From: Andrew Burgess <aburgess@redhat.com>
To: gdb-patches@sourceware.org
Subject: Re: [PATCHv2] gdb: new $_inferior_thread_count convenience variable
Date: Thu, 17 Nov 2022 14:51:00 +0000 [thread overview]
Message-ID: <87mt8p8wiz.fsf@redhat.com> (raw)
In-Reply-To: <20221103144239.98993-1-aburgess@redhat.com>
Andrew Burgess <aburgess@redhat.com> writes:
> Simon, Luis, thanks for your feedback.
>
> Changes since v1:
>
> 1. Rename variable to $_inferior_thread_count.
>
> 2. Use "live" in the docs and NEWS file to describe the threads
> being counted. I do still use "non-exited" within the commit
> message and comments, as this is how "live" is actually implemented
> within GDB.
>
> 3. Updated the docs to mention that in non-stop mode the value of
> $_inferior_thread_count will not be stable.
Thanks for the reviews. I've pushed this patch.
Andrew
>
> Thanks,
> Andrew
>
> ---
>
> Add a new convenience variable $_inferior_thread_count that contains
> the number of live (non-exited) threads in the current inferior. This
> can be used in command scripts, or breakpoint conditions, etc to
> adjust the behaviour for multi-threaded inferiors.
>
> This value is only stable in all-stop mode. In non-stop mode, where
> new threads can be started, and existing threads exit, at any time,
> this convenience variable can give a different value each time it is
> evaluated.
> ---
> gdb/NEWS | 3 +++
> gdb/doc/gdb.texinfo | 14 ++++++++++++--
> gdb/testsuite/gdb.base/default.exp | 1 +
> gdb/testsuite/gdb.multi/tids.exp | 20 ++++++++++++++++++++
> gdb/thread.c | 26 ++++++++++++++++++++++++++
> gdbsupport/iterator-range.h | 4 ++++
> 6 files changed, 66 insertions(+), 2 deletions(-)
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 8b519a648f7..8857dedb8b8 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -71,6 +71,9 @@
> For both /r and /b GDB is now better at using whitespace in order to
> align the disassembled instruction text.
>
> +* New convenience variable $_inferior_thread_count contains the number
> + of live threads in the current inferior.
> +
> * New commands
>
> maintenance set ignore-prologue-end-flag on|off
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index ea66f4ee42d..82f7fd66bf0 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -3642,8 +3642,15 @@
> @samp{$_gthread} contain, respectively, the per-inferior thread number
> and the global thread number of the current thread. You may find this
> useful in writing breakpoint conditional expressions, command scripts,
> -and so forth. @xref{Convenience Vars,, Convenience Variables}, for
> -general information on convenience variables.
> +and so forth. The convenience variable @samp{$_inferior_thread_count}
> +contains the number of live threads in the current inferior.
> +@xref{Convenience Vars,, Convenience Variables}, for general
> +information on convenience variables.
> +
> +When running in non-stop mode (@pxref{Non-Stop Mode}), where new
> +threads can be created, and existing threads exit, at any time,
> +@samp{$_inferior_thread_count} could return a different value each
> +time it is evaluated.
>
> If @value{GDBN} detects the program is multi-threaded, it augments the
> usual message about stopping at a breakpoint with the ID and name of
> @@ -12655,6 +12662,9 @@
> @item $_gthread
> The global number of the current thread. @xref{global thread numbers}.
>
> +@item $_inferior_thread_count
> +The number of live threads in the current inferior. @xref{Threads}.
> +
> @item $_gdb_major
> @itemx $_gdb_minor
> @vindex $_gdb_major@r{, convenience variable}
> diff --git a/gdb/testsuite/gdb.base/default.exp b/gdb/testsuite/gdb.base/default.exp
> index 29e76642830..f3e4b2867ef 100644
> --- a/gdb/testsuite/gdb.base/default.exp
> +++ b/gdb/testsuite/gdb.base/default.exp
> @@ -584,6 +584,7 @@ set show_conv_list \
> {$_thread = 0} \
> {$_gthread = 0} \
> {$_inferior = 1} \
> + {$_inferior_thread_count = 0} \
> {$_exception = <error: No frame selected>} \
> {$_probe_argc = <error: No frame selected>} \
> {$_probe_arg0 = <error: No frame selected>} \
> diff --git a/gdb/testsuite/gdb.multi/tids.exp b/gdb/testsuite/gdb.multi/tids.exp
> index fb7c2a29a71..23668caf18f 100644
> --- a/gdb/testsuite/gdb.multi/tids.exp
> +++ b/gdb/testsuite/gdb.multi/tids.exp
> @@ -123,6 +123,8 @@ with_test_prefix "single inferior" {
> info_threads "" "1"
>
> gdb_test "thread" "Current thread is 1 .*"
> +
> + gdb_test "print \$_inferior_thread_count" " = 1"
> }
>
> # "info threads" while there are multiple inferiors should show
> @@ -140,8 +142,14 @@ with_test_prefix "two inferiors" {
> gdb_test "inferior 2" "Switching to inferior 2 .*" "switch to inferior 2"
> gdb_test "file ${binfile}" ".*" "load file in inferior 2"
>
> + gdb_test "print \$_inferior_thread_count" " = 0" \
> + "no threads before we start the second inferior"
> +
> runto_main
>
> + gdb_test "print \$_inferior_thread_count" " = 1" \
> + "no other threads started yet"
> +
> # Now that we've added another inferior, thread IDs now show the
> # inferior number.
