[libcamera-devel] [PATCH v3 11/38] libcamera: Add IPAIPC

[Jacopo Mondi]

Hi Paul,

On Fri, Oct 02, 2020 at 11:31:27PM +0900, Paul Elder wrote:
> Create a virtual IPAIPC class that models an IPC/RPC system. IPA proxies
> and proxy workers will call into the IPAIPC, rather than implementing
> the IPC themselves.
>
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
>
> ---
> Changes in v3:
> - expand documentation a bit
> - move [[maybe_unused]] to after the parameters in the IPAIPC
>   constructor, to appease gcc <= 9.1
>
> Changes in v2:
> - add documentation
> ---
>  include/libcamera/internal/ipa_ipc.h |  41 ++++++++++
>  src/libcamera/ipa_ipc.cpp            | 114 +++++++++++++++++++++++++++
>  src/libcamera/meson.build            |   1 +
>  3 files changed, 156 insertions(+)
>  create mode 100644 include/libcamera/internal/ipa_ipc.h
>  create mode 100644 src/libcamera/ipa_ipc.cpp
>
> diff --git a/include/libcamera/internal/ipa_ipc.h b/include/libcamera/internal/ipa_ipc.h
> new file mode 100644
> index 00000000..09de36a5
> --- /dev/null
> +++ b/include/libcamera/internal/ipa_ipc.h
> @@ -0,0 +1,41 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2020, Google Inc.
> + *
> + * ipa_ipc.h - Image Processing Algorithm IPC module for IPA proxies
> + */
> +#ifndef __LIBCAMERA_INTERNAL_IPA_IPC_H__
> +#define __LIBCAMERA_INTERNAL_IPA_IPC_H__
> +
> +#include <vector>
> +
> +namespace libcamera {
> +
> +class IPAIPC
> +{
> +public:
> +	IPAIPC(const char *ipa_module_path [[maybe_unused]],
> +	       const char *ipa_proxy_worker_path [[maybe_unused]]);
> +	virtual ~IPAIPC();
> +
> +	bool isValid() const { return valid_; }

We usually have getters with the same name as the variable they "get".
I'm fine with 'isValid()' but I felt like pointing this out.

> +
> +	virtual int sendSync(uint32_t cmd,
> +			     const std::vector<uint8_t> &data_in,
> +			     const std::vector<int32_t> &fds_in,
> +			     std::vector<uint8_t> *data_out = nullptr,
> +			     std::vector<int32_t> *fds_out = nullptr) = 0;
> +
> +	virtual int sendAsync(uint32_t cmd,
> +			      const std::vector<uint8_t> &data_in,
> +			      const std::vector<int32_t> &fds_in) = 0;
> +
> +	Signal<std::vector<uint8_t> &, std::vector<int32_t> &> recvIPC;
> +
> +protected:
> +	bool valid_;
> +};
> +
> +} /* namespace libcamera */
> +
> +#endif /* __LIBCAMERA_INTERNAL_IPA_IPC_H__ */
> diff --git a/src/libcamera/ipa_ipc.cpp b/src/libcamera/ipa_ipc.cpp
> new file mode 100644
> index 00000000..b963351f
> --- /dev/null
> +++ b/src/libcamera/ipa_ipc.cpp
> @@ -0,0 +1,114 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2020, Google Inc.
> + *
> + * ipa_ipc.cpp - Image Processing Algorithm IPC module for IPA proxies
> + */
> +
> +#include <vector>
> +
> +#include "libcamera/internal/ipc_unixsocket.h"
> +#include "libcamera/internal/log.h"
> +#include "libcamera/internal/process.h"
> +#include "libcamera/internal/thread.h"
> +
> +#include <libcamera/event_dispatcher.h>
> +#include <libcamera/timer.h>
> +
> +#include "libcamera/internal/ipa_ipc.h"

The inclusion of the header corresponding to the cpp file is usually
placed first, to ensure it is self-contained and does not depend on
other include directives that might be placed before it.

