Files
polyphem/internal/api/ws/codeocean_writer.go
2024-08-12 10:02:36 +02:00

175 lines
5.9 KiB
Go

package ws
import (
"context"
"encoding/json"
"errors"
"fmt"
"github.com/gorilla/websocket"
"github.com/openHPI/poseidon/internal/runner"
"github.com/openHPI/poseidon/pkg/dto"
"io"
)
// CodeOceanOutputWriterBufferSize defines the number of messages.
const CodeOceanOutputWriterBufferSize = 64
// rawToCodeOceanWriter is a simple io.Writer implementation that just forwards the call to sendMessage.
type rawToCodeOceanWriter struct {
outputType dto.WebSocketMessageType
sendMessage func(*dto.WebSocketMessage)
ctx context.Context
}
// Write implements the io.Writer interface.
func (rc *rawToCodeOceanWriter) Write(p []byte) (int, error) {
switch {
case rc.ctx.Err() != nil:
return 0, fmt.Errorf("CodeOceanWriter context done: %w", rc.ctx.Err())
case len(p) == 0:
return 0, nil
default:
rc.sendMessage(&dto.WebSocketMessage{Type: rc.outputType, Data: string(p)})
return len(p), nil
}
}
// WebSocketWriter is an interface that defines which data is required and which information can be passed.
type WebSocketWriter interface {
StdOut() io.Writer
StdErr() io.Writer
Close(info *runner.ExitInfo)
}
// codeOceanOutputWriter is a concrete WebSocketWriter implementation.
// It forwards the data written to stdOut or stdErr (Nomad, AWS) to the WebSocket connection (CodeOcean).
type codeOceanOutputWriter struct {
connection Connection
stdOut *rawToCodeOceanWriter
stdErr *rawToCodeOceanWriter
queue chan *writingLoopMessage
ctx context.Context
}
// writingLoopMessage is an internal data structure to notify the writing loop when it should stop.
type writingLoopMessage struct {
done bool
data *dto.WebSocketMessage
}
// NewCodeOceanOutputWriter provides an codeOceanOutputWriter for the time the context ctx is active.
// The codeOceanOutputWriter handles all the messages defined in the websocket.schema.json (start, timeout, stdout, ...).
func NewCodeOceanOutputWriter(
connection Connection, ctx context.Context, done context.CancelFunc) WebSocketWriter {
cw := &codeOceanOutputWriter{
connection: connection,
queue: make(chan *writingLoopMessage, CodeOceanOutputWriterBufferSize),
ctx: ctx,
}
cw.stdOut = &rawToCodeOceanWriter{
outputType: dto.WebSocketOutputStdout,
sendMessage: cw.send,
ctx: ctx,
}
cw.stdErr = &rawToCodeOceanWriter{
outputType: dto.WebSocketOutputStderr,
sendMessage: cw.send,
ctx: ctx,
}
go cw.startWritingLoop(done)
cw.send(&dto.WebSocketMessage{Type: dto.WebSocketMetaStart})
return cw
}
// StdOut provides an io.Writer that forwards the written data to CodeOcean as StdOut stream.
func (cw *codeOceanOutputWriter) StdOut() io.Writer {
return cw.stdOut
}
// StdErr provides an io.Writer that forwards the written data to CodeOcean as StdErr stream.
func (cw *codeOceanOutputWriter) StdErr() io.Writer {
return cw.stdErr
}
// Close forwards the kind of exit (timeout, error, normal) to CodeOcean.
// This results in the closing of the WebSocket connection.
// The call of Close is mandatory!
func (cw *codeOceanOutputWriter) Close(info *runner.ExitInfo) {
defer func() { cw.queue <- &writingLoopMessage{done: true} }()
// Mask the internal stop reason before disclosing/forwarding it externally/to CodeOcean.
switch {
case info == nil:
return
case info.Err == nil:
cw.send(&dto.WebSocketMessage{Type: dto.WebSocketExit, ExitCode: info.Code})
case errors.Is(info.Err, runner.ErrorExecutionTimeout) || errors.Is(info.Err, runner.ErrorRunnerInactivityTimeout):
cw.send(&dto.WebSocketMessage{Type: dto.WebSocketMetaTimeout})
case errors.Is(info.Err, runner.ErrOOMKilled):
cw.send(&dto.WebSocketMessage{Type: dto.WebSocketOutputError, Data: dto.ErrOOMKilled.Error()})
case errors.Is(info.Err, runner.ErrDestroyedByAPIRequest):
message := "the allocation stopped as expected"
log.WithContext(cw.ctx).WithError(info.Err).Trace(message)
cw.send(&dto.WebSocketMessage{Type: dto.WebSocketOutputError, Data: message})
default:
errorMessage := "Error executing the request"
log.WithContext(cw.ctx).WithError(info.Err).Warn(errorMessage)
cw.send(&dto.WebSocketMessage{Type: dto.WebSocketOutputError, Data: errorMessage})
}
}
// send forwards the passed dto.WebSocketMessage to the writing loop.
func (cw *codeOceanOutputWriter) send(message *dto.WebSocketMessage) {
cw.queue <- &writingLoopMessage{done: false, data: message}
}
// startWritingLoop enables the writing loop.
// This is the central and only place where written changes to the WebSocket connection should be done.
// It synchronizes the messages to provide state checks of the WebSocket connection.
func (cw *codeOceanOutputWriter) startWritingLoop(writingLoopDone context.CancelFunc) {
defer func() {
message := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
err := cw.connection.WriteMessage(websocket.CloseMessage, message)
err2 := cw.connection.Close()
if err != nil || err2 != nil {
log.WithContext(cw.ctx).WithError(err).WithField("err2", err2).Warn("Error during websocket close")
}
}()
for {
message := <-cw.queue
done := true
if message.data != nil {
done = sendMessage(cw.connection, message.data, cw.ctx)
}
if done || message.done {
log.WithContext(cw.ctx).Trace("Writing loop done")
writingLoopDone()
return
}
}
}
// sendMessage is a helper function for the writing loop. It must not be called from somewhere else!
func sendMessage(connection Connection, message *dto.WebSocketMessage, ctx context.Context) (done bool) {
if message == nil {
return false
}
encodedMessage, err := json.Marshal(message)
if err != nil {
log.WithContext(ctx).WithField("message", message).WithError(err).Warn("Marshal error")
return false
}
log.WithContext(ctx).WithField("message", message).Trace("Sending message to client")
err = connection.WriteMessage(websocket.TextMessage, encodedMessage)
if err != nil {
errorMessage := "Error writing the message"
log.WithContext(ctx).WithField("message", message).WithError(err).Warn(errorMessage)
return true
}
return false
}