Re: [win-pv-devel] [PATCH 2/6] Add asynchronous device polling thread

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: win-pv-devel [mailto:win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> Behalf Of owen.smith@xxxxxxxxxx
> Sent: 24 July 2017 14:35
> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Owen Smith <owen.smith@xxxxxxxxxx>
> Subject: [win-pv-devel] [PATCH 2/6] Add asynchronous device polling thread
> 
> From: Owen Smith <owen.smith@xxxxxxxxxx>
> 
> Adds a thread that will asynchrously read the device handle.
> This will be used to read console data from the device, for passing
> to the named pipe.
> 
> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>

Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

> ---
>  src/monitor/monitor.c | 128
> ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 128 insertions(+)
> 
> diff --git a/src/monitor/monitor.c b/src/monitor/monitor.c
> index a2a3cc1..df94934 100644
> --- a/src/monitor/monitor.c
> +++ b/src/monitor/monitor.c
> @@ -65,6 +65,8 @@ typedef struct _MONITOR_CONTEXT {
>      HANDLE                  Device;
>      HANDLE                  MonitorEvent;
>      HANDLE                  MonitorThread;
> +    HANDLE                  DeviceEvent;
> +    HANDLE                  DeviceThread;
>  } MONITOR_CONTEXT, *PMONITOR_CONTEXT;
> 
>  MONITOR_CONTEXT MonitorContext;
> @@ -456,6 +458,96 @@ fail1:
>      return 1;
>  }
> 
> +DWORD WINAPI
> +DeviceThread(
> +    IN  LPVOID          Argument
> +    )
> +{
> +    PMONITOR_CONTEXT    Context = &MonitorContext;
> +    OVERLAPPED          Overlapped;
> +    HANDLE              Device;
> +    UCHAR               Buffer[MAXIMUM_BUFFER_SIZE];
> +    DWORD               Length;
> +    DWORD               Wait;
> +    HANDLE              Handles[2];
> +    DWORD               Error;
> +
> +    UNREFERENCED_PARAMETER(Argument);
> +
> +    Log("====>");
> +
> +    memset(&Overlapped, 0, sizeof(OVERLAPPED));
> +    Overlapped.hEvent = CreateEvent(NULL,
> +                                    TRUE,
> +                                    FALSE,
> +                                    NULL);
> +    if (Overlapped.hEvent == NULL)
> +        goto fail1;
> +
> +    Handles[0] = Context->DeviceEvent;
> +    Handles[1] = Overlapped.hEvent;
> +
> +    Device = CreateFile(Context->DevicePath,
> +                        GENERIC_READ,
> +                        FILE_SHARE_READ | FILE_SHARE_WRITE,
> +                        NULL,
> +                        OPEN_EXISTING,
> +                        FILE_FLAG_OVERLAPPED,
> +                        NULL);
> +    if (Device == INVALID_HANDLE_VALUE)
> +        goto fail2;
> +
> +    for (;;) {
> +        (VOID) ReadFile(Device,
> +                        Buffer,
> +                        sizeof(Buffer),
> +                        NULL,
> +                        &Overlapped);
> +
> +        Wait = WaitForMultipleObjects(ARRAYSIZE(Handles),
> +                                      Handles,
> +                                      FALSE,
> +                                      INFINITE);
> +        if (Wait == WAIT_OBJECT_0)
> +            break;
> +
> +        if (!GetOverlappedResult(Device,
> +                                 &Overlapped,
> +                                 &Length,
> +                                 FALSE))
> +            break;
> +
> +        ResetEvent(Overlapped.hEvent);
> +
> +        // Length bytes of Buffer have been read
> +    }
> +
> +    CloseHandle(Device);
> +
> +    CloseHandle(Overlapped.hEvent);
> +
> +    Log("<====");
> +
> +    return 0;
> +
> +fail2:
> +    Log("fail2\n");
> +
> +    CloseHandle(Overlapped.hEvent);
> +
> +fail1:
> +    Error = GetLastError();
> +
> +    {
> +        PTCHAR  Message;
> +        Message = GetErrorMessage(Error);
> +        Log("fail1 (%s)", Message);
> +        LocalFree(Message);
> +    }
> +
> +    return 1;
> +}
> +
>  static VOID
>  PutString(
>      IN  HANDLE      Handle,
> @@ -551,10 +643,40 @@ MonitorAdd(
>      if (Context->MonitorThread == INVALID_HANDLE_VALUE)
>          goto fail5;
> 
> +    Context->DeviceEvent = CreateEvent(NULL,
> +                                       TRUE,
> +                                       FALSE,
> +                                       NULL);
> +
> +    if (Context->DeviceEvent == NULL)
> +        goto fail6;
> +
> +    Context->DeviceThread = CreateThread(NULL,
> +                                         0,
> +                                         DeviceThread,
> +                                         NULL,
> +                                         0,
> +                                         NULL);
> +
> +    if (Context->DeviceThread == INVALID_HANDLE_VALUE)
> +        goto fail7;
> +
>      Log("<====");
> 
>      return;
> 
> +fail7:
> +    Log("fail7\n");
> +
> +    CloseHandle(Context->DeviceEvent);
> +    Context->DeviceEvent = NULL;
> +
> +fail6:
> +    Log("fail6\n");
> +
> +    SetEvent(Context->MonitorThread);
> +    WaitForSingleObject(Context->MonitorThread, INFINITE);
> +
>  fail5:
>      Log("fail5");
> 
> @@ -604,6 +726,12 @@ MonitorRemove(
> 
>      Log("====>");
> 
> +    SetEvent(Context->DeviceEvent);
> +    WaitForSingleObject(Context->DeviceThread, INFINITE);
> +
> +    CloseHandle(Context->DeviceEvent);
> +    Context->DeviceEvent = NULL;
> +
>      SetEvent(Context->MonitorEvent);
>      WaitForSingleObject(Context->MonitorThread, INFINITE);
> 
> --
> 2.8.3
> 
> 
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