From 8947adc312917ee47d091e716d6493e19df1bf5d Mon Sep 17 00:00:00 2001
From: Ben Johnson <benbjohnson@yahoo.com>
Date: Sat, 6 Mar 2021 08:33:19 -0700
Subject: [PATCH] Expose additional DB configuration settings

This commit exposes the monitor interval, checkpoint interval,
minimum checkpoint page count, and maximum checkpoint page count
via the YAML configuration file.
---
 cmd/litestream/main.go | 21 ++++++++++++++++++++-
 db.go                  |  5 +++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/cmd/litestream/main.go b/cmd/litestream/main.go
index fca5472..2a146d3 100644
--- a/cmd/litestream/main.go
+++ b/cmd/litestream/main.go
@@ -208,7 +208,12 @@ func ReadConfigFile(filename string) (_ Config, err error) {
 
 // DBConfig represents the configuration for a single database.
 type DBConfig struct {
-	Path     string           `yaml:"path"`
+	Path               string         `yaml:"path"`
+	MonitorInterval    *time.Duration `yaml:"monitor-interval"`
+	CheckpointInterval *time.Duration `yaml:"checkpoint-interval"`
+	MinCheckpointPageN *int           `yaml:"min-checkpoint-page-count"`
+	MaxCheckpointPageN *int           `yaml:"max-checkpoint-page-count"`
+
 	Replicas []*ReplicaConfig `yaml:"replicas"`
 }
 
@@ -222,6 +227,20 @@ func NewDBFromConfig(dbc *DBConfig) (*litestream.DB, error) {
 	// Initialize database with given path.
 	db := litestream.NewDB(path)
 
+	// Override default database settings if specified in configuration.
+	if dbc.MonitorInterval != nil {
+		db.MonitorInterval = *dbc.MonitorInterval
+	}
+	if dbc.CheckpointInterval != nil {
+		db.CheckpointInterval = *dbc.CheckpointInterval
+	}
+	if dbc.MinCheckpointPageN != nil {
+		db.MinCheckpointPageN = *dbc.MinCheckpointPageN
+	}
+	if dbc.MaxCheckpointPageN != nil {
+		db.MaxCheckpointPageN = *dbc.MaxCheckpointPageN
+	}
+
 	// Instantiate and attach replicas.
 	for _, rc := range dbc.Replicas {
 		r, err := NewReplicaFromConfig(rc, db)
diff --git a/db.go b/db.go
index 081ec9d..73b9ea9 100644
--- a/db.go
+++ b/db.go
@@ -260,6 +260,11 @@ func (db *DB) PageSize() int {
 
 // Open initializes the background monitoring goroutine.
 func (db *DB) Open() (err error) {
+	// Validate fields on database.
+	if db.MinCheckpointPageN <= 0 {
+		return fmt.Errorf("minimum checkpoint page count required")
+	}
+
 	// Validate that all replica names are unique.
 	m := make(map[string]struct{})
 	for _, r := range db.Replicas {