gRPC на Go: от внутреннего устройства до архитектуры

Современная архитектура приложений

Что такое gRPC и как он появился

История появления gRPC

Stubby RPC

SPDY

gRPC

HTTP/2

Проблема HTTP/1

Head-of-line Blocking

Что делает HTTP/2

Устройство HTTP/2

type http2FrameHeader struct {
	valid bool // caller can access []byte fields in the Frame

	// Type is the 1 byte frame type. There are ten standard frame
	// types, but extension frame types may be written by WriteRawFrame
	// and will be returned by ReadFrame (as UnknownFrame).
	Type http2FrameType

	// Flags are the 1 byte of 8 potential bit flags per frame.
	// They are specific to the frame type.
	Flags http2Flags

	// Length is the length of the frame, not including the 9 byte header.
	// The maximum size is one byte less than 16MB (uint24), but only
	// frames up to 16KB are allowed without peer agreement.
	Length uint32

	// StreamID is which stream this frame is for. Certain frames
	// are not stream-specific, in which case this field is 0.
	StreamID uint32
}

Типы фреймов

type http2FrameType uint8

const (
	http2FrameData           http2FrameType = 0x0
	http2FrameHeaders        http2FrameType = 0x1
	http2FramePriority       http2FrameType = 0x2
	http2FrameRSTStream      http2FrameType = 0x3
	http2FrameSettings       http2FrameType = 0x4
	http2FramePushPromise    http2FrameType = 0x5
	http2FramePing           http2FrameType = 0x6
	http2FrameGoAway         http2FrameType = 0x7
	http2FrameWindowUpdate   http2FrameType = 0x8
	http2FrameContinuation   http2FrameType = 0x9
	http2FramePriorityUpdate http2FrameType = 0x10
)

type http2DataFrame struct {
	http2FrameHeader // заголовок фрейма
	data []byte // сами данные
}

type http2HeadersFrame struct {
	http2FrameHeader // заголовок фрейма

	// Priority is set if FlagHeadersPriority is set in the FrameHeader.
	Priority http2PriorityParam // параметры приоритета

	headerFragBuf []byte // not owned // буфер с фрагментом заголовков
}

Флаги

type http2Flags uint8

// Frame-specific FrameHeader flag bits.
const (
	// Data Frame
	http2FlagDataEndStream http2Flags = 0x1
	http2FlagDataPadded    http2Flags = 0x8

	// Headers Frame
	http2FlagHeadersEndStream  http2Flags = 0x1
	http2FlagHeadersEndHeaders http2Flags = 0x4
	http2FlagHeadersPadded     http2Flags = 0x8
	http2FlagHeadersPriority   http2Flags = 0x20

	// Settings Frame
	http2FlagSettingsAck http2Flags = 0x1

	// Ping Frame
	http2FlagPingAck http2Flags = 0x1

	// Continuation Frame
	http2FlagContinuationEndHeaders http2Flags = 0x4

	http2FlagPushPromiseEndHeaders http2Flags = 0x4
	http2FlagPushPromisePadded     http2Flags = 0x8
)

Пример HTTP/2 запроса

POST /go HTTP/1
Content-Length: 24

{"hello": "@igorutine"}

HeaderFrame{
 StreamId: 1
 Flags: FlagEndHeaders
 [
 :method: POST
 :path: /go
 Content-Length: 24
 ]
}

DataFrame{
	StreamId: 1,
	Flags: FlagEndStream,
	PayloadLength: 24,
	Data: {"hello": "..."},
}

200 OK
Content-Length: 0
Date: Sat, 14 Feb 2026 16:34:56 GMT

HeadersFrame{
 StreamId: 1
 Flags: FlagEndHeaders | FlagEndStream
 [
 :status: 200
 Content-Length: 0
 Date: Sat, ...
 ]
}

Сжатие

HeadersFrame{
 StreamId: 1
 Flags: FlagEndHeaders | FlagEndStream
 [
 :method: POST
 :path: /go
 Content-Length: 0
 ]
}

HeadersFrame{
 StreamId: 3
 Flags: FlagEndHeaders | FlagEndStream
 [
 :method: POST
 :path: /go
 Content-Length: 0
 ]
}

