mirror of
https://github.com/apple/swift.git
synced 2025-12-14 20:36:38 +01:00
439edbce1f
Change the code generation patterns for `async let` bindings to use an ABI based on the following functions: - `swift_asyncLet_begin`, which starts an `async let` child task, but which additionally now associates the `async let` with a caller-owned buffer to receive the result of the task. This is intended to allow the task to emplace its result in caller-owned memory, allowing the child task to be deallocated after completion without invalidating the result buffer. - `swift_asyncLet_get[_throwing]`, which replaces `swift_asyncLet_wait[_throwing]`. Instead of returning a copy of the value, this entry point concerns itself with populating the local buffer. If the buffer hasn't been populated, then it awaits completion of the task and emplaces the result in the buffer; otherwise, it simply returns. The caller can then read the result out of its owned memory. These entry points are intended to be used before every read from the `async let` binding, after which point the local buffer is guaranteed to contain an initialized value. - `swift_asyncLet_finish`, which replaces `swift_asyncLet_end`. Unlike `_end`, this variant is async and will suspend the parent task after cancelling the child to ensure it finishes before cleaning up. The local buffer will also be deinitialized if necessary. This is intended to be used on exit from an `async let` scope, to handle cleaning up the local buffer if necessary as well as cancelling, awaiting, and deallocating the child task. - `swift_asyncLet_consume[_throwing]`, which combines `get` and `finish`. This will await completion of the task, leaving the result value in the result buffer (or propagating the error, if it throws), while destroying and deallocating the child task. This is intended as an optimization for reading `async let` variables that are read exactly once by their parent task. To avoid an epoch break with existing swiftinterfaces and ABI clients, the old builtins and entry points are kept intact for now, but SILGen now only generates code using the new interface. This new interface fixes several issues with the old async let codegen, including use-after-free crashes if the `async let` was never awaited, and the inability to read from an `async let` variable more than once. rdar://77855176
1146 lines
38 KiB
C++
1146 lines
38 KiB
C++
//===--- Task.cpp - Task object and management ----------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Object management routines for asynchronous task objects.
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//
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//===----------------------------------------------------------------------===//
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#include "../CompatibilityOverride/CompatibilityOverride.h"
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#include "swift/Runtime/Concurrency.h"
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#include "swift/ABI/Task.h"
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#include "swift/ABI/TaskLocal.h"
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#include "swift/ABI/TaskOptions.h"
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#include "swift/ABI/Metadata.h"
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#include "swift/Runtime/Mutex.h"
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#include "swift/Runtime/HeapObject.h"
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#include "TaskGroupPrivate.h"
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#include "TaskPrivate.h"
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#include "AsyncCall.h"
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#include "Debug.h"
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#include "Error.h"
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#include <dispatch/dispatch.h>
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#if !defined(_WIN32)
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#include <dlfcn.h>
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#endif
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#ifdef __APPLE__
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#if __POINTER_WIDTH__ == 64
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asm("\n .globl _swift_async_extendedFramePointerFlags" \
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"\n _swift_async_extendedFramePointerFlags = 0x1000000000000000");
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#elif __ARM64_ARCH_8_32__
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asm("\n .globl _swift_async_extendedFramePointerFlags" \
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"\n _swift_async_extendedFramePointerFlags = 0x10000000");
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#else
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asm("\n .globl _swift_async_extendedFramePointerFlags" \
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"\n _swift_async_extendedFramePointerFlags = 0x0");
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#endif
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#endif // __APPLE__
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using namespace swift;
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using FutureFragment = AsyncTask::FutureFragment;
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using TaskGroup = swift::TaskGroup;
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void FutureFragment::destroy() {
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auto queueHead = waitQueue.load(std::memory_order_acquire);
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switch (queueHead.getStatus()) {
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case Status::Executing:
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assert(false && "destroying a task that never completed");
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case Status::Success:
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resultType->vw_destroy(getStoragePtr());
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break;
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case Status::Error:
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swift_errorRelease(getError());
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break;
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}
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}
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FutureFragment::Status AsyncTask::waitFuture(AsyncTask *waitingTask,
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AsyncContext *waitingTaskContext,
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TaskContinuationFunction *resumeFn,
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AsyncContext *callerContext,
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OpaqueValue *result) {
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using Status = FutureFragment::Status;
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using WaitQueueItem = FutureFragment::WaitQueueItem;
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assert(isFuture());
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auto fragment = futureFragment();
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auto queueHead = fragment->waitQueue.load(std::memory_order_acquire);
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bool contextIntialized = false;
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while (true) {
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switch (queueHead.getStatus()) {
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case Status::Error:
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case Status::Success:
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#if SWIFT_TASK_PRINTF_DEBUG
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fprintf(stderr, "[%lu] task %p waiting on task %p, completed immediately\n",
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_swift_get_thread_id(), waitingTask, this);
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#endif
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_swift_tsan_acquire(static_cast<Job *>(this));
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// The task is done; we don't need to wait.
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return queueHead.getStatus();
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case Status::Executing:
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#if SWIFT_TASK_PRINTF_DEBUG
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fprintf(stderr, "[%lu] task %p waiting on task %p, going to sleep\n",
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_swift_get_thread_id(), waitingTask, this);
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#endif
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_swift_tsan_release(static_cast<Job *>(waitingTask));
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// Task is now complete. We'll need to add ourselves to the queue.
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break;
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}
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if (!contextIntialized) {
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contextIntialized = true;
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auto context =
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reinterpret_cast<TaskFutureWaitAsyncContext *>(waitingTaskContext);
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context->errorResult = nullptr;
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context->successResultPointer = result;
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context->ResumeParent = resumeFn;
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context->Parent = callerContext;
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}
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// Put the waiting task at the beginning of the wait queue.
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waitingTask->getNextWaitingTask() = queueHead.getTask();
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auto newQueueHead = WaitQueueItem::get(Status::Executing, waitingTask);
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if (fragment->waitQueue.compare_exchange_weak(
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queueHead, newQueueHead,
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/*success*/ std::memory_order_release,
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/*failure*/ std::memory_order_acquire)) {
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// Escalate the priority of this task based on the priority
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// of the waiting task.
