github.com/pilosa/pilosa"
 	main "github.com/pilosa/pilosa/cmd/pilosa"

glide.lock

@@ -1,5 +1,5 @@
-hash: d912921b0318c326771cd49debeec509d4ffb0558bd37e53570f6404fbec6604
-updated: 2016-11-29T16:10:39.53889541-06:00
+hash: 9afe91839785e89880061fd2919b0a5cdb10d6f4c06b344c2924eeed0c9bfd65
+updated: 2016-12-01T16:53:45.096741528-07:00
 imports:
 - name: github.com/boltdb/bolt
   version: 4b1ebc1869ad66568b313d0dc410e2be72670dda
@@ -21,14 +21,6 @@ imports:
   version: a6b377e3400b08991b80d6805d627f347f983866
   subpackages:
   - lru
-- name: golang.org/x/net
-  version: 4971afdc2f162e82d185353533d3cf16188a9f4e
-  subpackages:
-  - context
-- name: golang.org/x/sync
-  version: 1ae7c7b29e06598039be46c5083819ba6fd7a97e
-  subpackages:
-  - errgroup
 - name: golang.org/x/sys
   version: c200b10b5d5e122be351b67af224adc6128af5bf
   subpackages:

glide.yaml

@@ -24,6 +24,4 @@ import:
   version: c200b10b5d5e122be351b67af224adc6128af5bf
   subpackages:
   - unix
-- package: golang.org/x/sync
-  subpackages:
-  - errgroup
+