HeadersFrame{
 StreamId: 1
 Flags: FlagEndHeaders | FlagEndStream
 [
 :status: 20
 Content-Length: 0
 Date: Sat, ...
 ]
}

HeadersFrame{
 StreamId: 3
 Flags: FlagEndHeaders | FlagEndStream
 [
 :status: 20
 Content-Length: 0
 Date: Sat, ...
 ]
}

Внутреннее устройство gRPC

package grpctest.v1

service HelloService {
    rpc SayHello(HelloRequest) returns (HelloResponse);
}

:method: POST
:path: /grpctest.v1.HelloService/SayHello
content-type: application/grpc
user-agent: grpc-go/1.52.0

body: [...]

message HelloRequest {
    string name = 1;
}

message HelloResponse {
    string message = 1;
}

Protocol Buffers

Преимущества Protocol Buffers

Типы в Protocol Buffers

Scalar Types

message ScalarValueTypesExample {
    double double_field = 1; // Go Type: float64
    float api_field = 2; // Go Type: float32
    int32 int32_field = 3; // Go Type: int32
    int64 int64_field = 4; // Go Type: int64
    uint32 uint32_field = 5; // Go Type: uint32
    uint64 uint64_field = 6; // Go Type: uint64
    sint32 sint32_field = 7; // Go Type: int32
    sint64 sint64_field = 8; // Go Type: int64
    fixed32 fixed32_field = 9; // Go Type: uint32
    fixed64 fixed64_field = 10; // Go Type: uint64
    sfixed32 sfixed32_field = 11; // Go Type: int32
    sfixed64 sfixed64_field = 12; // Go Type: int64
    bool bool_field = 13; // Go Type: bool
    string string_field = 14; // Go Type: string
    bytes bytes_field = 15; // Go Type: []byte
}

Well-Known Types

message WellKnownTypesExample {
    google.protobuf.Any any_field = 1;
    google.protobuf.Api api_field = 2;
    google.protobuf.Duration duration_field = 3;
    google.protobuf.Empty empty_field = 4;
    google.protobuf.FieldMask field_mask_field = 5;
    google.protobuf.SourceContext source_context_field = 6;
    google.protobuf.Struct struct_field = 7;
    google.protobuf.Timestamp timestamp_field = 8;
    google.protobuf.Type type_field = 9;
    google.protobuf.DoubleValue double_field = 10;
    google.protobuf.FloatValue float_field = 11;
    google.protobuf.Int64Value int64_field = 12;
    google.protobuf.UInt64Value uint64_field = 13;
    google.protobuf.Int32Value int32_field = 14;
    google.protobuf.UInt32Value uint32_field = 15;
    google.protobuf.BoolValue bool_field = 16;
    google.protobuf.StringValue string_field = 17;
    google.protobuf.BytesValue bytes_field = 18;
    google.protobuf.Value value_field = 19;
}

Common Types

message CommonTypes {
    google.type.Interval interval_field = 1;
    google.type.Date date_field = 2;
    google.type.DayOfWeek day_of_week_field = 3;
    google.type.TimeOfDay time_of_day_field = 4;
    google.type.LatLng lat_lng_field = 5;
    google.type.Money money_field = 6;
    google.type.PostalAddress postal_address_field = 7;
    google.type.Color color_field = 8;
    google.type.Month month_field = 9;
    google.type.CalendarPeriod calendar_period_field = 10;
    google.type.Decimal decimal_field = 11;
    google.type.Expr expr_field = 12;
    google.type.Fraction fraction_field = 13;
    google.type.LocalizedText localized_text_field = 14;
    google.type.PhoneNumber phone_number_field = 15;
}

Optional

message OptionalExample {
    int32 required_field = 1; // required (if not provided we get default
value: 0) Go type: int32
    optional int32 optional_field = 2; // optional (if not provided we get
null) Go type: *int32
}

