Restructure project
We previously didn't really had any structure in our project apart from creating a new folder for each package in our project root. Now that we have accumulated some packages, we use the well-known Golang project layout in order to clearly communicate our intent with packages. See https://github.com/golang-standards/project-layout
This commit is contained in:
sirkrypt0
283
internal/api/websocket.go
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283
internal/api/websocket.go
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package api
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import (
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"github.com/gorilla/websocket"
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"gitlab.hpi.de/codeocean/codemoon/poseidon/internal/runner"
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"gitlab.hpi.de/codeocean/codemoon/poseidon/pkg/dto"
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"io"
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"net/http"
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)
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const CodeOceanToRawReaderBufferSize = 1024
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var ErrUnknownExecutionID = errors.New("execution id unknown")
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type webSocketConnection interface {
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WriteMessage(messageType int, data []byte) error
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Close() error
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NextReader() (messageType int, r io.Reader, err error)
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CloseHandler() func(code int, text string) error
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SetCloseHandler(handler func(code int, text string) error)
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}
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type WebSocketReader interface {
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io.Reader
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startReadInputLoop() context.CancelFunc
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}
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// codeOceanToRawReader is an io.Reader implementation that provides the content of the WebSocket connection
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// to CodeOcean. You have to start the Reader by calling readInputLoop. After that you can use the Read function.
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type codeOceanToRawReader struct {
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connection webSocketConnection
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// A buffered channel of bytes is used to store data coming from CodeOcean via WebSocket
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// and retrieve it when Read(..) is called. Since channels are thread-safe, we use one here
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// instead of bytes.Buffer.
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buffer chan byte
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}
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func newCodeOceanToRawReader(connection webSocketConnection) *codeOceanToRawReader {
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return &codeOceanToRawReader{
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connection: connection,
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buffer: make(chan byte, CodeOceanToRawReaderBufferSize),
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}
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}
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// readInputLoop reads from the WebSocket connection and buffers the user's input.
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// This is necessary because input must be read for the connection to handle special messages like close and call the
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// CloseHandler.
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func (cr *codeOceanToRawReader) readInputLoop(ctx context.Context) {
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readMessage := make(chan bool)
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for {
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var messageType int
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var reader io.Reader
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var err error
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go func() {
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messageType, reader, err = cr.connection.NextReader()
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readMessage <- true
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}()
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select {
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case <-readMessage:
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case <-ctx.Done():
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return
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}
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if err != nil {
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log.WithError(err).Warn("Error reading client message")
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return
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}
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if messageType != websocket.TextMessage {
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log.WithField("messageType", messageType).Warn("Received message of wrong type")
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return
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}
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message, err := io.ReadAll(reader)
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if err != nil {
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log.WithError(err).Warn("error while reading WebSocket message")
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return
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}
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for _, character := range message {
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select {
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case cr.buffer <- character:
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case <-ctx.Done():
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return
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}
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}
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}
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}
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// startReadInputLoop start the read input loop asynchronously and returns a context.CancelFunc which can be used
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// to cancel the read input loop.
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func (cr *codeOceanToRawReader) startReadInputLoop() context.CancelFunc {
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ctx, cancel := context.WithCancel(context.Background())
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go cr.readInputLoop(ctx)
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return cancel
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}
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// Read implements the io.Reader interface.
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// It returns bytes from the buffer.
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func (cr *codeOceanToRawReader) Read(p []byte) (int, error) {
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if len(p) == 0 {
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return 0, nil
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}
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// Ensure to not return until at least one byte has been read to avoid busy waiting.
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p[0] = <-cr.buffer
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var n int
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for n = 1; n < len(p); n++ {
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select {
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case p[n] = <-cr.buffer:
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default:
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return n, nil
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}
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}
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return n, nil
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}
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// rawToCodeOceanWriter is an io.Writer implementation that, when written to, wraps the written data in the appropriate
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// json structure and sends it to the CodeOcean via WebSocket.
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type rawToCodeOceanWriter struct {
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proxy *webSocketProxy
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outputType dto.WebSocketMessageType
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}
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// Write implements the io.Writer interface.
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// The passed data is forwarded to the WebSocket to CodeOcean.
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func (rc *rawToCodeOceanWriter) Write(p []byte) (int, error) {
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err := rc.proxy.sendToClient(dto.WebSocketMessage{Type: rc.outputType, Data: string(p)})
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return len(p), err
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}
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// webSocketProxy is an encapsulation of logic for forwarding between Runners and CodeOcean.
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type webSocketProxy struct {
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userExit chan bool
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connection webSocketConnection
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Stdin WebSocketReader
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Stdout io.Writer
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Stderr io.Writer
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}
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// upgradeConnection upgrades a connection to a websocket and returns a webSocketProxy for this connection.
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func upgradeConnection(writer http.ResponseWriter, request *http.Request) (webSocketConnection, error) {
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connUpgrader := websocket.Upgrader{}
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connection, err := connUpgrader.Upgrade(writer, request, nil)
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if err != nil {
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log.WithError(err).Warn("Connection upgrade failed")
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return nil, fmt.Errorf("error upgrading the connection: %w", err)
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}
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return connection, nil
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}
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// newWebSocketProxy returns a initiated and started webSocketProxy.
