384 lines
14 KiB
C++
384 lines
14 KiB
C++
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#include <mbgl/platform/platform.hpp>
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#include <mbgl/platform/request.hpp>
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#include <mbgl/util/uv_detail.hpp>
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#include <mbgl/util/std.hpp>
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#include <queue>
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#include <boost/lockfree/queue.hpp>
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#include <curl/curl.h>
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// This file contains code from http://curl.haxx.se/libcurl/c/multi-uv.html:
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/***************************************************************************
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* _ _ ____ _
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* Project ___| | | | _ \| |
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* / __| | | | |_) | |
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* | (__| |_| | _ <| |___
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* \___|\___/|_| \_\_____|
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*
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* Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
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*
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* This software is licensed as described in the file COPYING, which
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* you should have received as part of this distribution. The terms
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* are also available at http://curl.haxx.se/docs/copyright.html.
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*
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* You may opt to use, copy, modify, merge, publish, distribute and/or sell
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* copies of the Software, and permit persons to whom the Software is
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* furnished to do so, under the terms of the COPYING file.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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***************************************************************************/
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/* Example application code using the multi socket interface to download
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multiple files at once, but instead of using curl_multi_perform and
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curl_multi_wait, which uses select(), we use libuv.
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It supports epoll, kqueue, etc. on unixes and fast IO completion ports on
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Windows, which means, it should be very fast on all platforms..
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Written by Clemens Gruber, based on an outdated example from uvbook and
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some tests from libuv.
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Requires libuv and (of course) libcurl.
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See http://nikhilm.github.com/uvbook/ for more information on libuv.
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*/
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namespace mbgl {
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namespace platform {
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namespace request {
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struct curl_context {
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uv_poll_t poll_handle;
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curl_socket_t sockfd;
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};
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// Handles the request thread + messaging to the thread.
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static uv_thread_t thread;
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static uv::once init_thread_once;
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static uv_loop_t *loop = nullptr;
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static uv_async_t async_add;
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static uv_async_t async_cancel;
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// Stores pointers (!) to shared_ptrs. We use shared_ptrs so that request objects don't get
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// auto-destructed while they're in progress. The TileData object retains a weak_ptr to this
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// request, so we have to use a shared_ptr here to ensure that this object stays alive.
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static boost::lockfree::queue<std::shared_ptr<mbgl::platform::Request> *> add_queue(8);
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static boost::lockfree::queue<std::shared_ptr<mbgl::platform::Request> *> cancel_queue(8);
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// Used as the CURL timer function to periodically check for socket updates.
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static uv_timer_t timeout;
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// CURL multi handle that we use to request multiple URLs at the same time, without having to block
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// and spawn threads.
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static CURLM *curl_multi = nullptr;
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// CURL share handles are used for sharing session state (e.g.)
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static uv::mutex curl_share_mutex;
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static CURLSH *curl_share = nullptr;
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// A queue that we use for storing resuable CURL easy handles to avoid creating and destroying them
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// all the time.
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static std::queue<CURL *> curl_handle_cache;
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class CURLRequest : public mbgl::platform::Request {
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public:
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CURLRequest(const std::string &url,
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std::function<void(mbgl::platform::Response *)> callback,
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std::shared_ptr<uv::loop> loop)
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: Request(url, callback, loop) {}
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CURL *curl = nullptr;
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};
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// Implementation starts here.
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// Locks the CURL share handle
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void curl_share_lock(CURL *, curl_lock_data, curl_lock_access, void *) { curl_share_mutex.lock(); }
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// Unlocks the CURL share handle
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void curl_share_unlock(CURL *, curl_lock_data, void *) { curl_share_mutex.unlock(); }
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curl_context *create_curl_context(curl_socket_t sockfd) {
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curl_context *context = new curl_context;
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context->sockfd = sockfd;
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uv_poll_init_socket(loop, &context->poll_handle, sockfd);
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context->poll_handle.data = context;
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return context;
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}
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void curl_close_cb(uv_handle_t *handle) {
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curl_context *context = (curl_context *)handle->data;
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free(context);
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}
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void destroy_curl_context(curl_context *context) {
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uv_close((uv_handle_t *)&context->poll_handle, curl_close_cb);
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}
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void remove_curl_handle(CURL *handle) {
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CURLMcode error = curl_multi_remove_handle(curl_multi, handle);
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if (error != CURLM_OK) {
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throw std::runtime_error(std::string("CURL multi error: ") + curl_multi_strerror(error));
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}
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curl_easy_reset(handle);
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curl_handle_cache.push(handle);
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}
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void curl_perform(uv_poll_t *req, int /*status*/, int events) {
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int running_handles;
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int flags = 0;
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curl_context *context;
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CURLMsg *message;
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int pending;
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uv_timer_stop(&timeout);
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if (events & UV_READABLE)
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flags |= CURL_CSELECT_IN;
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if (events & UV_WRITABLE)
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flags |= CURL_CSELECT_OUT;
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context = (curl_context *)req;
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curl_multi_socket_action(curl_multi, context->sockfd, flags, &running_handles);
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while ((message = curl_multi_info_read(curl_multi, &pending))) {
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switch (message->msg) {
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case CURLMSG_DONE: {
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std::shared_ptr<Request> *req = nullptr;
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curl_easy_getinfo(message->easy_handle, CURLINFO_PRIVATE, (char *)&req);
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// Add human-readable error code
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if (message->data.result != CURLE_OK) {
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(*req)->res->error_message = curl_easy_strerror(message->data.result);
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(*req)->res->code = -1;
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} else {
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curl_easy_getinfo(message->easy_handle, CURLINFO_RESPONSE_CODE, &(*req)->res->code);
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}
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// We're currently in the CURL request thread. We're going to schedule a uv_work request
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// that executes the background function in a threadpool, and tell it to call the
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// after callback back in the main uv loop.
