Messages in this thread | | | From | Namhyung Kim <> | Subject | Re: [PATCH 4/8] perf tools: Introduce struct perf_log | Date | Fri, 03 Jan 2014 17:23:05 +0900 |
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Hi Arnaldo,
On Thu, 26 Dec 2013 11:50:51 -0300, Arnaldo Carvalho de Melo wrote: > Em Thu, Dec 26, 2013 at 02:38:00PM +0900, Namhyung Kim escreveu: >> From: Namhyung Kim <namhyung.kim@lge.com> >> >> Add new functions to save error messages in a temp file. It'll be >> used by some UI front-ends to see the messages.
[SNIP] >> +struct perf_log { >> + FILE *fp; >> + off_t *linemap; >> + u32 lines; >> + u32 nr_alloc; >> + bool seen_newline; >> +}; >> + >> +extern struct perf_log perf_log; >> + >> +int perf_log_init(void); >> +int perf_log_exit(void); >> +void perf_log_add(const char *msg); >> +void perf_log_addv(const char *fmt, va_list ap); > > The convention in tools/perf/ has been to use class__method, i.e. in the > above case we would have: > > int perf_log__init(void); > int perf_log__exit(void); > void perf_log__add(const char *msg); > void perf_log__addv(const char *fmt, va_list ap);
Okay. (I wasn't follow the convention since the functions do not pass the perf_log as an argument, but I agree it's better to follow it.) Will change.
> > > But I have some questions about the implementation, will we go on > allocating memory for each and every line?
Yes, it needs an offset for each line in order to find starting point.
> > Can't we just come out with a simple ui_file_browser class that would > then be usable for any file, including this one?
Yes we can do it if need be. Do you think of another use case?
> > The ui_file_browser__seek() method would have to go on reading lines and > seeking newlines, with the ui_file_browser__seek(browser, 0, SEEK_SET) > would map directly to fseek(log_fp, 0, SEEK_SET), etc.
It supposed to. But in this case, the ->seek() method is called in ui_browser__run() which is not protected by ui__lock. So it's possible that new log message alters file position if it's called after ->seek() method was executed.
If it's guaranteed that there's no concurrent access to the file, we can move fseek() to the ->seek() method IMHO.
> > It should handle "live" files, like the one we're feeding log lines, > etc. > > The way you implemented it will grow memory consumption without > limits, no?
Right, it'll consume 8 bytes for each line of the file. What's the reasonable limitation?
Thanks, Namhyung
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