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* [PATCH 0/3] Revive 'pcre2-chartables-leakfix'
@ 2019-10-16 12:06 Johannes Schindelin via GitGitGadget
  2019-10-16 12:06 ` [PATCH 1/3] grep: make PCRE1 aware of custom allocator Carlo Marcelo Arenas Belón via GitGitGadget
                   ` (3 more replies)
  0 siblings, 4 replies; 45+ messages in thread
From: Johannes Schindelin via GitGitGadget @ 2019-10-16 12:06 UTC (permalink / raw)
  To: git; +Cc: Carlo Marcelo Arenas Belón, Johannes Schindelin,
	Junio C Hamano

As I had stated several times, I was really unhappy how the original fix
harped on nedmalloc and totally ignored runtime-configured custom
allocators.

So this is, at long last, my attempt to give this a new life. It is based
off of maint and needs trivial merge conflict resolutions relative to master
.

Range-diff relative to cb/pcre2-chartables-leakfix:

1:  770584d697e ! 1:  4feb8cc83a6 grep: make PCRE1 aware of custom allocator
    @@ Commit message
         to override the system alocator, and so it is incompatible with
         USE_NED_ALLOCATOR as reported by Dscho[1] (in similar code from PCRE2)

    +    Note that nedmalloc, as well as other custom allocators like jemalloc
    +    and mi-malloc, can be configured at runtime (via `LD_PRELOAD`),
    +    therefore we cannot know at compile time whether a custom allocator is
    +    used or not.
    +
         Make the minimum change possible to ensure this combination is supported
    -    by extending grep_init to set the PCRE1 specific functions to the NED
    -    versions (using the aliased names though) and therefore making sure all
    -    alocations are done inside PCRE1 with the same allocator than the rest
    -    of git.
    +    by extending `grep_init()` to set the PCRE1 specific functions to Git's
    +    idea of `malloc()` and `free()` and therefore making sure all
    +    allocations are done inside PCRE1 with the same allocator than the rest
    +    of Git.

    -    This change might have performance impact (hopefully for the best) and
    -    so will be good idea to test it in a platform where NED might have a
    -    positive impact (ex: Windows 7)
    +    This change has negligible performance impact: PCRE needs to allocate
    +    memory once per program run for the character table and for each pattern
    +    compilation. These are both rare events compared to matching patterns
    +    against lines. Actual measurements[2] show that the impact is lost in
    +    the noise.

         [1] https://public-inbox.org/git/pull.306.git.gitgitgadget@gmail.com
    +    [2] https://public-inbox.org/git/7f42007f-911b-c570-17f6-1c6af0429586@web.de

         Signed-off-by: Carlo Marcelo Arenas Bel├│n <carenas@gmail.com>
    -    Signed-off-by: Junio C Hamano <gitster@pobox.com>
    -
    - ## Makefile ##
    -@@ Makefile: ifdef NATIVE_CRLF
    - endif
    - 
    - ifdef USE_NED_ALLOCATOR
    --    COMPAT_CFLAGS += -Icompat/nedmalloc
    -+    COMPAT_CFLAGS += -DUSE_NED_ALLOCATOR -Icompat/nedmalloc
    -     COMPAT_OBJS += compat/nedmalloc/nedmalloc.o
    -     OVERRIDE_STRDUP = YesPlease
    - endif
    +    Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

      ## grep.c ##
     @@ grep.c: int grep_config(const char *var, const char *value, void *cb)
    @@ grep.c: int grep_config(const char *var, const char *value, void *cb)
       * default values from the template we read the configuration
       * information in an earlier call to git_config(grep_config).
     + *
    -+ * If using PCRE make sure that the library is configured
    -+ * to use the right allocator (ex: NED)
    ++ * If using PCRE, make sure that the library is configured
    ++ * to use the same allocator as Git (e.g. nedmalloc on Windows).
       */
      void grep_init(struct grep_opt *opt, struct repository *repo, const char *prefix)
      {
          struct grep_opt *def = &grep_defaults;
          int i;

