Implement atomic layout updates for tree operations

This implements atomic layout updates for when views map, reparent or
unmap.

6 files changed, 160 insertions, 132 deletions

diff --git a/sway/tree/arrange.c b/sway/tree/arrange.c
index ac99c5df..cb3f8ba2 100644
--- a/sway/tree/arrange.c
+++ b/sway/tree/arrange.c
@@ -144,6 +144,19 @@ static void apply_tabbed_or_stacked_layout(struct sway_container *parent) {
 	}
 }
 
+/**
+ * If a container has been deleted from the pending tree state, we must add it
+ * to the transaction so it can be freed afterwards. To do this, we iterate the
+ * server's destroying_containers list and add all of them. We may add more than
+ * what we need to, but this is easy and has no negative consequences.
+ */
+static void add_deleted_containers(struct sway_transaction *transaction) {
+	for (int i = 0; i < server.destroying_containers->length; ++i) {
+		struct sway_container *child = server.destroying_containers->items[i];
+		transaction_add_container(transaction, child);
+	}
+}
+
 static void arrange_children_of(struct sway_container *parent,
 		struct sway_transaction *transaction);
 
@@ -158,6 +171,7 @@ static void arrange_floating(struct sway_container *floating,
 		}
 		transaction_add_container(transaction, floater);
 	}
+	transaction_add_container(transaction, floating);
 }
 
 static void arrange_children_of(struct sway_container *parent,
@@ -290,7 +304,16 @@ void arrange_windows(struct sway_container *container,
 	case C_TYPES:
 		break;
 	}
-	transaction_add_damage(transaction, container_get_box(container));
+	// Add damage for whatever container arrange_windows() was called with,
+	// unless it was called with the special floating container, in which case
+	// we'll damage the entire output.
+	if (container->type == C_CONTAINER && container->layout == L_FLOATING) {
+		struct sway_container *output = container_parent(container, C_OUTPUT);
+		transaction_add_damage(transaction, container_get_box(output));
+	} else {
+		transaction_add_damage(transaction, container_get_box(container));
+	}
+	add_deleted_containers(transaction);
 }
 
 void arrange_and_commit(struct sway_container *container) {
diff --git a/sway/tree/container.c b/sway/tree/container.c
index b071f394..484d26a5 100644
--- a/sway/tree/container.c
+++ b/sway/tree/container.c
@@ -16,7 +16,6 @@
 #include "sway/ipc-server.h"
 #include "sway/output.h"
 #include "sway/server.h"
-#include "sway/tree/arrange.h"
 #include "sway/tree/layout.h"
 #include "sway/tree/view.h"
 #include "sway/tree/workspace.h"
@@ -113,10 +112,11 @@ struct sway_container *container_create(enum sway_container_type type) {
 	c->layout = L_NONE;
 	c->type = type;
 	c->alpha = 1.0f;
+	c->instructions = create_list();
 
 	if (type != C_VIEW) {
 		c->children = create_list();
-		//c->pending.children = create_list();
+		c->current.children = create_list();
 	}
 
 	wl_signal_init(&c->events.destroy);
@@ -133,43 +133,68 @@ struct sway_container *container_create(enum sway_container_type type) {
 	return c;
 }
 
-static void _container_destroy(struct sway_container *cont) {
-	if (cont == NULL) {
-		return;
-	}
-
-	wl_signal_emit(&cont->events.destroy, cont);
+static void container_workspace_free(struct sway_workspace *ws) {
+	list_foreach(ws->output_priority, free);
+	list_free(ws->output_priority);
+	ws->floating->destroying = true;
+	container_free(ws->floating);
+	free(ws);
+}
 
-	struct sway_container *parent = cont->parent;
-	if (cont->children != NULL && cont->children->length) {
-		// remove children until there are no more, container_destroy calls
-		// container_remove_child, which removes child from this container
-		while (cont->children != NULL && cont->children->length > 0) {
-			struct sway_container *child = cont->children->items[0];
-			ipc_event_window(child, "close");
-			container_remove_child(child);
-			_container_destroy(child);
-		}
-	}
-	if (cont->marks) {
-		list_foreach(cont->marks, free);
-		list_free(cont->marks);
-	}
-	if (parent) {
-		parent = container_remove_child(cont);
+void container_free(struct sway_container *cont) {
+	if (!sway_assert(cont->destroying,
+				"Tried to free container which wasn't marked as destroying")) {
+		return;
 	}
-	if (cont->name) {
-		free(cont->name);
+	if (!sway_assert(cont->instructions->length == 0,
+				"Tried to free container with pending instructions")) {
+		return;
 	}
-
+	free(cont->name);
 	wlr_texture_destroy(cont->title_focused);
 	wlr_texture_destroy(cont->title_focused_inactive);
 	wlr_texture_destroy(cont->title_unfocused);
 	wlr_texture_destroy(cont->title_urgent);
 
