From c9650fc7d5e3f5ecaf2169691682c6fd3a77f460 Mon Sep 17 00:00:00 2001
From: Jakob Borg <jakob@kastelo.net>
Date: Sun, 6 Apr 2025 05:31:02 -0700
Subject: [PATCH] chore(model): delay starting a pull while there are incoming
 index updates (#10041)

This adds a simple delay to the process for starting the pull, by
default one second. In practice this means we're likely to wait for
initial index transfer, or multiple messages sent as part of a larger
change. This is better because we're more likely to have the whole
change for the purpose of handling renames etc, and also it's more
efficient to do one larger puller iteration instead of multiple while
also processing changes.

It does however introduce a certain amount of delay into the sync
process, so it can be tuned down or turned off entirely.
---
 lib/config/config_test.go         |  2 ++
 lib/config/folderconfiguration.go |  1 +
 lib/model/folder.go               | 13 +++++++++++++
 lib/model/testutils_test.go       |  1 +
 4 files changed, 17 insertions(+)

diff --git a/lib/config/config_test.go b/lib/config/config_test.go
index 27a6d8546..daf50eb57 100644
--- a/lib/config/config_test.go
+++ b/lib/config/config_test.go
@@ -108,6 +108,7 @@ func TestDefaultValues(t *testing.T) {
 				FSWatcherEnabled: true,
 				FSWatcherDelayS:  10,
 				IgnorePerms:      false,
+				PullerDelayS:     1,
 				AutoNormalize:    true,
 				MinDiskFree:      size,
 				Versioning: VersioningConfiguration{
@@ -184,6 +185,7 @@ func TestDeviceConfig(t *testing.T) {
 				FSWatcherDelayS:  10,
 				Copiers:          0,
 				Hashers:          0,
+				PullerDelayS:     1,
 				AutoNormalize:    true,
 				MinDiskFree:      Size{1, "%"},
 				MaxConflicts:     -1,
diff --git a/lib/config/folderconfiguration.go b/lib/config/folderconfiguration.go
index 1bfc898db..9d4876dde 100644
--- a/lib/config/folderconfiguration.go
+++ b/lib/config/folderconfiguration.go
@@ -68,6 +68,7 @@ type FolderConfiguration struct {
 	IgnoreDelete            bool                        `json:"ignoreDelete" xml:"ignoreDelete"`
 	ScanProgressIntervalS   int                         `json:"scanProgressIntervalS" xml:"scanProgressIntervalS"`
 	PullerPauseS            int                         `json:"pullerPauseS" xml:"pullerPauseS"`
+	PullerDelayS            float64                     `json:"pullerDelayS" xml:"pullerDelayS" default:"1"`
 	MaxConflicts            int                         `json:"maxConflicts" xml:"maxConflicts" default:"10"`
 	DisableSparseFiles      bool                        `json:"disableSparseFiles" xml:"disableSparseFiles"`
 	DisableTempIndexes      bool                        `json:"disableTempIndexes" xml:"disableTempIndexes"`
diff --git a/lib/model/folder.go b/lib/model/folder.go
index 05a5b1032..10f2ac40c 100644
--- a/lib/model/folder.go
+++ b/lib/model/folder.go
@@ -173,6 +173,8 @@ func (f *folder) Serve(ctx context.Context) error {
 	}
 
 	initialCompleted := f.initialScanFinished
+	pullTimer := time.NewTimer(0)
+	pullTimer.Stop()
 
 	for {
 		var err error
@@ -183,6 +185,17 @@ func (f *folder) Serve(ctx context.Context) error {
 			return nil
 
 		case <-f.pullScheduled:
+			if f.PullerDelayS > 0 {
+				// Wait for incoming updates to settle before doing the
+				// actual pull
+				f.setState(FolderSyncWaiting)
+				pullTimer.Reset(time.Duration(float64(time.Second) * f.PullerDelayS))
+			} else {
+				_, err = f.pull()
+			}
+
+		case <-pullTimer.C:
+			f.setState(FolderIdle)
 			_, err = f.pull()
 
 		case <-f.pullFailTimer.C:
diff --git a/lib/model/testutils_test.go b/lib/model/testutils_test.go
index 7949bc617..8d6140ec5 100644
--- a/lib/model/testutils_test.go
+++ b/lib/model/testutils_test.go
@@ -103,6 +103,7 @@ func newDefaultCfgWrapper() (config.Wrapper, config.FolderConfiguration, context
 func newFolderConfig() config.FolderConfiguration {
 	cfg := newFolderConfiguration(defaultCfgWrapper, "default", "default", config.FilesystemTypeFake, rand.String(32)+"?content=true")
 	cfg.FSWatcherEnabled = false
+	cfg.PullerDelayS = 0
 	cfg.Devices = append(cfg.Devices, config.FolderDeviceConfiguration{DeviceID: device1})
 	return cfg
 }