Use StringUtils.replace(…) instead of String.replaceAll(…) for mapKeyDotReplacement

[chzhong]

When configured to use mapKeyDotReplacement, MappingMongoConverter will use String.replaceAll to replace all dots in keys into specified replacement, which might cause unnecessary creation of java.util.regex.Pattern repeatly. This will lead to rapid GC serialize/deserialize a huge (>= 10MB) mongo document multiple times.

Codes in current version:

	/**
	 * Potentially replaces dots in the given map key with the configured map key replacement if configured or aborts
	 * conversion if none is configured.
	 *
	 * @see #setMapKeyDotReplacement(String)
	 * @param source
	 * @return
	 */
	protected String potentiallyEscapeMapKey(String source) {

		if (!source.contains(".")) {
			return source;
		}

		if (mapKeyDotReplacement == null) {
			throw new MappingException(String.format(
					"Map key %s contains dots but no replacement was configured! Make "
							+ "sure map keys don't contain dots in the first place or configure an appropriate replacement!",
					source));
		}

		return source.replaceAll("\\.", mapKeyDotReplacement);
	}


	/**
	 * Translates the map key replacements in the given key just read with a dot in case a map key replacement has been
	 * configured.
	 *
	 * @param source
	 * @return
	 */
	protected String potentiallyUnescapeMapKey(String source) {
		return mapKeyDotReplacement == null ? source : source.replaceAll(mapKeyDotReplacement, "\\.");
	}

Suggestion:
Use org.springframework.util.StringUtils#replace or org.apache.commons.lang3.StringUtils#replace(java.lang.String, java.lang.String, java.lang.String) to replace dots instead.

[mp911de]

Good catch. Care to submit a pull request that makes use of org.springframework.util.StringUtils#replace?

[chzhong]

Good catch. Care to submit a pull request that makes use of org.springframework.util.StringUtils#replace?

I'm behind a firewall so I can't submit a PR :-(

[mp911de]

Thanks for letting us know, we'll take care of this.

[HermanBovens]

@mp911de, note that this is a breaking change that, AFAICS, is not mentioned in any upgrade guide. We were using "\\+" in order to replace the dot with + (because + needs to be escaped in regex) and that code, although it still compiled, was broken.

It is only mentioned as a "new feature" in the release notes for this patch release:
https://github.com/spring-projects/spring-data-mongodb/releases/tag/3.1.7

In my opinion it shouldn't even have been included in a patch release since patch releases should not require any work to upgrade.