broker: refactor (#396)

* remove subscribe from server
* remove publish from client
* broker package refactoring

Co-authored-by: vtolstov <vtolstov@users.noreply.github.com>
Reviewed-on: #396
Co-authored-by: Vasiliy Tolstov <v.tolstov@unistack.org>
Co-committed-by: Vasiliy Tolstov <v.tolstov@unistack.org>

metadata/metadata.go

@@ -1,43 +1,462 @@
-//go:build !exclude
-
-// Package metadata is a way of defining message headers
 package metadata
 
 import (
+	"context"
+	"fmt"
 	"net/textproto"
 	"sort"
 	"strings"
 )
 
-var (
-	// HeaderTopic is the header name that contains topic name
-	HeaderTopic = "Micro-Topic"
-	// HeaderContentType specifies content type of message
-	HeaderContentType = "Content-Type"
-	// HeaderEndpoint specifies endpoint in service
-	HeaderEndpoint = "Micro-Endpoint"
-	// HeaderService specifies service
-	HeaderService = "Micro-Service"
-	// HeaderTimeout specifies timeout of operation
-	HeaderTimeout = "Micro-Timeout"
-	// HeaderAuthorization specifies Authorization header
-	HeaderAuthorization = "Authorization"
-	// HeaderXRequestID specifies request id
-	HeaderXRequestID = "X-Request-Id"
-)
-
-// Metadata is our way of representing request headers internally.
-// They're used at the RPC level and translate back and forth
-// from Transport headers.
-type Metadata map[string]string
-
-type rawMetadata struct {
-	md Metadata
-}
-
 // defaultMetadataSize used when need to init new Metadata
 var defaultMetadataSize = 2
 
