On 05/09/2012 08:22 AM, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
>
> Sometimes it is useful to see the callpath for log messages.
> This change enhances the log filter syntax so that stck traces
s/stck/stack/
> can be show by setting '1:+NAME' instead of '1:NAME'.
Cool.
> * docs/logging.html.in: Document new syntax
> * configure.ac: Check for execinfo.h
> * src/util/logging.c, src/util/logging.h: Add support for
> stack traces
Of course, this seems to be Linux-only, but still useful.
> +++ b/docs/logging.html.in
> @@ -114,8 +114,10 @@
> </h3>
> <p>The syntax for filters and outputs is the same for both types of
> variables.</p>
> - <p>The format for a filter is:</p>
> - <pre>x:name</pre>
> + <p>The format for a filter is one of:</p>
> + <pre>
> + x:name (log message only)
> + x:+name (log message + stack trace)</pre>
Does x:+name error out on systems where tracing is not built in, or does
it silently fall back to x:name?
> @@ -538,6 +546,7 @@ static int virLogFiltersCheck(const char *input) {
> for (i = 0;i < virLogNbFilters;i++) {
> if (strstr(input, virLogFilters[i].match)) {
> ret = virLogFilters[i].priority;
> + *flags = virLogFilters[i].flags;
Is the double space intentional?
> +
> +static void virLogStackTraceToFd(int fd)
> +{
> +#ifdef HAVE_EXECINFO_H
> + void *array[100];
> + int size;
> +
> +#define STRIP_DEPTH 3
> +
> + size = backtrace(array, sizeof(array)/sizeof(array[0]));
Write the second argument as ARRAY_CARDINALITY(array).
> + backtrace_symbols_fd(array + STRIP_DEPTH, size - STRIP_DEPTH, fd);
> + ignore_value(safewrite(fd, "\n", 1));
> +#else
> + const char *msg = "stack trace not available on this platform";
> + ignore_value(safewrite(fd, msg, strlen(msg)));
Is this a one-time error message, printed on first use, or will it
appear on every log message?
--
Eric Blake eblake@xxxxxxxxxx +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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