android.hardware.media.bufferpool@1.0 HAL

BufferPool HAL for allocating, deallocating, and recycling buffers on behalf of media.stagefright. Bug: 72651719 Change-Id: I30bf630e41de2c8718aaaf8cbf5ee3f48f2859bc
author: Sungtak Lee <taklee@google.com> 2018-01-25 15:07:40 -0800
committer: Sungtak Lee <taklee@google.com> 2018-01-29 15:49:41 -0800
commit: 108a2fe68cf68b76207b540457ab4e8bd97f5a76 (patch)
tree: 2b4b156bcba06974fd422ce9308d5b2b694a2385 /media
parent: 6327b866963d7bea96edf02332f9b24267b53e5f (diff)
download: platform_hardware_interfaces-108a2fe68cf68b76207b540457ab4e8bd97f5a76.tar.gz
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6 files changed, 331 insertions, 0 deletions
diff --git a/media/bufferpool/1.0/Android.bp b/media/bufferpool/1.0/Android.bp
new file mode 100644
index 0000000000..986da8a42a
--- /dev/null
+++ b/media/bufferpool/1.0/Android.bp
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+// This file is autogenerated by hidl-gen -Landroidbp.
+
+hidl_interface {
+    name: "android.hardware.media.bufferpool@1.0",
+    root: "android.hardware",
+    vndk: {
+        enabled: true,
+    },
+    srcs: [
+        "types.hal",
+        "IAccessor.hal",
+        "IClientManager.hal",
+        "IConnection.hal",
+    ],
+    interfaces: [
+        "android.hidl.base@1.0",
+    ],
+    types: [
+        "Buffer",
+        "BufferStatus",
+        "BufferStatusMessage",
+        "ResultStatus",
+    ],
+    gen_java: false,
+}
+
diff --git a/media/bufferpool/1.0/IAccessor.hal b/media/bufferpool/1.0/IAccessor.hal
new file mode 100644
index 0000000000..5b5aec0452
--- /dev/null
+++ b/media/bufferpool/1.0/IAccessor.hal
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2018 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
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.hardware.media.bufferpool@1.0;
+
+import IConnection;
+/**
+ * IAccessor creates IConnection which is used from IClientManager in order to
+ * use functionality of the specified buffer pool.
+ */
+interface IAccessor {
+
+    /**
+     * Registers a new client and creates IConnection to the buffer pool for
+     * the client. IConnection and FMQ are used by IClientManager in order to
+     * communicate with the buffer pool. Via FMQ IClientManager sends
+     * BufferStatusMesage(s) to the buffer pool.
+     *
+     * FMQ is used to send buffer ownership status changes to a buffer pool
+     * from a buffer pool client. A buffer pool synchronizes FMQ messages when
+     * there is a hidl request from the clients. Every client has its own
+     * connection and FMQ to communicate with the buffer pool. So sending an
+     * FMQ message on behalf of other clients is not possible.
+     *
+     * FMQ messages are sent when a buffer is acquired or released. Also, FMQ
+     * messages are sent when a buffer is transferred from a client to another
+     * client. FMQ has its own ID from a buffer pool. A client is specified
+     * with the ID.
+     *
+     * To transfer a buffer, a sender must send an FMQ message. The message
+     * must include a receiver's ID and a transaction ID. A receiver must send
+     * the transaction ID to fetch a buffer from a buffer pool. Since the
+     * sender already registered the receiver via an FMQ message, The buffer
+     * pool must verify the receiver with the transaction ID. In order to
+     * prevent faking a receiver, a connection to a buffer pool from client is
+     * made and kept private. Also part of transaction ID is a sender ID in
+     * order to prevent fake transactions from other clients. This must be
+     * verified with an FMQ message from a buffer pool.
+     *
+     * @return status The status of the call.
+     *     OK               - A connection is made successfully.
+     *     NO_MEMORY        - Memory allocation failure occurred.
+     *     ALREADY_EXISTS   - A connection was already made.
+     *     CRITICAL_ERROR   - Other errors.
+     * @return connection The IConnection have interfaces
+     *     to get shared buffers from the buffer pool.
+     * @return connectionId Id of IConnection. The Id identifies
+     *     sender and receiver in FMQ messages during buffer transfer.
+     * @return mqDesc FMQ descriptor. The descriptor can be used to
+     *     send/receive FMQ messages.
