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#include <mbgl/storage/default/request.hpp>
#include <mbgl/storage/response.hpp>
#include <mbgl/util/util.hpp>
#include <mbgl/util/uv.hpp>
#include <uv.h>
#include <cassert>
#include <functional>
namespace mbgl {
// Note: This requires that loop is running in the current thread (or not yet running).
Request::Request(const Resource &resource_, uv_loop_t *loop, const Environment &env_, Callback callback_)
: callback(callback_), resource(resource_), env(env_) {
// 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) {
notifyAsync = new uv_async_t;
notifyAsync->data = nullptr;
#if UV_VERSION_MAJOR == 0 && UV_VERSION_MINOR <= 10
uv_async_init(loop, notifyAsync, [](uv_async_t *async, int) { notifyCallback(async); });
#else
uv_async_init(loop, notifyAsync, notifyCallback);
#endif
}
}
void Request::notifyCallback(uv_async_t *async) {
auto request = reinterpret_cast<Request *>(async->data);
uv::close(async);
assert(request);
MBGL_VERIFY_THREAD(request->tid)
if (!request->destructAsync) {
// Call the callback with the result data. This will also delete this object. We haven't
// created a cancel request, so this is safe since it won't be accessed in the future.
// It is up to the user to not call cancel() on this Request object after the response was
// delivered.
request->invoke();
} else {
// Otherwise, we're waiting for for the destruct notification to be delivered in order
// to delete the Request object. We're doing this since we can't know whether the
// DefaultFileSource is still sending a cancel event, which means this object must still
// exist.
}
}
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() {
}
void Request::notify(const std::shared_ptr<const Response> &response_) {
response = response_;
assert(response);
if (notifyAsync) {
assert(!notifyAsync->data);
notifyAsync->data = this;
uv_async_send(notifyAsync);
} else {
// This request is not cancelable. This means that the callback will be executed in an
// arbitrary thread (== FileSource thread).
invoke();
}
}
void Request::cancel() {
MBGL_VERIFY_THREAD(tid)
assert(notifyAsync);
assert(!destructAsync);
destructAsync = new uv_async_t;
destructAsync->data = nullptr;
#if UV_VERSION_MAJOR == 0 && UV_VERSION_MINOR <= 10
uv_async_init(notifyAsync->loop, destructAsync, [](uv_async_t *async, int) { cancelCallback(async); });
#else
uv_async_init(notifyAsync->loop, destructAsync, cancelCallback);
#endif
}
void Request::cancelCallback(uv_async_t *async) {
// The destructAsync will be invoked *after* the notifyAsync callback has already run.
auto request = reinterpret_cast<Request *>(async->data);
uv::close(async);
assert(request);
MBGL_VERIFY_THREAD(request->tid)
delete request;
}
// This gets called from the FileSource thread, and will only ever be invoked after cancel() was called
// in the original requesting thread.
void Request::destruct() {
assert(notifyAsync);
assert(destructAsync);
if (!notifyAsync->data) {
// The async hasn't been triggered yet, but we need to so that it'll close the handle. The
// callback will not delete this object since we have a destructAsync handle as well.
notifyAsync->data = this;
uv_async_send(notifyAsync);
}
// This will finally destruct this object.
assert(!destructAsync->data);
destructAsync->data = this;
uv_async_send(destructAsync);
}
}
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