//===--- TaskPrivate.h - Concurrency library internal interface -*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// Internal functions for the concurrency library.
//
//===----------------------------------------------------------------------===//

#ifndef SWIFT_CONCURRENCY_TASKPRIVATE_H
#define SWIFT_CONCURRENCY_TASKPRIVATE_H

#include "swift/Runtime/Concurrency.h"
#include "swift/ABI/Task.h"
#include "swift/ABI/Metadata.h"
#include "swift/Runtime/HeapObject.h"
#include "swift/Runtime/Error.h"

namespace swift {

// Uncomment to enable helpful debug spew to stderr
//#define SWIFT_TASK_PRINTF_DEBUG 1

class AsyncTask;
class TaskGroup;

/// Initialize the task-local allocator in the given task.
void _swift_task_alloc_initialize(AsyncTask *task);

void _swift_task_alloc_initialize_with_slab(AsyncTask *task,
                   void *firstSlabBuffer,
                   size_t bufferCapacity);

/// Destroy the task-local allocator in the given task.
void _swift_task_alloc_destroy(AsyncTask *task);

/// Allocate task-local memory on behalf of a specific task,
/// not necessarily the current one.  Generally this should only be
/// done on behalf of a child task.
void *_swift_task_alloc_specific(AsyncTask *task, size_t size);

/// dellocate task-local memory on behalf of a specific task,
/// not necessarily the current one.  Generally this should only be
/// done on behalf of a child task.
void _swift_task_dealloc_specific(AsyncTask *task, void *ptr);

/// Given that we've already set the right executor as the active
/// executor, run the given job.  This does additional bookkeeping
/// related to the active task.
void runJobInEstablishedExecutorContext(Job *job);

/// Clear the active task reference for the current thread.
AsyncTask *_swift_task_clearCurrent();

AsyncTaskAndContext swift_task_create_async_let_future(size_t flags,
                     const Metadata *futureResultType,
                     void *closureEntry,
                     void *closureContext);

#if defined(SWIFT_STDLIB_SINGLE_THREADED_RUNTIME)
#define SWIFT_CONCURRENCY_COOPERATIVE_GLOBAL_EXECUTOR 1
#else
#define SWIFT_CONCURRENCY_COOPERATIVE_GLOBAL_EXECUTOR 0
#endif

#if SWIFT_CONCURRENCY_COOPERATIVE_GLOBAL_EXECUTOR
/// Donate this thread to the global executor until either the
/// given condition returns true or we've run out of cooperative
/// tasks to run.
void donateThreadToGlobalExecutorUntil(bool (*condition)(void*),
                                       void *context);
#endif

/// release() establishes a happens-before relation with a preceding acquire()
/// on the same address.
void _swift_tsan_acquire(void *addr);
void _swift_tsan_release(void *addr);

/// Special values used with DispatchQueueIndex to indicate the global and main
/// executors.
#define DISPATCH_QUEUE_GLOBAL_EXECUTOR (void *)1
#define DISPATCH_QUEUE_MAIN_EXECUTOR (void *)2

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wreturn-type-c-linkage"
// FIXME: remove this and switch to a representation that uses
// _dispatch_main_q somehow
extern "C" SWIFT_CC(swift)
ExecutorRef _swift_task_getMainExecutor();
#pragma clang diagnostic pop

// ==== ------------------------------------------------------------------------

namespace {

/// The layout of a context to call one of the following functions:
///
///   @_silgen_name("swift_task_future_wait")
///   func _taskFutureGet<T>(_ task: Builtin.NativeObject) async -> T
///
///   @_silgen_name("swift_task_future_wait_throwing")
///   func _taskFutureGetThrowing<T>(_ task: Builtin.NativeObject) async throws -> T
///
///   @_silgen_name("swift_asyncLet_wait")
///   func _asyncLetGet<T>(_ task: Builtin.RawPointer) async -> T
///
///   @_silgen_name("swift_asyncLet_waitThrowing")
///   func _asyncLetGetThrowing<T>(_ task: Builtin.RawPointer) async throws -> T
///
class TaskFutureWaitAsyncContext : public AsyncContext {
public:
  SwiftError *errorResult;

  OpaqueValue *successResultPointer;

  AsyncVoidClosureResumeEntryPoint *__ptrauth_swift_task_resume_function
      asyncResumeEntryPoint;

  void fillWithSuccess(AsyncTask::FutureFragment *future) {
    fillWithSuccess(future->getStoragePtr(), future->getResultType(),
                    successResultPointer);
  }
  void fillWithSuccess(OpaqueValue *src, const Metadata *successType,
                       OpaqueValue *result) {
    successType->vw_initializeWithCopy(result, src);
  }

  void fillWithError(AsyncTask::FutureFragment *future) {
    fillWithError(future->getError());
  }
  void fillWithError(SwiftError *error) {
    errorResult = error;
    swift_errorRetain(error);
  }
};

/// The layout of a frame to call the following function:
///
///   @_silgen_name("swift_taskGroup_wait_next_throwing")
///   func _taskGroupWaitNext<T>(group: Builtin.RawPointer) async throws -> T?
///
class TaskGroupNextAsyncContext : public AsyncContext {
public:
  SwiftError *errorResult;

  OpaqueValue *successResultPointer;

  AsyncVoidClosureResumeEntryPoint *__ptrauth_swift_task_resume_function
      asyncResumeEntryPoint;

  // Arguments.
  TaskGroup *group;

  const Metadata *successType;

  void fillWithSuccess(OpaqueValue *src, const Metadata *successType) {
    successType->vw_initializeWithCopy(successResultPointer, src);
  }

  void fillWithError(SwiftError *error) {
    errorResult = error;
    swift_errorRetain(error);
  }
};

} // end anonymous namespace

} // end namespace swift

#endif