+     */
+    connect()
+        generates (ResultStatus status, IConnection connection,
+                   int64_t connectionId, fmq_sync<BufferStatusMessage> mqDesc);
+};
diff --git a/media/bufferpool/1.0/IClientManager.hal b/media/bufferpool/1.0/IClientManager.hal
new file mode 100644
index 0000000000..e1e8f95b6b
--- /dev/null
+++ b/media/bufferpool/1.0/IClientManager.hal
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2018 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
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.hardware.media.bufferpool@1.0;
+
+import IAccessor;
+/**
+ * IClientManager manages IConnection(s) inside a process. A locally
+ * created IConnection represents a communication node(receiver) with the
+ * specified buffer pool(IAccessor).
+ * IConnection(s) are not exposed to other processes(IClientManager).
+ * IClientManager instance must be unique within a process.
+ */
+interface IClientManager {
+
+    /**
+     * Sets up a buffer receiving communication node for the specified
+     * buffer pool. A manager must create a IConnection to the buffer
+     * pool if it does not already have a connection.
+     *
+     * @param bufferPool a buffer pool which is specified with the IAccessor.
+     *     The specified buffer pool is the owner of received buffers.
+     * @return status The status of the call.
+     *     OK               - A sender was set successfully.
+     *     NO_MEMORY        - Memory allocation failure occurred.
+     *     ALREADY_EXISTS   - A sender was registered already.
+     *     CRITICAL_ERROR   - Other errors.
+     * @return connectionId the Id of the communication node to the buffer pool.
+     *     This id is used in FMQ to notify IAccessor that a buffer has been
+     *     sent to that connection during transfers.
+     */
+    registerSender(IAccessor bufferPool) generates
+        (ResultStatus status, int64_t connectionId);
+};
diff --git a/media/bufferpool/1.0/IConnection.hal b/media/bufferpool/1.0/IConnection.hal
new file mode 100644
index 0000000000..e284db2825
--- /dev/null
+++ b/media/bufferpool/1.0/IConnection.hal
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2018 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
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.hardware.media.bufferpool@1.0;
+
+/**
+ * A connection to a buffer pool which handles requests from a buffer pool
+ * client. The connection must be made in order to receive buffers from
+ * other buffer pool clients.
+ */
+interface IConnection {
+
+    /**
+     * Retrieves a buffer using bufferId. The method must be called from
+     * receiving side of buffer during transferring only when the specified
+     * buffer is neither cached nor used. This fails if the specified
+     * transaction is not valid.
+     *
+     * @param transactionId Unique transaction id for buffer transferring.
+     * @param bufferId Id of the buffer to be fetched.
+     * @return status The status of the call.
+     *     OK               - A buffer was fetched successfully.
+     *     NO_MEMORY        - Memory allocation failure occurred.
+     *     NOT_FOUND        - A buffer was not found due to invalidation.
+     *     CRITICAL_ERROR   - Other errors.
+     * @return buffer The actual buffer which is specified with bufferId.
+     */
+    fetch(uint64_t transactionId, uint32_t bufferId) generates
+        (ResultStatus status, Buffer buffer);
+};
diff --git a/media/bufferpool/1.0/README.md b/media/bufferpool/1.0/README.md
new file mode 100644
index 0000000000..ed985d8291
--- /dev/null
+++ b/media/bufferpool/1.0/README.md
@@ -0,0 +1,54 @@
+1. Overview
+
+A buffer pool enables processes to transfer buffers asynchronously.
+Without a buffer pool, a process calls a synchronous method of the other
+process and waits until the call finishes transferring a buffer. This adds
+unwanted latency due to context switching. With help from a buffer pool, a
+process can pass buffers asynchronously and reduce context switching latency.
+
+Passing an interface and a handle adds extra latency also. To mitigate the
+latency, passing IDs with local cache is used. For security concerns about
+rogue clients, FMQ is used to communicate between a buffer pool and a client
+process. FMQ is used to send buffer ownership change status from a client
+process to a buffer pool. Except FMQ, a buffer pool does not use any shared
+memory.
+
+2. FMQ
+
+FMQ is used to send buffer ownership status changes to a buffer pool from a
+buffer pool client. A buffer pool synchronizes FMQ messages when there is a
+hidl request from the clients. Every client has its own connection and FMQ
+to communicate with the buffer pool. So sending an FMQ message on behalf of
+other clients is not possible.
+
+FMQ messages are sent when a buffer is acquired or released. Also, FMQ messages
+are sent when a buffer is transferred from a client to another client. FMQ has
+its own ID from a buffer pool. A client is specified with the ID.
