[gnome-books/wip/carlosg/tracker3: 5/7] changeMonitor: Rewrite to use TrackerNotifier

[Carlos Garnacho <carlosg src gnome org>]

commit 5158278245d2ead155876153488e605dbaa63e80
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Jan 17 17:02:04 2021 +0100

    changeMonitor: Rewrite to use TrackerNotifier
    
    The GraphUpdated DBus signal became superseded by TrackerNotifier
    in 2.x, and completely removed on 3.x. Use TrackerNotifier here
    for event tracking.

 src/changeMonitor.js | 160 ++++++---------------------------------------------
 1 file changed, 18 insertions(+), 142 deletions(-)
---
diff --git a/src/changeMonitor.js b/src/changeMonitor.js
index a9e3a5ba..ec9d8a02 100644
--- a/src/changeMonitor.js
+++ b/src/changeMonitor.js
@@ -23,176 +23,52 @@ const Gio = imports.gi.Gio;
 const Lang = imports.lang;
 const Mainloop = imports.mainloop;
 const Signals = imports.signals;
+const Tracker = imports.gi.Tracker;
 
 const Application = imports.application;
 
-const TrackerResourcesServiceIface = '<node> \
-<interface name="org.freedesktop.Tracker1.Resources"> \
-    <signal name="GraphUpdated"> \
-        <arg name="className" type="s" /> \
-        <arg name="deleteEvents" type="a(iiii)" /> \
-        <arg name="insertEvents" type="a(iiii)" /> \
-    </signal> \
-</interface> \
-</node>';
-
-var TrackerResourcesServiceProxy = Gio.DBusProxy.makeProxyWrapper(TrackerResourcesServiceIface);
-function TrackerResourcesService() {
-    return new TrackerResourcesServiceProxy(Gio.DBus.session,
-                                            'org.freedesktop.Tracker1',
-                                            '/org/freedesktop/Tracker1/Resources');
-}
-
-var ChangeEventType = {
-    CHANGED: 0,
-    CREATED: 1,
-    DELETED: 2
-};
-
-const _RDF_TYPE = "http://www.w3.org/1999/02/22-rdf-syntax-ns#type";;
-
 const ChangeEvent = new Lang.Class({
     Name: 'ChangeEvent',
 
-    _init: function(urnId, predicateId, isDelete) {
-        this.urnId = urnId;
-        this.predicateId = predicateId;
-
-        if (isDelete)
-            this.type = ChangeEventType.DELETED;
-        else
-            this.type = ChangeEventType.CREATED;
-    },
-
-    setResolvedValues: function(urn, predicate) {
+    _init: function(type, urn) {
         this.urn = urn;
-        this.predicate = predicate;
 
-        if (predicate != _RDF_TYPE)
+        if (type == Tracker.NotifierEventType.CREATE)
+            this.type = ChangeEventType.CREATED;
+        else if (type == Tracker.NotifierEventType.DELETE)
+            this.type = ChangeEventType.DELETED;
+        else if (type == Tracker.NotifierEventType.UPDATE)
             this.type = ChangeEventType.CHANGED;
-    },
-
-    merge: function(event) {
-        // deletions or creations override the current type
-        if (event.type == ChangeEventType.DELETED ||
-            event.type == ChangeEventType.CREATED) {
-            this.type = event.type;
-        }
     }
 });
 
-const CHANGE_MONITOR_TIMEOUT = 500; // msecs
-const CHANGE_MONITOR_MAX_ITEMS = 500; // items
-
 var TrackerChangeMonitor = new Lang.Class({
     Name: 'TrackerChangeMonitor',
 
     _init: function() {
         this._pendingChanges = {};
-        this._unresolvedIds = {};
 
         this._pendingEvents = [];
         this._pendingEventsId = 0;
 
