Refactor Service to actor pattern

Makefile

@@ -82,7 +82,7 @@ all: build
 .PHONY: all
 
 test:
-	$(GOTESTSUM) -- -timeout 5m -p 1 ./...
+	$(GOTESTSUM) -- -race -timeout 5m -p 1 ./...
 .PHONY: test
 
 install: install-buf install-protoc

rpc/rpcserver.go

@@ -163,7 +163,7 @@ func (r *rpcServer) Submit(ctx context.Context, in *api.SubmitRequest) (*api.Sub
 	}
 
 	out := new(api.SubmitResponse)
-	out.RoundId = round.ID
+	out.RoundId = round
 	out.Hash = hash
 	return out, nil
 }

service/round.go

@@ -7,7 +7,6 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
-	"sync"
 	"time"
 
 	"github.com/spacemeshos/merkle-tree"
@@ -63,8 +62,6 @@ type round struct {
 	teardownChan         chan struct{}
 
 	stateCache *roundState
-
-	submitMtx sync.Mutex
 }
 
 func (r *round) Epoch() uint32 {
@@ -141,8 +138,6 @@ func (r *round) submit(key, challenge []byte) error {
 		return errors.New("round is not open")
 	}
 
-	r.submitMtx.Lock()
-	defer r.submitMtx.Unlock()
 	if has, err := r.challengesDb.Has(key); err != nil {
 		return err
 	} else if has {
@@ -177,13 +172,11 @@ func (r *round) execute(ctx context.Context, end time.Time, minMemoryLayer uint)
 
 	close(r.executionStartedChan)
 
-	r.submitMtx.Lock()
 	var err error
 	r.execution.Members, r.execution.Statement, err = r.calcMembersAndStatement()
 	if err != nil {
 		return err
 	}
-	r.submitMtx.Unlock()
 
 	if err := r.saveState(); err != nil {
 		return err

service/round_test.go

@@ -2,6 +2,7 @@ package service
 
 import (
 	"context"
+	"crypto/rand"
 	"fmt"
 	"path/filepath"
 	"testing"
@@ -12,6 +13,19 @@ import (
 	"github.com/spacemeshos/poet/prover"
 )
 
+func genChallenges(num int) ([][]byte, error) {
+	ch := make([][]byte, num)
+	for i := 0; i < num; i++ {
+		ch[i] = make([]byte, 32)
+		_, err := rand.Read(ch[i])
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return ch, nil
+}
+
 // TestRound_Recovery test round recovery functionality.
 // The scenario proceeds as follows:
 //   - Execute r1 as a reference round.
@@ -183,7 +197,7 @@ func TestRound_State(t *testing.T) {
 	req.Equal(prevState, state)
 
 	// Recover execution.
-	req.NoError(r.recoverExecution(ctx, state.Execution, time.Now().Add(100*time.Microsecond)))
+	req.NoError(r.recoverExecution(ctx, state.Execution, time.Now().Add(200*time.Millisecond)))
 
 	req.False(r.executionStarted.IsZero())
 	proof, err := r.proof(false)