[PATCH v5 07/12] eu-stacktrace [7/12]: use Dwflst_Process_Tracker for Elf * caching

[Aaron Merey]

On Thu, Apr 24, 2025 at 5:50 PM Serhei Makarov <serhei@serhei.io> wrote:
>
> Changes for v4:
>
> - Separate out libdwfl_stacktrace, as requested.
>
> * * *
>
> * src/Makefile.am (AM_CPPFLAGS): Include headers from
>   ../libdwfl_stacktrace.
> * src/stacktrace.c (tracker): New global variable.
>   (sample_callbacks): Use dwflst_tracker_linux_proc_find_elf for
>   caching.
>   (sysprof_init_dwfl): Use dwflst_tracker_dwfl_begin.
>   (main): Initialize and clean up tracker.
> ---
>  src/Makefile.am  |  3 ++-
>  src/stacktrace.c | 12 +++++++++---
>  2 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/src/Makefile.am b/src/Makefile.am
> index 6d713e88..4a3fb957 100644
> --- a/src/Makefile.am
> +++ b/src/Makefile.am
> @@ -23,7 +23,8 @@ DEFS += $(YYDEBUG) -DDEBUGPRED=@DEBUGPRED@ \
>  DEFAULT_INCLUDES =
>  AM_CPPFLAGS += -I$(srcdir)/../libelf -I$(srcdir)/../libebl \
>             -I$(srcdir)/../libdw -I$(srcdir)/../libdwelf \
> -           -I$(srcdir)/../libdwfl -I$(srcdir)/../libasm -I../debuginfod
> +           -I$(srcdir)/../libdwfl -I$(srcdir)/../libdwfl_stacktrace \
> +           -I$(srcdir)/../libasm -I../debuginfod
>
>  AM_LDFLAGS = -Wl,-rpath-link,../libelf:../libdw $(STACK_USAGE_NO_ERROR)
>
> diff --git a/src/stacktrace.c b/src/stacktrace.c
> index 3f5950fb..c0c9929d 100644
> --- a/src/stacktrace.c
> +++ b/src/stacktrace.c
> @@ -98,6 +98,7 @@
>  #include "../libdwfl/libdwflP.h"
>  /* XXX: Private header needed for find_procfile, sysprof_init_dwfl,
>     sample_set_initial_registers. */
> +#include ELFUTILS_HEADER(dwfl_stacktrace)
>
>  /*************************************
>   * Includes: sysprof data structures *
> @@ -657,6 +658,8 @@ static const Dwfl_Thread_Callbacks sample_thread_callbacks =
>   * Dwfl and statistics table for multiple processes *
>   ****************************************************/
>
> +Dwflst_Process_Tracker *tracker = NULL;
> +
>  /* This echoes lib/dynamicsizehash.* with some necessary modifications. */
>  typedef struct
>  {
> @@ -889,7 +892,7 @@ static char *debuginfo_path = NULL;
>
>  static const Dwfl_Callbacks sample_callbacks =
>    {
> -    .find_elf = dwfl_linux_proc_find_elf,
> +    .find_elf = dwflst_tracker_linux_proc_find_elf,
>      .find_debuginfo = dwfl_standard_find_debuginfo,
>      .debuginfo_path = &debuginfo_path,
>    };
> @@ -915,7 +918,7 @@ nop_find_debuginfo (Dwfl_Module *mod __attribute__((unused)),
>
>  static const Dwfl_Callbacks sample_callbacks =
>  {
> -  .find_elf = dwfl_linux_proc_find_elf,
> +  .find_elf = dwflst_tracker_linux_proc_find_elf,
>    .find_debuginfo = nop_find_debuginfo, /* work with CFI only */
>  };
>
> @@ -1038,7 +1041,7 @@ sysprof_init_dwfl (struct sysprof_unwind_info *sui,
>        cached = true;
>        goto reuse;
>      }
> -  dwfl = dwfl_begin (&sample_callbacks);
> +  dwfl = dwflst_tracker_dwfl_begin (tracker);
>
>    int err = dwfl_linux_proc_report (dwfl, pid);
>    if (err < 0)
> @@ -1532,6 +1535,7 @@ https://sourceware.org/cgit/elfutils/tree/README.eu-stacktrace?h=users/serhei/eu
>    (void)maxframes;
>  #else
>    fprintf(stderr, "\n=== starting eu-stacktrace ===\n");
> +  tracker = dwflst_tracker_begin (&sample_callbacks);
>
>    /* TODO: For now, code the processing loop for sysprof only; generalize later. */
>    assert (input_format == FORMAT_SYSPROF);
> @@ -1615,5 +1619,7 @@ https://sourceware.org/cgit/elfutils/tree/README.eu-stacktrace?h=users/serhei/eu
>    if (output_fd != -1)
>      close (output_fd);
>
> +  dwflst_tracker_end (tracker);
> +
>    return EXIT_OK;
>  }
> --
> 2.47.0
>

LGTM.

Aaron