    -+#ifdef USE_NED_ALLOCATOR
     +#ifdef USE_LIBPCRE1
     +    pcre_malloc = malloc;
     +    pcre_free = free;
     +#endif
    -+#endif
     +
          memset(opt, 0, sizeof(*opt));
          opt->repo = repo;
2:  cf8d36f34a2 ! 2:  39ad220c18b grep: make PCRE2 aware of custom allocator
    @@
      ## Metadata ##
    -Author: Carlo Marcelo Arenas Bel├│n <carenas@gmail.com>
    +Author: Johannes Schindelin <Johannes.Schindelin@gmx.de>

      ## Commit message ##
         grep: make PCRE2 aware of custom allocator

         94da9193a6 (grep: add support for PCRE v2, 2017-06-01) didn't include
         a way to override the system allocator, and so it is incompatible with
    -    USE_NED_ALLOCATOR.  The problem was made visible when an attempt to
    -    avoid a leak in a data structure that is created by the library was
    -    passed to NED's free for disposal triggering a segfault in Windows.
    +    custom allocators (e.g. nedmalloc). This problem became obvious when we
    +    tried to plug a memory leak by `free()`ing a data structure allocated by
    +    PCRE2, triggering a segfault in Windows (where we use nedmalloc by
    +    default).

         PCRE2 requires the use of a general context to override the allocator
         and therefore, there is a lot more code needed than in PCRE1, including
    @@ Commit message
         Extend the grep API with a "destructor" that could be called to cleanup
         any objects that were created and used globally.

    -    Update builtin/grep to use that new API, but any other future
    -    users should make sure to have matching grep_init/grep_destroy calls
    -    if they are using the pattern matching functionality (currently only
    -    relevant when using both NED and PCRE2)
    +    Update `builtin/grep.c` to use that new API, but any other future users
    +    should make sure to have matching `grep_init()`/`grep_destroy()` calls
    +    if they are using the pattern matching functionality.

         Move some of the logic that was before done per thread (in the workers)
    -    into an earlier phase to avoid degrading performance, but as the use
    -    of PCRE2 with NED is better understood it is expected more of its
    -    functions will be instructed to use the custom allocator as well as
    +    into an earlier phase to avoid degrading performance, but as the use of
    +    PCRE2 with custom allocators is better understood it is expected more of
    +    its functions will be instructed to use the custom allocator as well as
         was done in the original code[1] this work was based on.

         [1] https://public-inbox.org/git/3397e6797f872aedd18c6d795f4976e1c579514b.1565005867.git.gitgitgadget@gmail.com/

         Reported-by: Johannes Schindelin <johannes.schindelin@gmx.de>
         Signed-off-by: Carlo Marcelo Arenas Bel├│n <carenas@gmail.com>
    -    Signed-off-by: Junio C Hamano <gitster@pobox.com>
    +    Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

