Re: [Qemu-devel] [PATCH v3 27/29] qemu-io: New command 'sleep'

[Max Reitz <mreitz@redhat.com>]

On 17.01.2014 15:15, Kevin Wolf wrote:
> There is no easy way to check that a request correctly waits for a
> different request. With a sleep command we can at least approximate it.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   qemu-io-cmds.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 42 insertions(+)
>
> diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
> index 85e4982..978a3a0 100644
> --- a/qemu-io-cmds.c
> +++ b/qemu-io-cmds.c
> @@ -12,6 +12,7 @@
>   #include "block/block_int.h"
>   #include "block/qapi.h"
>   #include "qemu/main-loop.h"
> +#include "qemu/timer.h"
>   
>   #define CMD_NOFILE_OK   0x01
>   
> @@ -2038,6 +2039,46 @@ static const cmdinfo_t abort_cmd = {
>          .oneline        = "simulate a program crash using abort(3)",
>   };
>   
> +static void sleep_cb(void *opaque)
> +{
> +    bool *expired = opaque;
> +    *expired = true;
> +}
> +
> +static int sleep_f(BlockDriverState *bs, int argc, char **argv)
> +{
> +    char *endptr;
> +    long ms;
> +    struct QEMUTimer *timer;
> +    bool expired = false;
> +
> +    ms = strtol(argv[1], &endptr, 0);
> +    if (ms < 0 || *endptr != '\0') {
> +        printf("%s is not a valid number\n", argv[1]);
> +        return 0;
> +    }
> +
> +    timer = timer_new_ns(QEMU_CLOCK_HOST, sleep_cb, &expired);
> +    timer_mod(timer, qemu_clock_get_ns(QEMU_CLOCK_HOST) + SCALE_MS * ms);
> +
> +    while (!expired) {

I don't know whether compilers don't optimize accesses to variables 
whose addresses have been given to other functions, but shouldn't 
expired be marked volatile just to be sure?

Max

> +        main_loop_wait(false);
> +    }
> +
> +    timer_free(timer);
> +
> +    return 0;
> +}
> +
> +static const cmdinfo_t sleep_cmd = {
> +       .name           = "sleep",
> +       .argmin         = 1,
> +       .argmax         = 1,
> +       .cfunc          = sleep_f,
> +       .flags          = CMD_NOFILE_OK,
> +       .oneline        = "waits for the given value in milliseconds",
> +};
> +
>   static void help_oneline(const char *cmd, const cmdinfo_t *ct)
>   {
>       if (cmd) {
> @@ -2151,4 +2192,5 @@ static void __attribute((constructor)) init_qemuio_commands(void)
>       qemuio_add_command(&resume_cmd);
>       qemuio_add_command(&wait_break_cmd);
>       qemuio_add_command(&abort_cmd);
> +    qemuio_add_command(&sleep_cmd);
>   }