Tweak the database block cache size, and add config for it

internal/config/config.go

@@ -240,6 +240,7 @@ type OptionsConfiguration struct {
 	ProgressUpdateIntervalS int      `xml:"progressUpdateIntervalS" json:"progressUpdateIntervalS" default:"5"`
 	SymlinksEnabled         bool     `xml:"symlinksEnabled" json:"symlinksEnabled" default:"true"`
 	LimitBandwidthInLan     bool     `xml:"limitBandwidthInLan" json:"limitBandwidthInLan" default:"false"`
+	DatabaseBlockCacheMiB   int      `xml:"databaseBlockCacheMiB" json:"databaseBlockCacheMiB" default:"0"`
 }
 
 func (orig OptionsConfiguration) Copy() OptionsConfiguration {

internal/config/config_test.go

@@ -52,6 +52,7 @@ func TestDefaultValues(t *testing.T) {
 		ProgressUpdateIntervalS: 5,
 		SymlinksEnabled:         true,
 		LimitBandwidthInLan:     false,
+		DatabaseBlockCacheMiB:   0,
 	}
 
 	cfg := New(device1)
@@ -158,6 +159,7 @@ func TestOverriddenValues(t *testing.T) {
 		ProgressUpdateIntervalS: 10,
 		SymlinksEnabled:         false,
 		LimitBandwidthInLan:     true,
+		DatabaseBlockCacheMiB:   42,
 	}
 
 	cfg, err := Load("testdata/overridenvalues.xml", device1)

internal/config/testdata/overridenvalues.xml

@@ -23,5 +23,6 @@
         <progressUpdateIntervalS>10</progressUpdateIntervalS>
         <symlinksEnabled>false</symlinksEnabled>
         <limitBandwidthInLan>true</limitBandwidthInLan>
+        <databaseBlockCacheMiB>42</databaseBlockCacheMiB>
     </options>
 </configuration>