open-nomad/client/allocwatcher/group_alloc_watcher.go
Tim Gross d018fcbff7
allocrunner: provide factory function so we can build mock ARs (#17161)
Tools like `nomad-nodesim` are unable to implement a minimal implementation of
an allocrunner so that we can test the client communication without having to
lug around the entire allocrunner/taskrunner code base. The allocrunner was
implemented with an interface specifically for this purpose, but there were
circular imports that made it challenging to use in practice.

Move the AllocRunner interface into an inner package and provide a factory
function type. Provide a minimal test that exercises the new function so that
consumers have some idea of what the minimum implementation required is.
2023-05-12 13:29:44 -04:00

81 lines
1.9 KiB
Go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package allocwatcher
import (
"context"
"sync"
multierror "github.com/hashicorp/go-multierror"
"github.com/hashicorp/nomad/client/config"
)
type groupPrevAllocWatcher struct {
prevAllocs []config.PrevAllocWatcher
wg sync.WaitGroup
// waiting and migrating are true when alloc runner is waiting on the
// prevAllocWatcher. Writers must acquire the waitingLock and readers
// should use the helper methods IsWaiting and IsMigrating.
waiting bool
waitingLock sync.RWMutex
}
func NewGroupAllocWatcher(watchers ...config.PrevAllocWatcher) config.PrevAllocWatcher {
return &groupPrevAllocWatcher{
prevAllocs: watchers,
}
}
// Wait on the previous allocs to become terminal, exit, or, return due to
// context termination. Usage of the groupPrevAllocWatcher requires that all
// sub-watchers correctly handle context cancellation.
// We may need to adjust this to use channels rather than a wait group, if we
// wish to more strictly enforce timeouts.
func (g *groupPrevAllocWatcher) Wait(ctx context.Context) error {
g.waitingLock.Lock()
g.waiting = true
g.waitingLock.Unlock()
defer func() {
g.waitingLock.Lock()
g.waiting = false
g.waitingLock.Unlock()
}()
var merr multierror.Error
var errmu sync.Mutex
g.wg.Add(len(g.prevAllocs))
for _, alloc := range g.prevAllocs {
go func(ctx context.Context, alloc config.PrevAllocWatcher) {
defer g.wg.Done()
err := alloc.Wait(ctx)
if err != nil {
errmu.Lock()
merr.Errors = append(merr.Errors, err)
errmu.Unlock()
}
}(ctx, alloc)
}
g.wg.Wait()
// Check ctx.Err first, to avoid returning an mErr of ctx.Err from prevAlloc
// Wait routines.
if err := ctx.Err(); err != nil {
return err
}
return merr.ErrorOrNil()
}
func (g *groupPrevAllocWatcher) IsWaiting() bool {
g.waitingLock.RLock()
defer g.waitingLock.RUnlock()
return g.waiting
}