Move pod jobs to parallel execution

Make Podman pod operations that do not involve starting
containers (which needs to be done in a specific order) use the
same parallel operation code we use to make `podman stop` on
large numbers of containers fast. We were previously stopping
containers in a pod serially, which could take up to the timeout
(default 15 seconds) for each container - stopping 100 containers
that do not respond to SIGTERM would take 25 minutes.

To do this, refactor the parallel operation code a bit to remove
its dependency on libpod (damn circular import restrictions...)
and use parallel functions that just re-use the standard
container API operations - maximizes code reuse (previously each
pod handler had a separate implementation of the container
function it performed).

This is a bit of a palate cleanser after fighting CI for two
days - nice to be able to return to a land of sanity.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

1 files changed, 0 insertions, 57 deletions

diff --git a/pkg/parallel/parallel_linux.go b/pkg/parallel/parallel_linux.go
deleted file mode 100644
index 442db1502..000000000
--- a/pkg/parallel/parallel_linux.go
+++ /dev/null
@@ -1,57 +0,0 @@
-package parallel
-
-import (
-	"context"
-	"sync"
-
-	"github.com/containers/podman/v2/libpod"
-	"github.com/pkg/errors"
-	"github.com/sirupsen/logrus"
-)
-
-// ContainerOp performs the given function on the given set of
-// containers, using a number of parallel threads.
-// If no error is returned, each container specified in ctrs will have an entry
-// in the resulting map; containers with no error will be set to nil.
-func ContainerOp(ctx context.Context, ctrs []*libpod.Container, applyFunc func(*libpod.Container) error) (map[*libpod.Container]error, error) {
-	jobControlLock.RLock()
-	defer jobControlLock.RUnlock()
-
-	// We could use a sync.Map but given Go's lack of generic I'd rather
-	// just use a lock on a normal map...
-	// The expectation is that most of the time is spent in applyFunc
-	// anyways.
-	var (
-		errMap  = make(map[*libpod.Container]error)
-		errLock sync.Mutex
-		allDone sync.WaitGroup
-	)
-
-	for _, ctr := range ctrs {
-		// Block until a thread is available
-		if err := jobControl.Acquire(ctx, 1); err != nil {
-			return nil, errors.Wrapf(err, "error acquiring job control semaphore")
-		}
-
-		allDone.Add(1)
-
-		c := ctr
-		go func() {
-			logrus.Debugf("Launching job on container %s", c.ID())
-
-			err := applyFunc(c)
-			errLock.Lock()
-			errMap[c] = err
-			errLock.Unlock()
-
-			allDone.Done()
-			jobControl.Release(1)
-		}()
-	}
-
-	allDone.Wait()
-
-	return errMap, nil
-}
-
-// TODO: Add an Enqueue() function that returns a promise