+	for (int i = 0; i < server.destroying_containers->length; ++i) {
+		if (server.destroying_containers->items[i] == cont) {
+			list_del(server.destroying_containers, i);
+			break;
+		}
+	}
+
+	list_free(cont->instructions);
 	list_free(cont->children);
-	//list_free(cont->pending.children);
-	cont->children = NULL;
+	list_free(cont->current.children);
+
+	switch (cont->type) {
+	case C_ROOT:
+		break;
+	case C_OUTPUT:
+		cont->sway_output->swayc = NULL;
+		break;
+	case C_WORKSPACE:
+		container_workspace_free(cont->sway_workspace);
+		break;
+	case C_CONTAINER:
+		break;
+	case C_VIEW:
+		{
+			struct sway_view *view = cont->sway_view;
+			view->swayc = NULL;
+			free(view->title_format);
+			view->title_format = NULL;
+
+			if (view->destroying) {
+				view_free(view);
+			}
+		}
+		break;
+	case C_TYPES:
+		sway_assert(false, "Didn't expect to see C_TYPES here");
+		break;
+	}
+
 	free(cont);
 }
 
@@ -186,7 +211,6 @@ static struct sway_container *container_workspace_destroy(
 	}
 
 	wlr_log(L_DEBUG, "destroying workspace '%s'", workspace->name);
-	ipc_event_window(workspace, "close");
 
 	struct sway_container *parent = workspace->parent;
 	if (!workspace_is_empty(workspace) && output) {
@@ -209,25 +233,6 @@ static struct sway_container *container_workspace_destroy(
 			container_move_to(floating->children->items[i],
 					new_workspace->sway_workspace->floating);
 		}
-		arrange_and_commit(new_workspace);
-	}
-
-	struct sway_workspace *sway_workspace = workspace->sway_workspace;
-
-	// This emits the destroy event and also destroys the swayc.
-	_container_destroy(workspace);
-
-	// Clean up the floating container
-	sway_workspace->floating->parent = NULL;
-	_container_destroy(sway_workspace->floating);
-
-	list_foreach(sway_workspace->output_priority, free);
-	list_free(sway_workspace->output_priority);
-
-	free(sway_workspace);
-
-	if (output) {
-		output_damage_whole(output->sway_output);
 	}
 
 	return parent;
@@ -266,14 +271,13 @@ static struct sway_container *container_output_destroy(
 					container_add_child(new_output, workspace);
 					ipc_event_workspace(workspace, NULL, "move");
 				} else {
-					container_workspace_destroy(workspace);
+					container_destroy(workspace);
 				}
 
 				container_sort_workspaces(new_output);
 			}
 		}
 	}
-	arrange_and_commit(&root_container);
 
 	wl_list_remove(&output->sway_output->mode.link);
 	wl_list_remove(&output->sway_output->transform.link);
@@ -285,12 +289,8 @@ static struct sway_container *container_output_destroy(
 	output->sway_output->swayc = NULL;
 
 	wlr_log(L_DEBUG, "OUTPUT: Destroying output '%s'", output->name);
-	_container_destroy(output);
-	return &root_container;
-}
 
-static void container_root_finish(struct sway_container *con) {
-	wlr_log(L_ERROR, "TODO: destroy the root container");
+	return &root_container;
 }
 
 bool container_reap_empty(struct sway_container *con) {
@@ -306,13 +306,13 @@ bool container_reap_empty(struct sway_container *con) {
 	case C_WORKSPACE:
 		if (!workspace_is_visible(con) && workspace_is_empty(con)) {
 			wlr_log(L_DEBUG, "Destroying workspace via reaper");
-			container_workspace_destroy(con);
+			container_destroy(con);
 			return true;
 		}
 		break;
 	case C_CONTAINER:
 		if (con->children->length == 0) {
-			_container_destroy(con);
+			container_destroy(con);
 			return true;
 		}
 	case C_VIEW:
@@ -349,46 +349,48 @@ struct sway_container *container_flatten(struct sway_container *container) {
 	return container;
 }
 
