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Type: Improvement
Resolution: Fixed
Priority: Critical - P2
Fix Version/s: WT11.3.0, 8.0.0-rc0, 7.3.0-rc2
Affects Version/s: None
Component/s: None
Labels:
- code-quality
- perf-improvement

Assigned Teams:

Storage Engines

Story Points:
5
Sprint:
2024-02-06 tapioooooooooooooca

WT_STRING_MATCH is defined as:

#define WT_STRING_MATCH(str, bytes, len) __wt_string_match(str, bytes, len)

static inline bool
__wt_string_match(const char *str, const char *bytes, size_t len)
{
    return (len > 0 && (strlen(str) == len) && (strncmp(str, bytes, len) == 0));
}

Consider changing the function to:

static inline bool
__wt_string_match(const char *str, const char *bytes, size_t len)
{
    return (len > 0 && strncmp(str, bytes, len) == 0 && str[len] == '\0');
}

That should be equivalent and avoids walking the str string twice.

Also, why do we need the len > 0 check? It will only make a difference if the length of string is 0, like this:

WT_STRING_MATCH("", bytes, 0)

I'd argue that the current code gives the wrong answer (false - should be true). Usually the first arg is a literal, and never "", so the right/wrong-ness is perhaps moot, but if it gives the wrong answer and is slower, well then...

So the final proposed better solution is:

static inline bool
__wt_string_match(const char *str, const char *bytes, size_t len)
{
    return (strncmp(str, bytes, len) == 0 && str[len] == '\0');
}