      ## builtin/grep.c ##
     @@ builtin/grep.c: int cmd_grep(int argc, const char **argv, const char *prefix)
    @@ grep.c: static int grep_source_is_binary(struct grep_source *gs,
     +#ifdef USE_LIBPCRE2
     +static pcre2_general_context *pcre2_global_context;
     +
    -+#ifdef USE_NED_ALLOCATOR
     +static void *pcre2_malloc(PCRE2_SIZE size, MAYBE_UNUSED void *memory_data)
     +{
     +    return malloc(size);
    @@ grep.c: static int grep_source_is_binary(struct grep_source *gs,
     +    return free(pointer);
     +}
     +#endif
    -+#endif
     +
      static const char *color_grep_slots[] = {
          [GREP_COLOR_CONTEXT]        = "context",
          [GREP_COLOR_FILENAME]        = "filename",
     @@ grep.c: int grep_config(const char *var, const char *value, void *cb)
       *
    -  * If using PCRE make sure that the library is configured
    -  * to use the right allocator (ex: NED)
    -+ * if any object is created it should be cleaned up in grep_destroy()
    +  * If using PCRE, make sure that the library is configured
    +  * to use the same allocator as Git (e.g. nedmalloc on Windows).
    ++ *
    ++ * Any allocated memory needs to be released in grep_destroy().
       */
      void grep_init(struct grep_opt *opt, struct repository *repo, const char *prefix)
      {
    +     struct grep_opt *def = &grep_defaults;
    +     int i;
    + 
    ++#if defined(USE_LIBPCRE2)
    ++    if (!pcre2_global_context)
    ++        pcre2_global_context = pcre2_general_context_create(
    ++                    pcre2_malloc, pcre2_free, NULL);
    ++#endif
    ++
    + #ifdef USE_LIBPCRE1
    +     pcre_malloc = malloc;
    +     pcre_free = free;
     @@ grep.c: void grep_init(struct grep_opt *opt, struct repository *repo, const char *prefix
              color_set(opt->colors[i], def->colors[i]);
      }
    @@ grep.c: void grep_init(struct grep_opt *opt, struct repository *repo, const char
      static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, struct grep_opt *opt)
      {
          /*
    -@@ grep.c: void append_header_grep_pattern(struct grep_opt *opt,
    - void append_grep_pattern(struct grep_opt *opt, const char *pat,
    -              const char *origin, int no, enum grep_pat_token t)
    - {
    -+#if defined(USE_LIBPCRE2) && defined(USE_NED_ALLOCATOR)
    -+    if (!pcre2_global_context && opt->ignore_case && has_non_ascii(pat))
    -+        pcre2_global_context = pcre2_general_context_create(
    -+                    pcre2_malloc, pcre2_free, NULL);
    -+#endif
    -     append_grep_pat(opt, pat, strlen(pat), origin, no, t);
    - }
    - 
     @@ grep.c: static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt

          p->pcre2_compile_context = NULL;
    @@ grep.c: static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_
          if (opt->ignore_case) {
              if (has_non_ascii(p->pattern)) {
     -            character_tables = pcre2_maketables(NULL);
    -+#ifdef USE_NED_ALLOCATOR
     +            if (!pcre2_global_context)
     +                BUG("pcre2_global_context uninitialized");
    -+#endif
     +            character_tables = pcre2_maketables(pcre2_global_context);
                  p->pcre2_compile_context = pcre2_compile_context_create(NULL);
                  pcre2_set_character_tables(p->pcre2_compile_context, character_tables);
3:  54aef142151 ! 3:  3ced7c386a0 grep: avoid leak of chartables in PCRE2
    @@
      ## Metadata ##
    -Author: Carlo Marcelo Arenas Bel├│n <carenas@gmail.com>
    +Author: Johannes Schindelin <Johannes.Schindelin@gmx.de>

      ## Commit message ##
         grep: avoid leak of chartables in PCRE2
    @@ Commit message
         for PCRE1.

         Signed-off-by: Carlo Marcelo Arenas Bel├│n <carenas@gmail.com>
    -    Signed-off-by: Junio C Hamano <gitster@pobox.com>
    +    Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

      ## grep.c ##
     @@ grep.c: static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
    @@ grep.c: static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_
          int patinforet;
          size_t jitsizearg;
     @@ grep.c: static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
    +         if (has_non_ascii(p->pattern)) {
                  if (!pcre2_global_context)
                      BUG("pcre2_global_context uninitialized");
    - #endif
     -            character_tables = pcre2_maketables(pcre2_global_context);
     +            p->pcre2_tables = pcre2_maketables(pcre2_global_context);
                  p->pcre2_compile_context = pcre2_compile_context_create(NULL);

