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* Copyright 2017 The Android Open Source Project
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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#ifndef ANDROID_SYNC_H
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#define ANDROID_SYNC_H
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#include <sys/cdefs.h>
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#include <linux/sync_file.h>
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/* Fences indicate the status of an asynchronous task. They are initially
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* in unsignaled state (0), and make a one-time transition to either signaled
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* (1) or error (< 0) state. A sync file is a collection of one or more fences;
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* the sync file's status is error if any of its fences are in error state,
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* signaled if all of the child fences are signaled, or unsignaled otherwise.
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* Sync files are created by various device APIs in response to submitting
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* tasks to the device. Standard file descriptor lifetime syscalls like dup()
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* and close() are used to manage sync file lifetime.
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* The poll(), ppoll(), or select() syscalls can be used to wait for the sync
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* file to change status, or (with a timeout of zero) to check its status.
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* The functions below provide a few additional sync-specific operations.
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* Merge two sync files.
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* This produces a new sync file with the given name which has the union of the
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* two original sync file's fences; redundant fences may be removed.
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* If one of the input sync files is signaled or invalid, then this function
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* may behave like dup(): the new file descriptor refers to the valid/unsignaled
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* sync file with its original name, rather than a new sync file.
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* The original fences remain valid, and the caller is responsible for closing
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* Available since API level 26.
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int32_t sync_merge(const char* name, int32_t fd1, int32_t fd2) __INTRODUCED_IN(26);
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* Retrieve detailed information about a sync file and its fences.
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* The returned sync_file_info must be freed by calling sync_file_info_free().
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* Available since API level 26.
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struct sync_file_info* sync_file_info(int32_t fd) __INTRODUCED_IN(26);
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* Get the array of fence infos from the sync file's info.
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* The returned array is owned by the parent sync file info, and has
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* info->num_fences entries.
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* Available since API level 26.
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static inline struct sync_fence_info* sync_get_fence_info(const struct sync_file_info* info) {
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// This header should compile in C, but some C++ projects enable
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// warnings-as-error for C-style casts.
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wold-style-cast"
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return (struct sync_fence_info *)(uintptr_t)(info->sync_fence_info);
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#pragma GCC diagnostic pop
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* Free a struct sync_file_info structure
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* Available since API level 26.
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void sync_file_info_free(struct sync_file_info* info) __INTRODUCED_IN(26);
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#endif /* ANDROID_SYNC_H */