| // Copyright 2022 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef LIB_ASYNC_SEQUENCE_ID_H_ |
| #define LIB_ASYNC_SEQUENCE_ID_H_ |
| |
| #include <lib/async/dispatcher.h> |
| |
| __BEGIN_CDECLS |
| |
| // A dispatcher-specific sequence identifier, which identifies a set of actions |
| // with a total ordering of execution: each subsequent action will always |
| // observe side-effects from previous actions, if the thread(s) performing those |
| // actions have the same sequence identifier. |
| // |
| // For example, a dispatcher backed by a thread pool may choose to implement |
| // sequences by acquiring a sequence-specific lock before running any actions |
| // from that sequence, ensuring mutual exclusion within each sequence. |
| typedef struct async_sequence_id { |
| uint64_t value; |
| } async_sequence_id_t; |
| |
| // Gets the dispatcher-specific sequence identifier of the currently executing |
| // task. |
| // |
| // If the dispatcher supports a notion of sequences, it should populate a number |
| // representing the current sequence, or return |ZX_ERR_INVALID_ARGS| if the |
| // calling thread is not executing a task managed by the dispatcher. |
| // |
| // Otherwise, it should return |ZX_ERR_NOT_SUPPORTED|. |
| // |
| // Returns |ZX_OK| if the sequence identifier was successfully obtained. |
| // Returns |ZX_ERR_INVALID_ARGS| if the dispatcher supports sequences, but the |
| // calling thread is not executing a task managed by the dispatcher. |
| // Returns |ZX_ERR_NOT_SUPPORTED| if not supported by the dispatcher. |
| // |
| // This operation is thread-safe. |
| zx_status_t async_get_sequence_id(async_dispatcher_t* dispatcher, |
| async_sequence_id_t* out_sequence_id); |
| |
| __END_CDECLS |
| |
| #endif // LIB_ASYNC_SEQUENCE_ID_H_ |