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swift_task_escalate(this, waitingTask->Flags.getPriority());
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return FutureFragment::Status::Executing;
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}
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}
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}
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void NullaryContinuationJob::process(Job *_job) {
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auto *job = cast<NullaryContinuationJob>(_job);
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auto *task = job->Task;
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auto *continuation = job->Continuation;
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_swift_task_dealloc_specific(task, job);
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auto *context = cast<ContinuationAsyncContext>(continuation->ResumeContext);
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context->setErrorResult(nullptr);
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swift_continuation_resume(continuation);
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}
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void AsyncTask::completeFuture(AsyncContext *context) {
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using Status = FutureFragment::Status;
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using WaitQueueItem = FutureFragment::WaitQueueItem;
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assert(isFuture());
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auto fragment = futureFragment();
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// If an error was thrown, save it in the future fragment.
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auto asyncContextPrefix = reinterpret_cast<FutureAsyncContextPrefix *>(
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reinterpret_cast<char *>(context) - sizeof(FutureAsyncContextPrefix));
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bool hadErrorResult = false;
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auto errorObject = asyncContextPrefix->errorResult;
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fragment->getError() = errorObject;
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if (errorObject) {
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hadErrorResult = true;
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}
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_swift_tsan_release(static_cast<Job *>(this));
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// Update the status to signal completion.
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auto newQueueHead = WaitQueueItem::get(
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hadErrorResult ? Status::Error : Status::Success,
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nullptr
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);
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auto queueHead = fragment->waitQueue.exchange(
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newQueueHead, std::memory_order_acquire);
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assert(queueHead.getStatus() == Status::Executing);
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// If this is task group child, notify the parent group about the completion.
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if (hasGroupChildFragment()) {
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// then we must offer into the parent group that we completed,
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// so it may `next()` poll completed child tasks in completion order.
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auto group = groupChildFragment()->getGroup();
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group->offer(this, context);
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}
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// Schedule every waiting task on the executor.
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auto waitingTask = queueHead.getTask();
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#if SWIFT_TASK_PRINTF_DEBUG
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if (!waitingTask)
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fprintf(stderr, "[%lu] task %p had no waiting tasks\n",
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_swift_get_thread_id(), this);
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#endif
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while (waitingTask) {
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// Find the next waiting task before we invalidate it by resuming
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// the task.
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auto nextWaitingTask = waitingTask->getNextWaitingTask();
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#if SWIFT_TASK_PRINTF_DEBUG
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fprintf(stderr, "[%lu] waking task %p from future of task %p\n",
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_swift_get_thread_id(), waitingTask, this);
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#endif
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// Fill in the return context.
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auto waitingContext =
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static_cast<TaskFutureWaitAsyncContext *>(waitingTask->ResumeContext);
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if (hadErrorResult) {
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waitingContext->fillWithError(fragment);
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} else {
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waitingContext->fillWithSuccess(fragment);
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}
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_swift_tsan_acquire(static_cast<Job *>(waitingTask));
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// Enqueue the waiter on the global executor.
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// TODO: allow waiters to fill in a suggested executor
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swift_task_enqueueGlobal(waitingTask);
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// Move to the next task.
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waitingTask = nextWaitingTask;
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}
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}
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SWIFT_CC(swift)
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static void destroyJob(SWIFT_CONTEXT HeapObject *obj) {
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assert(false && "A non-task job should never be destroyed as heap metadata.");
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}
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AsyncTask::~AsyncTask() {
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// For a future, destroy the result.
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if (isFuture()) {
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futureFragment()->destroy();
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}
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Private.destroy();
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}
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SWIFT_CC(swift)
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static void destroyTask(SWIFT_CONTEXT HeapObject *obj) {
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auto task = static_cast<AsyncTask*>(obj);
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task->~AsyncTask();
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// The task execution itself should always hold a reference to it, so
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// if we get here, we know the task has finished running, which means
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// swift_task_complete should have been run, which will have torn down
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// the task-local allocator. There's actually nothing else to clean up
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// here.
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#if SWIFT_TASK_PRINTF_DEBUG
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fprintf(stderr, "[%lu] destroy task %p\n", _swift_get_thread_id(), task);
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#endif
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free(task);
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}
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static ExecutorRef executorForEnqueuedJob(Job *job) {
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void *jobQueue = job->SchedulerPrivate[Job::DispatchQueueIndex];
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if (jobQueue == DISPATCH_QUEUE_GLOBAL_EXECUTOR)
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return ExecutorRef::generic();
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else
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return ExecutorRef::forOrdinary(reinterpret_cast<HeapObject*>(jobQueue),
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_swift_task_getDispatchQueueSerialExecutorWitnessTable());
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}
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static void jobInvoke(void *obj, void *unused, uint32_t flags) {
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(void)unused;
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Job *job = reinterpret_cast<Job *>(obj);
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swift_job_run(job, executorForEnqueuedJob(job));
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}
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// Magic constant to identify Swift Job vtables to Dispatch.
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static const unsigned long dispatchSwiftObjectType = 1;
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FullMetadata<DispatchClassMetadata> swift::jobHeapMetadata = {
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{
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{
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&destroyJob
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},
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{
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/*value witness table*/ nullptr
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}
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},
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{
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MetadataKind::Job,
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dispatchSwiftObjectType,
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jobInvoke
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}
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};
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/// Heap metadata for an asynchronous task.
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static FullMetadata<DispatchClassMetadata> taskHeapMetadata = {
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{
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{
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&destroyTask
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},
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{
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/*value witness table*/ nullptr
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}
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},
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{
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MetadataKind::Task,
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dispatchSwiftObjectType,
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jobInvoke
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}
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};
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const void *const swift::_swift_concurrency_debug_jobMetadata =
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static_cast<Metadata *>(&jobHeapMetadata);
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const void *const swift::_swift_concurrency_debug_asyncTaskMetadata =
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static_cast<Metadata *>(&taskHeapMetadata);
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static void completeTaskImpl(AsyncTask *task,
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AsyncContext *context,
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SwiftError *error) {
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assert(task && "completing task, but there is no active task registered");
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// Store the error result.