+/**
+ * container_destroy() is the first step in destroying a container. We'll emit
+ * events, detach it from the tree and mark it as destroying. The container will
+ * remain in memory until it's no longer used by a transaction, then it will be
+ * freed via container_free().
+ */
 struct sway_container *container_destroy(struct sway_container *con) {
 	if (con == NULL) {
 		return NULL;
 	}
+	if (con->destroying) {
+		return NULL;
+	}
 
-	struct sway_container *parent = con->parent;
+	// The below functions move their children to somewhere else.
+	if (con->type == C_OUTPUT) {
+		container_output_destroy(con);
+	} else if (con->type == C_WORKSPACE) {
+		// Workspaces will refuse to be destroyed if they're the last workspace
+		// on their output.
+		if (!container_workspace_destroy(con)) {
+			return NULL;
+		}
+	}
 
-	switch (con->type) {
-		case C_ROOT:
-			container_root_finish(con);
-			break;
-		case C_OUTPUT:
-			// dont try to reap the root after this
-			container_output_destroy(con);
-			break;
-		case C_WORKSPACE:
-			// dont try to reap the output after this
-			container_workspace_destroy(con);
-			break;
-		case C_CONTAINER:
-			if (con->children->length) {
-				for (int i = 0; i < con->children->length; ++i) {
-					struct sway_container *child = con->children->items[0];
-					ipc_event_window(child, "close");
-					container_remove_child(child);
-					container_add_child(parent, child);
-				}
-			}
-			ipc_event_window(con, "close");
-			_container_destroy(con);
-			break;
-		case C_VIEW:
-			_container_destroy(con);
-			break;
-		case C_TYPES:
-			wlr_log(L_ERROR, "container_destroy called on an invalid "
-				"container");
-			break;
+	// At this point the container being destroyed shouldn't have any children
+	// unless sway is terminating.
+	if (!server.terminating) {
+		if (!sway_assert(!con->children || con->children->length == 0,
+					"Didn't expect to see children here")) {
+			return NULL;
+		}
 	}
 
+	wl_signal_emit(&con->events.destroy, con);
+	ipc_event_window(con, "close");
+
+	struct sway_container *parent = container_remove_child(con);
+
+	con->destroying = true;
+	list_add(server.destroying_containers, con);
+
 	return container_reap_empty_recursive(parent);
 }
 
diff --git a/sway/tree/layout.c b/sway/tree/layout.c
index 3724361d..14631ad4 100644
--- a/sway/tree/layout.c
+++ b/sway/tree/layout.c
@@ -30,7 +30,9 @@ void layout_init(void) {
 	root_container.type = C_ROOT;
 	root_container.layout = L_NONE;
 	root_container.name = strdup("root");
+	root_container.instructions = create_list();
 	root_container.children = create_list();
+	root_container.current.children = create_list();
 	wl_signal_init(&root_container.events.destroy);
 
 	root_container.sway_root = calloc(1, sizeof(*root_container.sway_root));
diff --git a/sway/tree/output.c b/sway/tree/output.c
index 8af319d5..e2927cdb 100644
--- a/sway/tree/output.c
+++ b/sway/tree/output.c
@@ -29,7 +29,6 @@ static void restore_workspaces(struct sway_container *output) {
 	}
 
 	container_sort_workspaces(output);
-	arrange_and_commit(&root_container);
 }
 
 struct sway_container *output_create(
@@ -66,7 +65,6 @@ struct sway_container *output_create(
 
 	struct sway_container *output = container_create(C_OUTPUT);
 	output->sway_output = sway_output;
-	sway_output->swayc = output;
 	output->name = strdup(name);
 	if (output->name == NULL) {
 		container_destroy(output);
diff --git a/sway/tree/view.c b/sway/tree/view.c
index 658a94e8..cb36f123 100644
--- a/sway/tree/view.c
+++ b/sway/tree/view.c
@@ -25,47 +25,60 @@ void view_init(struct sway_view *view, enum sway_view_type type,
 	view->impl = impl;
 	view->executed_criteria = create_list();
 	view->marks = create_list();
-	view->instructions = create_list();
 	wl_signal_init(&view->events.unmap);
 }
 
-void view_destroy(struct sway_view *view) {
-	if (view == NULL) {
+void view_free(struct sway_view *view) {
+	if (!sway_assert(view->surface == NULL, "Tried to free mapped view")) {
 		return;
 	}
-
-	if (view->surface != NULL) {
-		view_unmap(view);
+	if (!sway_assert(view->destroying,
+				"Tried to free view which wasn't marked as destroying")) {
+		return;
 	}
-
-	if (!sway_assert(view->instructions->length == 0,
-				"Tried to destroy view with pending instructions")) {
+	if (!sway_assert(view->swayc == NULL,
+				"Tried to free view which still has a swayc "
+				"(might have a pending transaction?)")) {
 		return;
 	}
-
 	list_free(view->executed_criteria);
 
