gstreamer/subprojects/gst-plugins-bad/sys/win32ipc/protocol/win32ipcmmf.cpp
Seungha Yang 4f846540cb win32ipc: Add WIN32 shared memory videosrc/sink elements
Windows supports various IPC methods but that's completely
different form that of *nix from implementation point of view.
So, instead of adding shared memory functionality to existing
shm plugin, new WIN32 shared memory source/sink elements
are implemented in this commit.

Each videosink (server) and videosrc (client) pair will communicate
using WIN32 named pipe and thus user should configure unique/proper
pipe name to them (e.g., \\.\pipe\MyPipeName).
Once connection is established, videosink will create named shared memory
object per frame and client will be able to consume the object
(i.e., memory mapped file handle) without additional copy operation.

Note that implementations under "protocol" directory are almost
pure C/C++ with WIN32 APIs except for a few defines and debug functions.
So, applications can take only the protocol part so that the application
can send/receive shared-memory object from/to the other end
even if it's not an actual GStreamer element.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3441>
2022-11-24 12:41:18 +00:00

241 lines
5.2 KiB
C++

/* GStreamer
* Copyright (C) 2022 Seungha Yang <seungha@centricular.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
* SPDX-License-Identifier: MIT
*/
#include "win32ipcmmf.h"
#include "win32ipcutils.h"
#include <string>
GST_DEBUG_CATEGORY_EXTERN (gst_win32_ipc_debug);
#define GST_CAT_DEFAULT gst_win32_ipc_debug
struct Win32IpcMmf
{
explicit Win32IpcMmf (HANDLE f, void * b, UINT32 s, const std::string & n)
: file (f), buffer (b), size (s), name (n), ref_count (1)
{
}
~Win32IpcMmf ()
{
GST_TRACE ("Freeing %p (%s)", this, name.c_str ());
if (buffer)
UnmapViewOfFile (buffer);
if (file)
CloseHandle (file);
}
HANDLE file;
void *buffer;
UINT32 size;
std::string name;
ULONG ref_count;
};
static Win32IpcMmf *
win32_pic_mmf_new (HANDLE file, UINT32 size, const char * name)
{
Win32IpcMmf *self;
void *buffer;
std::string msg;
UINT err_code;
buffer = MapViewOfFile (file, FILE_MAP_ALL_ACCESS, 0, 0, size);
if (!buffer) {
err_code = GetLastError ();
msg = win32_ipc_error_message (err_code);
GST_ERROR ("MapViewOfFile failed with 0x%x (%s)",
err_code, msg.c_str ());
CloseHandle (file);
return nullptr;
}
self = new Win32IpcMmf (file, buffer, size, name);
return self;
}
/**
* win32_ipc_mmf_alloc:
* @size: Size of memory to allocate
* @name: The name of Memory Mapped File
*
* Creates named shared memory
*
* Returns: a new Win32IpcMmf object
*/
Win32IpcMmf *
win32_ipc_mmf_alloc (UINT32 size, const char * name)
{
HANDLE file;
std::string msg;
UINT err_code;
if (!size) {
GST_ERROR ("Zero size is not allowed");
return nullptr;
}
if (!name) {
GST_ERROR ("Name must be specified");
return nullptr;
}
file = CreateFileMappingA (INVALID_HANDLE_VALUE, nullptr,
PAGE_READWRITE | SEC_COMMIT, 0, size, name);
if (!file) {
err_code = GetLastError ();
msg = win32_ipc_error_message (err_code);
GST_ERROR ("CreateFileMappingA failed with 0x%x (%s)",
err_code, msg.c_str ());
return nullptr;
}
/* The name is already occupied, it's caller's fault... */
if (GetLastError () == ERROR_ALREADY_EXISTS) {
GST_ERROR ("File already exists");
CloseHandle (file);
return nullptr;
}
return win32_pic_mmf_new (file, size, name);
}
/**
* win32_ipc_mmf_open:
* @size: Size of memory to allocate
* @name: The name of Memory Mapped File
*
* Opens named shared memory
*
* Returns: a new Win32IpcMmf object
*/
Win32IpcMmf *
win32_ipc_mmf_open (UINT32 size, const char * name)
{
HANDLE file;
std::string msg;
UINT err_code;
if (!size) {
GST_ERROR ("Zero size is not allowed");
return nullptr;
}
if (!name) {
GST_ERROR ("Name must be specified");
return nullptr;
}
file = OpenFileMappingA (FILE_MAP_ALL_ACCESS, FALSE, name);
if (!file) {
err_code = GetLastError ();
msg = win32_ipc_error_message (err_code);
GST_ERROR ("OpenFileMappingA failed with 0x%x (%s)",
err_code, msg.c_str ());
return nullptr;
}
return win32_pic_mmf_new (file, size, name);
}
/**
* win32_ipc_mmf_get_name:
* @mmf: a Win32IpcMmf object
*
* Returns: the name of @mmf
*/
const char *
win32_ipc_mmf_get_name (Win32IpcMmf * mmf)
{
if (!mmf)
return nullptr;
return mmf->name.c_str ();
}
/**
* win32_ipc_mmf_get_size:
* @mmf: a Win32IpcMmf object
*
* Returns: the size of allocated memory
*/
UINT32
win32_ipc_mmf_get_size (Win32IpcMmf * mmf)
{
if (!mmf)
return 0;
return mmf->size;
}
/**
* win32_ipc_mmf_get_raw:
* @mmf: a Win32IpcMmf object
*
* Returns: the address of allocated memory
*/
void *
win32_ipc_mmf_get_raw (Win32IpcMmf * mmf)
{
if (!mmf)
return nullptr;
return mmf->buffer;
}
/**
* win32_ipc_mmf_ref:
* @mmf: a Win32IpcMmf object
*
* Increase ref count
*/
Win32IpcMmf *
win32_ipc_mmf_ref (Win32IpcMmf * mmf)
{
if (!mmf)
return nullptr;
InterlockedIncrement (&mmf->ref_count);
return mmf;
}
/**
* win32_ipc_mmf_unref:
* @mmf: a Win32IpcMmf object
*
* Decrease ref count
*/
void
win32_ipc_mmf_unref (Win32IpcMmf * mmf)
{
ULONG count;
if (!mmf)
return;
count = InterlockedDecrement (&mmf->ref_count);
if (count == 0)
delete mmf;
}