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auto asyncContextPrefix = reinterpret_cast<AsyncContextPrefix *>(
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reinterpret_cast<char *>(context) - sizeof(AsyncContextPrefix));
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asyncContextPrefix->errorResult = error;
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task->Private.complete(task);
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#if SWIFT_TASK_PRINTF_DEBUG
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fprintf(stderr, "[%lu] task %p completed\n", _swift_get_thread_id(), task);
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#endif
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// Complete the future.
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// Warning: This deallocates the task in case it's an async let task.
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// The task must not be accessed afterwards.
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if (task->isFuture()) {
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task->completeFuture(context);
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}
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// TODO: set something in the status?
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// if (task->hasChildFragment()) {
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// TODO: notify the parent somehow?
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// TODO: remove this task from the child-task chain?
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// }
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}
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/// The function that we put in the context of a simple task
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/// to handle the final return.
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SWIFT_CC(swiftasync)
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static void completeTask(SWIFT_ASYNC_CONTEXT AsyncContext *context,
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SWIFT_CONTEXT SwiftError *error) {
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// Set that there's no longer a running task in the current thread.
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auto task = _swift_task_clearCurrent();
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assert(task && "completing task, but there is no active task registered");
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completeTaskImpl(task, context, error);
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}
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/// The function that we put in the context of a simple task
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/// to handle the final return.
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SWIFT_CC(swiftasync)
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static void completeTaskAndRelease(SWIFT_ASYNC_CONTEXT AsyncContext *context,
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SWIFT_CONTEXT SwiftError *error) {
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// Set that there's no longer a running task in the current thread.
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auto task = _swift_task_clearCurrent();
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assert(task && "completing task, but there is no active task registered");
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completeTaskImpl(task, context, error);
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// Release the task, balancing the retain that a running task has on itself.
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// If it was a group child task, it will remain until the group returns it.
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swift_release(task);
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}
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/// The function that we put in the context of a simple task
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/// to handle the final return from a closure.
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SWIFT_CC(swiftasync)
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static void completeTaskWithClosure(SWIFT_ASYNC_CONTEXT AsyncContext *context,
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SWIFT_CONTEXT SwiftError *error) {
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// Release the closure context.
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auto asyncContextPrefix = reinterpret_cast<AsyncContextPrefix *>(
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reinterpret_cast<char *>(context) - sizeof(AsyncContextPrefix));
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swift_release((HeapObject *)asyncContextPrefix->closureContext);
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// Clean up the rest of the task.
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return completeTaskAndRelease(context, error);
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}
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SWIFT_CC(swiftasync)
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static void non_future_adapter(SWIFT_ASYNC_CONTEXT AsyncContext *_context) {
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auto asyncContextPrefix = reinterpret_cast<AsyncContextPrefix *>(
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reinterpret_cast<char *>(_context) - sizeof(AsyncContextPrefix));
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return asyncContextPrefix->asyncEntryPoint(
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_context, asyncContextPrefix->closureContext);
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}
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SWIFT_CC(swiftasync)
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static void future_adapter(SWIFT_ASYNC_CONTEXT AsyncContext *_context) {
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auto asyncContextPrefix = reinterpret_cast<FutureAsyncContextPrefix *>(
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reinterpret_cast<char *>(_context) - sizeof(FutureAsyncContextPrefix));
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return asyncContextPrefix->asyncEntryPoint(
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asyncContextPrefix->indirectResult, _context,
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asyncContextPrefix->closureContext);
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}
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SWIFT_CC(swiftasync)
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static void task_wait_throwing_resume_adapter(SWIFT_ASYNC_CONTEXT AsyncContext *_context) {
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auto context = static_cast<TaskFutureWaitAsyncContext *>(_context);
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auto resumeWithError =
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reinterpret_cast<AsyncVoidClosureEntryPoint *>(context->ResumeParent);
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return resumeWithError(context->Parent, context->errorResult);
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}
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SWIFT_CC(swiftasync)
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static void
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task_future_wait_resume_adapter(SWIFT_ASYNC_CONTEXT AsyncContext *_context) {
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return _context->ResumeParent(_context->Parent);
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}
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/// Implementation of task creation.
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SWIFT_CC(swift)
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static AsyncTaskAndContext swift_task_create_commonImpl(
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size_t rawTaskCreateFlags,
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TaskOptionRecord *options,
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const Metadata *futureResultType,
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FutureAsyncSignature::FunctionType *function, void *closureContext,
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size_t initialContextSize) {
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TaskCreateFlags taskCreateFlags(rawTaskCreateFlags);
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// Propagate task-creation flags to job flags as appropriate.
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JobFlags jobFlags(JobKind::Task, taskCreateFlags.getPriority());
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jobFlags.task_setIsChildTask(taskCreateFlags.isChildTask());
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if (futureResultType) {
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jobFlags.task_setIsFuture(true);
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assert(initialContextSize >= sizeof(FutureAsyncContext));
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}
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// Collect the options we know about.
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ExecutorRef executor = ExecutorRef::generic();
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TaskGroup *group = nullptr;
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AsyncLet *asyncLet = nullptr;
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void *asyncLetBuffer = nullptr;
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bool hasAsyncLetResultBuffer = false;
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for (auto option = options; option; option = option->getParent()) {
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switch (option->getKind()) {
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case TaskOptionRecordKind::Executor:
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executor = cast<ExecutorTaskOptionRecord>(option)->getExecutor();
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break;
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case TaskOptionRecordKind::TaskGroup:
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group = cast<TaskGroupTaskOptionRecord>(option)->getGroup();
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assert(group && "Missing group");
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jobFlags.task_setIsGroupChildTask(true);
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break;
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case TaskOptionRecordKind::AsyncLet:
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asyncLet = cast<AsyncLetTaskOptionRecord>(option)->getAsyncLet();
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assert(asyncLet && "Missing async let storage");
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jobFlags.task_setIsAsyncLetTask(true);
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jobFlags.task_setIsChildTask(true);
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break;
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case TaskOptionRecordKind::AsyncLetWithBuffer:
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auto *aletRecord = cast<AsyncLetWithBufferTaskOptionRecord>(option);
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asyncLet = aletRecord->getAsyncLet();
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// TODO: Actually digest the result buffer into the async let task
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// context, so that we can emplace the eventual result there instead
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// of in a FutureFragment.