My merge conflict resolution with master
[https://github.com/dscho/git/commit/pcre2-chartables-leakfix-merge-with-master]
:

diff --cc grep.c
index 9556d13dc1d,0bb4cbd3d82..b7ae5a442a6
--- a/grep.c
+++ b/grep.c
@@@ -533,15 -470,11 +506,15 @@@ static void compile_pcre2_pattern(struc

      p->pcre2_compile_context = NULL;

 +    /* pcre2_global_context is initialized in append_grep_pattern */
      if (opt->ignore_case) {
-         if (has_non_ascii(p->pattern)) {
+         if (!opt->ignore_locale && has_non_ascii(p->pattern)) {
 -            character_tables = pcre2_maketables(NULL);
 +            if (!pcre2_global_context)
 +                BUG("pcre2_global_context uninitialized");
 +            p->pcre2_tables = pcre2_maketables(pcre2_global_context);
              p->pcre2_compile_context = pcre2_compile_context_create(NULL);
 -            pcre2_set_character_tables(p->pcre2_compile_context, character_tables);
 +            pcre2_set_character_tables(p->pcre2_compile_context,
 +                            p->pcre2_tables);
          }
          options |= PCRE2_CASELESS;
      }
@@@ -643,9 -571,6 +611,7 @@@ static void free_pcre2_pattern(struct g
      pcre2_compile_context_free(p->pcre2_compile_context);
      pcre2_code_free(p->pcre2_pattern);
      pcre2_match_data_free(p->pcre2_match_data);
-     pcre2_jit_stack_free(p->pcre2_jit_stack);
-     pcre2_match_context_free(p->pcre2_match_context);
 +    free((void *)p->pcre2_tables);
  }
  #else /* !USE_LIBPCRE2 */
  static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
diff --cc grep.h
index 533165c21a5,05dc1bb98e5..811fd274c95
--- a/grep.h
+++ b/grep.h
@@@ -94,12 -78,9 +78,10 @@@ struct grep_pat 
      pcre2_code *pcre2_pattern;
      pcre2_match_data *pcre2_match_data;
      pcre2_compile_context *pcre2_compile_context;
-     pcre2_match_context *pcre2_match_context;
-     pcre2_jit_stack *pcre2_jit_stack;
 +    const uint8_t *pcre2_tables;
      uint32_t pcre2_jit_on;
-     kwset_t kws;
      unsigned fixed:1;
+     unsigned is_fixed:1;
      unsigned ignore_case:1;
      unsigned word_regexp:1;
  };

Carlo Marcelo Arenas Belón (2):
  grep: make PCRE1 aware of custom allocator
  grep: make PCRE2 aware of custom allocator

Johannes Schindelin (1):
  grep: avoid leak of chartables in PCRE2

 builtin/grep.c |  1 +
 grep.c         | 47 ++++++++++++++++++++++++++++++++++++++++++++---
 grep.h         |  2 ++
 3 files changed, 47 insertions(+), 3 deletions(-)


base-commit: 51cf315870bbb7254ddf06c84fe03b41bc48eebd
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-402%2Fdscho%2Fpcre2-chartables-leakfix-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-402/dscho/pcre2-chartables-leakfix-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/402
-- 
gitgitgadget

^ permalink raw reply	[flat|nested] 45+ messages in thread
* Re: [PATCH 1/1] pcre2: allow overriding the system allocator
@ 2019-08-05 21:53 Junio C Hamano
  2019-08-06  8:50 ` [PATCH 0/3] grep: no leaks (WIP) Carlo Marcelo Arenas Belón
  0 siblings, 1 reply; 45+ messages in thread
From: Junio C Hamano @ 2019-08-05 21:53 UTC (permalink / raw)
  To: Carlo Arenas
  Cc: Johannes Schindelin via GitGitGadget, git, Johannes Schindelin

Carlo Arenas <carenas@gmail.com> writes:

