Reuse slice for the range vector allocations.

[cyriltovena]

Signed-off-by: Cyril Tovena cyril.tovena@gmail.com

❯ benchcmp old.txt new.txt
benchmark                         old ns/op      new ns/op      delta
BenchmarkRangeQuery100000-16      3356959        3097925        -7.72%
BenchmarkRangeQuery200000-16      15821777       14543104       -8.08%
BenchmarkRangeQuery500000-16      2107956639     1992137391     -5.49%
BenchmarkRangeQuery1000000-16     4051613799     4041557363     -0.25%

benchmark                         old allocs     new allocs     delta
BenchmarkRangeQuery100000-16      5241           5235           -0.11%
BenchmarkRangeQuery200000-16      5993           5835           -2.64%
BenchmarkRangeQuery500000-16      138631         130304         -6.01%
BenchmarkRangeQuery1000000-16     272021         255363         -6.12%

benchmark                         old bytes     new bytes     delta
BenchmarkRangeQuery100000-16      716984        714652        -0.33%
BenchmarkRangeQuery200000-16      1464403       1338725       -8.58%
BenchmarkRangeQuery500000-16      135321968     132657776     -1.97%
BenchmarkRangeQuery1000000-16     270999096     265668520     -1.97%

[codecov-commenter]

Codecov Report

Merging #2219 into master will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2219      +/-   ##
==========================================
+ Coverage   62.10%   62.18%   +0.07%     
==========================================
  Files         154      154              
  Lines       12457    12459       +2     
==========================================
+ Hits         7737     7748      +11     
+ Misses       4111     4106       -5     
+ Partials      609      605       -4     

Impacted Files	Coverage Δ
pkg/logql/range_vector.go	97.70% <100.00%> (+0.05%)	⬆️
pkg/logql/evaluator.go	92.72% <0.00%> (+0.41%)	⬆️
pkg/promtail/targets/filetarget.go	70.48% <0.00%> (+1.80%)	⬆️
pkg/promtail/targets/tailer.go	78.40% <0.00%> (+4.54%)	⬆️