feat: add HTTP APIs for cloud/metainfo (#31)

cloud/metainfo/http.go

@@ -0,0 +1,108 @@
+// Copyright 2021 ByteDance Inc.
+//
+// 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 metainfo
+
+import (
+	"context"
+	"strings"
+)
+
+// HTTP header prefixes.
+const (
+	HTTPPrefixTransient  = "rpc-transit-"
+	HTTPPrefixPersistent = "rpc-persist-"
+
+	lenHPT = len(HTTPPrefixTransient)
+	lenHPP = len(HTTPPrefixPersistent)
+)
+
+// HTTPHeaderToCGIVariable performs an CGI variable conversion.
+// For example, an HTTP header key `abc-def` will result in `ABC_DEF`.
+func HTTPHeaderToCGIVariable(key string) string {
+	return strings.ToUpper(strings.ReplaceAll(key, "-", "_"))
+}
+
+// CGIVariableToHTTPHeader converts a CGI variable into an HTTP header key.
+// For example, `ABC_DEF` will be converted to `abc-def`.
+func CGIVariableToHTTPHeader(key string) string {
+	return strings.ToLower(strings.ReplaceAll(key, "_", "-"))
+}
+
+// HTTPHeaderSetter sets a key with a value into a HTTP header.
+type HTTPHeaderSetter interface {
+	Set(key, value string)
+}
+
+// HTTPHeaderCarrier accepts a visitor to access all key value pairs in an HTTP header.
+type HTTPHeaderCarrier interface {
+	Visit(func(k, v string))
+}
+
+// HTTPHeader is provided to wrap an http.Header into an HTTPHeaderCarrier.
+type HTTPHeader map[string][]string
+
+// Visit implements the HTTPHeaderCarrier interface.
+func (h HTTPHeader) Visit(v func(k, v string)) {
+	for k, vs := range h {
+		v(k, vs[0])
+	}
+}
+
+// Set sets the header entries associated with key to the single element value.
+// The key will converted into lowercase as the HTTP/2 protocol requires.
+func (h HTTPHeader) Set(key, value string) {
+	h[strings.ToLower(key)] = []string{value}
+}
+
+// FromHTTPHeader reads metainfo from a given HTTP header and sets them into the context.
+// Note that this function does not call TransferForward inside.
+func FromHTTPHeader(ctx context.Context, h HTTPHeaderCarrier) context.Context {
+	if ctx == nil || h == nil {
+		return ctx
+	}
+
+	h.Visit(func(k, v string) {
+		kk := strings.ToLower(k)
+		ln := len(kk)
+
+		if ln > lenHPT && strings.HasPrefix(kk, HTTPPrefixTransient) {
+			kk = HTTPHeaderToCGIVariable(kk[lenHPT:])
+			ctx = WithValue(ctx, kk, v)
+		} else if ln > lenHPP && strings.HasPrefix(kk, HTTPPrefixPersistent) {
+			kk = HTTPHeaderToCGIVariable(kk[lenHPP:])
+			ctx = WithPersistentValue(ctx, kk, v)
+		}
+	})
+
+	return ctx
+}
+
+// ToHTTPHeader writes all metainfo into the given HTTP header.
+// Note that this function does not call TransferForward inside.
+func ToHTTPHeader(ctx context.Context, h HTTPHeaderSetter) {
+	if ctx == nil || h == nil {
+		return
+	}
+
+	for k, v := range GetAllValues(ctx) {
+		k := HTTPPrefixTransient + CGIVariableToHTTPHeader(k)
+		h.Set(k, v)
+	}
+
+	for k, v := range GetAllPersistentValues(ctx) {
+		k := HTTPPrefixPersistent + CGIVariableToHTTPHeader(k)
+		h.Set(k, v)
+	}
+}

cloud/metainfo/http_test.go

@@ -0,0 +1,101 @@
+// Copyright 2021 ByteDance Inc.
+//
+// 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 metainfo_test
+
+import (
+	"context"
+	"net/http"
+	"testing"
+
+	"github.com/bytedance/gopkg/cloud/metainfo"
+)
+
+func TestHTTPHeaderToCGIVariable(t *testing.T) {
+	for k, v := range map[string]string{
+		"a":           "A",
+		"aBc":         "ABC",
+		"a1z":         "A1Z",
+		"ab-":         "AB_",
+		"-cd":         "_CD",
+		"abc-def":     "ABC_DEF",
+		"Abc-def_ghi": "ABC_DEF_GHI",
+	} {
+		assert(t, metainfo.HTTPHeaderToCGIVariable(k) == v)
+	}
+}
+
+func TestCGIVariableToHTTPHeader(t *testing.T) {
+	for k, v := range map[string]string{
+		"a":           "a",
+		"aBc":         "abc",
+		"a1z":         "a1z",
+		"AB_":         "ab-",
+		"_CD":         "-cd",
+		"ABC_DEF":     "abc-def",
+		"ABC-def_GHI": "abc-def-ghi",
+	} {
+		assert(t, metainfo.CGIVariableToHTTPHeader(k) == v)
+	}
+}
+
+func TestFromHTTPHeader(t *testing.T) {
+	assert(t, metainfo.FromHTTPHeader(nil, nil) == nil)
+
+	h := make(http.Header)
+	c := context.Background()
+	c1 := metainfo.FromHTTPHeader(c, metainfo.HTTPHeader(h))
+	assert(t, c == c1)
+
+	h.Set("abc", "def")
+	h.Set(metainfo.HTTPPrefixTransient+"123", "456")
+	h.Set(metainfo.HTTPPrefixTransient+"abc-def", "ghi")
+	h.Set(metainfo.HTTPPrefixPersistent+"xyz", "000")
+	c1 = metainfo.FromHTTPHeader(c, metainfo.HTTPHeader(h))
+	assert(t, c != c1)
+	vs := metainfo.GetAllValues(c1)
+	assert(t, len(vs) == 2, vs)
+	assert(t, vs["ABC_DEF"] == "ghi" && vs["123"] == "456", vs)
+	vs = metainfo.GetAllPersistentValues(c1)
+	assert(t, len(vs) == 1 && vs["XYZ"] == "000")
+}
+
+func TestToHTTPHeader(t *testing.T) {
+	metainfo.ToHTTPHeader(nil, nil)
+
+	h := make(http.Header)
+	c := context.Background()
+	metainfo.ToHTTPHeader(c, h)
+	assert(t, len(h) == 0)
+
+	c = metainfo.WithValue(c, "123", "456")
+	c = metainfo.WithPersistentValue(c, "abc", "def")
+	metainfo.ToHTTPHeader(c, h)
+	assert(t, len(h) == 2)
+	assert(t, h.Get(metainfo.HTTPPrefixTransient+"123") == "456")
+	assert(t, h.Get(metainfo.HTTPPrefixPersistent+"abc") == "def")
+}
+
+func TestHTTPHeader(t *testing.T) {
+	h := make(metainfo.HTTPHeader)
+	h.Set("Hello", "halo")
+	h.Set("hello", "world")
+
+	kvs := make(map[string]string)
+	h.Visit(func(k, v string) {
+		kvs[k] = v
+	})
+	assert(t, len(kvs) == 1)
+	assert(t, kvs["hello"] == "world")
+}