[gnome-remote-desktop] clipboard-rdp: Get rid of all WaitForMultipleObjects calls

[Jonas Ådahl <jadahl src gnome org>]

commit d0277fef2b81fe62e7ca5dcb12e0672a9d71ceca
Author: Pascal Nowack <Pascal Nowack gmx de>
Date:   Wed Aug 3 12:27:08 2022 +0200

    clipboard-rdp: Get rid of all WaitForMultipleObjects calls
    
    Replacing WaitForMultipleObjects() calls is not necessarily trivial and
    cannot be done with a general scheme.
    It depends on how, where, and in which context these calls are used.
    In clipboard-rdp, they are all used in the CLIPRDR thread, waiting for
    actions to complete on the main thread.
    
    So, in order to replace all WaitForMultipleObjects() calls here, use
    for each action its own boolean value.
    In addition to that, use the existing protocol_stopped boolean value to
    check, whether the clipboard instance is torn down.
    Use both variables (protocol_stopped, action) in a typical GCond-GMutex
    code fragment to replace each WaitForMultipleObjects() call here.

 src/grd-clipboard-rdp.c | 125 ++++++++++++++++++++++++++++++++----------------
 src/grd-clipboard-rdp.h |   1 -
 src/grd-session-rdp.c   |   3 +-
 3 files changed, 84 insertions(+), 45 deletions(-)
---
diff --git a/src/grd-clipboard-rdp.c b/src/grd-clipboard-rdp.c
index 6f3d44ce..4147fe29 100644
--- a/src/grd-clipboard-rdp.c
+++ b/src/grd-clipboard-rdp.c
@@ -79,7 +79,6 @@ struct _GrdClipboardRdp
 
   CliprdrServerContext *cliprdr_context;
   gboolean protocol_stopped;
-  HANDLE stop_event;
 
   gboolean relieve_filename_restriction;
 
@@ -125,21 +124,24 @@ struct _GrdClipboardRdp
   unsigned int pending_server_formats_drop_id;
   unsigned int client_request_abort_id;
 
+  GCond completion_cond;
+  GMutex completion_mutex;
+
   GMutex clip_data_entry_mutex;
   unsigned int clipboard_retrieval_id;
   unsigned int clipboard_destruction_id;
-  HANDLE completed_clip_data_entry_event;
+  gboolean completed_clip_data_entry;
 
   GMutex server_format_list_update_mutex;
   unsigned int server_format_list_update_id;
-  HANDLE completed_format_list_event;
+  gboolean completed_format_list;
 
   GMutex client_format_list_response_mutex;
   unsigned int client_format_list_response_id;
 
   GMutex server_format_data_request_mutex;
   unsigned int server_format_data_request_id;
-  HANDLE completed_format_data_request_event;
+  gboolean completed_format_data_request;
 };
 
 G_DEFINE_TYPE (GrdClipboardRdp, grd_clipboard_rdp, GRD_TYPE_CLIPBOARD)
@@ -871,7 +873,10 @@ grd_clipboard_rdp_submit_requested_server_content (GrdClipboard *clipboard,
   g_free (dst_data);
   g_free (request_context);
 
-  SetEvent (clipboard_rdp->completed_format_data_request_event);
+  g_mutex_lock (&clipboard_rdp->completion_mutex);
+  clipboard_rdp->completed_format_data_request = TRUE;
+  g_cond_signal (&clipboard_rdp->completion_cond);
+  g_mutex_unlock (&clipboard_rdp->completion_mutex);
 }
 
 /**
@@ -1008,7 +1013,10 @@ update_server_format_list (gpointer user_data)
   clipboard_rdp->server_format_list_update_id = 0;
   g_mutex_unlock (&clipboard_rdp->server_format_list_update_mutex);
 
