firefox-main/toolkit/components/uniffi-js/Callbacks.cpp (file symbol)

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "nsPrintfCString.h"
#include "nsString.h"
#include "nsThreadUtils.h"
#include "mozilla/uniffi/OwnedRustBuffer.h"
#include "mozilla/dom/RootedDictionary.h"
#include "mozilla/dom/Promise.h"
#include "mozilla/dom/UniFFIBinding.h"
#include "mozilla/uniffi/Callbacks.h"
#include "mozilla/Atomics.h"
#include "mozilla/Logging.h"
#include "mozilla/RefPtr.h"
#include "mozilla/UniquePtr.h"
namespace mozilla::uniffi {
extern mozilla::LazyLogModule gUniffiLogger;
// Type we'll be using to store callback handle ref counts
//
// 32-bits should never overflow and ReleaseAcquire is the recommended memory
// ordering for reference counts:
using HandleRefCount = Atomic<uint32_t, MemoryOrdering::ReleaseAcquire>;
uint64_t CallbackHandleCreate() {
// This allocates an atomic u32 that stores the ref count.
// We cast the address to a `u64`, which will be the handle.
//
// Another approach would be to create a HashMap that maps handles to their
// refcounts. However, that would require a lock and global initialization.
// This works in a similar way, but instead of generating a handle and
// inserting it into the map, we call `new` to allocate a memory location and
// use the address as the handle.
//
// This will safely fit in a JS integer as long as pointers only set the lower
// 53 bits or so. This is okay since the JS code itself assumes only the lower
// 48 bits of the pointer are set:
//
// Finally, we always set the lowest bit on the handle. This allows UniFFI to
// tell if trait interface handles came from JS or Rust.
HandleRefCount* handlePointer = new HandleRefCount(1);
return reinterpret_cast<uint64_t>(handlePointer) | 1;
}
uint32_t CallbackHandleAddRef(uint64_t aHandle) {
HandleRefCount* handlePointer =
reinterpret_cast<HandleRefCount*>(aHandle & ~1);
return ++(*handlePointer);
}
uint32_t CallbackHandleRelease(uint64_t aHandle) {
HandleRefCount* handlePointer =
reinterpret_cast<HandleRefCount*>(aHandle & ~1);
return --(*handlePointer);
}
void CallbackHandleFree(uint64_t aHandle) {
HandleRefCount* handlePointer =
reinterpret_cast<HandleRefCount*>(aHandle & ~1);
delete handlePointer;
}
void AsyncCallbackMethodHandlerBase::ScheduleAsyncCall(
UniquePtr<AsyncCallbackMethodHandlerBase> aHandler,
StaticRefPtr<dom::UniFFICallbackHandler>* aJsHandler) {
nsresult dispatchResult = NS_DispatchToMainThread(NS_NewRunnableFunction(
"UniFFI callback", [handler = std::move(aHandler),
aJsHandler]() MOZ_CAN_RUN_SCRIPT_BOUNDARY mutable {
auto reportError = MakeScopeExit([&handler] {
dom::RootedDictionary<dom::UniFFIScaffoldingCallResult> callResult(
dom::RootingCx());
callResult.mCode = dom::UniFFIScaffoldingCallCode::Internal_error;
handler->HandleReturn(callResult, IgnoreErrors());
});
// Take our own reference to the callback handler to ensure that it
// stays alive for the duration of this call
RefPtr<dom::UniFFICallbackHandler> jsHandler = *aJsHandler;
if (!jsHandler) {
MOZ_LOG(gUniffiLogger, LogLevel::Error,
("[%s] called, but JS handler not registered",
handler->mUniffiMethodName));
return;
}
JSObject* global = jsHandler->CallbackGlobalOrNull();
if (!global) {
MOZ_LOG(
gUniffiLogger, LogLevel::Error,
("[%s] JS handler has null global", handler->mUniffiMethodName));
return;
}
dom::AutoEntryScript aes(global, handler->mUniffiMethodName);
IgnoredErrorResult error;
RefPtr<dom::Promise> promise =
handler->MakeCall(aes.cx(), jsHandler, error);
if (error.Failed()) {
MOZ_LOG(
gUniffiLogger, LogLevel::Error,
("[%s] Error invoking JS handler", handler->mUniffiMethodName));
return;
}
reportError.release();
if (promise) {
auto promiseHandler = MakeRefPtr<PromiseHandler>(std::move(handler));
promise->AppendNativeHandler(promiseHandler);
}
}));
if (NS_FAILED(dispatchResult)) {
MOZ_LOG(gUniffiLogger, LogLevel::Error,
("[UniFFI] Error dispatching UniFFI callback task"));
}
}
MOZ_CAN_RUN_SCRIPT
already_AddRefed<dom::Promise> CallbackFreeHandler::MakeCall(
JSContext* aCx, dom::UniFFICallbackHandler* aJsHandler,
ErrorResult& aError) {
aJsHandler->Destroy(mUniffiHandle.IntoRust(), aError);
// CallbackFreeHandler works like a fire-and-forget callback and returns
// nullptr. There's no Rust code that's awaiting this result.
return nullptr;
}
NS_IMPL_ISUPPORTS0(AsyncCallbackMethodHandlerBase::PromiseHandler);
void AsyncCallbackMethodHandlerBase::PromiseHandler::ResolvedCallback(
JSContext* aCx, JS::Handle<JS::Value> aValue, ErrorResult& aRv) {
dom::RootedDictionary<dom::UniFFIScaffoldingCallResult> callResult(aCx);
if (!callResult.Init(aCx, aValue)) {
JS_ClearPendingException(aCx);
MOZ_LOG(
gUniffiLogger, LogLevel::Error,
("[%s] callback method did not return a UniFFIScaffoldingCallResult",
mHandler->mUniffiMethodName));
callResult.mCode = dom::UniFFIScaffoldingCallCode::Internal_error;
}
mHandler->HandleReturn(callResult, aRv);
}
void AsyncCallbackMethodHandlerBase::PromiseHandler::RejectedCallback(
JSContext* aCx, JS::Handle<JS::Value>, ErrorResult& aRv) {
dom::RootedDictionary<dom::UniFFIScaffoldingCallResult> callResult(aCx);
callResult.mCode = dom::UniFFIScaffoldingCallCode::Internal_error;
mHandler->HandleReturn(callResult, aRv);
}
} // namespace mozilla::uniffi