HttpHeaderHelper: String.replace instead of Pattern.matcher().replaceAll

[amarkevich]

benchmark [1] results:

• old: 40 MB 47 ms
• new: 9 MB 0 ms

public class HttpHeaderHelperMapCharsetTest {
    private static final int CNT = 131072;
    static final String charset = java.nio.charset.StandardCharsets.UTF_8.name();
    private static final String[] STR = new String[CNT];
    static {
        for (int i = 0; i < CNT; ++i) {
            if (i % 3 == 0) {
                STR[i] = "\"" + charset + "\"";
            } else if (i % 3 == 1) {
                STR[i] = "'" + charset + "'";
            } else {
                STR[i] = charset;
            }
        }
    }

    @org.junit.Test
    public void mapCharset() {
        metrics("HttpHeaderHelper::mapCharset", HttpHeaderHelper::mapCharset);
    }

    @org.junit.Test
    public void mapCharset2() {
        metrics("HttpHeaderHelper::mapCharset2", HttpHeaderHelper::mapCharset2);
    }

    private static void metrics(String label, java.util.function.Function<String, String> f) {
        Runtime.getRuntime().gc();
        long m = Runtime.getRuntime().freeMemory();
        long t = System.currentTimeMillis();
        for (int i = 0; i < CNT; ++i) {
            org.junit.Assert.assertEquals(charset, f.apply(STR[i]));
        }
        System.out.println(label + ": " + ((m - Runtime.getRuntime().freeMemory()) / (1024 * 1024)) + " MB "
                + (System.currentTimeMillis() - t) + " ms");
    }

    public static void main(String[] args) {
        final HttpHeaderHelperMapCharsetTest splitTest = new HttpHeaderHelperMapCharsetTest();
        for (int i = 0; i < 10; ++i) {
            System.out.println("Round #" + i);
            splitTest.mapCharset();
            splitTest.mapCharset2();
        }
    }

}

[andymc12]

LGTM - thanks!