[ostree] fetcher: Track outstanding requests with a table

[Matthew Barnes <mbarnes src gnome org>]

commit e21188a24568a884c4a0b192dc2dc48a571b98b2
Author: Matthew Barnes <mbarnes redhat com>
Date:   Wed Sep 23 19:28:47 2015 -0400

    fetcher: Track outstanding requests with a table
    
    Track outstanding HTTP requests in a table for easier debugging.
    
    Also fixes a bug discussed in https://bugzilla.gnome.org/755224
    where the outstanding request counter was not decremented in the
    event of an error, which could result in the fetcher hitting its
    max request limit and locking up.
    
    The bug is fixed by removing the request struct from the table in
    pending_uri_free(), which is always called regardless of error,
    so the outstanding request count is always accurate.

 src/libostree/ostree-fetcher.c |   63 ++++++++++++++++++++++-----------------
 1 files changed, 35 insertions(+), 28 deletions(-)
---
diff --git a/src/libostree/ostree-fetcher.c b/src/libostree/ostree-fetcher.c
index fbfc0ae..904c580 100644
--- a/src/libostree/ostree-fetcher.c
+++ b/src/libostree/ostree-fetcher.c
@@ -58,30 +58,6 @@ typedef struct {
   GTask *task;
 } OstreeFetcherPendingURI;
 
-static int
-pending_task_compare (gconstpointer a,
-                      gconstpointer b,
-                      gpointer unused)
-{
-  gint priority_a = g_task_get_priority (G_TASK (a));
-  gint priority_b = g_task_get_priority (G_TASK (b));
-
-  return (priority_a == priority_b) ? 0 :
-         (priority_a < priority_b) ? -1 : 1;
-}
-
-static void
-pending_uri_free (OstreeFetcherPendingURI *pending)
-{
-  soup_uri_free (pending->uri);
-  g_clear_object (&pending->self);
-  g_clear_object (&pending->request);
-  g_clear_object (&pending->request_body);
-  g_free (pending->out_tmpfile);
-  g_clear_object (&pending->out_stream);
-  g_free (pending);
-}
-
 struct OstreeFetcher
 {
   GObject parent_instance;
@@ -101,13 +77,39 @@ struct OstreeFetcher
   guint total_requests;
 
   /* Queue for libsoup, see bgo#708591 */
-  gint outstanding;
   GQueue pending_queue;
+  GHashTable *outstanding;
   gint max_outstanding;
 };
 
 G_DEFINE_TYPE (OstreeFetcher, _ostree_fetcher, G_TYPE_OBJECT)
 
+static int
+pending_task_compare (gconstpointer a,
+                      gconstpointer b,
+                      gpointer unused)
+{
+  gint priority_a = g_task_get_priority (G_TASK (a));
+  gint priority_b = g_task_get_priority (G_TASK (b));
+
+  return (priority_a == priority_b) ? 0 :
+         (priority_a < priority_b) ? -1 : 1;
+}
+
+static void
+pending_uri_free (OstreeFetcherPendingURI *pending)
+{
+  g_hash_table_remove (pending->self->outstanding, pending);
+
+  soup_uri_free (pending->uri);
+  g_clear_object (&pending->self);
+  g_clear_object (&pending->request);
+  g_clear_object (&pending->request_body);
+  g_free (pending->out_tmpfile);
+  g_clear_object (&pending->out_stream);
+  g_free (pending);
+}
+
 static void
 _ostree_fetcher_finalize (GObject *object)
 {
@@ -124,6 +126,8 @@ _ostree_fetcher_finalize (GObject *object)
   while (!g_queue_is_empty (&self->pending_queue))
     g_object_unref (g_queue_pop_head (&self->pending_queue));
 
+  g_hash_table_destroy (self->outstanding);
+
   G_OBJECT_CLASS (_ostree_fetcher_parent_class)->finalize (object);
 }
 
@@ -199,6 +203,8 @@ _ostree_fetcher_init (OstreeFetcher *self)
   self->sending_messages = g_hash_table_new_full (NULL, NULL, NULL,
                                                   (GDestroyNotify)g_object_unref);
   self->output_stream_set = g_hash_table_new_full (NULL, NULL, NULL, (GDestroyNotify)g_object_unref);
+
+  self->outstanding = g_hash_table_new_full (NULL, NULL, NULL, NULL);
 }
 
 OstreeFetcher *
@@ -272,7 +278,7 @@ ostree_fetcher_process_pending_queue (OstreeFetcher *self)
 {
 
   while (g_queue_peek_head (&self->pending_queue) != NULL &&
-         self->outstanding < self->max_outstanding)
+         g_hash_table_size (self->outstanding) < self->max_outstanding)
     {
       GTask *task;
       OstreeFetcherPendingURI *pending;
@@ -283,7 +289,9 @@ ostree_fetcher_process_pending_queue (OstreeFetcher *self)
       pending = g_task_get_task_data (task);
       cancellable = g_task_get_cancellable (task);
 
-      self->outstanding++;
+      /* pending_uri_free() removes this. */
+      g_hash_table_add (self->outstanding, pending);
+
       soup_request_send_async (pending->request,
                                cancellable,
                                on_request_sent,
@@ -321,7 +329,6 @@ finish_stream (OstreeFetcherPendingURI *pending,
   /* Now that we've finished downloading, continue with other queued
    * requests.
    */
-  pending->self->outstanding--;
   ostree_fetcher_process_pending_queue (pending->self);
 
   if (stbuf.st_size < pending->content_length)