Ensure WebKit web process cleanup.

This change manually removes the connected signal by their id for
gotk3 and go-webkit2 objects for HTML pages when a tab is closed.
This prevents a leak where connected signals can prevent finalizers
from running (see conformal/gotk3#55).

Also, rather than waiting for the glib.Object finalizer on each
wk2.WebView (which may take up to 3 minutes before the Go GC runs),
explicitly .Destroy() the webview widget.  This causes the
WebKitWebProcess to be immediately closed.

pages.go

@@ -8,6 +8,7 @@ import (
  "fmt"
 
  "github.com/conformal/gotk3/gdk"
+ "github.com/conformal/gotk3/glib"
  "github.com/conformal/gotk3/gtk"
  "github.com/conformal/gotk3/pango"
  "github.com/jrick/go-webkit2/wk2"
@@ -158,6 +159,15 @@ func (p *PageManager) openNewPage(page Page) int {
  switch page := page.(type) {
  case *HTMLPage:
  delete(p.htmls, page.Native())
+
+ for _, s := range page.signals {
+ s.Object.HandlerDisconnect(s.SignalHandle)
+ }
+
+ // Do not wait for the garbage collector to finalize
+ // the webview and reap the web process.
+ page.wv.Destroy()
+
  case *DownloadsPage:
  p.downloads = nil
  case *SettingsPage:
@@ -209,6 +219,7 @@ type HTMLPage struct {
  navbar *NavigationBar
  wv *wk2.WebView
  crash *gtk.Label
+ signals []objectSignal
 }
 
 // BlankPage is the description for an empty HTML page.
@@ -243,10 +254,17 @@ func (d HTMLPageDescription) newHTMLPage() *HTMLPage {
  stack.AddNamed(crash, "crash")
  stack.SetVisibleChild(crash)
 
- page := &HTMLPage{stack, "New Tab", string(d), title, navbar, wv, crash}
+ page := &HTMLPage{Stack: stack,
+ title: "New Tab",
+ uri: string(d),
+ titleLabel: title,
+ navbar: navbar,
+ wv: wv,
+ crash: crash,
+ }
 
- page.connectNavbarSignals()
- page.connectWebViewSignals()
+ page.signals = append(page.signals, page.connectNavbarSignals()...)
+ page.signals = append(page.signals, page.connectWebViewSignals()...)
 
  page.setURI(string(d))
 
@@ -257,7 +275,12 @@ func (d HTMLPageDescription) newHTMLPage() *HTMLPage {
  return page
 }
 
-func (p *HTMLPage) connectNavbarSignals() {
+type objectSignal struct {
+ *glib.Object
+ glib.SignalHandle
+}
+
+func (p *HTMLPage) connectNavbarSignals() (signals []objectSignal) {
  // BUG: GTK does not set the correct actual GValue type for a GtkEntry
  // when marshaling values for a GClosure connecting to the "activate"
  // signal. Attempting to use a *gtk.Entry as the first argument to this
@@ -266,15 +289,16 @@ func (p *HTMLPage) connectNavbarSignals() {
  //
  // See https://bugzilla.gnome.org/show_bug.cgi?id=727678 for more
  // details.
- p.navbar.uriEntry.Connect("activate", func() {
+ h, _ := p.navbar.uriEntry.Connect("activate", func() {
  uri, _ := p.navbar.uriEntry.GetText()
  p.LoadURI(uri)
  p.wv.GrabFocus()
  })
+ signals = append(signals, objectSignal{p.navbar.uriEntry.Object, h})
 
  editing := false
 
- p.navbar.uriEntry.Connect("button-release-event", func(e *gtk.Entry) {
+ h, _ = p.navbar.uriEntry.Connect("button-release-event", func(e *gtk.Entry) {
  _, _, hasSelection := e.GetSelectionBounds()
  if !editing && !hasSelection {
  // TODO: Show icon to clear all text instead. Selecting
@@ -288,21 +312,24 @@ func (p *HTMLPage) connectNavbarSignals() {
  // was moved away from the widget before releasing.
  editing = true
  })
+ signals = append(signals, objectSignal{p.navbar.uriEntry.Object, h})
 
- p.navbar.uriEntry.Connect("notify::is-focus", func(e *gtk.Entry) {
+ h, _ = p.navbar.uriEntry.Connect("notify::is-focus", func(e *gtk.Entry) {
  if !e.IsFocus() {
  e.SelectRegion(0, 0)
  editing = false
  }
  })
+ signals = append(signals, objectSignal{p.navbar.uriEntry.Object, h})
 
  iconPressFn := func(e *gtk.Entry, p gtk.EntryIconPosition, ev *gdk.Event) {
  }
- p.navbar.uriEntry.Connect("icon-press", iconPressFn)
+ h, _ = p.navbar.uriEntry.Connect("icon-press", iconPressFn)
+ return append(signals, objectSignal{p.navbar.uriEntry.Object, h})
 }
 
-func (p *HTMLPage) connectWebViewSignals() {
- p.wv.Connect("load-changed", func(wv *wk2.WebView, e wk2.LoadEvent) {
+func (p *HTMLPage) connectWebViewSignals() (signals []objectSignal) {
+ h, _ := p.wv.Connect("load-changed", func(wv *wk2.WebView, e wk2.LoadEvent) {
  switch e {
  case wk2.LoadStarted:
  case wk2.LoadRedirected:
@@ -311,8 +338,9 @@ func (p *HTMLPage) connectWebViewSignals() {
  p.navbar.uriEntry.SetProgressFraction(0)
  }
  })
+ signals = append(signals, objectSignal{p.wv.Object, h})
 
- p.wv.Connect("load-failed", func(wv *wk2.WebView, e wk2.LoadEvent) {
+ h, _ = p.wv.Connect("load-failed", func(wv *wk2.WebView, e wk2.LoadEvent) {
  p.navbar.uriEntry.SetProgressFraction(0)
  switch e {
  case wk2.LoadStarted:
@@ -321,28 +349,33 @@ func (p *HTMLPage) connectWebViewSignals() {
  case wk2.LoadFinished:
  }
  })
+ signals = append(signals, objectSignal{p.wv.Object, h})
 
- p.wv.Connect("web-process-crashed", func() {
+ h, _ = p.wv.Connect("web-process-crashed", func() {
  p.crash.Show()
  p.SetVisibleChild(p.crash)
  })
+ signals = append(signals, objectSignal{p.wv.Object, h})
 
- p.wv.Connect("notify::estimated-load-progress", func() {
+ h, _ = p.wv.Connect("notify::estimated-load-progress", func() {
  if HTMLPageDescription(p.uri) != BlankPage {
  progress := p.wv.EstimatedLoadProgress()
  p.navbar.uriEntry.SetProgressFraction(progress)
  }
  })
+ signals = append(signals, objectSignal{p.wv.Object, h})
 
- p.wv.Connect("notify::uri", func() {
+ h, _ = p.wv.Connect("notify::uri", func() {
  if !p.navbar.uriEntry.IsFocus() {
  p.setURI(p.wv.URI())
  }
  })
+ signals = append(signals, objectSignal{p.wv.Object, h})
 
- p.wv.Connect("notify::title", func() {
+ h, _ = p.wv.Connect("notify::title", func() {
  p.setTitle(p.wv.Title())
  })
+ return append(signals, objectSignal{p.wv.Object, h})
 }
 
 // LoadURI begins loading the page's WebView with the URI described by uri.