fix(GODT-2829): Fix new sync service bugs

* Fix wrong context use for message downloads
* Fix delete of sync data failing due ErrNotFound
* Pre-allocate attachment data buffer before download
* Fix calculation of progress if message count is higher than total

internal/services/imapservice/sync_reporter.go

@@ -57,10 +57,20 @@ func (rep *syncReporter) OnError(ctx context.Context, err error) {
 func (rep *syncReporter) OnProgress(ctx context.Context, delta int64) {
 	rep.count += delta
 
+	var progress float64
+
+	// It's possible for count to be bigger or smaller than total depending on when the sync begins and whether new
+	// messages are added/removed during this period. When this happens just limited the progress to 100%.
+	if rep.count > rep.total {
+		progress = 1
+	} else {
+		progress = float64(rep.count) / float64(rep.total)
+	}
+
 	if time.Since(rep.last) > rep.freq {
 		rep.eventPublisher.PublishEvent(ctx, events.SyncProgress{
 			UserID:    rep.userID,
-			Progress:  float64(rep.count) / float64(rep.total),
+			Progress:  progress,
 			Elapsed:   time.Since(rep.start),
 			Remaining: time.Since(rep.start) * time.Duration(rep.total-(rep.count+1)) / time.Duration(rep.count+1),
 		})

internal/services/imapservice/sync_state_provider.go

@@ -222,7 +222,11 @@ func (s *SyncState) loadUnsafe() error {
 func DeleteSyncState(configDir, userID string) error {
 	path := getSyncConfigPath(configDir, userID)
 
-	return os.Remove(path)
+	if err := os.Remove(path); err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+
+	return nil
 }
 
 func MigrateVaultSettings(

internal/services/imapsmtpserver/service.go

@@ -359,8 +359,7 @@ func (sm *Service) handleAddIMAPUserImpl(ctx context.Context,
 			} else if isNew {
 				panic("IMAP user should already have a database")
 			}
-		}
-
+		} else {
 			status, err := syncStateProvider.GetSyncStatus(ctx)
 			if err != nil {
 				return fmt.Errorf("failed to get sync status: %w", err)
@@ -387,6 +386,7 @@ func (sm *Service) handleAddIMAPUserImpl(ctx context.Context,
 
 				log.WithField("gluonID", gluonID).Info("Re-created IMAP user")
 			}
+		}
 	} else {
 		log.Info("Creating new IMAP user")
 

internal/services/syncservice/limits.go

@@ -58,7 +58,7 @@ func newSyncLimits(maxSyncMemory uint64) syncLimits {
 		MinMessageBuildingMem: 64 * Megabyte,
 
 		// Maximum recommend value for parallel downloads by the API team.
-		MaxParallelDownloads: 20,
+		MaxParallelDownloads: 32,
 
 		MaxSyncMemory: maxSyncMemory,
 	}

internal/services/syncservice/service.go

@@ -49,7 +49,7 @@ func NewService(reporter reporter.Reporter,
 	return &Service{
 		limits:        limits,
 		metadataStage: NewMetadataStage(metaCh, downloadCh, limits.DownloadRequestMem, panicHandler),
-		downloadStage: NewDownloadStage(downloadCh, buildCh, 20, panicHandler),
+		downloadStage: NewDownloadStage(downloadCh, buildCh, limits.MaxParallelDownloads, panicHandler),
 		buildStage:    NewBuildStage(buildCh, applyCh, limits.MessageBuildMem, panicHandler, reporter),
 		applyStage:    NewApplyStage(applyCh),
 		metaCh:        metaCh,

internal/services/syncservice/stage_apply.go

@@ -76,7 +76,7 @@ func (a *ApplyStage) run(ctx context.Context) {
 			continue
 		}
 
