This patch fixes a few problems with GDB's time handling.
#1 - It avoids problems with gnulib's C++ namespace support
On MinGW, the struct timeval that should be passed to gnulib's
gettimeofday replacement is incompatible with libiberty's
timeval_sub/timeval_add. That's because gnulib also replaces "struct
timeval" with its own definition, while libiberty expects the
system's.
E.g., in code like this:
gettimeofday (&prompt_ended, NULL);
timeval_sub (&prompt_delta, &prompt_ended, &prompt_started);
timeval_add (&prompt_for_continue_wait_time,
&prompt_for_continue_wait_time, &prompt_delta);
That's currently handled in gdb by not using gnulib's gettimeofday at
all (see common/gdb_sys_time.h), but that #undef hack won't work with
if/when we enable gnulib's C++ namespace support, because that mode
adds compile time warnings for uses of ::gettimeofday, which are hard
errors with -Werror.
#2 - But there's an elephant in the room: gettimeofday is not monotonic...
We're using it to:
a) check how long functions take, for performance analysis
b) compute when in the future to fire events in the event-loop
c) print debug timestamps
But that's exactly what gettimeofday is NOT meant for. Straight from
the man page:
~~~
The time returned by gettimeofday() is affected by
discontinuous jumps in the system time (e.g., if the system
administrator manually changes the system time). If you need a
monotonically increasing clock, see clock_gettime(2).
~~~
std::chrono (part of the C++11 standard library) has a monotonic clock
exactly for such purposes (std::chrono::steady_clock). This commit
switches to use that instead of gettimeofday, fixing all the issues
mentioned above.
gdb/ChangeLog:
2016-11-23 Pedro Alves <palves@redhat.com>
* Makefile.in (SFILES): Add common/run-time-clock.c.
(HFILES_NO_SRCDIR): Add common/run-time-clock.h.
(COMMON_OBS): Add run-time-clock.o.
* common/run-time-clock.c, common/run-time-clock.h: New files.
* defs.h (struct timeval, print_transfer_performance): Delete
declarations.
* event-loop.c (struct gdb_timer) <when>: Now a
std::chrono::steady_clock::time_point.
(create_timer): use std::chrono::steady_clock instead of
gettimeofday. Use new instead of malloc.
(delete_timer): Use delete instead of xfree.
(duration_cast_timeval): New.
(update_wait_timeout): Use std::chrono::steady_clock instead of
gettimeofday.
* maint.c: Include <chrono> instead of "gdb_sys_time.h", <time.h>
and "timeval-utils.h".
(scoped_command_stats::~scoped_command_stats)
(scoped_command_stats::scoped_command_stats): Use
std::chrono::steady_clock instead of gettimeofday. Use
user_cpu_time_clock instead of get_run_time.
* maint.h: Include "run-time-clock.h" and <chrono>.
(scoped_command_stats): <m_start_cpu_time>: Now a
user_cpu_time_clock::time_point.
<m_start_wall_time>: Now a std::chrono::steady_clock::time_point.
* mi/mi-main.c: Include "run-time-clock.h" and <chrono> instead of
"gdb_sys_time.h" and <sys/resource.h>.
(rusage): Delete.
(mi_execute_command): Use new instead of XNEW.
(mi_load_progress): Use std::chrono::steady_clock instead of
gettimeofday.
(timestamp): Rewrite in terms of std::chrono::steady_clock,
user_cpu_time_clock and system_cpu_time_clock.
(timeval_diff): Delete.
(print_diff): Adjust to use std::chrono::steady_clock,
user_cpu_time_clock and system_cpu_time_clock.
* mi/mi-parse.h: Include "run-time-clock.h" and <chrono> instead
of "gdb_sys_time.h".
(struct mi_timestamp): Change fields types to
std::chrono::steady_clock::time_point, user_cpu_time_clock::time
and system_cpu_time_clock::time_point, instead of struct timeval.
* symfile.c: Include <chrono> instead of <time.h> and
"gdb_sys_time.h".
(struct time_range): New.
(generic_load): Use std::chrono::steady_clock instead of
gettimeofday.
(print_transfer_performance): Replace timeval parameters with a
std::chrono::steady_clock::duration parameter. Adjust.
* utils.c: Include <chrono> instead of "timeval-utils.h",
"gdb_sys_time.h", and <time.h>.
(prompt_for_continue_wait_time): Now a
std::chrono::steady_clock::duration.
(defaulted_query, prompt_for_continue): Use
std::chrono::steady_clock instead of
gettimeofday/timeval_sub/timeval_add.
(reset_prompt_for_continue_wait_time): Use
std::chrono::steady_clock::duration instead of struct timeval.
(get_prompt_for_continue_wait_time): Return a
std::chrono::steady_clock::duration instead of struct timeval.
(vfprintf_unfiltered): Use std::chrono::steady_clock instead of
gettimeofday. Use std::string. Use '.' instead of ':'.
* utils.h: Include <chrono>.
(get_prompt_for_continue_wait_time): Return a
std::chrono::steady_clock::duration instead of struct timeval.
gdb/gdbserver/ChangeLog:
2016-11-23 Pedro Alves <palves@redhat.com>
* debug.c: Include <chrono> instead of "gdb_sys_time.h".
(debug_vprintf): Use std::chrono::steady_clock instead of
gettimeofday. Use '.' instead of ':'.
* tracepoint.c: Include <chrono> instead of "gdb_sys_time.h".
(get_timestamp): Use std::chrono::steady_clock instead of
gettimeofday.
dcb07cfa15