lib: libcontainer references are linux only

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

lib/stats_linux.go

@@ -0,0 +1,61 @@
+package lib
+
+import (
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/opencontainers/runc/libcontainer"
+)
+
+// Returns the total number of bytes transmitted and received for the given container stats
+func getContainerNetIO(stats *libcontainer.Stats) (received uint64, transmitted uint64) {
+	for _, iface := range stats.Interfaces {
+		received += iface.RxBytes
+		transmitted += iface.TxBytes
+	}
+	return
+}
+
+func calculateCPUPercent(stats *libcontainer.Stats, previousCPU uint64, previousSystem int64) float64 {
+	var (
+		cpuPercent  = 0.0
+		cpuDelta    = float64(stats.CgroupStats.CpuStats.CpuUsage.TotalUsage - previousCPU)
+		systemDelta = float64(uint64(time.Now().UnixNano()) - uint64(previousSystem))
+	)
+	if systemDelta > 0.0 && cpuDelta > 0.0 {
+		// gets a ratio of container cpu usage total, multiplies it by the number of cores (4 cores running
+		// at 100% utilization should be 400% utilization), and multiplies that by 100 to get a percentage
+		cpuPercent = (cpuDelta / systemDelta) * float64(len(stats.CgroupStats.CpuStats.CpuUsage.PercpuUsage)) * 100
+	}
+	return cpuPercent
+}
+
+func calculateBlockIO(stats *libcontainer.Stats) (read uint64, write uint64) {
+	for _, blkIOEntry := range stats.CgroupStats.BlkioStats.IoServiceBytesRecursive {
+		switch strings.ToLower(blkIOEntry.Op) {
+		case "read":
+			read += blkIOEntry.Value
+		case "write":
+			write += blkIOEntry.Value
+		}
+	}
+	return
+}
+
+// getMemory limit returns the memory limit for a given cgroup
+// If the configured memory limit is larger than the total memory on the sys, the
+// physical system memory size is returned
+func getMemLimit(cgroupLimit uint64) uint64 {
+	si := &syscall.Sysinfo_t{}
+	err := syscall.Sysinfo(si)
+	if err != nil {
+		return cgroupLimit
+	}
+
+	physicalLimit := uint64(si.Totalram)
+	if cgroupLimit > physicalLimit {
+		return physicalLimit
+	}
+	return cgroupLimit
+}