[epiphany/gnome-3-28] Snapshot only the most-visited pages

[Michael Catanzaro <mcatanzaro src gnome org>]

commit db2adc77aead2264862ac0272dca1ea0596feea8
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Sun Mar 25 23:11:28 2018 -0500

    Snapshot only the most-visited pages
    
    My ~/.cache/epiphany/thumbnails is 287 MB large, and this directory did
    not exist at all until a couple months ago. It's also pretty bad for
    privacy that we currently save a PNG snapshot of every webpage ever
    visited on disk, even if we make an effort to delete them when removing
    history.
    
    Let's take snapshots only for the top 14 pages in history. The cache can
    still grow without bound, but it should never become very large with
    this limitation.

 embed/ephy-web-view.c |   70 +++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 62 insertions(+), 8 deletions(-)
---
diff --git a/embed/ephy-web-view.c b/embed/ephy-web-view.c
index 50de188..a8cbb9d 100644
--- a/embed/ephy-web-view.c
+++ b/embed/ephy-web-view.c
@@ -111,6 +111,7 @@ struct _EphyWebView {
   GCancellable *history_service_cancellable;
 
   guint snapshot_timeout_id;
+  char *pending_snapshot_uri;
 
   EphyHistoryPageVisitType visit_type;
 
@@ -628,21 +629,71 @@ got_snapshot_path_cb (EphySnapshotService *service,
   g_free (url);
 }
 
-static gboolean
-web_view_check_snapshot (WebKitWebView *web_view)
+static void
+take_snapshot (EphyWebView *view)
 {
-  EphyWebView *view = EPHY_WEB_VIEW (web_view);
   EphySnapshotService *service = ephy_snapshot_service_get_default ();
-  const char *url = webkit_web_view_get_uri (web_view);
+
+  ephy_snapshot_service_get_snapshot_path_async (service, WEBKIT_WEB_VIEW (view), NULL,
+                                                 (GAsyncReadyCallback)got_snapshot_path_cb,
+                                                 g_strdup (view->pending_snapshot_uri));
+}
+
+static void
+history_service_query_urls_cb (EphyHistoryService *service,
+                               gboolean            success,
+                               GList              *urls,
+                               EphyWebView        *view)
+{
+  const char *url = webkit_web_view_get_uri (WEBKIT_WEB_VIEW (view));
+
+  if (!success)
+    goto out;
+
+  /* Have we already started a new load? */
+  if (strcmp (url, view->pending_snapshot_uri) != 0)
+    goto out;
+
+  for (GList *l = urls; l; l = g_list_next (l)) {
+    EphyHistoryURL *history_url = l->data;
+
+    /* Take snapshot if this URL is one of the top history results. */
+    if (strcmp (history_url->url, view->pending_snapshot_uri) == 0) {
+      take_snapshot (view);
+      break;
+    }
+  }
+
+out:
+  g_clear_pointer (&view->pending_snapshot_uri, g_free);
+  g_object_unref (view);
+}
+
+static gboolean
+maybe_take_snapshot (EphyWebView *view)
+{
+  EphyEmbedShell *shell;
+  EphyHistoryService *service;
+  EphyHistoryQuery *query;
 
   view->snapshot_timeout_id = 0;
 
   if (view->error_page != EPHY_WEB_VIEW_ERROR_PAGE_NONE)
     return FALSE;
 
-  ephy_snapshot_service_get_snapshot_path_async (service, web_view, NULL,
-                                                 (GAsyncReadyCallback)got_snapshot_path_cb,
-                                                 g_strdup (url));
+  shell = ephy_embed_shell_get_default ();
+  service = ephy_embed_shell_get_global_history_service (shell);
+
+  /* We want to save snapshots for just a couple more pages than are present
+   * in the overview, so new snapshots are immediately available when the user
+   * deletes a couple pages from the overview. Let's say five more.
+   */
+  query = ephy_history_query_new_for_overview ();
+  query->limit += 5;
+  ephy_history_service_query_urls (service, query, NULL,
+                                   (EphyHistoryJobCallback)history_service_query_urls_cb,
+                                   g_object_ref (view));
+  ephy_history_query_free (query);
 
   return FALSE;
 }
@@ -921,6 +972,7 @@ ephy_web_view_finalize (GObject *object)
   g_free (view->link_message);
   g_free (view->loading_message);
   g_free (view->tls_error_failing_uri);
+  g_free (view->pending_snapshot_uri);
 
   G_OBJECT_CLASS (ephy_web_view_parent_class)->finalize (object);
 }
@@ -1821,8 +1873,10 @@ load_changed_cb (WebKitWebView  *web_view,
          */
         if (view->snapshot_timeout_id == 0) {
           view->snapshot_timeout_id = g_timeout_add_seconds_full (G_PRIORITY_LOW, 1,
-                                                                  (GSourceFunc)web_view_check_snapshot,
+                                                                  (GSourceFunc)maybe_take_snapshot,
                                                                   web_view, NULL);
+          g_free (view->pending_snapshot_uri);
+          view->pending_snapshot_uri = g_strdup (webkit_web_view_get_uri (WEBKIT_WEB_VIEW (view)));
         }
       }