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hasAsyncLetResultBuffer = true;
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asyncLetBuffer = aletRecord->getResultBuffer();
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assert(asyncLet && "Missing async let storage");
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jobFlags.task_setIsAsyncLetTask(true);
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jobFlags.task_setIsChildTask(true);
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break;
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}
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}
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// Add to the task group, if requested.
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if (taskCreateFlags.addPendingGroupTaskUnconditionally()) {
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assert(group && "Missing group");
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swift_taskGroup_addPending(group, /*unconditionally=*/true);
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}
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AsyncTask *parent = nullptr;
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if (jobFlags.task_isChildTask()) {
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parent = swift_task_getCurrent();
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assert(parent != nullptr && "creating a child task with no active task");
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}
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// Inherit the priority of the currently-executing task if unspecified and
|
|
// we want to inherit.
|
|
if (jobFlags.getPriority() == JobPriority::Unspecified &&
|
|
(jobFlags.task_isChildTask() || taskCreateFlags.inheritContext())) {
|
|
AsyncTask *currentTask = parent;
|
|
if (!currentTask)
|
|
currentTask = swift_task_getCurrent();
|
|
|
|
if (currentTask)
|
|
jobFlags.setPriority(currentTask->getPriority());
|
|
else
|
|
jobFlags.setPriority(swift_task_getCurrentThreadPriority());
|
|
}
|
|
|
|
// Figure out the size of the header.
|
|
size_t headerSize = sizeof(AsyncTask);
|
|
if (parent) {
|
|
headerSize += sizeof(AsyncTask::ChildFragment);
|
|
}
|
|
if (group) {
|
|
headerSize += sizeof(AsyncTask::GroupChildFragment);
|
|
}
|
|
if (futureResultType) {
|
|
headerSize += FutureFragment::fragmentSize(futureResultType);
|
|
// Add the future async context prefix.
|
|
headerSize += sizeof(FutureAsyncContextPrefix);
|
|
} else {
|
|
// Add the async context prefix.
|
|
headerSize += sizeof(AsyncContextPrefix);
|
|
}
|
|
|
|
headerSize = llvm::alignTo(headerSize, llvm::Align(alignof(AsyncContext)));
|
|
|
|
// Allocate the initial context together with the job.
|
|
// This means that we never get rid of this allocation.
|
|
size_t amountToAllocate = headerSize + initialContextSize;
|
|
|
|
assert(amountToAllocate % MaximumAlignment == 0);
|
|
|
|
unsigned initialSlabSize = 512;
|
|
|
|
void *allocation = nullptr;
|
|
if (asyncLet) {
|
|
assert(parent);
|
|
|
|
// If there isn't enough room in the fixed async let allocation to
|
|
// set up the initial context, then we'll have to allocate more space
|
|
// from the parent.
|
|
if (asyncLet->getSizeOfPreallocatedSpace() < amountToAllocate) {
|
|
hasAsyncLetResultBuffer = false;
|
|
}
|
|
|
|
// DEPRECATED. This is separated from the above condition because we
|
|
// also have to handle an older async let ABI that did not provide
|
|
// space for the initial slab in the compiler-generated preallocation.
|
|
if (!hasAsyncLetResultBuffer) {
|
|
allocation = _swift_task_alloc_specific(parent,
|
|
amountToAllocate + initialSlabSize);
|
|
} else {
|
|
allocation = asyncLet->getPreallocatedSpace();
|
|
assert(asyncLet->getSizeOfPreallocatedSpace() >= amountToAllocate
|
|
&& "async let does not preallocate enough space for child task");
|
|
initialSlabSize = asyncLet->getSizeOfPreallocatedSpace()
|
|
- amountToAllocate;
|
|
}
|
|
} else {
|
|
allocation = malloc(amountToAllocate);
|
|
}
|
|
#if SWIFT_TASK_PRINTF_DEBUG
|
|
fprintf(stderr, "[%lu] allocate task %p, parent = %p, slab %u\n",
|
|
_swift_get_thread_id(), allocation, parent, initialSlabSize);
|
|
#endif
|
|
|
|
AsyncContext *initialContext =
|
|
reinterpret_cast<AsyncContext*>(
|
|
reinterpret_cast<char*>(allocation) + headerSize);
|
|
|
|
// We can't just use `function` because it uses the new async function entry
|
|
// ABI -- passing parameters, closure context, indirect result addresses
|
|
// directly -- but AsyncTask->ResumeTask expects the signature to be
|
|
// `void (*, *, swiftasync *)`.
|
|
// Instead we use an adapter. This adaptor should use the storage prefixed to
|
|
// the async context to get at the parameters.
|
|
// See e.g. FutureAsyncContextPrefix.
|
|
|
|
if (!futureResultType) {
|
|
auto asyncContextPrefix = reinterpret_cast<AsyncContextPrefix *>(
|
|
reinterpret_cast<char *>(allocation) + headerSize -
|
|
sizeof(AsyncContextPrefix));
|
|
asyncContextPrefix->asyncEntryPoint =
|
|
reinterpret_cast<AsyncVoidClosureEntryPoint *>(function);
|
|
asyncContextPrefix->closureContext = closureContext;
|
|
function = non_future_adapter;
|
|
assert(sizeof(AsyncContextPrefix) == 3 * sizeof(void *));
|
|
} else {
|
|
auto asyncContextPrefix = reinterpret_cast<FutureAsyncContextPrefix *>(
|
|
reinterpret_cast<char *>(allocation) + headerSize -
|
|
sizeof(FutureAsyncContextPrefix));
|
|
asyncContextPrefix->asyncEntryPoint =
|
|
reinterpret_cast<AsyncGenericClosureEntryPoint *>(function);
|
|
function = future_adapter;
|
|
asyncContextPrefix->closureContext = closureContext;
|
|
assert(sizeof(FutureAsyncContextPrefix) == 4 * sizeof(void *));
|
|
}
|
|
|
|
// Initialize the task so that resuming it will run the given
|
|
// function on the initial context.
