cosmic-workspaces: abstract transaction-addon

This allows to use it for a future ext-workspace implementation.
It is also more generalized so can be used for other protocol
implementation in the future in case the protocols require some
kind of transaction management.

src/protocols/transaction-addon.c

@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <assert.h>
+#include <wayland-server-core.h>
+#include "common/list.h"
+#include "common/mem.h"
+#include "protocols/transaction-addon.h"
+
+void
+lab_transaction_op_destroy(struct lab_transaction_op *trans_op)
+{
+	wl_signal_emit_mutable(&trans_op->events.destroy, trans_op);
+	wl_list_remove(&trans_op->link);
+	free(trans_op);
+}
+
+static void
+transaction_destroy(struct wl_list *list)
+{
+	struct lab_transaction_op *trans_op, *trans_op_tmp;
+	wl_list_for_each_safe(trans_op, trans_op_tmp, list, link) {
+		lab_transaction_op_destroy(trans_op);
+	}
+}
+
+void
+lab_resource_addon_destroy(struct lab_wl_resource_addon *addon)
+{
+	assert(addon);
+	assert(addon->ctx);
+
+	addon->ctx->ref_count--;
+	assert(addon->ctx->ref_count >= 0);
+
+	if (!addon->ctx->ref_count) {
+		transaction_destroy(&addon->ctx->transaction_ops);
+		free(addon->ctx);
+	}
+
+	free(addon);
+}
+
+struct lab_wl_resource_addon *
+lab_resource_addon_create(struct lab_transaction_session_context *ctx)
+{
+	struct lab_wl_resource_addon *addon = znew(*addon);
+	if (!ctx) {
+		ctx = znew(*ctx);
+		wl_list_init(&ctx->transaction_ops);
+	}
+	addon->ctx = ctx;
+	addon->ctx->ref_count++;
+	return addon;
+}
+
+struct lab_transaction_op *
+lab_transaction_op_add(struct lab_transaction_session_context *ctx,
+		uint32_t pending_change, void *src, void *data)
+{
+	assert(ctx);
+
+	struct lab_transaction_op *trans_op = znew(*trans_op);
+	trans_op->change = pending_change;
+	trans_op->src = src;
+	trans_op->data = data;
+
+	wl_signal_init(&trans_op->events.destroy);
+	wl_list_append(&ctx->transaction_ops, &trans_op->link);
+
+	return trans_op;
+}