Publish ITWorx Pulse source

internal/hostcollect/memory.go

@@ -0,0 +1,71 @@
+package hostcollect
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/itworx/pulse/internal/host"
+)
+
+// parseMeminfo converts /proc/meminfo into bytes.
+//
+// meminfo is kB based ("MemTotal: 16316420 kB"), where kB means KiB, and a handful of
+// counters carry no unit at all. Treating either as bytes is the classic off-by-1024
+// bug, so the unit is read per line instead of assumed.
+func parseMeminfo(data []byte) (host.RawMemory, error) {
+	values := make(map[string]uint64, 8)
+	for _, line := range lines(data) {
+		key, rest, found := strings.Cut(line, ":")
+		if !found {
+			continue
+		}
+		fields := strings.Fields(rest)
+		if len(fields) == 0 {
+			continue
+		}
+		amount, ok := parseUint(fields[0])
+		if !ok {
+			continue
+		}
+		if len(fields) > 1 && strings.EqualFold(fields[1], "kB") {
+			const kib = 1024
+			if amount > (1<<64-1)/kib {
+				continue
+			}
+			amount *= kib
+		}
+		values[strings.TrimSpace(key)] = amount
+	}
+	total := values["MemTotal"]
+	if total == 0 {
+		return host.RawMemory{}, errNoMemTotal
+	}
+	available, ok := values["MemAvailable"]
+	if !ok {
+		// Kernels before 3.14 have no MemAvailable. The traditional approximation is
+		// free plus the reclaimable page cache; it is an estimate, never above total.
+		available = values["MemFree"] + values["Buffers"] + values["Cached"] + values["SReclaimable"]
+	}
+	if available > total {
+		available = total
+	}
+	memory := host.RawMemory{TotalBytes: total, AvailableBytes: available}
+	swapTotal := values["SwapTotal"]
+	if swapTotal > 0 {
+		swapFree := values["SwapFree"]
+		if swapFree > swapTotal {
+			swapFree = swapTotal
+		}
+		memory.SwapTotalBytes = swapTotal
+		memory.SwapUsedBytes = swapTotal - swapFree
+	}
+	return memory, nil
+}
+
+func (c *Collector) memory() (host.RawMemory, error) {
+	data, err := readLimited(c.procPath("meminfo"), maxFileBytes)
+	if err != nil {
+		return host.RawMemory{}, fmt.Errorf("hostcollect: read meminfo: %w", err)
+	}
+	return parseMeminfo(data)
+}