Adam Barth | 57eacf5 | 2020-11-04 00:38:09 +0000 | [diff] [blame] | 1 | // Copyright 2017 The Fuchsia Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #include <lib/async/cpp/task.h> |
| 6 | |
| 7 | #include <lib/async/cpp/time.h> |
| 8 | #include <zircon/assert.h> |
| 9 | |
| 10 | #include <utility> |
| 11 | |
| 12 | namespace async { |
| 13 | namespace internal { |
| 14 | |
| 15 | struct RetainedTask : public async_task_t { |
| 16 | RetainedTask(fit::closure handler, zx::time deadline) |
| 17 | : async_task_t{{ASYNC_STATE_INIT}, &RetainedTask::Handler, deadline.get()}, |
| 18 | handler(static_cast<fit::closure&&>(handler)) {} |
| 19 | |
| 20 | fit::closure handler; |
| 21 | |
| 22 | static void Handler(async_dispatcher_t* dispatcher, async_task_t* task, zx_status_t status) { |
| 23 | auto self = static_cast<RetainedTask*>(task); |
| 24 | if (status == ZX_OK) |
| 25 | self->handler(); |
| 26 | delete self; |
| 27 | } |
| 28 | }; |
| 29 | |
| 30 | } // namespace internal |
| 31 | |
| 32 | zx_status_t PostTask(async_dispatcher_t* dispatcher, fit::closure handler) { |
| 33 | return PostTaskForTime(dispatcher, static_cast<fit::closure&&>(handler), async::Now(dispatcher)); |
| 34 | } |
| 35 | |
| 36 | zx_status_t PostDelayedTask(async_dispatcher_t* dispatcher, fit::closure handler, |
| 37 | zx::duration delay) { |
| 38 | return PostTaskForTime(dispatcher, static_cast<fit::closure&&>(handler), |
| 39 | async::Now(dispatcher) + delay); |
| 40 | } |
| 41 | |
| 42 | zx_status_t PostTaskForTime(async_dispatcher_t* dispatcher, fit::closure handler, |
| 43 | zx::time deadline) { |
| 44 | auto* task = new internal::RetainedTask(static_cast<fit::closure&&>(handler), deadline); |
| 45 | zx_status_t status = async_post_task(dispatcher, task); |
| 46 | if (status != ZX_OK) |
| 47 | delete task; |
| 48 | return status; |
| 49 | } |
| 50 | |
| 51 | TaskBase::TaskBase(async_task_handler_t* handler) |
| 52 | : task_{{ASYNC_STATE_INIT}, handler, ZX_TIME_INFINITE} {} |
| 53 | |
| 54 | TaskBase::~TaskBase() { |
| 55 | if (dispatcher_) { |
| 56 | // Failure to cancel here may result in a dangling pointer... |
| 57 | zx_status_t status = async_cancel_task(dispatcher_, &task_); |
| 58 | ZX_ASSERT_MSG(status == ZX_OK, "status=%d", status); |
| 59 | } |
| 60 | } |
| 61 | |
| 62 | zx_status_t TaskBase::Post(async_dispatcher_t* dispatcher) { |
| 63 | return PostForTime(dispatcher, async::Now(dispatcher)); |
| 64 | } |
| 65 | |
| 66 | zx_status_t TaskBase::PostDelayed(async_dispatcher_t* dispatcher, zx::duration delay) { |
| 67 | return PostForTime(dispatcher, async::Now(dispatcher) + delay); |
| 68 | } |
| 69 | |
| 70 | zx_status_t TaskBase::PostForTime(async_dispatcher_t* dispatcher, zx::time deadline) { |
| 71 | if (dispatcher_) |
| 72 | return ZX_ERR_ALREADY_EXISTS; |
| 73 | |
| 74 | dispatcher_ = dispatcher; |
| 75 | task_.deadline = deadline.get(); |
| 76 | zx_status_t status = async_post_task(dispatcher, &task_); |
| 77 | if (status != ZX_OK) { |
| 78 | dispatcher_ = nullptr; |
| 79 | } |
| 80 | return status; |
| 81 | } |
| 82 | |
| 83 | zx_status_t TaskBase::Cancel() { |
| 84 | if (!dispatcher_) |
| 85 | return ZX_ERR_NOT_FOUND; |
| 86 | |
| 87 | async_dispatcher_t* dispatcher = dispatcher_; |
| 88 | dispatcher_ = nullptr; |
| 89 | |
| 90 | zx_status_t status = async_cancel_task(dispatcher, &task_); |
| 91 | // |dispatcher| is required to be single-threaded, Cancel() is |
| 92 | // only supposed to be called on |dispatcher|'s thread, and we |
| 93 | // verified that the task was pending before calling |
| 94 | // async_cancel_task(). Assuming that |dispatcher| does not yield |
| 95 | // between removing the task and invoking the task's handler, |
| 96 | // |task_| must have been pending with |dispatcher|. |
| 97 | ZX_DEBUG_ASSERT(status != ZX_ERR_NOT_FOUND); |
| 98 | return status; |
| 99 | } |
| 100 | |
| 101 | Task::Task(Handler handler) : TaskBase(&Task::CallHandler), handler_(std::move(handler)) {} |
| 102 | |
| 103 | Task::~Task() = default; |
| 104 | |
| 105 | void Task::CallHandler(async_dispatcher_t* dispatcher, async_task_t* task, zx_status_t status) { |
| 106 | auto self = Dispatch<Task>(task); |
| 107 | self->handler_(dispatcher, self, status); |
| 108 | } |
| 109 | |
| 110 | TaskClosure::TaskClosure(fit::closure handler) |
| 111 | : TaskBase(&TaskClosure::CallHandler), handler_(std::move(handler)) {} |
| 112 | |
| 113 | TaskClosure::~TaskClosure() = default; |
| 114 | |
| 115 | void TaskClosure::CallHandler(async_dispatcher_t* dispatcher, async_task_t* task, |
| 116 | zx_status_t status) { |
| 117 | auto self = Dispatch<TaskClosure>(task); // must do this if status is not ok |
| 118 | if (status == ZX_OK) { |
| 119 | self->handler_(); |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | } // namespace async |