1 // Copyright 2023 The Pigweed Authors
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
4 // use this file except in compliance with the License. You may obtain a copy of
5 // the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12 // License for the specific language governing permissions and limitations under
13 // the License.
14
15 #include "pw_async/heap_dispatcher.h"
16
17 #include "pw_async/task.h"
18 #include "pw_result/result.h"
19
20 namespace pw::async {
21
22 namespace {
23
24 // TODO: b/277793223 - Optimize to avoid double virtual indirection and double
25 // allocation. In situations in which pw::Function is large enough and the
26 // captures are small enough, we could eliminate this by reshaping the task as
27 // just a pw::Function.
28 struct TaskAndFunction {
Newpw::async::__anon402024a60111::TaskAndFunction29 static Result<TaskAndFunction*> New(TaskFunction&& task) {
30 // std::nothrow causes new to return a nullptr on failure instead of
31 // throwing.
32 TaskAndFunction* t = new (std::nothrow) TaskAndFunction();
33 if (!t) {
34 return Status::ResourceExhausted();
35 }
36 t->func = std::move(task);
37
38 // Closure captures must not include references, as that would be UB due to
39 // the `delete` at the end of the function. See
40 // https://reviews.llvm.org/D48239.
41 t->task.set_function([t](Context& ctx, Status status) {
42 t->func(ctx, status);
43
44 // Delete must appear at the very end of this closure to avoid
45 // use-after-free of captures or Context.task.
46 delete t;
47 });
48
49 return t;
50 }
51 Task task;
52 TaskFunction func;
53 };
54 } // namespace
55
PostAt(TaskFunction && task_func,chrono::SystemClock::time_point time)56 Status HeapDispatcher::PostAt(TaskFunction&& task_func,
57 chrono::SystemClock::time_point time) {
58 Result<TaskAndFunction*> result = TaskAndFunction::New(std::move(task_func));
59 if (!result.ok()) {
60 return result.status();
61 }
62 dispatcher_.PostAt((*result)->task, time);
63 return Status();
64 }
65
66 } // namespace pw::async
67