Added optional container restore statistics

This adds the parameter '--print-stats' to 'podman container restore'.
With '--print-stats' Podman will measure how long Podman itself, the OCI
runtime and CRIU requires to restore a checkpoint and print out these
information. CRIU already creates process restore statistics which are
just read in addition to the added measurements. In contrast to just
printing out the ID of the restored container, Podman will now print
out JSON:

 # podman container restore --latest --print-stats
 {
     "podman_restore_duration": 305871,
     "container_statistics": [
         {
             "Id": "47b02e1d474b5d5fe917825e91ac653efa757c91e5a81a368d771a78f6b5ed20",
             "runtime_restore_duration": 140614,
             "criu_statistics": {
                 "forking_time": 5,
                 "restore_time": 67672,
                 "pages_restored": 14
             }
         }
     ]
 }

The output contains 'podman_restore_duration' which contains the
number of microseconds Podman required to restore the checkpoint. The
output also includes 'runtime_restore_duration' which is the time
the runtime needed to restore that specific container. Each container
also includes 'criu_statistics' which displays the timing information
collected by CRIU.

Signed-off-by: Adrian Reber <areber@redhat.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/libpod/container_api.go b/libpod/container_api.go
index b0ea7c0de..a41bb03df 100644
--- a/libpod/container_api.go
+++ b/libpod/container_api.go
@@ -832,7 +832,11 @@ func (c *Container) Checkpoint(ctx context.Context, options ContainerCheckpointO
 }
 
 // Restore restores a container
-func (c *Container) Restore(ctx context.Context, options ContainerCheckpointOptions) error {
+// The return values *define.CRIUCheckpointRestoreStatistics and int64 (time
+// the runtime needs to restore the container) are only set if
+// options.PrintStats is set to true. Not setting options.PrintStats to true
+// will return nil and 0.
+func (c *Container) Restore(ctx context.Context, options ContainerCheckpointOptions) (*define.CRIUCheckpointRestoreStatistics, int64, error) {
 	if options.Pod == "" {
 		logrus.Debugf("Trying to restore container %s", c.ID())
 	} else {
@@ -843,7 +847,7 @@ func (c *Container) Restore(ctx context.Context, options ContainerCheckpointOpti
 		defer c.lock.Unlock()
 
 		if err := c.syncContainer(); err != nil {
-			return err
+			return nil, 0, err
 		}
 	}
 	defer c.newContainerEvent(events.Restore)