-  SetEvent (clipboard_rdp->completed_format_list_event);
+  g_mutex_lock (&clipboard_rdp->completion_mutex);
+  clipboard_rdp->completed_format_list = TRUE;
+  g_cond_signal (&clipboard_rdp->completion_cond);
+  g_mutex_unlock (&clipboard_rdp->completion_mutex);
 
   return G_SOURCE_REMOVE;
 }
@@ -1037,7 +1045,6 @@ cliprdr_client_format_list (CliprdrServerContext      *cliprdr_context,
   GList *mime_type_tables = NULL;
   GrdMimeType mime_type;
   gboolean already_has_text_format = FALSE;
-  HANDLE events[2];
   uint32_t i;
 
   found_mime_types = g_hash_table_new (NULL, NULL);
@@ -1193,9 +1200,14 @@ cliprdr_client_format_list (CliprdrServerContext      *cliprdr_context,
                "without being able to response to last update first");
     }
 
-  events[0] = clipboard_rdp->stop_event;
-  events[1] = clipboard_rdp->completed_format_list_event;
-  WaitForMultipleObjects (2, events, FALSE, INFINITE);
+  g_mutex_lock (&clipboard_rdp->completion_mutex);
+  while (!clipboard_rdp->protocol_stopped &&
+         !clipboard_rdp->completed_format_list)
+    {
+      g_cond_wait (&clipboard_rdp->completion_cond,
+                   &clipboard_rdp->completion_mutex);
+    }
+  g_mutex_unlock (&clipboard_rdp->completion_mutex);
 
   if (clipboard_rdp->protocol_stopped)
     {
@@ -1203,7 +1215,9 @@ cliprdr_client_format_list (CliprdrServerContext      *cliprdr_context,
       return CHANNEL_RC_OK;
     }
 
-  ResetEvent (clipboard_rdp->completed_format_list_event);
+  g_assert (clipboard_rdp->completed_format_list);
+  clipboard_rdp->completed_format_list = FALSE;
+
   update_context = g_malloc0 (sizeof (ServerFormatListUpdateContext));
   update_context->clipboard_rdp = clipboard_rdp;
   update_context->mime_type_tables = mime_type_tables;
@@ -1306,7 +1320,10 @@ retrieve_current_clipboard (gpointer user_data)
   clipboard_rdp->clipboard_retrieval_id = 0;
   g_mutex_unlock (&clipboard_rdp->clip_data_entry_mutex);
 
-  SetEvent (clipboard_rdp->completed_clip_data_entry_event);
+  g_mutex_lock (&clipboard_rdp->completion_mutex);
+  clipboard_rdp->completed_clip_data_entry = TRUE;
+  g_cond_signal (&clipboard_rdp->completion_cond);
+  g_mutex_unlock (&clipboard_rdp->completion_mutex);
 
   return G_SOURCE_REMOVE;
 }
@@ -1332,7 +1349,6 @@ cliprdr_client_lock_clipboard_data (CliprdrServerContext              *cliprdr_c
   GrdClipboardRdp *clipboard_rdp = cliprdr_context->custom;
   uint32_t clip_data_id = lock_clipboard_data->clipDataId;
   g_autofree ClipDataEntry *entry = NULL;
-  HANDLE events[2];
 
   if (clipboard_rdp->protocol_stopped)
     return CHANNEL_RC_OK;
@@ -1352,7 +1368,9 @@ cliprdr_client_lock_clipboard_data (CliprdrServerContext              *cliprdr_c
       clipboard_rdp->clipboard_retrieval_context.entry_to_replace = entry;
     }
 
-  ResetEvent (clipboard_rdp->completed_clip_data_entry_event);
+  g_assert (clipboard_rdp->completed_clip_data_entry);
+  clipboard_rdp->completed_clip_data_entry = FALSE;
+
   entry = g_malloc0 (sizeof (ClipDataEntry));
   clipboard_rdp->clipboard_retrieval_context.entry = entry;
 
@@ -1361,13 +1379,20 @@ cliprdr_client_lock_clipboard_data (CliprdrServerContext              *cliprdr_c
     g_idle_add (retrieve_current_clipboard, clipboard_rdp);
   g_mutex_unlock (&clipboard_rdp->clip_data_entry_mutex);
 
