libsysprof-analyze: break out string helper

We'll want strings to be deduplicated a bunch, and may need to pass this
around to make that a bit easier to ensure.

src/libsysprof-analyze/sysprof-strings.c

@@ -0,0 +1,96 @@
+/* sysprof-strings.c
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "config.h"
+
+#include "sysprof-strings-private.h"
+
+struct _SysprofStrings
+{
+  GMutex      mutex;
+  GHashTable *hashtable;
+};
+
+SysprofStrings *
+sysprof_strings_new (void)
+{
+  SysprofStrings *self;
+
+  self = g_atomic_rc_box_new0 (SysprofStrings);
+  g_mutex_init (&self->mutex);
+  self->hashtable = g_hash_table_new_full (g_str_hash,
+                                           g_str_equal,
+                                           (GDestroyNotify)g_ref_string_release,
+                                           NULL);
+
+  return self;
+}
+
+SysprofStrings *
+sysprof_strings_ref (SysprofStrings *self)
+{
+  return g_atomic_rc_box_acquire (self);
+}
+
+static void
+sysprof_strings_finalize (gpointer data)
+{
+  SysprofStrings *self = data;
+
+  g_mutex_clear (&self->mutex);
+  g_clear_pointer (&self->hashtable, g_hash_table_unref);
+}
+
+void
+sysprof_strings_unref (SysprofStrings *self)
+{
+  g_atomic_rc_box_release_full (self, sysprof_strings_finalize);
+}
+
+GRefString *
+sysprof_strings_get (SysprofStrings *self,
+                     const char     *string)
+{
+  GRefString *ret;
+
+  g_mutex_lock (&self->mutex);
+  if (!(ret = g_hash_table_lookup (self->hashtable, string)))
+    {
+      ret = g_ref_string_new (string);
+      g_hash_table_insert (self->hashtable, ret, ret);
+    }
+  g_ref_string_acquire (ret);
+  g_mutex_unlock (&self->mutex);
+
+  return ret;
+}
+
+GRefString *
+sysprof_strings_lookup (SysprofStrings *self,
+                        const char     *string)
+{
+  GRefString *ret;
+
+  g_mutex_lock (&self->mutex);
+  ret = g_hash_table_lookup (self->hashtable, string);
+  g_mutex_unlock (&self->mutex);
+
+  return ret;
+}