Перечисления

enum Corpus {
    CORPUS_UNSPECIFIED = 0;
    CORPUS_UNIVERSAL = 1;
    CORPUS_WEB = 2;
    CORPUS_IMAGES = 3;
    CORPUS_LOCAL = 4;
    CORPUS_NEWS = 5;
    CORPUS_PRODUCTS = 6;
    CORPUS_VIDEO = 7;
}

Deprecated Fields

message DeprecatedExample {
    // Use new_field instead old_field
    int32 old_field = 1 [deprecated = true];
    int64 new_field = 2;
}

type DeprecatedExample struct {
    state protoimpl.MessageState
    sizeCache protoimpl.SizeCache
    unknownFields protoimpl.UnknownFields
    // Use new_field instead old_field
    //
    // Deprecated: Do not use.
    OldField int32
`protobuf:"varint,1,opt,name=old_field,json=oldField,proto3"
json:"old_field,omitempty"`
    NewField int64
`protobuf:"varint,2,opt,name=new_field,json=newField,proto3"
json:"new_field,omitempty"`
}

Reserved Fields

enum Foo {
    reserved 2, 15, 9 to 11, 40 to max;
    reserved "FOO", "BAR";
    FOO = 2;
}

api/examples/enum.proto: Enum value "FOO" uses reserved number 2.
api/examples/enum.proto:22:5: Enum value "FOO" is reserved.

Вложенные сообщения и массивы

message SearchResponse {
    message Result {
        string url = 1;
        string title = 2;
        repeated string snippets = 3;
    }
    repeated Result result = 1;
}

Oneof

message Stock {
    // Stock-specific data
}
message Currency {
    // Currency-specific data
}
message ChangeNotification {
    int32 id = 1;
    oneof instrument {
    Stock stock = 2;
    Currency currency = 3;
    }
}

Map

message GetProjectResponse {
    message Project {
    // data
    }
    
    map<string, Project> projects = 1;
}

Сериализация

Protobuf и gRPC

// Один запрос, один ответ:
rpc Send(Message) returns (Result);

// Один запрос, поток ответов:
rpc Send(Message) returns (stream Result);

// Поток запросов, один ответ:
rpc Send(stream Message) returns (Result);

// Поток запросов, поток ответов:
rpc Send(stream Message) returns (stream Result);

gRPC workflow

Прямая и обратная совместимость в protobuf

Protobuf на практике

syntax = "proto3";

package user.v1;

option go_package = "example.com/project/gen/user/v1;userv1";

service UserService {
    rpc GetUser(GetUserRequest) returns (GetUserResponse);
}

message GetUserRequest {
    string id = 1;
}

message GetUserResponse {
    string id = 1;
    string name = 2;
}

go install google.golang.org/protobuf/cmd/protoc-gen-go@latest

go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest

protoc \
 -I {{.PROTO_DIR}} \
 --go_out={{.GEN_DIR}} \
 --go_opt=paths=source_relative \
 --go-grpc_out={{.GEN_DIR}} \
 --go-grpc_opt=paths=source_relative \
 {{.PROTO_DIR}}/user/v1/user.proto

type GetUserRequest struct {
    state protoimpl.MessageState
    sizeCache protoimpl.SizeCache
    unknownFields protoimpl.UnknownFields
 
    Id string `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
}

type GetUserResponse struct {
    state protoimpl.MessageState
    sizeCache protoimpl.SizeCache
    unknownFields protoimpl.UnknownFields
 
    Id string `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
    Name string `protobuf:"bytes,2,opt,name=name,proto3"
json:"name,omitempty"`
}

var file_user_v1_user_proto_rawDesc = []byte{
 0x0a, 0x12, 0x75, 0x73, 0x65, 0x72, 0x2f, 0x76, 0x31, 0x2f, 0x75, 0x73,
0x65, 0x72, 0x2e, 0x70,
 0x72, 0x6f, 0x74, 0x6f, 0x12, 0x07, 0x75, 0x73, 0x65, 0x72, 0x2e, 0x76,
0x31, 0x22, 0x20, 0x0a,
 0x0e, 0x47, 0x65, 0x74, 0x55, 0x73, 0x65, 0x72, 0x52, 0x65, 0x71, 0x75,
0x65, 0x73, 0x74, 0x12,
...
}

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