Execute commands in runner via WebSocket

This enables executing commands in runners and forwarding input and
output between the runner and the websocket to the client.

Co-authored-by: Maximilian Paß <maximilian.pass@student.hpi.uni-potsdam.de>

runner/execution_storage.go

@@ -0,0 +1,46 @@
+package runner
+
+import (
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/api/dto"
+	"sync"
+)
+
+// ExecutionStorage stores executions.
+type ExecutionStorage interface {
+	// Add adds a runner to the storage.
+	// It overwrites the existing execution if an execution with the same id already exists.
+	Add(id ExecutionId, executionRequest *dto.ExecutionRequest)
+
+	// Pop deletes the execution with the given id from the storage and returns it.
+	// If no such execution exists, ok is false and true otherwise.
+	Pop(id ExecutionId) (request *dto.ExecutionRequest, ok bool)
+}
+
+// localExecutionStorage stores execution objects in the local application memory.
+// ToDo: Create implementation that use some persistent storage like a database
+type localExecutionStorage struct {
+	sync.RWMutex
+	executions map[ExecutionId]*dto.ExecutionRequest
+}
+
+// NewLocalExecutionStorage responds with an ExecutionStorage implementation.
+// This implementation stores the data thread-safe in the local application memory.
+func NewLocalExecutionStorage() *localExecutionStorage {
+	return &localExecutionStorage{
+		executions: make(map[ExecutionId]*dto.ExecutionRequest),
+	}
+}
+
+func (s *localExecutionStorage) Add(id ExecutionId, executionRequest *dto.ExecutionRequest) {
+	s.Lock()
+	defer s.Unlock()
+	s.executions[id] = executionRequest
+}
+
+func (s *localExecutionStorage) Pop(id ExecutionId) (request *dto.ExecutionRequest, ok bool) {
+	s.Lock()
+	defer s.Unlock()
+	request, ok = s.executions[id]
+	delete(s.executions, id)
+	return
+}