|
|
AsyncTask *task = nullptr;
|
|
if (asyncLet) {
|
|
// Initialize the refcount bits to "immortal", so that
|
|
// ARC operations don't have any effect on the task.
|
|
task = new(allocation) AsyncTask(&taskHeapMetadata,
|
|
InlineRefCounts::Immortal, jobFlags,
|
|
function, initialContext);
|
|
} else {
|
|
task = new(allocation) AsyncTask(&taskHeapMetadata, jobFlags,
|
|
function, initialContext);
|
|
}
|
|
|
|
// Initialize the child fragment if applicable.
|
|
if (parent) {
|
|
auto childFragment = task->childFragment();
|
|
new (childFragment) AsyncTask::ChildFragment(parent);
|
|
}
|
|
|
|
// Initialize the group child fragment if applicable.
|
|
if (group) {
|
|
auto groupChildFragment = task->groupChildFragment();
|
|
new (groupChildFragment) AsyncTask::GroupChildFragment(group);
|
|
}
|
|
|
|
// Initialize the future fragment if applicable.
|
|
if (futureResultType) {
|
|
assert(task->isFuture());
|
|
auto futureFragment = task->futureFragment();
|
|
new (futureFragment) FutureFragment(futureResultType);
|
|
|
|
// Set up the context for the future so there is no error, and a successful
|
|
// result will be written into the future fragment's storage.
|
|
auto futureAsyncContextPrefix =
|
|
reinterpret_cast<FutureAsyncContextPrefix *>(
|
|
reinterpret_cast<char *>(allocation) + headerSize -
|
|
sizeof(FutureAsyncContextPrefix));
|
|
futureAsyncContextPrefix->indirectResult = futureFragment->getStoragePtr();
|
|
}
|
|
|
|
#if SWIFT_TASK_PRINTF_DEBUG
|
|
fprintf(stderr, "[%lu] creating task %p with parent %p\n",
|
|
_swift_get_thread_id(), task, parent);
|
|
#endif
|
|
|
|
// Initialize the task-local allocator.
|
|
initialContext->ResumeParent = reinterpret_cast<TaskContinuationFunction *>(
|
|
asyncLet ? &completeTask
|
|
: closureContext ? &completeTaskWithClosure
|
|
: &completeTaskAndRelease);
|
|
if (asyncLet && initialSlabSize > 0) {
|
|
assert(parent);
|
|
void *initialSlab = (char*)allocation + amountToAllocate;
|
|
task->Private.initializeWithSlab(task, initialSlab, initialSlabSize);
|
|
} else {
|
|
task->Private.initialize(task);
|
|
}
|
|
|
|
// Perform additional linking between parent and child task.
|
|
if (parent) {
|
|
// If the parent was already cancelled, we carry this flag forward to the child.
|
|
//
|
|
// In a task group we would not have allowed the `add` to create a child anymore,
|
|
// however better safe than sorry and `async let` are not expressed as task groups,
|
|
// so they may have been spawned in any case still.
|
|
if (swift_task_isCancelled(parent) ||
|
|
(group && group->isCancelled()))
|
|
swift_task_cancel(task);
|
|
|
|
// Initialize task locals with a link to the parent task.
|
|
task->_private().Local.initializeLinkParent(task, parent);
|
|
}
|
|
|
|
// Configure the initial context.
|
|
//
|
|
// FIXME: if we store a null pointer here using the standard ABI for
|
|
// signed null pointers, then we'll have to authenticate context pointers
|
|
// as if they might be null, even though the only time they ever might
|
|
// be is the final hop. Store a signed null instead.
|
|
initialContext->Parent = nullptr;
|
|
initialContext->Flags = AsyncContextKind::Ordinary;
|
|
initialContext->Flags.setShouldNotDeallocateInCallee(true);
|
|
|
|
// Attach to the group, if needed.
|
|
if (group) {
|
|
swift_taskGroup_attachChild(group, task);
|
|
}
|
|
|
|
// If we're supposed to copy task locals, do so now.
|
|
if (taskCreateFlags.copyTaskLocals()) {
|
|
swift_task_localsCopyTo(task);
|
|
}
|
|
|
|
// Push the async let task status record.
|
|
if (asyncLet) {
|
|
asyncLet_addImpl(task, asyncLet, !hasAsyncLetResultBuffer);
|
|
}
|
|
|
|
// If we're supposed to enqueue the task, do so now.
|
|
if (taskCreateFlags.enqueueJob()) {
|
|
swift_retain(task);
|
|
swift_task_enqueue(task, executor);
|
|
}
|
|
|
|
return {task, initialContext};
|
|
}
|
|
|
|
/// Extract the entry point address and initial context size from an async closure value.
