Add new per NUMA node memory statistics collector

It is sometimes useful to understand the distribution of free/occupied
memory between NUMA nodes to deal with performance problems. To do so,
add new meminfo_numa collector that enables exporting of per node
statistics along with unit and end-to-end tests for it.

Signed-off-by: Pavel Borzenkov <pavel.borzenkov@gmail.com>

collector/meminfo_numa_linux_test.go

@@ -0,0 +1,59 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+	"os"
+	"testing"
+)
+
+func TestMemInfoNuma(t *testing.T) {
+	file, err := os.Open("fixtures/sys/devices/system/node/node0/meminfo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer file.Close()
+
+	memInfo, err := parseMemInfoNuma(file)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := 707915776.0, memInfo[meminfoKey{"Active_anon", "0"}]; want != got {
+		t.Errorf("want memory Active(anon) %f, got %f", want, got)
+	}
+
+	if want, got := 150994944.0, memInfo[meminfoKey{"AnonHugePages", "0"}]; want != got {
+		t.Errorf("want memory AnonHugePages %f, got %f", want, got)
+	}
+
+	file, err = os.Open("fixtures/sys/devices/system/node/node1/meminfo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer file.Close()
+
+	memInfo, err = parseMemInfoNuma(file)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := 291930112.0, memInfo[meminfoKey{"Inactive_anon", "1"}]; want != got {
+		t.Errorf("want memory Inactive(anon) %f, got %f", want, got)
+	}
+
+	if want, got := 85585088512.0, memInfo[meminfoKey{"FilePages", "1"}]; want != got {
+		t.Errorf("want memory FilePages %f, got %f", want, got)
+	}
+}