import (
	"os"
	"syscall"

	"github.com/ncw/directio"
	"golang.org/x/sys/unix"
)

// ODirectPlatform indicates if the platform supports O_DIRECT
const ODirectPlatform = true

// OpenFileDirectIO - bypass kernel cache.
func OpenFileDirectIO(filePath string, flag int, perm os.FileMode) (*os.File, error) {
	return directio.OpenFile(filePath, flag, perm)
}

// DisableDirectIO - disables directio mode.

	stats, err := readStat(statsFile)
	if err != nil {
		return IOStats{}, err
	}
	if len(stats) < 11 {
		return IOStats{}, fmt.Errorf("found invalid format while reading %v", statsFile)
	}
	// refer https://www.kernel.org/doc/Documentation/block/stat.txt
	iostats = IOStats{
		ReadIOs:      stats[0],
		ReadMerges:   stats[1],
		ReadSectors:  stats[2],
		ReadTicks:    stats[3],
		WriteIOs:     stats[4],

Each node is responsible of healing its local drives; Each drive will have multiple heal workers which is the quarter of the number of CPU cores of the node or the quarter of the configured nr_requests of the drive (https://www.kernel.org/doc/Documentation/block/queue-sysfs.txt). It is also possible to provide a custom number of workers by using this command: `mc admin config set alias/ heal drive_workers=100` .


```
~ mc admin config set alias/ heal

		Name:      readTotal,
		Help:      "Total read SysCalls to the kernel. /proc/[pid]/io syscr",
		Type:      counterMetric,
	}
}

func getMinIOProcessSysCallWMD() MetricDescription {
	return MetricDescription{
		Namespace: nodeMetricNamespace,
		Subsystem: sysCallSubsystem,
		Name:      writeTotal,
		Help:      "Total write SysCalls to the kernel. /proc/[pid]/io syscw",
		Type:      counterMetric,
	}
}

// Tests for port availability logic written for server startup sequence.
func TestCheckPortAvailability(t *testing.T) {
	if runtime.GOOS != "linux" {
		t.Skip()
	}

	l, err := net.Listen("tcp", "localhost:0") // ask kernel for a free port.
	if err != nil {
		t.Fatal(err)
	}
	defer l.Close()

	port := l.Addr().(*net.TCPAddr).Port

	testCases := []struct {
		host        string
		port        int
		expectedErr error
	}{

	"runtime/debug"

	"github.com/dustin/go-humanize"
	"github.com/minio/cli"
	"github.com/minio/madmin-go/v3/kernel"
	"github.com/minio/minio/internal/logger"
	"github.com/minio/pkg/v2/sys"
)

func oldLinux() bool {
	currentKernel, err := kernel.CurrentVersion()
	if err != nil {
		// Could not probe the kernel version
		return false
	}

	if currentKernel == 0 {
		// We could not get any valid value return false

func fixLongPath(path string) string {
	// Do nothing (and don't allocate) if the path is "short".
	// Empirically (at least on the Windows Server 2013 builder),
	// the kernel is arbitrarily okay with < 248 bytes. That
	// matches what the docs above say:
	// "When using an API to create a directory, the specified
	// path cannot be so long that you cannot append an 8.3 file

| `syscall_read_total`          | `counter` | Total read SysCalls to the kernel. /proc/[pid]/io syscr                                                        | `server` |
| `syscall_write_total`         | `counter` | Total write SysCalls to the kernel. /proc/[pid]/io syscw                                                       | `server` |

| `minio_node_scanner_versions_scanned`      | Total number of object versions scanned since server start. |
| `minio_node_syscall_read_total`            | Total read SysCalls to the kernel. /proc/[pid]/io syscr.    |
| `minio_node_syscall_write_total`           | Total write SysCalls to the kernel. /proc/[pid]/io syscw.   |
| `minio_usage_last_activity_nano_seconds`   | Time elapsed (in nano seconds) since last scan activity.    |

# Bucket Metrics

	processSyscallReadTotalMD         = NewCounterMD(processSyscallReadTotal, "Total read SysCalls to the kernel. /proc/[pid]/io syscr")
	processSyscallWriteTotalMD        = NewCounterMD(processSyscallWriteTotal, "Total write SysCalls to the kernel. /proc/[pid]/io syscw")
	processResidentMemoryBytesMD      = NewGaugeMD(processResidentMemoryBytes, "Resident memory size in bytes")