openxr DestroySwapchain流程

1、oxr_xrDestroySwapchain

函数入口src/xrt/state_trackers/oxr/oxr_api_swapchain.c

XrResult
oxr_xrDestroySwapchain(XrSwapchain swapchain)
{
   OXR_TRACE_MARKER();

   struct oxr_swapchain *sc;
   struct oxr_logger log;
   OXR_VERIFY_SWAPCHAIN_AND_INIT_LOG(&log, swapchain, sc, "xrDestroySwapchain");

   return oxr_handle_destroy(&log, &sc->handle);
}

oxr_handle_destroy

src/xrt/state_trackers/oxr/oxr_handle_base.c

XrResult
oxr_handle_destroy(struct oxr_logger *log, struct oxr_handle_base *hb)
{
    XrResult result = oxr_handle_do_destroy(log, hb, 0);
}

下面递归销毁所有的oxr_handle_base

static XrResult
oxr_handle_do_destroy(struct oxr_logger *log, struct oxr_handle_base *hb, int level)
{
    for (size_t i = 0; i < XRT_MAX_HANDLE_CHILDREN; ++i) {
        struct oxr_handle_base *child = hb->children[i];

        if (child != NULL) {
            XrResult result = oxr_handle_do_destroy(log, child, level + 1);
            
            //这一行真正执行销毁
            XrResult result = hb->destroy(log, hb);
}

要想找到hb->destroy(log, hb); 对应的方法，需要回到上面oxr_xrDestroySwapchain

hb就是&sc->handle sc就是oxr_swapchain *sc

进入oxr_swapchain 看看初始化函数src/xrt/state_trackers/oxr/oxr_swapchain.c

XrResult
oxr_create_swapchain(struct oxr_logger *log,
                     struct oxr_session *sess,
                     const XrSwapchainCreateInfo *createInfo,
                     struct oxr_swapchain **out_swapchain)
{
//这里没直接指定destory函数指针，而是宏定义了一个
OXR_ALLOCATE_HANDLE_OR_RETURN(log, sc, OXR_XR_DEBUG_SWAPCHAIN, oxr_swapchain_destroy, &sess->handle);
}
宏定义OXR_ALLOCATE_HANDLE_OR_RETURN->
XrResult allocResult = OXR_ALLOCATE_HANDLE(LOG, OUT, DEBUG, DESTROY, PARENT);  

继续看看
#define OXR_ALLOCATE_HANDLE(LOG, OUT, DEBUG, DESTROY, PARENT)                                                          \
    oxr_handle_allocate_and_init(LOG, sizeof(*OUT), DEBUG, DESTROY, PARENT, (void **)&OUT)

看看oxr_handle_allocate_and_init 函数 又回到了base：src/xrt/state_trackers/oxr/oxr_handle_base.c

XrResult result = oxr_handle_init(log, hb, debug, destroy, parent);


XrResult
oxr_handle_init(struct oxr_logger *log,
                struct oxr_handle_base *hb,
                uint64_t debug,
                oxr_handle_destroyer destroy,
                struct oxr_handle_base *parent)
{
hb->destroy = destroy;
}

这里指定了hb->destroy = destroy;，上面我们还在找hb->destroy(log, hb);

综上oxr_handle_do_destroy 不就是oxr_swapchain.c 里面的oxr_swapchain_destroy

static XrResult
oxr_swapchain_destroy(struct oxr_logger *log, struct oxr_handle_base *hb)
{
   struct oxr_swapchain *sc = (struct oxr_swapchain *)hb;

   XrResult ret = sc->destroy(log, sc);
   free(sc);
   return ret;
}

接着我们要找sc->destroy

oxr_swapchain 文件里我们没找到sc->destroy 赋值的地方

我们搜搜oxr_create_swapchain 在哪

我们在src/xrt/state_trackers/oxr/oxr_swapchain_gl.c 里发现了他

//这个函数是赋值给sess->create_swapchain = oxr_swapchain_gl_create; 先于oxr_create_swapchain
XrResult
oxr_swapchain_gl_create(struct oxr_logger *log,
                        struct oxr_session *sess,
                        const XrSwapchainCreateInfo *createInfo,
                        struct oxr_swapchain **out_swapchain)
{
   struct oxr_swapchain *sc;
   XrResult ret;

   ret = oxr_create_swapchain(log, sess, createInfo, &sc);
   if (ret != XR_SUCCESS) {
      return ret;
   }

   sc->destroy = oxr_swapchain_gl_destroy;
   这里的oxr_swapchain_gl_destroy就是我们要找的sc->destroy

也把这个函数列出来吧

static XrResult
oxr_swapchain_gl_destroy(struct oxr_logger *log, struct oxr_swapchain *sc)
{
   // Release any waited image.
   if (sc->waited.yes) {
      sc->release_image(log, sc, NULL);
   }

   // Release any acquired images.
   XrSwapchainImageWaitInfo waitInfo = {0};
   while (!u_index_fifo_is_empty(&sc->acquired.fifo)) {
      sc->wait_image(log, sc, &waitInfo);
      sc->release_image(log, sc, NULL);
   }

   // Drop our reference, does NULL checking.
   xrt_swapchain_reference(&sc->swapchain, NULL);

   return XR_SUCCESS;
}

综上oxr_xrDestroySwapchain - > oxr_swapchain_gl_destroy 就没然后了