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add pcre2_get_match_data_heapframes_size() #191

Merged
merged 1 commit into from
Jan 17, 2023
Merged

add pcre2_get_match_data_heapframes_size() #191

merged 1 commit into from
Jan 17, 2023

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carenas
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@carenas carenas commented Jan 13, 2023

The proposed code, allows for an external application to implement logic similar to:

PCRE2 version 10.42 2022-12-11
  re> /\[(a)]{1000}/expand,framesize
Frame size for pcre2_match(): 16128
data> \[a]{1000}\=ovector=1
Matched, but too many substrings
 0: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
data> 
  re> /a/memory,heapframes_size
Memory allocation (code space): 9
Heapframes size for pcre2_match(): 20643840
data> a\=ovector=0
 0: a
data> 
  re> /a/heapframes_size
Heapframes size for pcre2_match(): 20480

So that the system could recover from memory pressure in cases were match_data is being reused.

@carenas carenas marked this pull request as draft January 13, 2023 19:43
@carenas
add pcre2_get_match_data_heapframes_size()
173443b 
Since PCRE2 10.41, the match data contains a pointer to a vector of
frames allocated in the heap and that are used by pcre2_match()
when doing non JIT matches.

There is though, no outside visibility on the size of it, and therefore
the memory it uses is locked away until match_data itself is freed.

Add an API that allows getting that value, so an application could
decide based on its own experienced memory pressure to keep reusing
that match_data or not.

While at it, update the documentation of other related functions for
clarity.
@carenas carenas marked this pull request as ready for review January 13, 2023 21:28
@PhilipHazel PhilipHazel merged commit c80c633 into PCRE2Project:master Jan 17, 2023
@carenas carenas deleted the mdheapsize branch January 17, 2023 19:37
@PhilipHazel
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I have now played with this a bit. I'm happy with the new function, but I'm going to re-work the changes to pcre2test. It seems wrong to me for the heapframes_size option to be a pattern option; I'm going to change it to a subject option. As a pattern option, it gives information about the previous match, which doesn't seem right.

@SolitaryGrass SolitaryGrass mentioned this pull request May 31, 2023
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@carenas @PhilipHazel