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(*req)->complete();
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CURL *handle = message->easy_handle;
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remove_curl_handle(handle);
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// We're setting this to NULL because there might still be shared_ptrs around that could
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// be cancelled.
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((CURLRequest *)req->get())->curl = nullptr;
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// Delete the shared_ptr pointer we created earlier.
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delete req;
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break;
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}
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default:
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// This should never happen, because there are no other message types.
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throw std::runtime_error("CURLMSG returned unknown message type");
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}
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}
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}
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int handle_socket(CURL * /*easy*/, curl_socket_t s, int action, void * /*userp*/, void *socketp) {
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curl_context *context = nullptr;
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if (socketp) {
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context = (curl_context *)socketp;
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} else if (action != CURL_POLL_REMOVE) {
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context = create_curl_context(s);
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}
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if (context) {
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curl_multi_assign(curl_multi, s, (void *)context);
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if (action == CURL_POLL_IN || action == CURL_POLL_INOUT) {
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uv_poll_start(&context->poll_handle, UV_READABLE, curl_perform);
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}
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if (action == CURL_POLL_OUT || action == CURL_POLL_INOUT) {
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uv_poll_start(&context->poll_handle, UV_WRITABLE, curl_perform);
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}
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if (action == CURL_POLL_REMOVE && socketp) {
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uv_poll_stop(&context->poll_handle);
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destroy_curl_context(context);
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curl_multi_assign(curl_multi, s, NULL);
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}
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}
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return 0;
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}
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void on_timeout(uv_timer_t * /*req*/) {
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int running_handles;
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CURLMcode error =
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curl_multi_socket_action(curl_multi, CURL_SOCKET_TIMEOUT, 0, &running_handles);
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if (error != CURLM_OK) {
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throw std::runtime_error(std::string("CURL multi error: ") + curl_multi_strerror(error));
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}
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}
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void start_timeout(CURLM * /*multi*/, long timeout_ms, void * /*userp*/) {
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if (timeout_ms <= 0) {
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on_timeout(&timeout);
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} else {
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uv_timer_start(&timeout, on_timeout, timeout_ms, 0);
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}
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}
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// This function is the first function called in the request thread. It sets up the CURL share/multi
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// handles and runs the thread loop.
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void thread_init(void * /*ptr*/) {
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uv_timer_init(loop, &timeout);
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CURLSHcode share_error;
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curl_share = curl_share_init();
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share_error = curl_share_setopt(curl_share, CURLSHOPT_LOCKFUNC, curl_share_lock);
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if (share_error != CURLSHE_OK) {
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throw std::runtime_error(std::string("CURL share error: ") + curl_share_strerror(share_error));
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}
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share_error = curl_share_setopt(curl_share, CURLSHOPT_UNLOCKFUNC, curl_share_unlock);
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if (share_error != CURLSHE_OK) {
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throw std::runtime_error(std::string("CURL share error: ") + curl_share_strerror(share_error));
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}
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CURLMcode multi_error;
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curl_multi = curl_multi_init();
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multi_error = curl_multi_setopt(curl_multi, CURLMOPT_SOCKETFUNCTION, handle_socket);
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if (multi_error != CURLM_OK) {
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throw std::runtime_error(std::string("CURL multi error: ") + curl_multi_strerror(multi_error));
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}
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multi_error = curl_multi_setopt(curl_multi, CURLMOPT_TIMERFUNCTION, start_timeout);
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if (multi_error != CURLM_OK) {
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throw std::runtime_error(std::string("CURL multi error: ") + curl_multi_strerror(multi_error));
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}
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// Main event loop. This will not return until the request loop is terminated.
