Only set valuesRecorded if its false

[jack-berg]

Reading a volatile is cheap. Writing it under contention, even when the value doesn't change, is expensive.

This simple change to read before write yields huge perf improvement for contended cases:

Benchmark	Threads	Temporality	Cardinality	Instrument	Baseline (ops/s)	After (ops/s)	Δ ops/s	Δ %
threads1	1	CUMULATIVE	1	COUNTER_SUM	158,568,637	157,745,534	-823,103	-0.5%
threads1	1	CUMULATIVE	1	GAUGE_LAST_VALUE	84,391,938	65,769,849	-18,622,089	-22.1%
threads1	1	CUMULATIVE	1	HISTOGRAM_BASE2_EXPONENTIAL	42,063,874	37,577,277	-4,486,597	-10.7%
threads1	1	CUMULATIVE	1	HISTOGRAM_EXPLICIT	96,618,066	92,650,458	-3,967,609	-4.1%
threads1	1	CUMULATIVE	1	UP_DOWN_COUNTER_SUM	155,066,532	161,825,761	+6,759,229	+4.4%
threads1	1	CUMULATIVE	128	COUNTER_SUM	113,296,533	115,410,215	+2,113,682	+1.9%
threads1	1	CUMULATIVE	128	GAUGE_LAST_VALUE	133,640,492	112,619,646	-21,020,846	-15.7%
threads1	1	CUMULATIVE	128	HISTOGRAM_BASE2_EXPONENTIAL	42,456,092	42,146,264	-309,828	-0.7%
threads1	1	CUMULATIVE	128	HISTOGRAM_EXPLICIT	68,795,746	74,813,002	+6,017,255	+8.7%
threads1	1	CUMULATIVE	128	UP_DOWN_COUNTER_SUM	110,120,331	97,792,286	-12,328,045	-11.2%
threads1	1	DELTA	1	COUNTER_SUM	116,642,454	90,174,325	-26,468,129	-22.7%
threads1	1	DELTA	1	GAUGE_LAST_VALUE	41,310,133	38,184,273	-3,125,860	-7.6%
threads1	1	DELTA	1	HISTOGRAM_BASE2_EXPONENTIAL	42,801,022	39,383,490	-3,417,532	-8.0%
threads1	1	DELTA	1	HISTOGRAM_EXPLICIT	58,788,702	61,343,010	+2,554,308	+4.3%
threads1	1	DELTA	1	UP_DOWN_COUNTER_SUM	113,438,421	84,526,251	-28,912,169	-25.5%
threads1	1	DELTA	128	COUNTER_SUM	90,648,633	90,330,455	-318,178	-0.4%
threads1	1	DELTA	128	GAUGE_LAST_VALUE	30,048,822	30,424,414	+375,592	+1.2%
threads1	1	DELTA	128	HISTOGRAM_BASE2_EXPONENTIAL	40,351,625	40,730,215	+378,590	+0.9%
threads1	1	DELTA	128	HISTOGRAM_EXPLICIT	68,966,473	68,001,089	-965,384	-1.4%
threads1	1	DELTA	128	UP_DOWN_COUNTER_SUM	96,706,975	94,746,379	-1,960,596	-2.0%
threads4	4	CUMULATIVE	1	COUNTER_SUM	71,299,570	533,356,066	+462,056,496	+648.0%
threads4	4	CUMULATIVE	1	GAUGE_LAST_VALUE	31,089,443	43,956,894	+12,867,451	+41.4%
threads4	4	CUMULATIVE	1	HISTOGRAM_BASE2_EXPONENTIAL	18,315,218	18,228,940	-86,278	-0.5%
threads4	4	CUMULATIVE	1	HISTOGRAM_EXPLICIT	17,130,737	22,713,877	+5,583,140	+32.6%
threads4	4	CUMULATIVE	1	UP_DOWN_COUNTER_SUM	67,441,580	538,397,008	+470,955,428	+698.3%
threads4	4	CUMULATIVE	128	COUNTER_SUM	101,917,926	213,724,611	+111,806,685	+109.7%
threads4	4	CUMULATIVE	128	GAUGE_LAST_VALUE	99,772,907	176,344,073	+76,571,166	+76.7%
threads4	4	CUMULATIVE	128	HISTOGRAM_BASE2_EXPONENTIAL	69,414,310	76,851,238	+7,436,928	+10.7%
threads4	4	CUMULATIVE	128	HISTOGRAM_EXPLICIT	71,859,876	82,288,364	+10,428,488	+14.5%
threads4	4	CUMULATIVE	128	UP_DOWN_COUNTER_SUM	102,675,867	165,755,957	+63,080,090	+61.4%
threads4	4	DELTA	1	COUNTER_SUM	17,860,366	38,440,179	+20,579,813	+115.2%
threads4	4	DELTA	1	GAUGE_LAST_VALUE	18,414,726	15,757,082	-2,657,643	-14.4%
threads4	4	DELTA	1	HISTOGRAM_BASE2_EXPONENTIAL	10,272,237	13,658,068	+3,385,831	+33.0%
threads4	4	DELTA	1	HISTOGRAM_EXPLICIT	12,299,067	13,142,512	+843,446	+6.9%
threads4	4	DELTA	1	UP_DOWN_COUNTER_SUM	17,354,541	33,054,925	+15,700,383	+90.5%
threads4	4	DELTA	128	COUNTER_SUM	70,640,757	92,842,661	+22,201,904	+31.4%
threads4	4	DELTA	128	GAUGE_LAST_VALUE	52,635,745	54,919,519	+2,283,774	+4.3%
threads4	4	DELTA	128	HISTOGRAM_BASE2_EXPONENTIAL	52,465,326	57,485,882	+5,020,556	+9.6%
threads4	4	DELTA	128	HISTOGRAM_EXPLICIT	53,967,236	58,726,086	+4,758,850	+8.8%
threads4	4	DELTA	128	UP_DOWN_COUNTER_SUM	68,654,779	88,332,691	+19,677,912	+28.7%

It provides even bigger wins for #8527 contended test cases. I.e.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.96%. Comparing base (ed81bf2) to head (534066c).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8559      +/-   ##
============================================
- Coverage     90.97%   90.96%   -0.01%     
- Complexity    10206    10207       +1     
============================================
  Files          1013     1013              
  Lines         27166    27168       +2     
  Branches       3182     3184       +2     
============================================
  Hits          24713    24713              
- Misses         1729     1730       +1     
- Partials        724      725       +1     

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