Performance: Escape fields and keys more efficiently

[mschaefers]

Under heavy load a profiler shows that calling String.replace() in FIELD_ESCAPER or KEY_ESCAPER is significantly slower than escaping manually by writing directly into the current StringBuffer.

This pull request does not change behavior but only execution speed

[codecov-io]

Codecov Report

Merging #424 into master will increase coverage by 0.11%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master     #424      +/-   ##
============================================
+ Coverage     84.86%   84.98%   +0.11%     
- Complexity      270      274       +4     
============================================
  Files            19       19              
  Lines          1183     1192       +9     
  Branches        119      121       +2     
============================================
+ Hits           1004     1013       +9     
  Misses          118      118              
  Partials         61       61

Impacted Files	Coverage Δ	Complexity Δ
src/main/java/org/influxdb/dto/Point.java	82.82% <100%> (+1%)	31 <6> (+4)	⬆️

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[majst01]

Any numbers about performance improvements ?

[mschaefers]

I used jvmtop (https://github.com/patric-r/jvmtop) as a simple profiler. Profiling our application resulted in 14-15% of CPU time to be used in closure KEY_ESCAPER. With this patch the CPU percentage of escapeKey was reported with 1-2%.

[mschaefers]

Another very simple test can be done by executing the following testcase in PointTest.java

It creates 2M different lineProtocol Strings in a loop of 1M, single threaded, having to escape 7M keys and 2M values

Execution time on my laptop without this merge request: ~7.2sec vs. with merge request: ~1.8sec.

@org.junit.Test
public void lineProtocolPerformanceTest() {

	String[] value = new String[2];
	final long start = System.currentTimeMillis();
	IntStream.range(1, 1000000).forEach((i) -> {
		Map<String, Object> fields1 = Collections.singletonMap("foo ", "bar\""+i);
		Map<String, Object> fields2 = Collections.singletonMap("foo,"+i, "baz\"");

		String measurement = "measurement"+i;

		TimeUnit precision = TimeUnit.NANOSECONDS;

		Map<String, String> tags = Collections.singletonMap("bar \"\\"+i, "b\"a\"z"+i);

		Long time = System.currentTimeMillis();

		Point p1 = new Point();
		p1.setFields(fields1);
		p1.setMeasurement(measurement);
		p1.setPrecision(precision);
		p1.setTags(tags);
		p1.setTime(time);

		Point p2 = new Point();
		p2.setFields(fields2);
		p2.setMeasurement(measurement);
		p2.setPrecision(precision);
		p2.setTags(tags);
		p2.setTime(time);

		value[0] = p1.lineProtocol();
		value[1] = p2.lineProtocol();
	});
	System.out.println(System.currentTimeMillis() - start);
	System.out.println(value[0]);
	System.out.println(value[1]);
}

[majst01]

looks good to me, just two formatting changes required.

[majst01]

reset this formatting

[majst01]

same here