1. docker
  2. Commit 1aa67071cb3e6bc8a08f662d913cdb1b1eda1645
Browse code

Merge pull request #8550 from aluzzardi/f-meminfo

system: Add MemInfo utility.

unclejack authored on 2014/10/23 15:31:28
Showing 4 changed files
pkg/system/meminfo.go
History View file @ 1aa6707
1 1 
new file mode 100644
... ... 
@@ -0,0 +1,17 @@
0 
+package system
1 
+
2 
+// MemInfo contains memory statistics of the host system.
3 
+type MemInfo struct {
4 
+	// Total usable RAM (i.e. physical RAM minus a few reserved bits and the
5 
+	// kernel binary code).
6 
+	MemTotal int64
7 
+
8 
+	// Amount of free memory.
9 
+	MemFree int64
10 
+
11 
+	// Total amount of swap space available.
12 
+	SwapTotal int64
13 
+
14 
+	// Amount of swap space that is currently unused.
15 
+	SwapFree int64
16 
+}
pkg/system/meminfo_linux.go
History View file @ 1aa6707
0 17 
new file mode 100644
... ... 
@@ -0,0 +1,67 @@
0 
+package system
1 
+
2 
+import (
3 
+	"bufio"
4 
+	"errors"
5 
+	"io"
6 
+	"os"
7 
+	"strconv"
8 
+	"strings"
9 
+
10 
+	"github.com/docker/docker/pkg/units"
11 
+)
12 
+
13 
+var (
14 
+	ErrMalformed = errors.New("malformed file")
15 
+)
16 
+
17 
+// Retrieve memory statistics of the host system and parse them into a MemInfo
18 
+// type.
19 
+func ReadMemInfo() (*MemInfo, error) {
20 
+	file, err := os.Open("/proc/meminfo")
21 
+	if err != nil {
22 
+		return nil, err
23 
+	}
24 
+	defer file.Close()
25 
+	return parseMemInfo(file)
26 
+}
27 
+
28 
+func parseMemInfo(reader io.Reader) (*MemInfo, error) {
29 
+	meminfo := &MemInfo{}
30 
+	scanner := bufio.NewScanner(reader)
31 
+	for scanner.Scan() {
32 
+		// Expected format: ["MemTotal:", "1234", "kB"]
33 
+		parts := strings.Fields(scanner.Text())
34 
+
35 
+		// Sanity checks: Skip malformed entries.
36 
+		if len(parts) < 3 || parts[2] != "kB" {
37 
+			continue
38 
+		}
39 
+
40 
+		// Convert to bytes.
41 
+		size, err := strconv.Atoi(parts[1])
42 
+		if err != nil {
43 
+			continue
44 
+		}
45 
+		bytes := int64(size) * units.KiB
46 
+
47 
+		switch parts[0] {
48 
+		case "MemTotal:":
49 
+			meminfo.MemTotal = bytes
50 
+		case "MemFree:":
51 
+			meminfo.MemFree = bytes
52 
+		case "SwapTotal:":
53 
+			meminfo.SwapTotal = bytes
54 
+		case "SwapFree:":
55 
+			meminfo.SwapFree = bytes
56 
+		}
57 
+
58 
+	}
59 
+
60 
+	// Handle errors that may have occurred during the reading of the file.
61 
+	if err := scanner.Err(); err != nil {
62 
+		return nil, err
63 
+	}
64 
+
65 
+	return meminfo, nil
66 
+}
pkg/system/meminfo_linux_test.go
History View file @ 1aa6707
0 67 
new file mode 100644
... ... 
@@ -0,0 +1,37 @@
0 
+package system
1 
+
2 
+import (
3 
+	"strings"
4 
+	"testing"
5 
+
6 
+	"github.com/docker/docker/pkg/units"
7 
+)
8 
+
9 
+func TestMemInfo(t *testing.T) {
10 
+	const input = `
11 
+	MemTotal:      1 kB
12 
+	MemFree:       2 kB
13 
+	SwapTotal:     3 kB
14 
+	SwapFree:      4 kB
15 
+	Malformed1:
16 
+	Malformed2:    1
17 
+	Malformed3:    2 MB
18 
+	Malformed4:    X kB
19 
+	`
20 
+	meminfo, err := parseMemInfo(strings.NewReader(input))
21 
+	if err != nil {
22 
+		t.Fatal(err)
23 
+	}
24 
+	if meminfo.MemTotal != 1*units.KiB {
25 
+		t.Fatalf("Unexpected MemTotal: %d", meminfo.MemTotal)
26 
+	}
27 
+	if meminfo.MemFree != 2*units.KiB {
28 
+		t.Fatalf("Unexpected MemFree: %d", meminfo.MemFree)
29 
+	}
30 
+	if meminfo.SwapTotal != 3*units.KiB {
31 
+		t.Fatalf("Unexpected SwapTotal: %d", meminfo.SwapTotal)
32 
+	}
33 
+	if meminfo.SwapFree != 4*units.KiB {
34 
+		t.Fatalf("Unexpected SwapFree: %d", meminfo.SwapFree)
35 
+	}
36 
+}
pkg/system/meminfo_unsupported.go
History View file @ 1aa6707
0 37 
new file mode 100644
... ... 
@@ -0,0 +1,7 @@
0 
+// +build !linux
1 
+
2 
+package system
3 
+
4 
+func ReadMemInfo() (*MemInfo, error) {
5 
+	return nil, ErrNotSupportedPlatform
6 
+}