Valentin Shergin c25d5948a5 Fabric: Exposing EventEmitter's ownership model as a shared_ptr
Summary:
As we did in the previous diff, here we implemented `EventEmitter`'s ownership model as a `shared_ptr`. This change fixes problem with leaking `WeakObject`s which happens on hot-reload.

So, in short:
 * `EventTargetWrapper` object owns `jsi::WeakObject` that can be converted to actual `jsi::Object` that represent event target in JavaScript realm;
 * `EventTargetWrapper` and `jsi::WeakObject` objects must be deallocated as soon as native part does not need them anymore;
 * `EventEmitter` objects retain `EventTarget` objects;
 * `EventEmitter` can loose event target object in case if assosiated `ShadowNode` got unmounted (not deallocated); in this case `EventEmitter` is loosing possibility to dispatch event even if some mounting-layer code is still retaining it.

Reviewed By: mdvacca

Differential Revision: D9762755

fbshipit-source-id: 96e989767a32914db9f4627fce51b044c71f257a
2018-09-13 23:02:37 -07:00

91 lines
2.0 KiB
C++

/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#include "EventEmitter.h"
#include <folly/dynamic.h>
#include "RawEvent.h"
namespace facebook {
namespace react {
// TODO(T29874519): Get rid of "top" prefix once and for all.
/*
* Capitalizes the first letter of the event type and adds "top" prefix
* (e.g. "layout" becames "topLayout").
*/
static std::string normalizeEventType(const std::string &type) {
auto prefixedType = type;
prefixedType[0] = toupper(prefixedType[0]);
prefixedType.insert(0, "top");
return prefixedType;
}
std::recursive_mutex &EventEmitter::DispatchMutex() {
static std::recursive_mutex mutex;
return mutex;
}
EventEmitter::EventEmitter(
SharedEventTarget eventTarget,
Tag tag,
WeakEventDispatcher eventDispatcher
):
eventTarget_(std::move(eventTarget)),
tag_(tag),
eventDispatcher_(std::move(eventDispatcher)) {}
void EventEmitter::dispatchEvent(
const std::string &type,
const folly::dynamic &payload,
const EventPriority &priority
) const {
const auto &eventDispatcher = eventDispatcher_.lock();
if (!eventDispatcher) {
return;
}
// Mixing `target` into `payload`.
assert(payload.isObject());
folly::dynamic extendedPayload = folly::dynamic::object("target", tag_);
extendedPayload.merge_patch(payload);
auto weakEventEmitter = std::weak_ptr<const EventEmitter> {shared_from_this()};
eventDispatcher->dispatchEvent(
RawEvent(
normalizeEventType(type),
extendedPayload,
eventTarget_,
[weakEventEmitter]() {
auto eventEmitter = weakEventEmitter.lock();
if (!eventEmitter) {
return false;
}
return eventEmitter->getEnabled();
}
),
priority
);
}
void EventEmitter::setEnabled(bool enabled) const {
enabled_ = enabled;
if (!enabled) {
eventTarget_ = nullptr;
}
}
bool EventEmitter::getEnabled() const {
return enabled_;
}
} // namespace react
} // namespace facebook