-  events[0] = clipboard_rdp->stop_event;
-  events[1] = clipboard_rdp->completed_clip_data_entry_event;
-  WaitForMultipleObjects (2, events, FALSE, INFINITE);
+  g_mutex_lock (&clipboard_rdp->completion_mutex);
+  while (!clipboard_rdp->protocol_stopped &&
+         !clipboard_rdp->completed_clip_data_entry)
+    {
+      g_cond_wait (&clipboard_rdp->completion_cond,
+                   &clipboard_rdp->completion_mutex);
+    }
+  g_mutex_unlock (&clipboard_rdp->completion_mutex);
 
   if (clipboard_rdp->protocol_stopped)
     return CHANNEL_RC_OK;
 
+  g_assert (clipboard_rdp->completed_clip_data_entry);
+
   if (clipboard_rdp->clipboard_retrieval_context.serial_already_in_use)
     {
       uint64_t serial = entry->serial;
@@ -1409,7 +1434,10 @@ handle_clip_data_entry_destruction (gpointer user_data)
   clipboard_rdp->clipboard_destruction_id = 0;
   g_mutex_unlock (&clipboard_rdp->clip_data_entry_mutex);
 
-  SetEvent (clipboard_rdp->completed_clip_data_entry_event);
+  g_mutex_lock (&clipboard_rdp->completion_mutex);
+  clipboard_rdp->completed_clip_data_entry = TRUE;
+  g_cond_signal (&clipboard_rdp->completion_cond);
+  g_mutex_unlock (&clipboard_rdp->completion_mutex);
 
   return G_SOURCE_REMOVE;
 }
@@ -1425,7 +1453,6 @@ cliprdr_client_unlock_clipboard_data (CliprdrServerContext                *clipr
   GrdClipboardRdp *clipboard_rdp = cliprdr_context->custom;
   uint32_t clip_data_id = unlock_clipboard_data->clipDataId;
   ClipDataEntry *entry;
-  HANDLE events[2];
 
   if (clipboard_rdp->protocol_stopped)
     return CHANNEL_RC_OK;
@@ -1443,7 +1470,9 @@ cliprdr_client_unlock_clipboard_data (CliprdrServerContext                *clipr
 
   g_debug ("[RDP.CLIPRDR] Removing lock with clipDataId: %u", clip_data_id);
 
-  ResetEvent (clipboard_rdp->completed_clip_data_entry_event);
+  g_assert (clipboard_rdp->completed_clip_data_entry);
+  clipboard_rdp->completed_clip_data_entry = FALSE;
+
   clipboard_rdp->clipboard_destruction_context.entry = entry;
 
   g_mutex_lock (&clipboard_rdp->clip_data_entry_mutex);
@@ -1451,9 +1480,14 @@ cliprdr_client_unlock_clipboard_data (CliprdrServerContext                *clipr
     g_idle_add (handle_clip_data_entry_destruction, clipboard_rdp);
   g_mutex_unlock (&clipboard_rdp->clip_data_entry_mutex);
 
-  events[0] = clipboard_rdp->stop_event;
-  events[1] = clipboard_rdp->completed_clip_data_entry_event;
-  WaitForMultipleObjects (2, events, FALSE, INFINITE);
+  g_mutex_lock (&clipboard_rdp->completion_mutex);
+  while (!clipboard_rdp->protocol_stopped &&
+         !clipboard_rdp->completed_clip_data_entry)
+    {
+      g_cond_wait (&clipboard_rdp->completion_cond,
+                   &clipboard_rdp->completion_mutex);
+    }
+  g_mutex_unlock (&clipboard_rdp->completion_mutex);
 
   g_debug ("[RDP.CLIPRDR] Untracking lock with clipDataId %u", clip_data_id);
   g_hash_table_remove (clipboard_rdp->clip_data_table,
@@ -1491,7 +1525,10 @@ request_server_format_data (gpointer user_data)
       clipboard_rdp->server_format_data_request_id = 0;
       g_mutex_unlock (&clipboard_rdp->server_format_data_request_mutex);
 
