> On 15 Feb 2018, at 11:04, Frediano Ziglio <fziglio@xxxxxxxxxx> wrote:
>
>>
>> From: Christophe de Dinechin <dinechin@xxxxxxxxxx>
>>
>> This lets us get rid of C-style 'goto done' in do_capture.
>>
>> Signed-off-by: Christophe de Dinechin <dinechin@xxxxxxxxxx>
>
> I honestly prefer the "defer" style way.
The standard C++ practice for resource management is RAII, not defer. RAII is a composable abstraction, i.e. I can pile structs in structs and it still works.
I don’t know how you can prefer ‘defer’. It is, in all honestly, a clever but vile and ugly hack. Frankly, a C macro? With a lambda? Using a variable named after the __LINE__ in the code? It’s not reusable, it stays very low level, it’s brittle, hard to write (forget the ; and die). Smart people like Uri had to ask on IRC how it worked and what it was supposed to do…
>
> Beside that you correctly pointed out that there's a race condition
> on cursor thread which could lead the cursor thread to attempt writing
> the cursor shape before the device is open and you proposed some fixes
> in a different series.
> I think would be a better fix for this.
But it follows this patch and requires it.
>
>> ---
>> src/spice-streaming-agent.cpp | 32 ++++++++++++++++++++------------
>> 1 file changed, 20 insertions(+), 12 deletions(-)
>>
>> diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-agent.cpp
>> index 25a38a6..e9ef310 100644
>> --- a/src/spice-streaming-agent.cpp
>> +++ b/src/spice-streaming-agent.cpp
>> @@ -53,6 +53,23 @@ struct SpiceStreamDataMessage
>> StreamMsgData msg;
>> };
>>
>> +struct Stream
>> +{
>> + Stream(const char *name, int &fd): fd(fd)
>> + {
>> + fd = open(name, O_RDWR);
>> + if (fd < 0)
>> + throw std::runtime_error("failed to open streaming device");
>> + }
>> + ~Stream()
>> + {
>> + if (fd >= 0)
>> + close(fd);
>> + fd = -1;
>> + }
>> + int &fd;
>> +};
>> +
>> static bool streaming_requested = false;
>> static bool quit_requested = false;
>> static bool log_binary = false;
>> @@ -354,17 +371,14 @@ static void cursor_changes(Display *display, int
>> event_base)
>> static void
>> do_capture(const char *streamport, FILE *f_log)
>> {
>> - streamfd = open(streamport.c_str(), O_RDWR);
>> - if (streamfd < 0)
>> - throw std::runtime_error("failed to open the streaming device (" +
>> - streamport + "): " + strerror(errno));
>> + Stream stream(streamport, streamfd);
>>
>> unsigned int frame_count = 0;
>> while (!quit_requested) {
>> while (!quit_requested && !streaming_requested) {
>> if (read_command(true) < 0) {
>> syslog(LOG_ERR, "FAILED to read command\n");
>> - goto done;
>> + return;
>> }
>> }
>>
>> @@ -422,16 +436,10 @@ do_capture(const char *streamport, FILE *f_log)
>> //usleep(1);
>> if (read_command(false) < 0) {
>> syslog(LOG_ERR, "FAILED to read command\n");
>> - goto done;
>> + return;
>> }
>> }
>> }
>> -
>> -done:
>> - if (streamfd >= 0) {
>> - close(streamfd);
>> - streamfd = -1;
>> - }
>> }
>>
>> #define arg_error(...) syslog(LOG_ERR, ## __VA_ARGS__);
>
> Frediano
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