-		if err := req.job.updateApplier.ApplySyncUpdates(ctx, req.messages); err != nil {
+		if err := req.job.updateApplier.ApplySyncUpdates(req.getContext(), req.messages); err != nil {
 			a.log.WithError(err).Error("Failed to apply sync updates")
 			req.job.onError(err)
 			continue

internal/services/syncservice/stage_download.go

@@ -18,6 +18,7 @@
 package syncservice
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"sync/atomic"
@@ -58,7 +59,7 @@ func NewDownloadStage(
 	return &DownloadStage{
 		input:                input,
 		output:               output,
-		maxParallelDownloads: maxParallelDownloads,
+		maxParallelDownloads: maxParallelDownloads * 2,
 		panicHandler:         panicHandler,
 		log:                  logrus.WithField("sync-stage", "download"),
 	}
@@ -94,7 +95,7 @@ func (d *DownloadStage) run(ctx context.Context) {
 
 		// Step 1: Download Messages.
 		result, err := autoDownloadRate(
-			ctx,
+			request.getContext(),
 			&DefaultDownloadRateModifier{},
 			request.job.client,
 			d.maxParallelDownloads,
@@ -155,14 +156,15 @@ func (d *DownloadStage) run(ctx context.Context) {
 
 		// Step 3: Download attachments data to the message.
 		attachments, err := autoDownloadRate(
-			ctx,
+			request.getContext(),
 			&DefaultDownloadRateModifier{},
 			request.job.client,
 			d.maxParallelDownloads,
 			attachmentIndices,
 			newCoolDown,
 			func(ctx context.Context, client APIClient, input attachmentMeta) ([]byte, error) {
-				return downloadAttachment(ctx, request.job.downloadCache, client, result[input.msgIdx].Attachments[input.attIdx].ID)
+				attachment := result[input.msgIdx].Attachments[input.attIdx]
+				return downloadAttachment(ctx, request.job.downloadCache, client, attachment.ID, attachment.Size)
 			},
 		)
 		if err != nil {
@@ -202,17 +204,22 @@ func downloadMessage(ctx context.Context, cache *DownloadCache, client APIClient
 	return msg, nil
 }
 
-func downloadAttachment(ctx context.Context, cache *DownloadCache, client APIClient, id string) ([]byte, error) {
+func downloadAttachment(ctx context.Context, cache *DownloadCache, client APIClient, id string, size int64) ([]byte, error) {
 	data, ok := cache.GetAttachment(id)
 	if ok {
 		return data, nil
 	}
 
-	data, err := client.GetAttachment(ctx, id)
-	if err != nil {
+	var buffer bytes.Buffer
+
+	buffer.Grow(int(size))
+
+	if err := client.GetAttachmentInto(ctx, id, &buffer); err != nil {
 		return nil, err
 	}
 
+	data = buffer.Bytes()
+
 	cache.StoreAttachment(id, data)
 
 	return data, nil
@@ -236,6 +243,10 @@ func autoDownloadRate[T any, R any](
 	proton429or5xxCounter := int32(0)
 	parallelTasks := maxParallelDownloads
 	for _, chunk := range xslices.Chunk(data, maxParallelDownloads) {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
+
 		parallelTasks = modifier.Apply(atomic.LoadInt32(&proton429or5xxCounter) != 0, parallelTasks, maxParallelDownloads)
 
 		atomic.StoreInt32(&proton429or5xxCounter, 0)

internal/services/syncservice/stage_download_test.go

@@ -18,6 +18,7 @@
 package syncservice
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -61,9 +62,9 @@ func TestDownloadAttachment_NotInCache(t *testing.T) {
 	mockCtrl := gomock.NewController(t)
 	client := NewMockAPIClient(mockCtrl)
 	cache := newDownloadCache()
-	client.EXPECT().GetAttachment(gomock.Any(), gomock.Any()).Return(nil, nil)
+	client.EXPECT().GetAttachmentInto(gomock.Any(), gomock.Any(), gomock.Any()).Return(nil)
 
-	_, err := downloadAttachment(context.Background(), cache, client, "id")
+	_, err := downloadAttachment(context.Background(), cache, client, "id", 1024)
 	require.NoError(t, err)
 }
 
@@ -74,7 +75,7 @@ func TestDownloadAttachment_InCache(t *testing.T) {
 	attachment := []byte("hello world")
 	cache.StoreAttachment("id", attachment)
 
