Buffer with time and merge fix

[akarnokd]

Bug report #1867.

I'm not sure if the wrong guard in merge contributed to this bug or not.

[YannRobert]

It's working beautifully 👍
Thank you.

[benjchristensen]

Perf tests of merge

Benchmark                                          (size)   Mode   Samples        Score  Score error    Units
r.o.OperatorMergePerf.merge1SyncStreamOfN               1  thrpt         5  5056126.238  1489854.625    ops/s
r.o.OperatorMergePerf.merge1SyncStreamOfN            1000  thrpt         5    48889.584     3944.930    ops/s
r.o.OperatorMergePerf.merge1SyncStreamOfN         1000000  thrpt         5       50.529        7.219    ops/s
r.o.OperatorMergePerf.mergeNAsyncStreamsOfN             1  thrpt         5    95693.030    10501.261    ops/s
r.o.OperatorMergePerf.mergeNAsyncStreamsOfN          1000  thrpt         5        4.729        1.727    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOf1              1  thrpt         5  4383561.626   420591.436    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOf1            100  thrpt         5   382415.710    39897.757    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOf1           1000  thrpt         5    47428.436     2493.894    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOfN              1  thrpt         5  5437166.989   441177.419    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOfN           1000  thrpt         5       48.300        4.429    ops/s
r.o.OperatorMergePerf.mergeTwoAsyncStreamsOfN           1  thrpt         5    67341.025    22664.809    ops/s
r.o.OperatorMergePerf.mergeTwoAsyncStreamsOfN        1000  thrpt         5     3013.450       53.701    ops/s
r.o.OperatorMergePerf.oneStreamOfNthatMergesIn1         1  thrpt         5  5021306.733   937088.943    ops/s
r.o.OperatorMergePerf.oneStreamOfNthatMergesIn1      1000  thrpt         5    33963.450     2205.739    ops/s
r.o.OperatorMergePerf.oneStreamOfNthatMergesIn1   1000000  thrpt         5       33.774        4.188    ops/s

with fix

Benchmark                                          (size)   Mode   Samples        Score  Score error    Units
r.o.OperatorMergePerf.merge1SyncStreamOfN               1  thrpt         5  5157406.562    93678.702    ops/s
r.o.OperatorMergePerf.merge1SyncStreamOfN            1000  thrpt         5    49586.647     4800.166    ops/s
r.o.OperatorMergePerf.merge1SyncStreamOfN         1000000  thrpt         5       52.275        2.159    ops/s
r.o.OperatorMergePerf.mergeNAsyncStreamsOfN             1  thrpt         5    95986.554     1927.689    ops/s
r.o.OperatorMergePerf.mergeNAsyncStreamsOfN          1000  thrpt         5        4.693        0.852    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOf1              1  thrpt         5  4369891.782   414414.159    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOf1            100  thrpt         5   378988.311    36901.253    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOf1           1000  thrpt         5    41667.135     2393.558    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOfN              1  thrpt         5  5580359.713   151912.092    ops/s
r.o.OperatorMergePerf.mergeNSyncStreamsOfN           1000  thrpt         5       48.946        4.488    ops/s
r.o.OperatorMergePerf.mergeTwoAsyncStreamsOfN           1  thrpt         5    75020.475     4388.141    ops/s
r.o.OperatorMergePerf.mergeTwoAsyncStreamsOfN        1000  thrpt         5     3023.293      160.967    ops/s
r.o.OperatorMergePerf.oneStreamOfNthatMergesIn1         1  thrpt         5  5126337.920   181061.969    ops/s
r.o.OperatorMergePerf.oneStreamOfNthatMergesIn1      1000  thrpt         5    34047.837     2441.180    ops/s
r.o.OperatorMergePerf.oneStreamOfNthatMergesIn1   1000000  thrpt         5       25.979        0.572    ops/s

I reran oneStreamOfNthatMergesIn1 since it was lower and got this:

Benchmark                                          (size)   Mode   Samples        Score  Score error    Units
r.o.OperatorMergePerf.oneStreamOfNthatMergesIn1         1  thrpt         5  4911459.888   578204.885    ops/s
r.o.OperatorMergePerf.oneStreamOfNthatMergesIn1      1000  thrpt         5    32966.718     2195.493    ops/s
r.o.OperatorMergePerf.oneStreamOfNthatMergesIn1   1000000  thrpt         5       33.389        3.311    ops/s

So it looks like perf is okay on this change.