-        this._resourceService = new TrackerResourcesService();
-        this._resourceService.connectSignal('GraphUpdated', Lang.bind(this, this._onGraphUpdated));
-    },
-
-    _onGraphUpdated: function(proxy, senderName, [className, deleteEvents, insertEvents]) {
-        deleteEvents.forEach(Lang.bind(this,
-            function(event) {
-                this._addPendingEvent(event, true);
-            }));
-
-        insertEvents.forEach(Lang.bind(this,
-            function(event) {
-                this._addPendingEvent(event, false);
-            }));
-    },
-
-    _addPendingEvent: function(event, isDelete) {
-        if (this._pendingEventsId != 0)
-            Mainloop.source_remove(this._pendingEventsId);
-
-        this._unresolvedIds[event[1]] = event[1];
-        this._unresolvedIds[event[2]] = event[2];
-        this._pendingEvents.push(new ChangeEvent(event[1], event[2], isDelete));
-
-        if (this._pendingEvents.length >= CHANGE_MONITOR_MAX_ITEMS)
-            this._processEvents();
-        else
-            this._pendingEventsId =
-                Mainloop.timeout_add(CHANGE_MONITOR_TIMEOUT, Lang.bind(this, this._processEvents));
-    },
-
-    _processEvents: function() {
-        let events = this._pendingEvents;
-        let idTable = this._unresolvedIds;
-
-        this._pendingEventsId = 0;
-        this._pendingEvents = [];
-        this._unresolvedIds = {};
-
-        let sparql = 'SELECT';
-        Object.keys(idTable).forEach(Lang.bind(this,
-            function(unresolvedId) {
-                sparql += (' tracker:uri(%d)').format(unresolvedId);
-            }));
-        sparql += ' {}';
-
-        // resolve all the unresolved IDs we got so far
-        Application.connectionQueue.add(sparql, null, Lang.bind(this,
-            function(object, res) {
-                let cursor = object.query_finish(res);
-
-                cursor.next_async(null, Lang.bind(this,
-                    function(object, res) {
-                        let valid = false;
-                        try {
-                            valid = cursor.next_finish(res);
-                        } catch(e) {
-                            logError(e, 'Unable to resolve item URNs for graph changes');
-                        }
-
-                        if (valid) {
-                            let idx = 0;
-                            Object.keys(idTable).forEach(Lang.bind(this,
-                                function(unresolvedId) {
-                                    idTable[unresolvedId] = cursor.get_string(idx)[0];
-                                    idx++;
-                                }));
-
-                            this._sendEvents(events, idTable);
-                        }
-
-                        cursor.close();
-                    }));
-            }));
-
-        return false;
+        this._notifier = Application.connection.create_notifier();
+        this._notifier.signal_subscribe(Gio.DBus.session,
+                                        'org.freedesktop.Tracker3.Miner.Files',
+                                        null, 'tracker:Documents');
+        this._notifier.connect('events', Lang.bind(this, this._onNotifierEvents));
     },
 
-    _addEvent: function(event) {
-        let urn = event.urn;
-        let oldEvent = this._pendingChanges[urn];
+    _onNotifierEvents: function(notifier, service, graph, events) {
+        let pendingChanges = {};
 
-        if (oldEvent != null) {
-            oldEvent.merge(event);
-            this._pendingChanges[urn] = oldEvent;
-        } else {
-            this._pendingChanges[urn] = event;
-        }
-    },
-
-    _sendEvents: function(events, idTable) {
         events.forEach(Lang.bind(this,
             function(event) {
-                event.setResolvedValues(idTable[event.urnId], idTable[event.predicateId]);
-                this._addEvent(event);
+                let urn = event.get_urn();
+                let changeEvent = new ChangeEvent(urn, event.get_type());
+                pendingEvents[urn] = changeEvent;
             }));
 
-        this.emit('changes-pending', this._pendingChanges);
-        this._pendingChanges = {};
+        this.emit('changes-pending', event);
     }
 });
 Signals.addSignalMethods(TrackerChangeMonitor.prototype);