-      SetEvent (clipboard_rdp->completed_format_data_request_event);
+      g_mutex_lock (&clipboard_rdp->completion_mutex);
+      clipboard_rdp->completed_format_data_request = TRUE;
+      g_cond_signal (&clipboard_rdp->completion_cond);
+      g_mutex_unlock (&clipboard_rdp->completion_mutex);
 
       return G_SOURCE_REMOVE;
     }
@@ -1521,7 +1558,6 @@ cliprdr_client_format_data_request (CliprdrServerContext              *cliprdr_c
   uint32_t dst_format_id;
   gboolean needs_null_terminator = FALSE;
   gboolean needs_conversion = FALSE;
-  HANDLE events[2];
 
   dst_format_id = format_data_request->requestedFormatId;
   switch (dst_format_id)
@@ -1584,16 +1620,23 @@ cliprdr_client_format_data_request (CliprdrServerContext              *cliprdr_c
                "yet.");
     }
 
-  events[0] = clipboard_rdp->stop_event;
-  events[1] = clipboard_rdp->completed_format_data_request_event;
-  WaitForMultipleObjects (2, events, FALSE, INFINITE);
+  g_mutex_lock (&clipboard_rdp->completion_mutex);
+  while (!clipboard_rdp->protocol_stopped &&
+         !clipboard_rdp->completed_format_data_request)
+    {
+      g_cond_wait (&clipboard_rdp->completion_cond,
+                   &clipboard_rdp->completion_mutex);
+    }
+  g_mutex_unlock (&clipboard_rdp->completion_mutex);
 
   if (clipboard_rdp->protocol_stopped)
     return CHANNEL_RC_OK;
 
   if (mime_type != GRD_MIME_TYPE_NONE)
     {
-      ResetEvent (clipboard_rdp->completed_format_data_request_event);
+      g_assert (clipboard_rdp->completed_format_data_request);
+      clipboard_rdp->completed_format_data_request = FALSE;
+
       request_context = g_malloc0 (sizeof (ServerFormatDataRequestContext));
       request_context->clipboard_rdp = clipboard_rdp;
       request_context->mime_type = mime_type;
@@ -2314,7 +2357,6 @@ create_new_winpr_clipboard (GrdClipboardRdp *clipboard_rdp)
 GrdClipboardRdp *
 grd_clipboard_rdp_new (GrdSessionRdp *session_rdp,
                        HANDLE         vcm,
-                       HANDLE         stop_event,
                        gboolean       relieve_filename_restriction)
 {
   g_autoptr (GrdClipboardRdp) clipboard_rdp = NULL;
@@ -2330,7 +2372,6 @@ grd_clipboard_rdp_new (GrdSessionRdp *session_rdp,
     }
 
   clipboard_rdp->cliprdr_context = cliprdr_context;
-  clipboard_rdp->stop_event = stop_event;
   clipboard_rdp->relieve_filename_restriction = relieve_filename_restriction;
 
   clipboard = GRD_CLIPBOARD (clipboard_rdp);
@@ -2402,7 +2443,11 @@ grd_clipboard_rdp_dispose (GObject *object)
   GrdClipboardRdp *clipboard_rdp = GRD_CLIPBOARD_RDP (object);
   GrdClipboard *clipboard = GRD_CLIPBOARD (clipboard_rdp);
 
+  g_mutex_lock (&clipboard_rdp->completion_mutex);
   clipboard_rdp->protocol_stopped = TRUE;
+  g_cond_signal (&clipboard_rdp->completion_cond);
+  g_mutex_unlock (&clipboard_rdp->completion_mutex);
+
   if (clipboard_rdp->cliprdr_context)
     {
       clipboard_rdp->cliprdr_context->Stop (clipboard_rdp->cliprdr_context);
@@ -2446,11 +2491,6 @@ grd_clipboard_rdp_dispose (GObject *object)
   g_clear_pointer (&clipboard_rdp->clip_data_table, g_hash_table_destroy);
   g_clear_pointer (&clipboard_rdp->serial_entry_table, g_hash_table_destroy);
   g_clear_pointer (&clipboard_rdp->allowed_server_formats, g_hash_table_destroy);
-  g_clear_pointer (&clipboard_rdp->completed_format_data_request_event,
-                   CloseHandle);
-  g_clear_pointer (&clipboard_rdp->completed_format_list_event, CloseHandle);
-  g_clear_pointer (&clipboard_rdp->completed_clip_data_entry_event,
-                   CloseHandle);
   g_clear_pointer (&clipboard_rdp->system, ClipboardDestroy);
   g_clear_pointer (&clipboard_rdp->cliprdr_context, cliprdr_server_context_free);
 