+// Metadata is a mapping from metadata keys to values. Users should use the following
+// two convenience functions New and Pairs to generate Metadata.
+type Metadata map[string][]string
+
+// New creates an zero Metadata.
+func New(l int) Metadata {
+	if l == 0 {
+		l = defaultMetadataSize
+	}
+	md := make(Metadata, l)
+	return md
+}
+
+// NewWithMetadata creates an Metadata from a given key-value map.
+func NewWithMetadata(m map[string]string) Metadata {
+	md := make(Metadata, len(m))
+	for key, val := range m {
+		md[key] = append(md[key], val)
+	}
+	return md
+}
+
+// Pairs returns an Metadata formed by the mapping of key, value ...
+// Pairs panics if len(kv) is odd.
+func Pairs(kv ...string) Metadata {
+	if len(kv)%2 == 1 {
+		panic(fmt.Sprintf("metadata: Pairs got the odd number of input pairs for metadata: %d", len(kv)))
+	}
+	md := make(Metadata, len(kv)/2)
+	for i := 0; i < len(kv); i += 2 {
+		md[kv[i]] = append(md[kv[i]], kv[i+1])
+	}
+	return md
+}
+
+// Len returns the number of items in Metadata.
+func (md Metadata) Len() int {
+	return len(md)
+}
+
+// Copy returns a copy of Metadata.
+func Copy(src Metadata) Metadata {
+	out := make(Metadata, len(src))
+	for k, v := range src {
+		out[k] = copyOf(v)
+	}
+	return out
+}
+
+// Copy returns a copy of Metadata.
+func (md Metadata) Copy() Metadata {
+	out := make(Metadata, len(md))
+	for k, v := range md {
+		out[k] = copyOf(v)
+	}
+	return out
+}
+
+// AsHTTP1 returns a copy of Metadata
+// with CanonicalMIMEHeaderKey.
+func (md Metadata) AsHTTP1() map[string][]string {
+	out := make(map[string][]string, len(md))
+	for k, v := range md {
+		out[textproto.CanonicalMIMEHeaderKey(k)] = copyOf(v)
+	}
+	return out
+}
+
+// AsHTTP1 returns a copy of Metadata
+// with strings.ToLower.
+func (md Metadata) AsHTTP2() map[string][]string {
+	out := make(map[string][]string, len(md))
+	for k, v := range md {
+		out[strings.ToLower(k)] = copyOf(v)
+	}
+	return out
+}
+
+// CopyTo copies Metadata to out.
+func (md Metadata) CopyTo(out Metadata) {
+	for k, v := range md {
+		out[k] = copyOf(v)
+	}
+}
+
+// Get obtains the values for a given key.
+func (md Metadata) MustGet(k string) []string {
+	v, ok := md.Get(k)
+	if !ok {
+		panic("missing metadata key")
+	}
+	return v
+}
+
+// Get obtains the values for a given key.
+func (md Metadata) Get(k string) ([]string, bool) {
+	v, ok := md[k]
+	if !ok {
+		v, ok = md[strings.ToLower(k)]
+	}
+	if !ok {
+		v, ok = md[textproto.CanonicalMIMEHeaderKey(k)]
+	}
+	return v, ok
+}
+
+// MustGetJoined obtains the values for a given key
+// with joined values with "," symbol
+func (md Metadata) MustGetJoined(k string) string {
+	v, ok := md.GetJoined(k)
+	if !ok {
+		panic("missing metadata key")
+	}
+	return v
+}
+
+// GetJoined obtains the values for a given key
+// with joined values with "," symbol
+func (md Metadata) GetJoined(k string) (string, bool) {
+	v, ok := md.Get(k)
+	if !ok {
+		return "", ok
+	}
+	return strings.Join(v, ","), true
+}
+
+// Set sets the value of a given key with a slice of values.
+func (md Metadata) Add(key string, vals ...string) {
+	if len(vals) == 0 {
+		return
+	}
+	md[key] = vals
+}
+
+// Set sets the value of a given key with a slice of values.
+func (md Metadata) Set(kvs ...string) {
+	if len(kvs)%2 == 1 {
+		panic(fmt.Sprintf("metadata: Set got an odd number of input pairs for metadata: %d", len(kvs)))
+	}
+
+	for i := 0; i < len(kvs); i += 2 {
+		md[kvs[i]] = append(md[kvs[i]], kvs[i+1])
+	}
+}
+
+// Append adds the values to key k, not overwriting what was already stored at
+// that key.
+func (md Metadata) Append(key string, vals ...string) {
+	if len(vals) == 0 {
+		return
+	}
+	md[key] = append(md[key], vals...)
+}
+
+// Del removes the values for a given keys k.
+func (md Metadata) Del(k ...string) {
+	for i := range k {
+		delete(md, k[i])
+		delete(md, strings.ToLower(k[i]))
+		delete(md, textproto.CanonicalMIMEHeaderKey(k[i]))
+	}
+}
+
+// Join joins any number of Metadatas into a single Metadata.
+//
+// The order of values for each key is determined by the order in which the Metadatas
+// containing those values are presented to Join.
+func Join(mds ...Metadata) Metadata {
+	out := Metadata{}
+	for _, Metadata := range mds {
+		for k, v := range Metadata {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return out
+}
+
+type (