-	for (int i = 0; i < view->marks->length; ++i) {
-		free(view->marks->items[i]);
-	}
+	list_foreach(view->marks, free);
 	list_free(view->marks);
 
-	list_free(view->instructions);
-
 	wlr_texture_destroy(view->marks_focused);
 	wlr_texture_destroy(view->marks_focused_inactive);
 	wlr_texture_destroy(view->marks_unfocused);
 	wlr_texture_destroy(view->marks_urgent);
 
-	container_destroy(view->swayc);
-
-	if (view->impl->destroy) {
-		view->impl->destroy(view);
+	if (view->impl->free) {
+		view->impl->free(view);
 	} else {
 		free(view);
 	}
 }
 
+/**
+ * The view may or may not be involved in a transaction. For example, a view may
+ * unmap then attempt to destroy itself before we've applied the new layout. If
+ * an unmapping view is still involved in a transaction then it'll still have a
+ * swayc.
+ *
+ * If there's no transaction we can simply free the view. Otherwise the
+ * destroying flag will make the view get freed when the transaction is
+ * finished.
+ */
+void view_destroy(struct sway_view *view) {
+	if (!sway_assert(view->surface == NULL, "Tried to destroy a mapped view")) {
+		return;
+	}
+	view->destroying = true;
+
+	if (!view->swayc) {
+		view_free(view);
+	}
+}
+
 const char *view_get_title(struct sway_view *view) {
 	if (view->impl->get_string_prop) {
 		return view->impl->get_string_prop(view, VIEW_PROP_TITLE);
@@ -356,6 +369,9 @@ static void view_get_layout_box(struct sway_view *view, struct wlr_box *box) {
 
 void view_for_each_surface(struct sway_view *view,
 		wlr_surface_iterator_func_t iterator, void *user_data) {
+	if (!view->surface) {
+		return;
+	}
 	if (view->impl->for_each_surface) {
 		view->impl->for_each_surface(view, iterator, user_data);
 	} else {
@@ -523,11 +539,7 @@ void view_map(struct sway_view *view, struct wlr_surface *wlr_surface) {
 	view_handle_container_reparent(&view->container_reparent, NULL);
 }
 
-void view_unmap(struct sway_view *view) {
-	if (!sway_assert(view->surface != NULL, "cannot unmap unmapped view")) {
-		return;
-	}
-
+struct sway_container *view_unmap(struct sway_view *view) {
 	wl_signal_emit(&view->events.unmap, view);
 
 	if (view->is_fullscreen) {
@@ -535,22 +547,10 @@ void view_unmap(struct sway_view *view) {
 		ws->sway_workspace->fullscreen = NULL;
 	}
 
-	container_damage_whole(view->swayc);
-
 	wl_list_remove(&view->surface_new_subsurface.link);
 	wl_list_remove(&view->container_reparent.link);
 
-	struct sway_container *parent = container_destroy(view->swayc);
-
-	view->swayc = NULL;
-	view->surface = NULL;
-
-	if (view->title_format) {
-		free(view->title_format);
-		view->title_format = NULL;
-	}
-
-	arrange_and_commit(parent);
+	return container_destroy(view->swayc);
 }
 
 void view_update_position(struct sway_view *view, double lx, double ly) {
@@ -924,7 +924,7 @@ void view_update_marks_textures(struct sway_view *view) {
 }
 
 bool view_is_visible(struct sway_view *view) {
-	if (!view->swayc) {
+	if (!view->swayc || view->swayc->destroying) {
 		return false;
 	}
 	struct sway_container *workspace =
diff --git a/sway/tree/workspace.c b/sway/tree/workspace.c
index ead752ad..5eb4be0f 100644
--- a/sway/tree/workspace.c
+++ b/sway/tree/workspace.c
@@ -430,6 +430,9 @@ bool workspace_switch(struct sway_container *workspace) {
 }
 
 bool workspace_is_visible(struct sway_container *ws) {
+	if (ws->destroying) {
+		return false;
+	}
 	struct sway_container *output = container_parent(ws, C_OUTPUT);
 	struct sway_seat *seat = input_manager_current_seat(input_manager);
 	struct sway_container *focus = seat_get_focus_inactive(seat, output);