Introduce runtime2/config. (istio#2447)

Automatic merge from submit-queue.

Introduce runtime2/config.

This is the first part of a major refactoring of the runtime code. This part solely deals with config.

- Collects all config related code under runtime2/config package.
- Introduces a strongly-typed object model to ease use at the client-code.
- Adds perf counters for config state changes.

Some further details can be found here: https://docs.google.com/document/d/1tYlZuDQYkoikNcuD_DEA4SCi_t-SNwURkEyA8ND_mbw

NOTE: This PR contains code for some of the pending PRs:
istio#2448
istio#2450

The important parts to look at are pkg/runtime2/config and pkg/expr changes.

mixer/pkg/expr/BUILD

@@ -5,6 +5,7 @@ go_library(
     srcs = [
         "evaluator.go",
         "expr.go",
+        "finder.go",
         "func.go",
     ],
     visibility = ["//visibility:public"],
@@ -22,6 +23,7 @@ go_test(
     size = "small",
     srcs = [
         "expr_test.go",
+        "finter_test.go",
     ],
     library = ":go_default_library",
     deps = [

mixer/pkg/expr/finder.go

@@ -0,0 +1,65 @@
+// Copyright 2018 Istio 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 expr
+
+import (
+	"fmt"
+	"sort"
+
+	configpb "istio.io/istio/mixer/pkg/config/proto"
+	"istio.io/istio/mixer/pkg/pool"
+)
+
+// NewFinder returns a new AttributeDescriptorFinder instance, based on the given attributes
+func NewFinder(attributes map[string]*configpb.AttributeManifest_AttributeInfo) AttributeDescriptorFinder {
+	return finder{
+		attributes: attributes,
+	}
+}
+
+// finder exposes expr.AttributeDescriptorFinder
+type finder struct {
+	attributes map[string]*configpb.AttributeManifest_AttributeInfo
+}
+
+var _ AttributeDescriptorFinder = finder{}
+
+// GetAttribute finds an attribute by name. returns nil if not found.
+func (a finder) GetAttribute(name string) *configpb.AttributeManifest_AttributeInfo {
+	return a.attributes[name]
+}
+
+func (a finder) String() string {
+	b := pool.GetBuffer()
+
+	// Sort by attribute names for stable ordering.
+	i := 0
+	names := make([]string, len(a.attributes))
+	for name := range a.attributes {
+		names[i] = name
+		i++
+	}
+	sort.Strings(names)
+
+	fmt.Fprintln(b, "Attributes:")
+	for _, n := range names {
+		fmt.Fprintf(b, "  %s: %s", n, a.attributes[n].ValueType.String())
+		fmt.Fprintln(b)
+	}
+
+	s := b.String()
+	pool.PutBuffer(b)
+	return s
+}

mixer/pkg/expr/finder_test.go

@@ -0,0 +1,59 @@
+// Copyright 2018 Istio 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 expr
+
+import (
+	"fmt"
+	"testing"
+
+	descriptorpb "istio.io/api/mixer/v1/config/descriptor"
+	configpb "istio.io/istio/mixer/pkg/config/proto"
+)
+
+func TestFinder(t *testing.T) {
+
+	var finder AttributeDescriptorFinder = finder{
+		attributes: map[string]*configpb.AttributeManifest_AttributeInfo{
+			"foo": {
+				ValueType: descriptorpb.DOUBLE,
+			},
+			"baz": {
+				ValueType: descriptorpb.INT64,
+			},
+		},
+	}
+
+	foo := finder.GetAttribute("foo")
+	if foo == nil || foo.ValueType != descriptorpb.DOUBLE {
+		t.Fail()
+	}
+
+	bar := finder.GetAttribute("bar")
+	if bar != nil {
+		t.Fail()
+	}
+
+	expected := `Attributes:
+  baz: INT64
+  foo: DOUBLE
+`
+	s := fmt.Sprintf("%v", finder)
+	if s != expected {
+		t.Log(s)
+		t.Log("!=")
+		t.Logf(expected)
+		t.Fatal("finder.String() mismatch")
+	}
+}