|
|
template<typename AsyncSignature, uint16_t AuthDiscriminator>
|
|
SWIFT_ALWAYS_INLINE // so this doesn't hang out as a ptrauth gadget
|
|
std::pair<typename AsyncSignature::FunctionType *, size_t>
|
|
getAsyncClosureEntryPointAndContextSize(void *function,
|
|
HeapObject *functionContext) {
|
|
auto fnPtr =
|
|
reinterpret_cast<const AsyncFunctionPointer<AsyncSignature> *>(function);
|
|
#if SWIFT_PTRAUTH
|
|
fnPtr = (const AsyncFunctionPointer<AsyncSignature> *)ptrauth_auth_data(
|
|
(void *)fnPtr, ptrauth_key_process_independent_data, AuthDiscriminator);
|
|
#endif
|
|
return {reinterpret_cast<typename AsyncSignature::FunctionType *>(
|
|
fnPtr->Function.get()),
|
|
fnPtr->ExpectedContextSize};
|
|
}
|
|
|
|
SWIFT_CC(swift)
|
|
AsyncTaskAndContext swift::swift_task_create(
|
|
size_t taskCreateFlags,
|
|
TaskOptionRecord *options,
|
|
const Metadata *futureResultType,
|
|
void *closureEntry, HeapObject *closureContext) {
|
|
FutureAsyncSignature::FunctionType *taskEntry;
|
|
size_t initialContextSize;
|
|
std::tie(taskEntry, initialContextSize)
|
|
= getAsyncClosureEntryPointAndContextSize<
|
|
FutureAsyncSignature,
|
|
SpecialPointerAuthDiscriminators::AsyncFutureFunction
|
|
>(closureEntry, closureContext);
|
|
|
|
return swift_task_create_common(
|
|
taskCreateFlags, options, futureResultType, taskEntry, closureContext,
|
|
initialContextSize);
|
|
}
|
|
|
|
#ifdef __ARM_ARCH_7K__
|
|
__attribute__((noinline))
|
|
SWIFT_CC(swiftasync) static void workaround_function_swift_task_future_waitImpl(
|
|
OpaqueValue *result, SWIFT_ASYNC_CONTEXT AsyncContext *callerContext,
|
|
AsyncTask *task, TaskContinuationFunction resumeFunction,
|
|
AsyncContext *callContext) {
|
|
// Make sure we don't eliminate calls to this function.
|
|
asm volatile("" // Do nothing.
|
|
: // Output list, empty.
|
|
: "r"(result), "r"(callerContext), "r"(task) // Input list.
|
|
: // Clobber list, empty.
|
|
);
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
SWIFT_CC(swiftasync)
|
|
static void swift_task_future_waitImpl(
|
|
OpaqueValue *result,
|
|
SWIFT_ASYNC_CONTEXT AsyncContext *callerContext,
|
|
AsyncTask *task,
|
|
TaskContinuationFunction *resumeFn,
|
|
AsyncContext *callContext) {
|
|
// Suspend the waiting task.
|
|
auto waitingTask = swift_task_getCurrent();
|
|
waitingTask->ResumeTask = task_future_wait_resume_adapter;
|
|
waitingTask->ResumeContext = callContext;
|
|
|
|
// Wait on the future.
|
|
assert(task->isFuture());
|
|
|
|
switch (task->waitFuture(waitingTask, callContext, resumeFn, callerContext,
|
|
result)) {
|
|
case FutureFragment::Status::Executing:
|
|
// The waiting task has been queued on the future.
|
|
#ifdef __ARM_ARCH_7K__
|
|
return workaround_function_swift_task_future_waitImpl(
|
|
result, callerContext, task, resumeFn, callContext);
|
|
#else
|
|
return;
|
|
#endif
|
|
|
|
case FutureFragment::Status::Success: {
|
|
// Run the task with a successful result.
|
|
auto future = task->futureFragment();
|
|
future->getResultType()->vw_initializeWithCopy(result,
|
|
future->getStoragePtr());
|
|
return resumeFn(callerContext);
|
|
}
|
|
|
|
case FutureFragment::Status::Error:
|
|
swift_Concurrency_fatalError(0, "future reported an error, but wait cannot throw");
|
|
}
|
|
}
|
|
|
|
#ifdef __ARM_ARCH_7K__
|
|
__attribute__((noinline))
|
|
SWIFT_CC(swiftasync) static void workaround_function_swift_task_future_wait_throwingImpl(
|
|
OpaqueValue *result, SWIFT_ASYNC_CONTEXT AsyncContext *callerContext,
|
|
AsyncTask *task, ThrowingTaskFutureWaitContinuationFunction resumeFunction,
|
|
AsyncContext *callContext) {
|
|
// Make sure we don't eliminate calls to this function.
|
|
asm volatile("" // Do nothing.
|
|
: // Output list, empty.
|
|
: "r"(result), "r"(callerContext), "r"(task) // Input list.
|
|
: // Clobber list, empty.
|
|
);
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
SWIFT_CC(swiftasync)
|
|
void swift_task_future_wait_throwingImpl(
|
|
OpaqueValue *result, SWIFT_ASYNC_CONTEXT AsyncContext *callerContext,
|
|
AsyncTask *task,
|
|
ThrowingTaskFutureWaitContinuationFunction *resumeFunction,
|
|
AsyncContext *callContext) {
|
|
auto waitingTask = swift_task_getCurrent();
|
|
// Suspend the waiting task.
|
|
waitingTask->ResumeTask = task_wait_throwing_resume_adapter;
|
|
waitingTask->ResumeContext = callContext;
|
|
|
|
auto resumeFn = reinterpret_cast<TaskContinuationFunction *>(resumeFunction);
|
|
|
|
// Wait on the future.
|
|
assert(task->isFuture());
|
|
|
|
switch (task->waitFuture(waitingTask, callContext, resumeFn, callerContext,
|
|
result)) {
|
|
case FutureFragment::Status::Executing:
|
|
// The waiting task has been queued on the future.
|
|
#ifdef __ARM_ARCH_7K__
|
|
return workaround_function_swift_task_future_wait_throwingImpl(
|
|
result, callerContext, task, resumeFunction, callContext);
|
|
#else
|
|
return;
|
|
#endif
|
|
|
|
case FutureFragment::Status::Success: {
|
|
auto future = task->futureFragment();
|
|
future->getResultType()->vw_initializeWithCopy(result,
|
|
future->getStoragePtr());
|
|
return resumeFunction(callerContext, nullptr /*error*/);
|
|
}
|
|
|
|
case FutureFragment::Status::Error: {
|
|
// Run the task with an error result.
|
|
auto future = task->futureFragment();
|
|
auto error = future->getError();
|
|
swift_errorRetain(error);
|
|
return resumeFunction(callerContext, error);
|
|
}
|
|
}
|
|
}
|
|
|
|
namespace {
|
|
|
|
#if SWIFT_CONCURRENCY_COOPERATIVE_GLOBAL_EXECUTOR
|
|
|
|
class RunAndBlockSemaphore {
|
|
bool Finished = false;
|
|
public:
|
|
void wait() {
|
|
donateThreadToGlobalExecutorUntil([](void *context) {
|
|
return *reinterpret_cast<bool*>(context);
|
|
}, &Finished);
|
|
|
|
assert(Finished && "ran out of tasks before we were signalled");
|
|
}
|
|
|
|
void signal() {
|
|
Finished = true;
|
|
}
|
|
};
|
|
|
|
#else
|
|
|
|
class RunAndBlockSemaphore {
|
|
ConditionVariable Queue;
|
|
ConditionVariable::Mutex Lock;
|
|
bool Finished = false;
|
|
public:
|
|
/// Wait for a signal.