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// As this proxy is already started, a start message is send to the client.
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func newWebSocketProxy(connection webSocketConnection) (*webSocketProxy, error) {
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stdin := newCodeOceanToRawReader(connection)
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proxy := &webSocketProxy{
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connection: connection,
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Stdin: stdin,
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userExit: make(chan bool),
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}
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proxy.Stdout = &rawToCodeOceanWriter{proxy: proxy, outputType: dto.WebSocketOutputStdout}
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proxy.Stderr = &rawToCodeOceanWriter{proxy: proxy, outputType: dto.WebSocketOutputStderr}
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err := proxy.sendToClient(dto.WebSocketMessage{Type: dto.WebSocketMetaStart})
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if err != nil {
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return nil, err
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}
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closeHandler := connection.CloseHandler()
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connection.SetCloseHandler(func(code int, text string) error {
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//nolint:errcheck // The default close handler always returns nil, so the error can be safely ignored.
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_ = closeHandler(code, text)
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close(proxy.userExit)
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return nil
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})
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return proxy, nil
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}
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// waitForExit waits for an exit of either the runner (when the command terminates) or the client closing the WebSocket
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// and handles WebSocket exit messages.
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func (wp *webSocketProxy) waitForExit(exit <-chan runner.ExitInfo, cancelExecution context.CancelFunc) {
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defer wp.close()
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cancelInputLoop := wp.Stdin.startReadInputLoop()
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var exitInfo runner.ExitInfo
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select {
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case exitInfo = <-exit:
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cancelInputLoop()
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log.Info("Execution returned")
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case <-wp.userExit:
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cancelInputLoop()
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cancelExecution()
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log.Info("Client closed the connection")
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return
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}
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if errors.Is(exitInfo.Err, context.DeadlineExceeded) || errors.Is(exitInfo.Err, runner.ErrorRunnerInactivityTimeout) {
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err := wp.sendToClient(dto.WebSocketMessage{Type: dto.WebSocketMetaTimeout})
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if err != nil {
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log.WithError(err).Warn("Failed to send timeout message to client")
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}
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return
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} else if exitInfo.Err != nil {
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errorMessage := "Error executing the request"
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log.WithError(exitInfo.Err).Warn(errorMessage)
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err := wp.sendToClient(dto.WebSocketMessage{Type: dto.WebSocketOutputError, Data: errorMessage})
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if err != nil {
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log.WithError(err).Warn("Failed to send output error message to client")
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}
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return
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}
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log.WithField("exit_code", exitInfo.Code).Debug()
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err := wp.sendToClient(dto.WebSocketMessage{
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Type: dto.WebSocketExit,
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ExitCode: exitInfo.Code,
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})
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if err != nil {
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return
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}
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}
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func (wp *webSocketProxy) sendToClient(message dto.WebSocketMessage) error {
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encodedMessage, err := json.Marshal(message)
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if err != nil {
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log.WithField("message", message).WithError(err).Warn("Marshal error")
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wp.closeWithError("Error creating message")
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return fmt.Errorf("error marshaling WebSocket message: %w", err)
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}
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err = wp.connection.WriteMessage(websocket.TextMessage, encodedMessage)
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if err != nil {
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errorMessage := "Error writing the exit message"
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log.WithError(err).Warn(errorMessage)
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wp.closeWithError(errorMessage)
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return fmt.Errorf("error writing WebSocket message: %w", err)
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}
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return nil
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}
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func (wp *webSocketProxy) closeWithError(message string) {
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err := wp.connection.WriteMessage(websocket.CloseMessage,
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websocket.FormatCloseMessage(websocket.CloseInternalServerErr, message))
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if err != nil {
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log.WithError(err).Warn("Error during websocket close")
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}
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}
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func (wp *webSocketProxy) close() {
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err := wp.connection.WriteMessage(websocket.CloseMessage,
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websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
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_ = wp.connection.Close()
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if err != nil {
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log.WithError(err).Warn("Error during websocket close")
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}
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}
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// connectToRunner is the endpoint for websocket connections.
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func (r *RunnerController) connectToRunner(writer http.ResponseWriter, request *http.Request) {
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targetRunner, _ := runner.FromContext(request.Context())
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executionID := runner.ExecutionID(request.URL.Query().Get(ExecutionIDKey))
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executionRequest, ok := targetRunner.Pop(executionID)
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if !ok {
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writeNotFound(writer, ErrUnknownExecutionID)
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return
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}
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connection, err := upgradeConnection(writer, request)
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if err != nil {
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writeInternalServerError(writer, err, dto.ErrorUnknown)
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return
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}
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proxy, err := newWebSocketProxy(connection)
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if err != nil {
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return
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}
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log.WithField("runnerId", targetRunner.ID()).WithField("executionID", executionID).Info("Running execution")
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exit, cancel := targetRunner.ExecuteInteractively(executionRequest, proxy.Stdin, proxy.Stdout, proxy.Stderr)
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proxy.waitForExit(exit, cancel)
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}
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