100 lines
3.0 KiB
C++
100 lines
3.0 KiB
C++
#include <mbgl/storage/default/request.hpp>
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#include <mbgl/storage/response.hpp>
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#include <mbgl/util/util.hpp>
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#include <mbgl/util/uv.hpp>
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#include <uv.h>
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#include <cassert>
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#include <functional>
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namespace mbgl {
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// Note: This requires that loop is running in the current thread (or not yet running).
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Request::Request(const Resource &resource_, uv_loop_t *loop, Callback callback_)
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: callback(callback_), resource(resource_) {
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// When there is no loop supplied (== nullptr), the callback will be fired in an arbitrary
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// thread (the thread notify() is called from) rather than kicking back to the calling thread.
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if (loop) {
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notify_async = new uv_async_t;
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notify_async->data = this;
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#if UV_VERSION_MAJOR == 0 && UV_VERSION_MINOR <= 10
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uv_async_init(loop, notify_async, [](uv_async_t *async, int) { notifyCallback(async); });
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#else
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uv_async_init(loop, notify_async, notifyCallback);
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#endif
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}
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}
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void Request::notifyCallback(uv_async_t *async) {
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auto request = reinterpret_cast<Request *>(async->data);
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uv::close(async);
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if (!request->destruct_async) {
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// We haven't created a cancel request, so we can safely delete this Request object
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// since it won't be accessed in the future.
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assert(request->response);
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request->callback(*request->response);
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delete request;
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} else {
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// Otherwise, we're waiting for for the destruct notification to be delivered in order
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// to delete the Request object. We're doing this since we can't know whether the
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// DefaultFileSource is still sending a cancel event, which means this object must still
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// exist.
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}
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}
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Request::~Request() {
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if (notify_async) {
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// Request objects can be destructed in other threads when the user didn't supply a loop.
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MBGL_VERIFY_THREAD(tid)
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}
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}
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void Request::notify(const std::shared_ptr<const Response> &response_) {
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response = response_;
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if (notify_async) {
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uv_async_send(notify_async);
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} else {
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assert(response);
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callback(*response);
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delete this;
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}
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}
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void Request::cancel() {
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MBGL_VERIFY_THREAD(tid)
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assert(notify_async);
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assert(!destruct_async);
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destruct_async = new uv_async_t;
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destruct_async->data = this;
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#if UV_VERSION_MAJOR == 0 && UV_VERSION_MINOR <= 10
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uv_async_init(notify_async->loop, destruct_async, [](uv_async_t *async, int) { cancelCallback(async); });
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#else
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uv_async_init(notify_async->loop, destruct_async, cancelCallback);
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#endif
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}
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void Request::cancelCallback(uv_async_t *async) {
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// The destruct_async will be invoked *after* the notify_async callback has already run.
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auto request = reinterpret_cast<Request *>(async->data);
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uv::close(async);
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delete request;
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}
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// This gets called from the FileSource thread, and will only ever be invoked after cancel() was called
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// in the original requesting thread.
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void Request::destruct() {
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if (notify_async) {
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notify(nullptr);
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}
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assert(destruct_async);
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uv_async_send(destruct_async);
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}
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}
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