|
|
void wait() {
|
|
Lock.withLockOrWait(Queue, [&] {
|
|
return Finished;
|
|
});
|
|
}
|
|
|
|
void signal() {
|
|
Lock.withLockThenNotifyAll(Queue, [&]{
|
|
Finished = true;
|
|
});
|
|
}
|
|
};
|
|
|
|
#endif
|
|
|
|
using RunAndBlockSignature =
|
|
AsyncSignature<void(HeapObject*), /*throws*/ false>;
|
|
struct RunAndBlockContext: AsyncContext {
|
|
const void *Function;
|
|
HeapObject *FunctionContext;
|
|
RunAndBlockSemaphore *Semaphore;
|
|
};
|
|
using RunAndBlockCalleeContext =
|
|
AsyncCalleeContext<RunAndBlockContext, RunAndBlockSignature>;
|
|
|
|
} // end anonymous namespace
|
|
|
|
/// Second half of the runAndBlock async function.
|
|
SWIFT_CC(swiftasync)
|
|
static void runAndBlock_finish(SWIFT_ASYNC_CONTEXT AsyncContext *_context) {
|
|
auto calleeContext = static_cast<RunAndBlockCalleeContext*>(_context);
|
|
|
|
auto context = popAsyncContext(calleeContext);
|
|
|
|
context->Semaphore->signal();
|
|
|
|
return context->ResumeParent(context);
|
|
}
|
|
|
|
/// First half of the runAndBlock async function.
|
|
SWIFT_CC(swiftasync)
|
|
static void runAndBlock_start(SWIFT_ASYNC_CONTEXT AsyncContext *_context,
|
|
SWIFT_CONTEXT HeapObject *closureContext) {
|
|
auto callerContext = static_cast<RunAndBlockContext*>(_context);
|
|
|
|
RunAndBlockSignature::FunctionType *function;
|
|
size_t calleeContextSize;
|
|
auto functionContext = callerContext->FunctionContext;
|
|
assert(closureContext == functionContext);
|
|
std::tie(function, calleeContextSize)
|
|
= getAsyncClosureEntryPointAndContextSize<
|
|
RunAndBlockSignature,
|
|
SpecialPointerAuthDiscriminators::AsyncRunAndBlockFunction
|
|
>(const_cast<void*>(callerContext->Function), functionContext);
|
|
|
|
auto calleeContext =
|
|
pushAsyncContext<RunAndBlockSignature>(callerContext,
|
|
calleeContextSize,
|
|
&runAndBlock_finish,
|
|
functionContext);
|
|
return reinterpret_cast<AsyncVoidClosureEntryPoint *>(function)(
|
|
calleeContext, functionContext);
|
|
}
|
|
|
|
// TODO: Remove this hack.
|
|
void swift::swift_task_runAndBlockThread(const void *function,
|
|
HeapObject *functionContext) {
|
|
RunAndBlockSemaphore semaphore;
|
|
|
|
// Set up a task that runs the runAndBlock async function above.
|
|
auto flags = TaskCreateFlags();
|
|
flags.setPriority(JobPriority::Default);
|
|
auto pair = swift_task_create_common(
|
|
flags.getOpaqueValue(),
|
|
/*options=*/nullptr,
|
|
/*futureResultType=*/nullptr,
|
|
reinterpret_cast<ThinNullaryAsyncSignature::FunctionType *>(
|
|
&runAndBlock_start),
|
|
nullptr,
|
|
sizeof(RunAndBlockContext));
|
|
auto context = static_cast<RunAndBlockContext*>(pair.InitialContext);
|
|
context->Function = function;
|
|
context->FunctionContext = functionContext;
|
|
context->Semaphore = &semaphore;
|
|
|
|
// Enqueue the task.
|
|
swift_task_enqueueGlobal(pair.Task);
|
|
|
|
// Wait until the task completes.
|
|
semaphore.wait();
|
|
}
|
|
|
|
size_t swift::swift_task_getJobFlags(AsyncTask *task) {
|
|
return task->Flags.getOpaqueValue();
|
|
}
|
|
|
|
AsyncTask *swift::swift_continuation_init(ContinuationAsyncContext *context,
|
|
AsyncContinuationFlags flags) {
|
|
context->Flags = AsyncContextKind::Continuation;
|
|
if (flags.canThrow()) context->Flags.setCanThrow(true);
|
|
context->ErrorResult = nullptr;
|
|
|
|
// Set the current executor as the target executor unless there's
|
|
// an executor override.
|
|
if (!flags.hasExecutorOverride())
|
|
context->ResumeToExecutor = swift_task_getCurrentExecutor();
|
|
|
|
// We can initialize this with a relaxed store because resumption
|
|
// must happen-after this call.
|
|
context->AwaitSynchronization.store(flags.isPreawaited()
|
|
? ContinuationStatus::Awaited
|
|
: ContinuationStatus::Pending,
|
|
std::memory_order_relaxed);
|
|
|
|
auto task = swift_task_getCurrent();
|
|
assert(task && "initializing a continuation with no current task");
|
|
task->ResumeContext = context;
|
|
task->ResumeTask = context->ResumeParent;
|
|
|
|
return task;
|
|
}
|
|
|
|
static void resumeTaskAfterContinuation(AsyncTask *task,
|
|
ContinuationAsyncContext *context) {
|
|
auto &sync = context->AwaitSynchronization;
|
|
auto status = sync.load(std::memory_order_acquire);
|
|
assert(status != ContinuationStatus::Resumed &&
|
|
"continuation was already resumed");
|
|
|
|
// Make sure TSan knows that the resume call happens-before the task
|
|
// restarting.