> LGTM except from the suggestion below that might make the code more "standard"
> and probably be a good base for a similar PCRE1 fix
>>
>> +static pcre2_general_context *get_pcre2_context(void)
>> +{
>> +       static pcre2_general_context *context;
>> +
>> +       if (!context)
>> +               context = pcre2_general_context_create(pcre2_malloc,
>> +                                                      pcre2_free, NULL);
>> +
>> +       return context;
>> +}
>
> instead of using a static variable inside this helper function it
> might be better to use
> one extra field inside the (struct grep_pat *p), where all other
> variables are kept
>
> Additionally to being more consistent will avoid creating the global

"standard" and "more consistent" are good things, but I am not sure
I should agree with the argument without knowing what you are
comparing your suggested improvement with.  Whose standard practice
are we trying to be consistent with?  Keeping dynamic resources hooked
to "struct grep_pat" so that (1) different patterns could use different
settings when they desire and (2) the resources are not hidden behind
a function-scope static and can be discarded when we are done with
the pattern, which is the standard in our "grep" subsystem?

I think general context probably corresponds to a bit higher level
than individual grep_pat.  E.g. when running "grep -e foo -e bar",
do we expect resources needed by patterns "foo" and "bar" would want
to be allocated and freed by potentially separate <alloc,free>
function pairs?

> context for the
> most common case (when the locale is either C/POSIX or UTF-8) and therefore
> have a smaller impact on performance.

I am not sure about the impact on performance, but if it helps us
keep the subsystem reusable by avoiding function-scope static that
we cannot clear, that would be a good thing.  But "struct grep_pat"
may be a bit too fine-grained to control general context.


^ permalink raw reply	[flat|nested] 45+ messages in thread
end of thread, other threads:[~2021-03-04  1:11 UTC | newest]