+	metadataIncomingKey struct{}
+	metadataOutgoingKey struct{}
+	metadataCurrentKey  struct{}
+)
+
+// NewContext creates a new context with Metadata attached. Metadata must
+// not be modified after calling this function.
+func NewContext(ctx context.Context, md Metadata) context.Context {
+	return context.WithValue(ctx, metadataCurrentKey{}, rawMetadata{md: md})
+}
+
+// NewIncomingContext creates a new context with incoming Metadata attached. Metadata must
+// not be modified after calling this function.
+func NewIncomingContext(ctx context.Context, md Metadata) context.Context {
+	return context.WithValue(ctx, metadataIncomingKey{}, rawMetadata{md: md})
+}
+
+// NewOutgoingContext creates a new context with outgoing Metadata attached. If used
+// in conjunction with AppendOutgoingContext, NewOutgoingContext will
+// overwrite any previously-appended metadata. Metadata must not be modified after
+// calling this function.
+func NewOutgoingContext(ctx context.Context, md Metadata) context.Context {
+	return context.WithValue(ctx, metadataOutgoingKey{}, rawMetadata{md: md})
+}
+
+// AppendContext returns a new context with the provided kv merged
+// with any existing metadata in the context. Please refer to the documentation
+// of Pairs for a description of kv.
+func AppendContext(ctx context.Context, kv ...string) context.Context {
+	if len(kv)%2 == 1 {
+		panic(fmt.Sprintf("metadata: AppendContext got an odd number of input pairs for metadata: %d", len(kv)))
+	}
+	md, _ := ctx.Value(metadataCurrentKey{}).(rawMetadata)
+	added := make([][]string, len(md.added)+1)
+	copy(added, md.added)
+	kvCopy := make([]string, 0, len(kv))
+	for i := 0; i < len(kv); i += 2 {
+		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
+	}
+	added[len(added)-1] = kvCopy
+	return context.WithValue(ctx, metadataCurrentKey{}, rawMetadata{md: md.md, added: added})
+}
+
+// AppendIncomingContext returns a new context with the provided kv merged
+// with any existing metadata in the context. Please refer to the documentation
+// of Pairs for a description of kv.
+func AppendIncomingContext(ctx context.Context, kv ...string) context.Context {
+	if len(kv)%2 == 1 {
+		panic(fmt.Sprintf("metadata: AppendIncomingContext got an odd number of input pairs for metadata: %d", len(kv)))
+	}
+	md, _ := ctx.Value(metadataIncomingKey{}).(rawMetadata)
+	added := make([][]string, len(md.added)+1)
+	copy(added, md.added)
+	kvCopy := make([]string, 0, len(kv))
+	for i := 0; i < len(kv); i += 2 {
+		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
+	}
+	added[len(added)-1] = kvCopy
+	return context.WithValue(ctx, metadataIncomingKey{}, rawMetadata{md: md.md, added: added})
+}
+
+// AppendOutgoingContext returns a new context with the provided kv merged
+// with any existing metadata in the context. Please refer to the documentation
+// of Pairs for a description of kv.
+func AppendOutgoingContext(ctx context.Context, kv ...string) context.Context {
+	if len(kv)%2 == 1 {
+		panic(fmt.Sprintf("metadata: AppendOutgoingContext got an odd number of input pairs for metadata: %d", len(kv)))
+	}
+	md, _ := ctx.Value(metadataOutgoingKey{}).(rawMetadata)
+	added := make([][]string, len(md.added)+1)
+	copy(added, md.added)
+	kvCopy := make([]string, 0, len(kv))
+	for i := 0; i < len(kv); i += 2 {
+		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
+	}
+	added[len(added)-1] = kvCopy
+	return context.WithValue(ctx, metadataOutgoingKey{}, rawMetadata{md: md.md, added: added})
+}
+
+// FromContext returns the metadata in ctx if it exists.
+func FromContext(ctx context.Context) (Metadata, bool) {
+	raw, ok := ctx.Value(metadataCurrentKey{}).(rawMetadata)
+	if !ok {
+		return nil, false
+	}
+	metadataSize := len(raw.md)
+	for i := range raw.added {
+		metadataSize += len(raw.added[i]) / 2
+	}
+
+	out := make(Metadata, metadataSize)
+	for k, v := range raw.md {
+		out[k] = copyOf(v)
+	}
+	for _, added := range raw.added {
+		if len(added)%2 == 1 {
+			panic(fmt.Sprintf("metadata: FromContext got an odd number of input pairs for metadata: %d", len(added)))
+		}
+
+		for i := 0; i < len(added); i += 2 {
+			out[added[i]] = append(out[added[i]], added[i+1])
+		}
+	}
+	return out, true
+}
+
+// MustContext returns the metadata in ctx.
+func MustContext(ctx context.Context) Metadata {
+	md, ok := FromContext(ctx)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md
