html: EscapeString could be made faster using a strings.Replacer

[kbloom]

Consider the following benchmark:

package escaping

import (
        "html"
        "strings"
        "testing"
)

const noHTMLString = `Can you hear the people sing, singing the song of
angry men. It is the music of a people who will not be slaves again.`
const withHTMLString = `We're going to demand <strong>one million
dollars</strong> or we're going to threaten Earth with a "Laser".`

var escaper = strings.NewReplacer(
        `&`, "&amp;",
        `'`, "&#39;",
        `<`, "&lt;",
        `>`, "&gt;",
        `"`, "&#34;",
)

func BenchmarkHtml_EscapeString_nochanges(b *testing.B) {
        for i := 0; i < b.N; i++ {
                html.EscapeString(noHTMLString)
        }
}

func BenchmarkStrings_Replacer_nochanges(b *testing.B) {
        for i := 0; i < b.N; i++ {
                escaper.Replace(noHTMLString)
        }
}

func BenchmarkHtml_EscapeString_changes(b *testing.B) {
        for i := 0; i < b.N; i++ {
                html.EscapeString(withHTMLString)
        }
}

func BenchmarkStrings_Replacer_changes(b *testing.B) {
        for i := 0; i < b.N; i++ {
                escaper.Replace(withHTMLString)
        }
}

The performance is as follows:

BenchmarkHtml_EscapeString_nochanges      500000              3912 ns/op
BenchmarkStrings_Replacer_nochanges      5000000               368 ns/op
BenchmarkHtml_EscapeString_changes        500000              4597 ns/op
BenchmarkStrings_Replacer_changes        1000000              1360 ns/op


I've written https://golang.org/cl/141930043/ to change html.EscapeString so
that it uses a replacer internally, but it needs to wait until Go 1.5 development opens.

[ianlancetaylor]

Comment 1:

Labels changed: added repo-main, release-go1.5.

[josharian]

@kbloom do you plan to migrate your CL to Gerrit (the new codereview system)? If not, would you like one of us to do so for you? Thanks!

[dspezia]

I'm not sure the OP is still following this thread. I prepare a similar CL (crediting him, of course).

[gopherbot]

CL https://golang.org/cl/9808 mentions this issue.

[kbloom]

Thanks. I had lost track of your ping because it was in my personal email
rather than my corp email. (Plus the friction of getting set up on a new
review environment.) I can't even figure out how to LGTM your CL, but it
looks good to me.

On Fri, May 8, 2015 at 1:01 PM, GopherBot [email protected] wrote:

CL https://golang.org/cl/9808 mentions this issue.

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