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* Copyright 2017 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <stdint.h>
#include <linux/sync_file.h>
/* Fences indicate the status of an asynchronous task. They are initially
* in unsignaled state (0), and make a one-time transition to either signaled
* (1) or error (< 0) state. A sync file is a collection of one or more fences;
* the sync file's status is error if any of its fences are in error state,
* signaled if all of the child fences are signaled, or unsignaled otherwise.
* Sync files are created by various device APIs in response to submitting
* tasks to the device. Standard file descriptor lifetime syscalls like dup()
* and close() are used to manage sync file lifetime.
* The poll(), ppoll(), or select() syscalls can be used to wait for the sync
* file to change status, or (with a timeout of zero) to check its status.
* The functions below provide a few additional sync-specific operations.
* Merge two sync files.
* This produces a new sync file with the given name which has the union of the
* two original sync file's fences; redundant fences may be removed.
* If one of the input sync files is signaled or invalid, then this function
* may behave like dup(): the new file descriptor refers to the valid/unsignaled
* sync file with its original name, rather than a new sync file.
* The original fences remain valid, and the caller is responsible for closing
* them.
int32_t sync_merge(const char *name, int32_t fd1, int32_t fd2);
* Retrieve detailed information about a sync file and its fences.
* The returned sync_file_info must be freed by calling sync_file_info_free().
struct sync_file_info *sync_file_info(int32_t fd);
* Get the array of fence infos from the sync file's info.
* The returned array is owned by the parent sync file info, and has
* info->num_fences entries.
static inline struct sync_fence_info* sync_get_fence_info(const struct sync_file_info* info) {
// This header should compile in C, but some C++ projects enable
// warnings-as-error for C-style casts.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
return (struct sync_fence_info *)(uintptr_t)(info->sync_fence_info);
#pragma GCC diagnostic pop
/** Free a struct sync_file_info structure */
void sync_file_info_free(struct sync_file_info *info);
#endif // __ANDROID_API__ >= __ANDROID_API_O__
#endif /* ANDROID_SYNC_H */