|
|
_swift_tsan_release(static_cast<Job *>(task));
|
|
|
|
// The status should be either Pending or Awaited. If it's Awaited,
|
|
// which is probably the most likely option, then we should immediately
|
|
// enqueue; we don't need to update the state because there shouldn't
|
|
// be a racing attempt to resume the continuation. If it's Pending,
|
|
// we need to set it to Resumed; if that fails (with a strong cmpxchg),
|
|
// it should be because the original thread concurrently set it to
|
|
// Awaited, and so we need to enqueue.
|
|
if (status == ContinuationStatus::Pending &&
|
|
sync.compare_exchange_strong(status, ContinuationStatus::Resumed,
|
|
/*success*/ std::memory_order_release,
|
|
/*failure*/ std::memory_order_relaxed)) {
|
|
return;
|
|
}
|
|
assert(status == ContinuationStatus::Awaited &&
|
|
"detected concurrent attempt to resume continuation");
|
|
|
|
// TODO: maybe in some mode we should set the status to Resumed here
|
|
// to make a stronger best-effort attempt to catch racing attempts to
|
|
// resume the continuation?
|
|
|
|
swift_task_enqueue(task, context->ResumeToExecutor);
|
|
}
|
|
|
|
SWIFT_CC(swift)
|
|
static void swift_continuation_resumeImpl(AsyncTask *task) {
|
|
auto context = cast<ContinuationAsyncContext>(task->ResumeContext);
|
|
resumeTaskAfterContinuation(task, context);
|
|
}
|
|
|
|
SWIFT_CC(swift)
|
|
static void swift_continuation_throwingResumeImpl(AsyncTask *task) {
|
|
auto context = cast<ContinuationAsyncContext>(task->ResumeContext);
|
|
resumeTaskAfterContinuation(task, context);
|
|
}
|
|
|
|
|
|
SWIFT_CC(swift)
|
|
static void swift_continuation_throwingResumeWithErrorImpl(AsyncTask *task,
|
|
/* +1 */ SwiftError *error) {
|
|
auto context = cast<ContinuationAsyncContext>(task->ResumeContext);
|
|
context->ErrorResult = error;
|
|
resumeTaskAfterContinuation(task, context);
|
|
}
|
|
|
|
bool swift::swift_task_isCancelled(AsyncTask *task) {
|
|
return task->isCancelled();
|
|
}
|
|
|
|
SWIFT_CC(swift)
|
|
static CancellationNotificationStatusRecord*
|
|
swift_task_addCancellationHandlerImpl(
|
|
CancellationNotificationStatusRecord::FunctionType handler,
|
|
void *context) {
|
|
void *allocation =
|
|
swift_task_alloc(sizeof(CancellationNotificationStatusRecord));
|
|
auto unsigned_handler = swift_auth_code(handler, 3848);
|
|
auto *record = new (allocation)
|
|
CancellationNotificationStatusRecord(unsigned_handler, context);
|
|
|
|
swift_task_addStatusRecord(record);
|
|
return record;
|
|
}
|
|
|
|
SWIFT_CC(swift)
|
|
static void swift_task_removeCancellationHandlerImpl(
|
|
CancellationNotificationStatusRecord *record) {
|
|
swift_task_removeStatusRecord(record);
|
|
swift_task_dealloc(record);
|
|
}
|
|
|
|
SWIFT_CC(swift)
|
|
static NullaryContinuationJob*
|
|
swift_task_createNullaryContinuationJobImpl(
|
|
size_t priority,
|
|
AsyncTask *continuation) {
|
|
void *allocation =
|
|
swift_task_alloc(sizeof(NullaryContinuationJob));
|
|
auto *job =
|
|
new (allocation) NullaryContinuationJob(
|
|
swift_task_getCurrent(), static_cast<JobPriority>(priority),
|
|
continuation);
|
|
|
|
return job;
|
|
}
|
|
|
|
SWIFT_CC(swift)
|
|
void swift::swift_continuation_logFailedCheck(const char *message) {
|
|
swift_reportError(0, message);
|
|
}
|
|
|
|
SWIFT_CC(swift)
|
|
static void swift_task_asyncMainDrainQueueImpl() {
|
|
#if SWIFT_CONCURRENCY_COOPERATIVE_GLOBAL_EXECUTOR
|
|
bool Finished = false;
|
|
donateThreadToGlobalExecutorUntil([](void *context) {
|
|
return *reinterpret_cast<bool*>(context);
|
|
}, &Finished);
|
|
#else
|
|
#if defined(_WIN32)
|
|
static void(FAR *pfndispatch_main)(void) = NULL;
|
|
|
|
if (pfndispatch_main)
|
|
return pfndispatch_main();
|
|
|
|
HMODULE hModule = LoadLibraryW(L"dispatch.dll");
|
|
if (hModule == NULL)
|
|
abort();
|
|
|
|
pfndispatch_main =
|
|
reinterpret_cast<void (FAR *)(void)>(GetProcAddress(hModule,
|
|
"dispatch_main"));
|
|
if (pfndispatch_main == NULL)
|
|
abort();
|
|
|
|
pfndispatch_main();
|
|
exit(0);
|
|
#else
|
|
// CFRunLoop is not available on non-Darwin targets. Foundation has an
|
|
// implementation, but CoreFoundation is not meant to be exposed. We can only
|
|
// assume the existence of `CFRunLoopRun` on Darwin platforms, where the
|
|
// system provides an implementation of CoreFoundation.
|
|
#if defined(__APPLE__)
|
|
auto runLoop =
|
|
reinterpret_cast<void (*)(void)>(dlsym(RTLD_DEFAULT, "CFRunLoopRun"));
|
|
if (runLoop) {
|
|
runLoop();
|
|
exit(0);
|
|
}
|
|
#endif
|
|
|
|
dispatch_main();
|
|
#endif
|
|
#endif
|
|
}
|
|
|
|
#define OVERRIDE_TASK COMPATIBILITY_OVERRIDE
|
|
#include COMPATIBILITY_OVERRIDE_INCLUDE_PATH
|