+
+To transfer a buffer, a sender must send an FMQ message. The message must
+include a receiver's ID and a transaction ID. A receiver must send the
+transaction ID to fetch a buffer from a buffer pool. Since the sender already
+registered the receiver via an FMQ message, The buffer pool must verify the
+receiver with the transaction ID. In order to prevent faking a receiver, a
+connection to a buffer pool from client is made and kept privately. Also part of
+transaction ID is a sender ID in order to prevent fake transactions from other
+clients. This must be verified with an FMQ message from a buffer pool.
+
+FMQ messages are defined in BufferStatus and BufferStatusMessage of 'types.hal'.
+
+3. Interfaces
+
+IConnection
+A connection to a buffer pool from a buffer pool client. The connection
+provides the functionalities to share buffers between buffer pool clients.
+The connection must be unique for each client.
+
+IAccessor
+An accessor to a buffer pool which makes a connection to the buffer pool.
+IAccesssor#connect creates an IConnection.
+
+IClientManager
+A manager of buffer pool clients and clients' connections to buffer pools. It
+sets up a process to be a receiver of buffers from a buffer pool. The manager
+is unique in a process.
+
diff --git a/media/bufferpool/1.0/types.hal b/media/bufferpool/1.0/types.hal
new file mode 100644
index 0000000000..d8ab59774f
--- /dev/null
+++ b/media/bufferpool/1.0/types.hal
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2018 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
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.hardware.media.bufferpool@1.0;
+
+enum ResultStatus : int32_t {
+    OK                  = 0,
+
+    NO_MEMORY           = 1,
+    ALREADY_EXISTS      = 2,
+    NOT_FOUND           = 3,
+    CRITICAL_ERROR      = 4,
+};
+
+/**
+ * Generic buffer for fast recycling for media/stagefright.
+ *
+ * During media pipeline buffer references are created, shared and
+ * destroyed frequently. The underlying buffers are allocated on demand
+ * by a buffer pool, and are recycled to the buffer pool when they are
+ * no longer referenced by the clients.
+ *
+ * E.g. ion or gralloc buffer
+ */
+struct Buffer {
+    uint32_t id;
+    handle buffer;
+};
+
+/**
+ * Buffer ownership status for the specified client.
+ * Buffer transfer status for the specified buffer transafer transaction.
+ * BufferStatus is posted along with BufferStatusMessage from a client to
+ * the buffer pool for synchronization after status change.
+ */
+enum BufferStatus : int32_t {
+    /** No longer used by the specified client. */
+    NOT_USED            = 0,
+    /** Buffer is acquired by the specified client. */
+    USED                = 1,
+    /** Buffer is sent by the specified client. */
+    TRANSFER_TO         = 2,
+    /** Buffer transfer is acked by the receiver client. */
+    TRANSFER_FROM       = 3,
+    /** Buffer transfer is timed out by receiver client. */
+    TRANSFER_TIMEOUT    = 4,
+    /** Buffer transfer is not acked by the receiver. */
+    TRANSFER_LOST       = 5,
+    /** Buffer fetch request from the client. */
+    TRANSFER_FETCH      = 6,
+    /** Buffer transaction succeeded. */
+    TRANSFER_OK         = 7,
+    /** Buffer transaction failure. */
+    TRANSFER_ERROR      = 8,
+};
+
+/**
+ * Buffer ownership status change message. This message is
+ * sent via fmq to the buffer pool from client processes.
+ */
+struct BufferStatusMessage {
+    /**
+     * Transaction Id = (SenderId : sender local transaction Id)
+     * Transaction Id is created from sender and posted via fmq within
+     * TRANSFER_TO message.
+     */
+    uint64_t transactionId;
+    uint32_t bufferId;
+    BufferStatus newStatus;
+    /** Used by the buffer pool. not by client. */
+    int64_t connectionId;
+    /** Valid only when TRANSFER_TO is posted. */
+    int64_t targetConnectionId;
+    /**
+     * Used by the buffer pool, not by client.
+     * Monotonic timestamp in Us since fixed point in time as decided
+     * by the sender of the message
+     */
+    int64_t timestampUs;
+};
author	Sungtak Lee <taklee@google.com>	2018-01-25 15:07:40 -0800
committer	Sungtak Lee <taklee@google.com>	2018-01-29 15:49:41 -0800
commit	108a2fe68cf68b76207b540457ab4e8bd97f5a76 (patch)
tree	2b4b156bcba06974fd422ce9308d5b2b694a2385 /media
parent	6327b866963d7bea96edf02332f9b24267b53e5f (diff)
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