)

var (
	// OpenFileDirectIO allows overriding default function.
	OpenFileDirectIO = disk.OpenFileDirectIO
	// OsOpen allows overriding default function.
	OsOpen = os.Open
	// OsOpenFile allows overriding default function.
	OsOpenFile = os.OpenFile
)

// ReadFileWithFileInfo reads the named file and returns the contents.
// A successful call returns err == nil, not err == EOF.

	osMetricCreate
	osMetricReadDirent
	osMetricFdatasync
	osMetricSync

	// .... add more

	osMetricLast
)

var globalOSMetrics osMetrics

func init() {
	// Inject metrics.
	ioutilx.OsOpenFile = OpenFile
	ioutilx.OpenFileDirectIO = OpenFileDirectIO
	ioutilx.OsOpen = Open
}

type osMetrics struct {
	// All fields must be accessed atomically and aligned.
	operations [osMetricLast]uint64