@@ -2471,6 +2511,8 @@ grd_clipboard_rdp_finalize (GObject *object)
 {
   GrdClipboardRdp *clipboard_rdp = GRD_CLIPBOARD_RDP (object);
 
+  g_cond_clear (&clipboard_rdp->completion_cond);
+  g_mutex_clear (&clipboard_rdp->completion_mutex);
   g_mutex_clear (&clipboard_rdp->server_format_data_request_mutex);
   g_mutex_clear (&clipboard_rdp->client_format_list_response_mutex);
   g_mutex_clear (&clipboard_rdp->server_format_list_update_mutex);
@@ -2529,12 +2571,9 @@ grd_clipboard_rdp_init (GrdClipboardRdp *clipboard_rdp)
   clipboard_rdp->delegate->basePath = NULL;
   clipboard_rdp->delegate->custom = clipboard_rdp;
 
-  clipboard_rdp->completed_clip_data_entry_event =
-    CreateEvent (NULL, TRUE, TRUE, NULL);
-  clipboard_rdp->completed_format_list_event =
-    CreateEvent (NULL, TRUE, TRUE, NULL);
-  clipboard_rdp->completed_format_data_request_event =
-    CreateEvent (NULL, TRUE, TRUE, NULL);
+  clipboard_rdp->completed_clip_data_entry = TRUE;
+  clipboard_rdp->completed_format_list = TRUE;
+  clipboard_rdp->completed_format_data_request = TRUE;
 
   clipboard_rdp->allowed_server_formats = g_hash_table_new (NULL, NULL);
   clipboard_rdp->serial_entry_table = g_hash_table_new_full (NULL, NULL, NULL,
@@ -2549,6 +2588,8 @@ grd_clipboard_rdp_init (GrdClipboardRdp *clipboard_rdp)
   g_mutex_init (&clipboard_rdp->server_format_list_update_mutex);
   g_mutex_init (&clipboard_rdp->client_format_list_response_mutex);
   g_mutex_init (&clipboard_rdp->server_format_data_request_mutex);
+  g_mutex_init (&clipboard_rdp->completion_mutex);
+  g_cond_init (&clipboard_rdp->completion_cond);
 
   clipboard_rdp->fuse_mount_path = g_steal_pointer (&template_path);
   clipboard_rdp->rdp_fuse_clipboard =
diff --git a/src/grd-clipboard-rdp.h b/src/grd-clipboard-rdp.h
index 6594c005..26e3c98c 100644
--- a/src/grd-clipboard-rdp.h
+++ b/src/grd-clipboard-rdp.h
@@ -32,7 +32,6 @@ G_DECLARE_FINAL_TYPE (GrdClipboardRdp,
 
 GrdClipboardRdp *grd_clipboard_rdp_new (GrdSessionRdp *session_rdp,
                                         HANDLE         vcm,
-                                        HANDLE         stop_event,
                                         gboolean       relieve_filename_restriction);
 
 void grd_clipboard_rdp_lock_remote_clipboard_data (GrdClipboardRdp *clipboard_rdp,
diff --git a/src/grd-session-rdp.c b/src/grd-session-rdp.c
index 2c0bd4bb..840a5a5a 100644
--- a/src/grd-session-rdp.c
+++ b/src/grd-session-rdp.c
@@ -2477,8 +2477,7 @@ initialize_remaining_virtual_channels (GrdSessionRdp *session_rdp)
 
       peer_is_on_ms_windows = rdp_settings->OsMajorType == OSMAJORTYPE_WINDOWS;
       rdp_peer_context->clipboard_rdp =
-        grd_clipboard_rdp_new (session_rdp, vcm, session_rdp->stop_event,
-                               !peer_is_on_ms_windows);
+        grd_clipboard_rdp_new (session_rdp, vcm, !peer_is_on_ms_windows);
     }
   if (rdp_settings->AudioPlayback && !rdp_settings->RemoteConsoleAudio)
     {