+}
+
+// FromIncomingContext returns the incoming metadata in ctx if it exists.
+func FromIncomingContext(ctx context.Context) (Metadata, bool) {
+	raw, ok := ctx.Value(metadataIncomingKey{}).(rawMetadata)
+	if !ok {
+		return nil, false
+	}
+	metadataSize := len(raw.md)
+	for i := range raw.added {
+		metadataSize += len(raw.added[i]) / 2
+	}
+
+	out := make(Metadata, metadataSize)
+	for k, v := range raw.md {
+		out[k] = copyOf(v)
+	}
+	for _, added := range raw.added {
+		if len(added)%2 == 1 {
+			panic(fmt.Sprintf("metadata: FromIncomingContext got an odd number of input pairs for metadata: %d", len(added)))
+		}
+
+		for i := 0; i < len(added); i += 2 {
+			out[added[i]] = append(out[added[i]], added[i+1])
+		}
+	}
+	return out, true
+}
+
+// MustIncomingContext returns the incoming metadata in ctx.
+func MustIncomingContext(ctx context.Context) Metadata {
+	md, ok := FromIncomingContext(ctx)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md
+}
+
+// ValueFromIncomingContext returns the metadata value corresponding to the metadata
+// key from the incoming metadata if it exists. Keys are matched in a case insensitive
+// manner.
+func ValueFromIncomingContext(ctx context.Context, key string) []string {
+	raw, ok := ctx.Value(metadataIncomingKey{}).(rawMetadata)
+	if !ok {
+		return nil
+	}
+
+	if v, ok := raw.md[key]; ok {
+		return copyOf(v)
+	}
+	for k, v := range raw.md {
+		// Case insensitive comparison: Metadata is a map, and there's no guarantee
+		// that the Metadata attached to the context is created using our helper
+		// functions.
+		if strings.EqualFold(k, key) {
+			return copyOf(v)
+		}
+	}
+	return nil
+}
+
+// ValueFromCurrentContext returns the metadata value corresponding to the metadata
+// key from the incoming metadata if it exists. Keys are matched in a case insensitive
+// manner.
+func ValueFromCurrentContext(ctx context.Context, key string) []string {
+	md, ok := ctx.Value(metadataCurrentKey{}).(rawMetadata)
+	if !ok {
+		return nil
+	}
+
+	if v, ok := md.md[key]; ok {
+		return copyOf(v)
+	}
+	for k, v := range md.md {
+		// Case insensitive comparison: Metadata is a map, and there's no guarantee
+		// that the Metadata attached to the context is created using our helper
+		// functions.
+		if strings.EqualFold(k, key) {
+			return copyOf(v)
+		}
+	}
+	return nil
+}
+
+// MustOutgoingContext returns the outgoing metadata in ctx.
+func MustOutgoingContext(ctx context.Context) Metadata {
+	md, ok := FromOutgoingContext(ctx)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md
+}
+
+// ValueFromOutgoingContext returns the metadata value corresponding to the metadata
+// key from the incoming metadata if it exists. Keys are matched in a case insensitive
+// manner.
+func ValueFromOutgoingContext(ctx context.Context, key string) []string {
+	md, ok := ctx.Value(metadataOutgoingKey{}).(rawMetadata)
+	if !ok {
+		return nil
+	}
+
+	if v, ok := md.md[key]; ok {
+		return copyOf(v)
+	}
+	for k, v := range md.md {
+		// Case insensitive comparison: Metadata is a map, and there's no guarantee
+		// that the Metadata attached to the context is created using our helper
+		// functions.
+		if strings.EqualFold(k, key) {
+			return copyOf(v)
+		}
+	}
+	return nil
+}
+
+func copyOf(v []string) []string {
+	vals := make([]string, len(v))
+	copy(vals, v)
+	return vals
+}
+
+// FromOutgoingContext returns the outgoing metadata in ctx if it exists.
+func FromOutgoingContext(ctx context.Context) (Metadata, bool) {
+	raw, ok := ctx.Value(metadataOutgoingKey{}).(rawMetadata)
+	if !ok {
+		return nil, false
+	}
+
+	metadataSize := len(raw.md)
+	for i := range raw.added {
+		metadataSize += len(raw.added[i]) / 2
+	}
+
+	out := make(Metadata, metadataSize)
+	for k, v := range raw.md {
+		out[k] = copyOf(v)
+	}
+	for _, added := range raw.added {
+		if len(added)%2 == 1 {
+			panic(fmt.Sprintf("metadata: FromOutgoingContext got an odd number of input pairs for metadata: %d", len(added)))
+		}
+
+		for i := 0; i < len(added); i += 2 {
+			out[added[i]] = append(out[added[i]], added[i+1])
+		}
+	}
+	return out, ok
+}
+
+type rawMetadata struct {
+	md    Metadata
+	added [][]string
+}
+
 // Iterator used to iterate over metadata with order
 type Iterator struct {
 	md   Metadata
@@ -47,14 +466,18 @@ type Iterator struct {
 }
 