Thread overview: 45+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-16 12:06 [PATCH 0/3] Revive 'pcre2-chartables-leakfix' Johannes Schindelin via GitGitGadget
2019-10-16 12:06 ` [PATCH 1/3] grep: make PCRE1 aware of custom allocator Carlo Marcelo Arenas Belón via GitGitGadget
2019-10-16 12:06 ` [PATCH 2/3] grep: make PCRE2 " Carlo Marcelo Arenas Belón via GitGitGadget
2019-10-16 12:06 ` [PATCH 3/3] grep: avoid leak of chartables in PCRE2 Johannes Schindelin via GitGitGadget
2019-10-16 12:10 ` [PATCH v2 0/3] Revive 'pcre2-chartables-leakfix' Johannes Schindelin via GitGitGadget
2019-10-16 12:10   ` [PATCH v2 1/3] grep: make PCRE1 aware of custom allocator Carlo Marcelo Arenas Belón via GitGitGadget
2019-10-16 12:10   ` [PATCH v2 2/3] grep: make PCRE2 " Carlo Marcelo Arenas Belón via GitGitGadget
2019-10-18  1:38     ` Junio C Hamano
2021-02-04 21:05     ` [PATCH 00/10] grep/pcre2: memory allocation fixes Ævar Arnfjörð Bjarmason
2021-02-10 21:34       ` Junio C Hamano
2021-02-18  0:07       ` [PATCH v2 " Ævar Arnfjörð Bjarmason
2021-03-04  0:34         ` Junio C Hamano
2021-02-18  0:07       ` [PATCH v2 01/10] grep/pcre2: drop needless assignment + assert() on opt->pcre2 Ævar Arnfjörð Bjarmason
2021-02-18  0:07       ` [PATCH v2 02/10] grep/pcre2: drop needless assignment to NULL Ævar Arnfjörð Bjarmason
2021-02-18  0:07       ` [PATCH v2 03/10] grep/pcre2: correct reference to grep_init() in comment Ævar Arnfjörð Bjarmason
2021-02-18  0:07       ` [PATCH v2 04/10] grep/pcre2: prepare to add debugging to pcre2_malloc() Ævar Arnfjörð Bjarmason
2021-02-18  0:07       ` [PATCH v2 05/10] grep/pcre2: add GREP_PCRE2_DEBUG_MALLOC debug mode Ævar Arnfjörð Bjarmason
2021-02-18  0:07       ` [PATCH v2 06/10] grep/pcre2: use compile-time PCREv2 version test Ævar Arnfjörð Bjarmason
2021-03-04  0:14         ` Junio C Hamano
2021-02-18  0:07       ` [PATCH v2 07/10] grep/pcre2: use pcre2_maketables_free() function Ævar Arnfjörð Bjarmason
2021-02-18  0:07       ` [PATCH v2 08/10] grep/pcre2: actually make pcre2 use custom allocator Ævar Arnfjörð Bjarmason
2021-03-04  0:24         ` Junio C Hamano
2021-02-18  0:07       ` [PATCH v2 09/10] grep/pcre2: move back to thread-only PCREv2 structures Ævar Arnfjörð Bjarmason
2021-03-04  0:27         ` Junio C Hamano
2021-02-18  0:07       ` [PATCH v2 10/10] grep/pcre2: move definitions of pcre2_{malloc,free} Ævar Arnfjörð Bjarmason
2021-03-04  0:28         ` Junio C Hamano
2021-02-04 21:05     ` [PATCH 01/10] grep/pcre2: drop needless assignment + assert() on opt->pcre2 Ævar Arnfjörð Bjarmason
2021-02-04 21:05     ` [PATCH 02/10] grep/pcre2: drop needless assignment to NULL Ævar Arnfjörð Bjarmason
2021-02-04 21:05     ` [PATCH 03/10] grep/pcre2: correct reference to grep_init() in comment Ævar Arnfjörð Bjarmason
2021-02-04 21:05     ` [PATCH 04/10] grep/pcre2: prepare to add debugging to pcre2_malloc() Ævar Arnfjörð Bjarmason
2021-02-04 21:05     ` [PATCH 05/10] grep/pcre2: add GREP_PCRE2_DEBUG_MALLOC debug mode Ævar Arnfjörð Bjarmason
2021-02-10 10:38       ` Johannes Schindelin
2021-02-04 21:05     ` [PATCH 06/10] grep/pcre2: use compile-time PCREv2 version test Ævar Arnfjörð Bjarmason
2021-02-04 21:05     ` [PATCH 07/10] grep/pcre2: use pcre2_maketables_free() function Ævar Arnfjörð Bjarmason
2021-02-10 10:43       ` Johannes Schindelin
2021-03-04  0:16       ` Junio C Hamano
2021-02-04 21:05     ` [PATCH 08/10] grep/pcre2: actually make pcre2 use custom allocator Ævar Arnfjörð Bjarmason
2021-02-10 12:38       ` Johannes Schindelin
2021-02-04 21:05     ` [PATCH 09/10] grep/pcre2: move back to thread-only PCREv2 structures Ævar Arnfjörð Bjarmason
2021-02-04 21:05     ` [PATCH 10/10] grep/pcre2: move definitions of pcre2_{malloc,free} Ævar Arnfjörð Bjarmason
2021-02-10 12:40       ` Johannes Schindelin
2019-10-16 12:10   ` [PATCH v2 3/3] grep: avoid leak of chartables in PCRE2 Carlo Marcelo Arenas Belón via GitGitGadget
  -- strict thread matches above, loose matches on Subject: below --
2019-08-05 21:53 [PATCH 1/1] pcre2: allow overriding the system allocator Junio C Hamano
2019-08-06  8:50 ` [PATCH 0/3] grep: no leaks (WIP) Carlo Marcelo Arenas Belón
2019-08-06  8:50   ` [PATCH 1/3] grep: make PCRE1 aware of custom allocator Carlo Marcelo Arenas Belón
2019-08-08 13:54     ` Johannes Schindelin
2019-08-08 15:19       ` Carlo Arenas

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