-	downloaded, err := downloadAttachment(context.Background(), cache, client, "id")
+	downloaded, err := downloadAttachment(context.Background(), cache, client, "id", 1024)
 	require.NoError(t, err)
 	require.Equal(t, attachment, downloaded)
 }
@@ -343,7 +344,7 @@ func TestDownloadStage_JobAbortsOnAttachmentDownloadError(t *testing.T) {
 			ID: "attach",
 		}},
 	}, nil)
-	tj.client.EXPECT().GetAttachment(gomock.Any(), gomock.Eq("attach")).Return(nil, expectedErr)
+	tj.client.EXPECT().GetAttachmentInto(gomock.Any(), gomock.Eq("attach"), gomock.Any()).Return(expectedErr)
 
 	tj.job.begin()
 	childJob := tj.job.newChildJob("f", 10)
@@ -403,7 +404,13 @@ func buildDownloadStageData(tj *tjob, numMessages int, with422 bool) ([]string,
 		tj.client.EXPECT().GetMessage(gomock.Any(), gomock.Eq(m.ID)).Return(m.Message, nil)
 
 		for idx, a := range m.Attachments {
-			tj.client.EXPECT().GetAttachment(gomock.Any(), gomock.Eq(a.ID)).Return(m.AttData[idx], nil)
+			attData := m.AttData[idx]
+			tj.client.EXPECT().GetAttachmentInto(gomock.Any(), gomock.Eq(a.ID), gomock.Any()).DoAndReturn(
+				func(_ context.Context, _ string, b *bytes.Buffer) error {
+					_, err := b.Write(attData)
+					return err
+				},
+			)
 		}
 	}
 

internal/services/syncservice/stage_metadata.go

@@ -57,8 +57,8 @@ func NewMetadataStage(
 	}
 }
 
-const MetadataPageSize = 150
-const MetadataMaxMessages = 250
+const MetadataPageSize = 128
+const MetadataMaxMessages = 64
 
 func (m *MetadataStage) Run(group *async.Group) {
 	group.Once(func(ctx context.Context) {

internal/user/migration.go

@@ -0,0 +1,42 @@
+// Copyright (c) 2023 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package user
+
+import (
+	"fmt"
+
+	"github.com/ProtonMail/proton-bridge/v3/internal/services/imapservice"
+	"github.com/ProtonMail/proton-bridge/v3/internal/vault"
+)
+
+func migrateSyncStatusFromVault(encVault *vault.User, syncConfigDir string, userID string) error {
+	syncStatus := encVault.SyncStatus()
+
+	migrated, err := imapservice.MigrateVaultSettings(syncConfigDir, userID, syncStatus.HasLabels, syncStatus.HasMessages, syncStatus.FailedMessageIDs)
+	if err != nil {
+		return fmt.Errorf("failed to migrate user sync settings: %w", err)
+	}
+
+	if migrated {
+		if err := encVault.ClearSyncStatus(); err != nil {
+			return fmt.Errorf("failed to clear sync settings from vault: %w", err)
+		}
+	}
+
+	return nil
+}

internal/user/user.go

@@ -156,19 +156,8 @@ func newImpl(
 	logrus.WithField("userID", apiUser.ID).Info("Creating new user")
 
 	// Migrate Sync Status from Vault.
-	{
-		syncStatus := encVault.SyncStatus()
-
-		migrated, err := imapservice.MigrateVaultSettings(syncConfigDir, apiUser.ID, syncStatus.HasLabels, syncStatus.HasMessages, syncStatus.FailedMessageIDs)
-		if err != nil {
-			return nil, fmt.Errorf("failed to migrate user sync settings: %w", err)
-		}
-
-		if migrated {
-			if err := encVault.ClearSyncStatus(); err != nil {
-				return nil, fmt.Errorf("failed to clear sync settings from vault: %w", err)
-			}
-		}
+	if err := migrateSyncStatusFromVault(encVault, syncConfigDir, apiUser.ID); err != nil {
+		return nil, err
 	}
 
 	// Get the user's API addresses.