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uv_run(loop, UV_RUN_DEFAULT);
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curl_multi_cleanup(curl_multi);
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curl_multi = nullptr;
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curl_share_cleanup(curl_share);
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curl_share = nullptr;
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// Clean up all the CURL easy handles that we kept around for potential future reuse.
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while (!curl_handle_cache.empty()) {
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curl_easy_cleanup(curl_handle_cache.front());
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curl_handle_cache.pop();
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}
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}
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// This function is called when we have new data for a request. We just append it to the string
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// containing the previous data.
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size_t curl_write_cb(void *contents, size_t size, size_t nmemb, void *userp) {
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((std::string *)userp)->append((char *)contents, size * nmemb);
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return size * nmemb;
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}
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// This callback is called in the request event loop (on the request thread).
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// It initializes newly queued up download requests and adds them to the CURL
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// multi handle.
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void async_add_cb(uv_async_t * /*async*/) {
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std::shared_ptr<Request> *req = nullptr;
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while (add_queue.pop(req)) {
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// Make sure that we're not starting requests that have been cancelled
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// already by async_cancel_cb.
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if ((*req)->cancelled) {
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delete req;
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continue;
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}
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// Obtain a curl handle (and try to reuse existing handles before creating new ones).
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CURL *handle = nullptr;
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if (!curl_handle_cache.empty()) {
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handle = curl_handle_cache.front();
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curl_handle_cache.pop();
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} else {
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handle = curl_easy_init();
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}
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((CURLRequest *)req->get())->curl = handle;
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curl_easy_setopt(handle, CURLOPT_PRIVATE, req);
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curl_easy_setopt(handle, CURLOPT_CAINFO, "ca-bundle.crt");
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curl_easy_setopt(handle, CURLOPT_URL, (*req)->url.c_str());
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curl_easy_setopt(handle, CURLOPT_WRITEFUNCTION, curl_write_cb);
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curl_easy_setopt(handle, CURLOPT_WRITEDATA, &(*req)->res->body);
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curl_easy_setopt(handle, CURLOPT_ACCEPT_ENCODING, "gzip, deflate");
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curl_easy_setopt(handle, CURLOPT_SHARE, curl_share);
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curl_multi_add_handle(curl_multi, handle);
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}
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}
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void async_cancel_cb(uv_async_t * /*async*/) {
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std::shared_ptr<Request> *req = nullptr;
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while (cancel_queue.pop(req)) {
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// It is possible that the request has not yet been started, but that it already has been
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// added to the queue for scheduling new requests. In this case, the CURL handle is invalid
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// and we manually mark the Request as cancelled.
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CURL *handle = ((CURLRequest *)req->get())->curl;
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if (handle && !(*req)->cancelled) {
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remove_curl_handle(handle);
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((CURLRequest *)req->get())->curl = nullptr;
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}
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(*req)->cancelled = true;
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delete req;
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req = nullptr;
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}
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}
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void thread_init_cb() {
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curl_global_init(CURL_GLOBAL_ALL);
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loop = uv_loop_new();
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uv_async_init(loop, &async_add, async_add_cb);
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uv_async_init(loop, &async_cancel, async_cancel_cb);
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uv_thread_create(&thread, thread_init, nullptr);
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}
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} // end namespace request
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} // end namespace platform
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std::shared_ptr<platform::Request>
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platform::request_http(const std::string &url,
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std::function<void(Response *)> callback,
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std::shared_ptr<uv::loop> loop) {
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using namespace request;
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init_thread_once(thread_init_cb);
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std::shared_ptr<CURLRequest> req = std::make_shared<CURLRequest>(url, callback, loop);
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// Note that we are creating a new shared_ptr pointer(!) because the lockless queue can't store
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// objects with nontrivial destructors. We have to make absolutely sure that we manually delete
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// the shared_ptr when we pop it from the queue.
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add_queue.push(new std::shared_ptr<Request>(req));
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uv_async_send(&async_add);
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return req;
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}
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// Cancels an HTTP request.
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void platform::cancel_request_http(const std::shared_ptr<Request> &req) {
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if (req) {
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using namespace request;
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// Note that we are creating a new shared_ptr pointer(!) because the lockless queue can't
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// store objects with nontrivial destructors. We have to make absolutely shure that we
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// manually delete the shared_ptr when we pop it from the queue.
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cancel_queue.push(new std::shared_ptr<Request>(req));
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uv_async_send(&async_cancel);
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}
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}
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} // end namespace mbgl
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