 // Next advance iterator to next element
-func (iter *Iterator) Next(k, v *string) bool {
+func (iter *Iterator) Next(k *string, v *[]string) bool {
 	if iter.cur+1 > iter.cnt {
 		return false
 	}
 
-	*k = iter.keys[iter.cur]
-	*v = iter.md[*k]
-	iter.cur++
+	if k != nil && v != nil {
+		*k = iter.keys[iter.cur]
+		vv := iter.md[*k]
+		*v = make([]string, len(vv))
+		copy(*v, vv)
+		iter.cur++
+	}
 	return true
 }
 
@@ -68,102 +491,3 @@ func (md Metadata) Iterator() *Iterator {
 	sort.Strings(iter.keys)
 	return iter
 }
-
-func (md Metadata) MustGet(key string) string {
-	val, ok := md.Get(key)
-	if !ok {
-		panic("missing metadata key")
-	}
-	return val
-}
-
-// Get returns value from metadata by key
-func (md Metadata) Get(key string) (string, bool) {
-	// fast path
-	val, ok := md[key]
-	if !ok {
-		// slow path
-		val, ok = md[textproto.CanonicalMIMEHeaderKey(key)]
-		if !ok {
-			val, ok = md[strings.ToLower(key)]
-		}
-	}
-	return val, ok
-}
-
-// Set is used to store value in metadata
-func (md Metadata) Set(kv ...string) {
-	if len(kv)%2 == 1 {
-		kv = kv[:len(kv)-1]
-	}
-	for idx := 0; idx < len(kv); idx += 2 {
-		md[textproto.CanonicalMIMEHeaderKey(kv[idx])] = kv[idx+1]
-	}
-}
-
-// Del is used to remove value from metadata
-func (md Metadata) Del(keys ...string) {
-	for _, key := range keys {
-		// fast path
-		delete(md, key)
-		// slow path
-		delete(md, textproto.CanonicalMIMEHeaderKey(key))
-		// very slow path
-		delete(md, strings.ToLower(key))
-	}
-}
-
-// Copy makes a copy of the metadata
-func (md Metadata) CopyTo(dst Metadata) {
-	for k, v := range md {
-		dst[k] = v
-	}
-}
-
-// Copy makes a copy of the metadata
-func Copy(md Metadata, exclude ...string) Metadata {
-	nmd := New(len(md))
-	for k, v := range md {
-		nmd[k] = v
-	}
-	nmd.Del(exclude...)
-	return nmd
-}
-
-// New return new sized metadata
-func New(size int) Metadata {
-	if size == 0 {
-		size = defaultMetadataSize
-	}
-	return make(Metadata, size)
-}
-
-// Merge merges metadata to existing metadata, overwriting if specified
-func Merge(omd Metadata, mmd Metadata, overwrite bool) Metadata {
-	var ok bool
-	nmd := Copy(omd)
-	for key, val := range mmd {
-		_, ok = nmd[key]
-		switch {
-		case ok && !overwrite:
-			continue
-		case val != "":
-			nmd[key] = val
-		case ok && val == "":
-			nmd.Del(key)
-		}
-	}
-	return nmd
-}
-
-// Pairs from which metadata created
-func Pairs(kv ...string) (Metadata, bool) {
-	if len(kv)%2 == 1 {
-		return nil, false
-	}
-	md := New(len(kv) / 2)
-	for idx := 0; idx < len(kv); idx += 2 {
-		md[kv[idx]] = kv[idx+1]
-	}
-	return md, true
-}