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Optimize CGI.escapeHTML by reducing buffer extension

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and switch-case branches.

Buffer allocation optimization using `ALLOCA_N` would be the main
benefit of patch. It eliminates the O(N) buffer extensions.

It also reduces the number of branches using escape table like
https://mattn.kaoriya.net/software/lang/c/20160817011915.htm.

Closes: https://github.com/ruby/ruby/pull/2226

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
Co-authored-by: Yasuhiro MATSUMOTO <mattn.jp@gmail.com>
This commit is contained in:
Takashi Kokubun 2019-06-04 19:58:39 +09:00
parent b31e1b4a7c
commit 8d81e59aa7
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GPG Key ID: 6FFC433B12EE23DD
2 changed files with 72 additions and 48 deletions
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40
benchmark/cgi_escape_html.yml Normal file
View File

@ -0,0 +1,40 @@
prelude: require 'cgi/escape'
benchmark:
- name: escape_html_blank
prelude: str = ""
script: CGI.escapeHTML(str)
loop_count: 20000000
- name: escape_html_short_none
prelude: str = "abcde"
script: CGI.escapeHTML(str)
loop_count: 20000000
- name: escape_html_short_one
prelude: str = "abcd<"
script: CGI.escapeHTML(str)
loop_count: 20000000
- name: escape_html_short_all
prelude: str = "'&\"<>"
script: CGI.escapeHTML(str)
loop_count: 5000000
- name: escape_html_long_none
prelude: str = "abcde" * 300
script: CGI.escapeHTML(str)
loop_count: 1000000
- name: escape_html_long_all
prelude: str = "'&\"<>" * 10
script: CGI.escapeHTML(str)
loop_count: 1000000
- name: escape_html_real
prelude: | # http://example.com/
str = <<~HTML
<body>
<div>
<h1>Example Domain</h1>
<p>This domain is established to be used for illustrative examples in documents. You may use this
domain in examples without prior coordination or asking for permission.</p>
<p><a href="http://www.iana.org/domains/example">More information...</a></p>
</div>
</body>
HTML
script: CGI.escapeHTML(str)
loop_count: 1000000

80
ext/cgi/escape/escape.c
View File

@ -11,27 +11,20 @@ RUBY_EXTERN const signed char ruby_digit36_to_number_table[];
static VALUE rb_cCGI, rb_mUtil, rb_mEscape; static VALUE rb_cCGI, rb_mUtil, rb_mEscape;
static ID id_accept_charset; static ID id_accept_charset;
static void #define HTML_ESCAPE_MAX_LEN 6
html_escaped_cat(VALUE str, char c)
{ static const struct {
switch (c) { uint8_t len;
case '\'': char str[HTML_ESCAPE_MAX_LEN+1];
rb_str_cat_cstr(str, "&#39;"); } html_escape_table[UCHAR_MAX+1] = {
break; #define HTML_ESCAPE(c, str) [c] = {rb_strlen_lit(str), str}
case '&': HTML_ESCAPE('\'', "&#39;"),
rb_str_cat_cstr(str, "&amp;"); HTML_ESCAPE('&', "&amp;"),
break; HTML_ESCAPE('"', "&quot;"),
case '"': HTML_ESCAPE('<', "&lt;"),
rb_str_cat_cstr(str, "&quot;"); HTML_ESCAPE('>', "&gt;"),
break; #undef HTML_ESCAPE
case '<': };
rb_str_cat_cstr(str, "&lt;");
break;
case '>':
rb_str_cat_cstr(str, "&gt;");
break;
}
}
static inline void static inline void
preserve_original_state(VALUE orig, VALUE dest) preserve_original_state(VALUE orig, VALUE dest)
@ -44,36 +37,27 @@ preserve_original_state(VALUE orig, VALUE dest)
static VALUE static VALUE
optimized_escape_html(VALUE str) optimized_escape_html(VALUE str)
{ {
long i, len, beg = 0; const char *cstr = RSTRING_PTR(str);
VALUE dest = 0; const char *end = cstr + RSTRING_LEN(str);
const char *cstr; char *buf = ALLOCA_N(char, RSTRING_LEN(str) * HTML_ESCAPE_MAX_LEN);
len = RSTRING_LEN(str); char *dest = buf;
cstr = RSTRING_PTR(str); while (cstr < end) {
const unsigned char c = *cstr++;
for (i = 0; i < len; i++) { uint8_t len = html_escape_table[c].len;
switch (cstr[i]) { if (len) {
case '\'': memcpy(dest, html_escape_table[c].str, len);
case '&': dest += len;
case '"': }
case '<': else {
case '>': *dest++ = c;
if (!dest) { }
dest = rb_str_buf_new(len);
}
rb_str_cat(dest, cstr + beg, i - beg);
beg = i + 1;
html_escaped_cat(dest, cstr[i]);
break;
}
} }
if (dest) { if (RSTRING_LEN(str) < (dest - buf)) {
rb_str_cat(dest, cstr + beg, len - beg); VALUE escaped = rb_str_new(buf, dest - buf);
preserve_original_state(str, dest); preserve_original_state(str, escaped);
return dest; return escaped;
} }
else { else {
return rb_str_dup(str); return rb_str_dup(str);