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69 lines
3.2 KiB
69 lines
3.2 KiB
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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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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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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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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*/
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package android.hardware.media.bufferpool@1.0;
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import IConnection;
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/**
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* IAccessor creates IConnection which is used from IClientManager in order to
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* use functionality of the specified buffer pool.
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*/
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interface IAccessor {
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/**
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* Registers a new client and creates IConnection to the buffer pool for
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* the client. IConnection and FMQ are used by IClientManager in order to
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* communicate with the buffer pool. Via FMQ IClientManager sends
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* BufferStatusMesage(s) to the buffer pool.
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*
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* FMQ is used to send buffer ownership status changes to a buffer pool
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* from a buffer pool client. A buffer pool synchronizes FMQ messages when
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* there is a hidl request from the clients. Every client has its own
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* connection and FMQ to communicate with the buffer pool. So sending an
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* FMQ message on behalf of other clients is not possible.
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*
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* FMQ messages are sent when a buffer is acquired or released. Also, FMQ
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* messages are sent when a buffer is transferred from a client to another
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* client. FMQ has its own ID from a buffer pool. A client is specified
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* with the ID.
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*
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* To transfer a buffer, a sender must send an FMQ message. The message
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* must include a receiver's ID and a transaction ID. A receiver must send
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* the transaction ID to fetch a buffer from a buffer pool. Since the
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* sender already registered the receiver via an FMQ message, The buffer
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* pool must verify the receiver with the transaction ID. In order to
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* prevent faking a receiver, a connection to a buffer pool from client is
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* made and kept private. Also part of transaction ID is a sender ID in
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* order to prevent fake transactions from other clients. This must be
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* verified with an FMQ message from a buffer pool.
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*
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* @return status The status of the call.
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* OK - A connection is made successfully.
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* NO_MEMORY - Memory allocation failure occurred.
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* ALREADY_EXISTS - A connection was already made.
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* CRITICAL_ERROR - Other errors.
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* @return connection The IConnection have interfaces
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* to get shared buffers from the buffer pool.
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* @return connectionId Id of IConnection. The Id identifies
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* sender and receiver in FMQ messages during buffer transfer.
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* @return mqDesc FMQ descriptor. The descriptor can be used to
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* send/receive FMQ messages.
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*/
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connect()
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generates (ResultStatus status, IConnection connection,
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int64_t connectionId, fmq_sync<BufferStatusMessage> mqDesc);
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};
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