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#include <mbgl/storage/request.hpp>
#include <mbgl/storage/response.hpp>
#include <mbgl/util/util.hpp>
#include <mbgl/util/std.hpp>
#include <mbgl/util/uv.hpp>
#include <uv.h>
#include <cassert>
#include <functional>
namespace mbgl {
struct Request::Canceled { std::mutex mutex; bool confirmed = false; };
// Note: This requires that loop is running in the current thread (or not yet running).
Request::Request(const Resource &resource_, uv_loop_t *loop, Callback callback_)
: callback(callback_), resource(resource_) {
// When there is no loop supplied (== nullptr), the callback will be fired in an arbitrary
// thread (the thread notify() is called from) rather than kicking back to the calling thread.
if (loop) {
async = new uv_async_t;
async->data = this;
#if UV_VERSION_MAJOR == 0 && UV_VERSION_MINOR <= 10
uv_async_init(loop, async, [](uv_async_t *a, int) { reinterpret_cast<Request *>(a->data)->notifyCallback(); });
#else
uv_async_init(loop, async, [](uv_async_t *a) { reinterpret_cast<Request *>(a->data)->notifyCallback(); });
#endif
}
}
// Called in the originating thread.
void Request::notifyCallback() {
MBGL_VERIFY_THREAD(tid)
if (!canceled) {
invoke();
} else {
bool destroy = false;
{
std::unique_lock<std::mutex> lock(canceled->mutex);
destroy = canceled->confirmed;
}
// Don't delete right way, because we have to unlock the mutex before deleting.
if (destroy) {
delete this;
}
}
}
void Request::invoke() {
assert(response);
// The user could supply a null pointer or empty std::function as a callback. In this case, we
// still do the file request, but we don't need to deliver a result.
if (callback) {
callback(*response);
}
delete this;
}
Request::~Request() {
if (async) {
uv_close(reinterpret_cast<uv_handle_t*>(async), [](uv_handle_t* handle) {
delete reinterpret_cast<uv_async_t*>(handle);
});
}
}
// Called in the FileSource thread.
void Request::notify(const std::shared_ptr<const Response> &response_) {
assert(!response);
response = response_;
assert(response);
if (async) {
uv_async_send(async);
} else {
// This request is not cancelable. This means that the callback will be executed in an
// arbitrary thread (== FileSource thread).
invoke();
}
}
// Called in the originating thread.
void Request::cancel() {
MBGL_VERIFY_THREAD(tid)
assert(async);
assert(!canceled);
canceled = util::make_unique<Canceled>();
}
// Called in the FileSource thread.
// Will only ever be invoked after cancel() was called in the original requesting thread.
void Request::destruct() {
assert(async);
assert(canceled);
std::unique_lock<std::mutex> lock(canceled->mutex);
canceled->confirmed = true;
uv_async_send(async);
// after this method returns, the FileSource thread has no knowledge of
// this object anymore.
}
}
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