Merge pull request #178 from prometheus/mdl-powersupply-noreflect

sysfs: rewrite PowerSupply parsing code without reflect

go.mod

@@ -1,3 +1,6 @@
 module github.com/prometheus/procfs
 
-require golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4
+require (
+	github.com/google/go-cmp v0.3.0
+	golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4
+)

go.sum

@@ -1,2 +1,4 @@
+github.com/google/go-cmp v0.3.0 h1:crn/baboCvb5fXaQ0IJ1SGTsTVrWpDsCWC8EGETZijY=
+github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4 h1:YUO/7uOKsKeq9UokNS62b8FYywz3ker1l1vDZRCRefw=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=

internal/util/valueparser.go

@@ -0,0 +1,58 @@
+// Copyright 2019 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 util
+
+import (
+	"strconv"
+)
+
+// TODO(mdlayher): util packages are an anti-pattern and this should be moved
+// somewhere else that is more focused in the future.
+
+// A ValueParser enables parsing a single string into a variety of data types
+// in a concise and safe way. The Err method must be invoked after invoking
+// any other methods to ensure a value was successfully parsed.
+type ValueParser struct {
+	v   string
+	err error
+}
+
+// NewValueParser creates a ValueParser using the input string.
+func NewValueParser(v string) *ValueParser {
+	return &ValueParser{v: v}
+}
+
+// PInt64 interprets the underlying value as an int64 and returns a pointer to
+// that value.
+func (vp *ValueParser) PInt64() *int64 {
+	if vp.err != nil {
+		return nil
+	}
+
+	// A base value of zero makes ParseInt infer the correct base using the
+	// string's prefix, if any.
+	const base = 0
+	v, err := strconv.ParseInt(vp.v, base, 64)
+	if err != nil {
+		vp.err = err
+		return nil
+	}
+
+	return &v
+}
+
+// Err returns the last error, if any, encountered by the ValueParser.
+func (vp *ValueParser) Err() error {
+	return vp.err
+}

internal/util/valueparser_test.go

@@ -0,0 +1,92 @@
+// Copyright 2019 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 util_test
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/prometheus/procfs/internal/util"
+)
+
+func TestValueParser(t *testing.T) {
+	tests := []struct {
+		name string
+		v    string
+		ok   bool
+		fn   func(t *testing.T, vp *util.ValueParser)
+	}{
+		{
+			name: "bad PInt64",
+			v:    "hello",
+			fn: func(_ *testing.T, vp *util.ValueParser) {
+				_ = vp.PInt64()
+			},
+		},
+		{
+			name: "bad hex PInt64",
+			v:    "0xhello",
+			fn: func(_ *testing.T, vp *util.ValueParser) {
+				_ = vp.PInt64()
+			},
+		},
+		{
+			name: "ok PInt64",
+			v:    "1",
+			ok:   true,
+			fn: func(t *testing.T, vp *util.ValueParser) {
+				want := int64(1)
+				got := vp.PInt64()
+
+				if diff := cmp.Diff(&want, got); diff != "" {
+					t.Fatalf("unexpected integer (-want +got):\n%s", diff)
+				}
+			},
+		},
+		{
+			name: "ok hex PInt64",
+			v:    "0xff",
+			ok:   true,
+			fn: func(t *testing.T, vp *util.ValueParser) {
+				want := int64(255)
+				got := vp.PInt64()
+
+				if diff := cmp.Diff(&want, got); diff != "" {
+					t.Fatalf("unexpected integer (-want +got):\n%s", diff)
+				}
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			vp := util.NewValueParser(tt.v)
+			tt.fn(t, vp)
+
+			err := vp.Err()
+			if err != nil {
+				if tt.ok {
+					t.Fatalf("unexpected error: %v", err)
+				}
+
+				t.Logf("OK err: %v", err)
+				return
+			}
+
+			if !tt.ok {
+				t.Fatal("expected an error, but none occurred")
+			}
+		})
+	}
+}