[tracker-miners/wip/carlosg/speed-track: 13/40] libtracker-miner: Add private object to hold LRU queue

[Carlos Garnacho <carlosg src gnome org>]

commit 64b646d85018a7d0f9fb1581b5919b009422f24b
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Oct 4 20:28:02 2020 +0200

    libtracker-miner: Add private object to hold LRU queue
    
    This is a generic LRU, that we'll use for our convenience.

 src/libtracker-miner/meson.build   |   1 +
 src/libtracker-miner/tracker-lru.c | 181 +++++++++++++++++++++++++++++++++++++
 src/libtracker-miner/tracker-lru.h |  51 +++++++++++
 3 files changed, 233 insertions(+)
---
diff --git a/src/libtracker-miner/meson.build b/src/libtracker-miner/meson.build
index a22662381..540239c61 100644
--- a/src/libtracker-miner/meson.build
+++ b/src/libtracker-miner/meson.build
@@ -10,6 +10,7 @@ private_sources = [
     'tracker-file-data-provider.c',
     'tracker-file-notifier.c',
     'tracker-file-system.c',
+    'tracker-lru.c',
     'tracker-monitor.c',
     'tracker-priority-queue.c',
     'tracker-task-pool.c',
diff --git a/src/libtracker-miner/tracker-lru.c b/src/libtracker-miner/tracker-lru.c
new file mode 100644
index 000000000..629b159b2
--- /dev/null
+++ b/src/libtracker-miner/tracker-lru.c
@@ -0,0 +1,181 @@
+/*
+ * Copyright (C) 2020, Red Hat Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301, USA.
+ *
+ * Author: Carlos Garnacho  <carlosg gnome org>
+ */
+
+#include "config-miners.h"
+
+#include "tracker-lru.h"
+
+typedef struct _TrackerLRUElement TrackerLRUElement;
+
+struct _TrackerLRUElement {
+       gpointer element;
+       gpointer data;
+       GList *link;
+};
+
+struct _TrackerLRU {
+       GQueue queue;
+       GHashTable *items;
+       GDestroyNotify elem_destroy;
+       GDestroyNotify data_destroy;
+       guint max_size;
+       gint ref_count;
+};
+
+static void
+free_node (TrackerLRUElement *node,
+           TrackerLRU        *lru)
+{
+       g_hash_table_remove (lru->items, node->element);
+       lru->elem_destroy (node->element);
+       lru->data_destroy (node->data);
+       g_slice_free (TrackerLRUElement, node);
+}
+
+TrackerLRU *
+tracker_lru_new (guint                size,
+                 GHashFunc            elem_hash_func,
+                 GEqualFunc           elem_equal_func,
+                 GDestroyNotify       elem_destroy,
+                 GDestroyNotify       data_destroy)
+{
+       TrackerLRU *lru;
+
+       lru = g_new0 (TrackerLRU, 1);
+       g_queue_init (&lru->queue);
+       lru->max_size = size;
+       lru->elem_destroy = elem_destroy;
+       lru->data_destroy = data_destroy;
+       lru->items = g_hash_table_new (elem_hash_func,
+                                      elem_equal_func);
+       lru->ref_count = 1;
+
+       return lru;
+}
+
+TrackerLRU *
+tracker_lru_ref (TrackerLRU *lru)
+{
+       g_atomic_int_inc (&lru->ref_count);
+       return lru;
+}
+
+void
+tracker_lru_unref (TrackerLRU *lru)
+{
+       if (g_atomic_int_dec_and_test (&lru->ref_count)) {
+               TrackerLRUElement *node;
+               GHashTableIter iter;
+
+               g_hash_table_iter_init (&iter, lru->items);
+
+               while (g_hash_table_iter_next (&iter, NULL, (gpointer *) &node)) {
+                       g_hash_table_iter_remove (&iter);
+                       free_node (node, lru);
+               }
+
+               g_hash_table_unref (lru->items);
+               g_queue_clear (&lru->queue);
+               g_free (lru);
+       }
+}
+
+gboolean
+tracker_lru_find (TrackerLRU *lru,
+                  gpointer    elem,
+                  gpointer   *data)
+{
+       TrackerLRUElement *node;
+
+       node = g_hash_table_lookup (lru->items, elem);
+       if (!node)
+               return FALSE;
+
+       if (data)
+               *data = node->data;
+
+       if (node->link != lru->queue.head) {
+               /* Push to head */
+               g_queue_unlink (&lru->queue, node->link);
+               g_queue_push_head_link (&lru->queue, node->link);
+       }
+
+       return TRUE;
+}
+
+void
+tracker_lru_add (TrackerLRU *lru,
+                 gpointer    elem,
+                 gpointer    data)
+{
+       TrackerLRUElement *node, *last;
+
+       node = g_slice_new0 (TrackerLRUElement);
+       node->element = elem;
+       node->data = data;
+       node->link = g_list_alloc ();
+       node->link->data = node;
+
+       g_queue_push_head_link (&lru->queue, node->link);
+
+       g_hash_table_insert (lru->items, elem, node);
+
+       if (g_hash_table_size (lru->items) > lru->max_size) {
+               /* Remove last element */
+               last = g_queue_pop_tail (&lru->queue);
+               free_node (last, lru);
+       }
+}
+
+void
+tracker_lru_remove (TrackerLRU *lru,
+                    gpointer    elem)
+{
+       TrackerLRUElement *node;
+
+       node = g_hash_table_lookup (lru->items, elem);
+       if (!node)
+               return;
+
+       g_queue_remove (&lru->queue, node->link);
+       free_node (node, lru);
+}
+
+void
+tracker_lru_remove_foreach (TrackerLRU *lru,
+                            GEqualFunc  equal_func,
+                            gpointer    elem)
+{
+       TrackerLRUElement *node;
+       GList *next, *link = lru->queue.head;
+
+       while (link) {
+               node = link->data;
+               next = link->next;
+
+               if (equal_func (node->element, elem) == TRUE) {
+                       g_queue_unlink (&lru->queue, node->link);
+                       free_node (node, lru);
+               }
+
+               link = next;
+       }
+}
diff --git a/src/libtracker-miner/tracker-lru.h b/src/libtracker-miner/tracker-lru.h
new file mode 100644
index 000000000..f9afec64f
--- /dev/null
+++ b/src/libtracker-miner/tracker-lru.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2020, Red Hat Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301, USA.
+ *
+ * Author: Carlos Garnacho  <carlosg gnome org>
+ */
+#ifndef __TRACKER_LRU_H__
+#define __TRACKER_LRU_H__
+
+#include <glib.h>
+
+typedef struct _TrackerLRU TrackerLRU;
+
+TrackerLRU * tracker_lru_new (guint                size,
+                              GHashFunc            elem_hash_func,
+                              GEqualFunc           elem_equal_func,
+                              GDestroyNotify       elem_destroy,
+                              GDestroyNotify       data_destroy);
+
+TrackerLRU *tracker_lru_ref (TrackerLRU *lru);
+void tracker_lru_unref (TrackerLRU *lru);
+
+gboolean tracker_lru_find (TrackerLRU *lru,
+                           gpointer    elem,
+                           gpointer   *data);
+
+void tracker_lru_add (TrackerLRU *lru,
+                      gpointer    elem,
+                      gpointer    data);
+void tracker_lru_remove (TrackerLRU *lru,
+                         gpointer    elem);
+
+void tracker_lru_remove_foreach (TrackerLRU *lru,
+                                 GEqualFunc  compare_func,
+                                 gpointer    elem);
+
+#endif /* __TRACKER_LRU_H__ */