> info_threads "" "1.1 2.1" \
> @@ -153,8 +161,14 @@ with_test_prefix "two inferiors" {
> gdb_breakpoint "thread_function1"
>
> gdb_continue_to_breakpoint "once"
> + gdb_test "print \$_inferior_thread_count" " = 2" \
> + "second thread started in inferior 2"
> gdb_test "inferior 1" "Switching to inferior 1 .*"
> + gdb_test "print \$_inferior_thread_count" " = 1" \
> + "still only one thread in inferior 1"
> gdb_continue_to_breakpoint "twice"
> + gdb_test "print \$_inferior_thread_count" " = 2" \
> + "second thread started in inferior 1"
>
> info_threads "" "1.1 1.2 2.1 2.2" \
> "info threads again"
> @@ -187,9 +201,15 @@ with_test_prefix "two inferiors" {
>
> gdb_test "inferior 2" "Switching to inferior 2 .*"
> gdb_continue_to_breakpoint "once"
> + gdb_test "print \$_inferior_thread_count" " = 3" \
> + "third thread started in inferior 2"
>
> gdb_test "inferior 1" "Switching to inferior 1 .*"
> + gdb_test "print \$_inferior_thread_count" " = 2" \
> + "still only two threads in inferior 1"
> gdb_continue_to_breakpoint "twice"
> + gdb_test "print \$_inferior_thread_count" " = 3" \
> + "third thread started in inferior 1"
> }
>
> thr_apply_info_thr "1" \
> diff --git a/gdb/thread.c b/gdb/thread.c
> index 349fc01dd48..d176d1d9895 100644
> --- a/gdb/thread.c
> +++ b/gdb/thread.c
> @@ -2123,6 +2123,22 @@ global_thread_id_make_value (struct gdbarch *gdbarch, struct internalvar *var,
> return thread_num_make_value_helper (gdbarch, 1);
> }
>
> +/* Return a new value for the number of non-exited threads in the current
> + inferior. If there are no threads in the current inferior return a
> + value of 0. */
> +
> +static struct value *
> +inferior_thread_count_make_value (struct gdbarch *gdbarch,
> + struct internalvar *var, void *ignore)
> +{
> + int int_val = 0;
> +
> + if (inferior_ptid != null_ptid)
> + int_val = current_inferior ()->non_exited_threads ().size ();
> +
> + return value_from_longest (builtin_type (gdbarch)->builtin_int, int_val);
> +}
> +
> /* Commands with a prefix of `thread'. */
> struct cmd_list_element *thread_cmd_list = NULL;
>
> @@ -2142,6 +2158,14 @@ static const struct internalvar_funcs gthread_funcs =
> NULL,
> };
>
> +/* Implementation of `_inferior_thread_count` convenience variable. */
> +
> +static const struct internalvar_funcs inferior_thread_count_funcs =
> +{
> + inferior_thread_count_make_value,
> + NULL,
> +};
> +
> void _initialize_thread ();
> void
> _initialize_thread ()
> @@ -2258,4 +2282,6 @@ When on messages about thread creation and deletion are printed."),
>
> create_internalvar_type_lazy ("_thread", &thread_funcs, NULL);
> create_internalvar_type_lazy ("_gthread", >hread_funcs, NULL);
> + create_internalvar_type_lazy ("_inferior_thread_count",
> + &inferior_thread_count_funcs, NULL);
> }
> diff --git a/gdbsupport/iterator-range.h b/gdbsupport/iterator-range.h
> index d35b03a3392..c99bdc8de07 100644
> --- a/gdbsupport/iterator-range.h
> +++ b/gdbsupport/iterator-range.h
> @@ -53,6 +53,10 @@ struct iterator_range
> IteratorType end () const
> { return m_end; }
>
> + /* The number of items in this iterator_range. */
> + std::size_t size () const
> + { return std::distance (m_begin, m_end); }
> +
> private:
> IteratorType m_begin, m_end;
> };
> --
> 2.25.4
prev parent reply other threads:[~2022-11-17 14:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-02 14:34 [PATCH] gdb: new $_inferior_threads " Andrew Burgess
2022-11-02 14:56 ` Simon Marchi
2022-11-02 15:07 ` Luis Machado
2022-11-03 14:42 ` [PATCHv2] gdb: new $_inferior_thread_count " Andrew Burgess
2022-11-03 14:48 ` Eli Zaretskii
2022-11-03 15:03 ` Luis Machado
2022-11-17 14:51 ` Andrew Burgess [this message]
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