added: testing
This commit is contained in:
Brett Wandel
parent
76b5c1995f
commit
aaf56ffd26
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@ -186,6 +186,7 @@ func (c *BuildCommand) Run(args []string) int {
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if err := limitParallel.Acquire(buildCtx, 1); err != nil {
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ui.Error(fmt.Sprintf("Build '%s' failed to acquire semaphore: %s", name, err))
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errors[name] = err
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return
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}
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defer limitParallel.Release(1)
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@ -0,0 +1,98 @@
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package command
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import (
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"bytes"
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"context"
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"fmt"
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"math"
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"path/filepath"
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"sync"
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"testing"
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"github.com/hashicorp/packer/packer"
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)
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type ParallelTestBuilder struct {
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Prepared int
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Built int
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wg *sync.WaitGroup
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m *sync.Mutex
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}
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func (b *ParallelTestBuilder) Prepare(raws ...interface{}) ([]string, error) {
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b.Prepared++
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return nil, nil
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}
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func (b *ParallelTestBuilder) Run(ctx context.Context, ui packer.Ui, hook packer.Hook) (packer.Artifact, error) {
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ui.Say(fmt.Sprintf("count: %d", b.Built))
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b.Built++
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b.wg.Done()
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b.m.Lock()
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b.m.Unlock()
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return nil, nil
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}
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// testMetaFile creates a Meta object that includes a file builder
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func testMetaParallel(t *testing.T, builder *ParallelTestBuilder) Meta {
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var out, err bytes.Buffer
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return Meta{
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CoreConfig: &packer.CoreConfig{
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Components: packer.ComponentFinder{
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Builder: func(n string) (packer.Builder, error) {
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switch n {
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case "parallel-test":
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return builder, nil
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default:
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panic(n)
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}
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},
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},
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},
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Ui: &packer.BasicUi{
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Writer: &out,
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ErrorWriter: &err,
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},
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}
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}
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func TestBuildParallel(t *testing.T) {
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defer cleanup()
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m := &sync.Mutex{}
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m.Lock()
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expected := 2
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wg := &sync.WaitGroup{}
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wg.Add(expected)
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b := &ParallelTestBuilder{
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wg: wg,
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m: m,
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}
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c := &BuildCommand{
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Meta: testMetaParallel(t, b),
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}
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args := []string{
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fmt.Sprintf("-parallel=%d", expected),
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filepath.Join(testFixture("parallel"), "template.json"),
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}
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go func(t *testing.T, c *BuildCommand) {
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if code := c.Run(args); code != 0 {
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fatalCommand(t, c.Meta)
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}
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}(t, c)
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wg.Wait()
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if b.Prepared != 6 {
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t.Errorf("Expected all builds to be prepared, was %d", b.Prepared)
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}
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if b.Built != expected {
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t.Errorf("Expected only %d running/completed builds, was %d", expected, b.Built)
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}
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m.Unlock()
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wg.Add(math.MaxInt32)
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}
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@ -0,0 +1,10 @@
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{
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"builders": [
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{"type": "parallel-test", "name": "build0"},
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{"type": "parallel-test", "name": "build1"},
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{"type": "parallel-test", "name": "build2"},
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{"type": "parallel-test", "name": "build3"},
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{"type": "parallel-test", "name": "build4"},
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{"type": "parallel-test", "name": "build5"}
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]
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}
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@ -1,127 +0,0 @@
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// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package semaphore provides a weighted semaphore implementation.
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package semaphore // import "golang.org/x/sync/semaphore"
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import (
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"container/list"
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"context"
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"sync"
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)
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type waiter struct {
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n int64
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ready chan<- struct{} // Closed when semaphore acquired.
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}
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// NewWeighted creates a new weighted semaphore with the given
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// maximum combined weight for concurrent access.
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func NewWeighted(n int64) *Weighted {
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w := &Weighted{size: n}
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return w
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}
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// Weighted provides a way to bound concurrent access to a resource.
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// The callers can request access with a given weight.
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type Weighted struct {
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size int64
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cur int64
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mu sync.Mutex
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waiters list.List
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}
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// Acquire acquires the semaphore with a weight of n, blocking until resources
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// are available or ctx is done. On success, returns nil. On failure, returns
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// ctx.Err() and leaves the semaphore unchanged.
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//
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// If ctx is already done, Acquire may still succeed without blocking.
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func (s *Weighted) Acquire(ctx context.Context, n int64) error {
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s.mu.Lock()
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if s.size-s.cur >= n && s.waiters.Len() == 0 {
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s.cur += n
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s.mu.Unlock()
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return nil
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}
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if n > s.size {
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// Don't make other Acquire calls block on one that's doomed to fail.
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s.mu.Unlock()
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<-ctx.Done()
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return ctx.Err()
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}
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ready := make(chan struct{})
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w := waiter{n: n, ready: ready}
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elem := s.waiters.PushBack(w)
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s.mu.Unlock()
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select {
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case <-ctx.Done():
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err := ctx.Err()
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s.mu.Lock()
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select {
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case <-ready:
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// Acquired the semaphore after we were canceled. Rather than trying to
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// fix up the queue, just pretend we didn't notice the cancelation.
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err = nil
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default:
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s.waiters.Remove(elem)
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}
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s.mu.Unlock()
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return err
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case <-ready:
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return nil
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}
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}
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// TryAcquire acquires the semaphore with a weight of n without blocking.
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// On success, returns true. On failure, returns false and leaves the semaphore unchanged.
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func (s *Weighted) TryAcquire(n int64) bool {
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s.mu.Lock()
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success := s.size-s.cur >= n && s.waiters.Len() == 0
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if success {
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s.cur += n
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}
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s.mu.Unlock()
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return success
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}
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// Release releases the semaphore with a weight of n.
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func (s *Weighted) Release(n int64) {
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s.mu.Lock()
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s.cur -= n
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if s.cur < 0 {
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s.mu.Unlock()
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panic("semaphore: bad release")
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}
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for {
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next := s.waiters.Front()
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if next == nil {
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break // No more waiters blocked.
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}
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w := next.Value.(waiter)
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if s.size-s.cur < w.n {
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// Not enough tokens for the next waiter. We could keep going (to try to
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// find a waiter with a smaller request), but under load that could cause
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// starvation for large requests; instead, we leave all remaining waiters
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// blocked.
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//
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// Consider a semaphore used as a read-write lock, with N tokens, N
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// readers, and one writer. Each reader can Acquire(1) to obtain a read
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// lock. The writer can Acquire(N) to obtain a write lock, excluding all
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// of the readers. If we allow the readers to jump ahead in the queue,
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// the writer will starve — there is always one token available for every
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// reader.
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break
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}
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s.cur += w.n
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s.waiters.Remove(next)
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close(w.ready)
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}
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s.mu.Unlock()
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}
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