> +
> +/**
> + * \file ipa_ipc.h
> + * \brief IPC mechanism for IPA isolation
> + */
> +
> +namespace libcamera {
> +
> +LOG_DEFINE_CATEGORY(IPAIPC)
> +
> +/**
> + * \class IPAIPC
> + * \brief IPC mechanism for IPA isolation
> + *
> + * Virtual class to model an IPC mechanism for use by IPA proxies for IPA
> + * isolation. sendSync() and sendAsync() must be implemented, and the recvIPC
> + * signal must be emitted whenever new data is available.
> + */
> +
> +/**
> + * \brief Construct an IPAIPC instance
> + * \param[in] ipa_module_path Path to the IPA module shared object
> + * \param[in] ipa_proxy_worker_path Path to the IPA proxy worker shared object
> + */
> +IPAIPC::IPAIPC([[maybe_unused]] const char *ipa_module_path,
> +	       [[maybe_unused]] const char *ipa_proxy_worker_path)

nit: parameters alignment

If these fields are not used by the base virtual class, do we need
them in the constructor ?

> +	: valid_(false)
> +{
> +}
> +
> +IPAIPC::~IPAIPC()
> +{
> +}
> +
> +/**
> + * \fn IPAIPC::isValid()
> + * \brief Check if the IPAIPC instance is valid
> + *
> + * An IPAIPC instance is valid if the IPA interface is successfully created in
> + * isolation, and IPC is successfully set up.
> + *
> + * \return True if the IPAIPC is valid, false otherwise
> + */
> +
> +/**
> + * \fn IPAIPC::sendSync()
> + * \brief Send a message over IPC synchronously
> + * \param[in] cmd Command ID
> + * \param[in] data_in Data to send, as a byte vector
> + * \param[in] fds_in Fds to send, in a vector
> + * \param[in] data_out Byte vector in which to receive data, if applicable
> + * \param[in] fds_out Fds vector in which to receive fds, if applicable

Could you spell 'file descriptors' entirely ?
 * \param[in] fds_out Vector in which to receive file descriptors, if applicable

Same for other locations.

I a bit wonder why fds should be kept separate and not serialized
in the data_in vector. Does it depend on the fact that fds as
serialized separately by the IPADataSerializer module ?

A final minor note on this: are _in and _out the best names we can have ?
Should this be expressed as '_msg' and '_reply' ?

> + *
> + * This function will not return until a response is received. The event loop
> + * will still continue to execute, however.
> + *
> + * \return Zero on success, negative error code otherwise
> + */
> +
> +/**
> + * \fn IPAIPC::sendAsync()
> + * \brief Send a message over IPC asynchronously
> + * \param[in] cmd Command ID
> + * \param[in] data_in Data to send, as a byte vector
> + * \param[in] fds_in Fds to send, in a vector
> + *
> + * This function will return immediately after sending the message.
> + *
> + * \return Zero on success, negative error code otherwise
> + */
> +
> +/**
> + * \var IPAIPC::recvIPC
> + * \brief Signal to be emitted when data is received over IPC
> + *
> + * When data is received over IPC, this signal shall be emitted. Users must
> + * connect to this to receive new data.
> + *
> + * The parameters of the signal are a vector of bytes and a vector of file
> + * descriptors.

I assume this completes the sendAsync() method, right ? Can we state
that explicitely, if that's the case ?

Mostly minor comments, please add
Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>

Thanks
  j


> + */
> +
> +/**
> + * \var IPAIPC::valid_
> + * \brief Flag to indicate if the IPAIPC instance is valid
> + *
> + * An IPAIPC instance is valid if the IPA interface is successfully created in
> + * isolation, and IPC is successfully set up.
> + *
> + * This flag can be read via IPAIPC::isValid().
> + *
> + * Implementations of the IPAIPC class should set this flag upon successful
> + * construction.
> + */
> +
> +} /* namespace libcamera */
> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> index 190d7490..e0a2ab47 100644
> --- a/src/libcamera/meson.build
> +++ b/src/libcamera/meson.build
> @@ -25,6 +25,7 @@ libcamera_sources = files([
>      'ipa_context_wrapper.cpp',
>      'ipa_controls.cpp',
>      'ipa_data_serializer.cpp',
> +    'ipa_ipc.cpp',
>      'ipa_interface.cpp',
>      'ipa_manager.cpp',
>      'ipa_module.cpp',
> --
> 2.27.0
>
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