feat: move initialization of StableBTreeMap cursors into Iter

[hpeebles]

I've been doing the work to move all chat events in OpenChat to stable memory, but this required StableBTreeMap to implement DoubleEndedIterator since we need to be able to iterate chat events in either direction.
I have implemented this on my own fork (here).

Rather than submit a fairly large PR containing the entire change, I have broken it into 2 deliverable pieces, with this PR being the first one.

Before this PR, the StableBTreeMap cursors would be initialised before iteration starts, which is fine if you'll always be iterating forwards.
But once you can iterate in either direction, it is beneficial to only calculate the cursors for your direction of iteration when required, because if you only iterate in one direction, the cursors for the other direction are never needed.

So all this PR does is delay the initialization of the cursors until the first call to Iterator::next.

[github-actions]

canbench 🏋 (dir: .)

Significant performance change detected! ⚠️

./canbench_results.yml is not up to date ❌
If the performance change is expected, run canbench --persist to save the updated benchmark results.

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Benchmark: btreemap_insert_blob_4_1024
  total:
    instructions: 702.29 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 123 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_4_1024_v2
  total:
    instructions: 787.28 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 92 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_8_1024
  total:
    instructions: 828.11 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 183 pages (no change)

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Benchmark: btreemap_insert_blob_8_1024_v2
  total:
    instructions: 919.90 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 138 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_16_1024
  total:
    instructions: 914.66 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 215 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_16_1024_v2
  total:
    instructions: 1.01 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 161 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_32_1024
  total:
    instructions: 971.20 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 230 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_32_1024_v2
  total:
    instructions: 1.06 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 173 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_64_1024
  total:
    instructions: 1.24 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 245 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_64_1024_v2
  total:
    instructions: 1.35 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 183 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_128_1024
  total:
    instructions: 1.52 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 260 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_128_1024_v2
  total:
    instructions: 1.65 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 195 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_256_1024
  total:
    instructions: 2.07 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 292 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_256_1024_v2
  total:
    instructions: 2.26 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 219 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_512_1024
  total:
    instructions: 3.20 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 351 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_512_1024_v2
  total:
    instructions: 3.46 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 263 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_4
  total:
    instructions: 5.01 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 235 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_4_v2
  total:
    instructions: 5.41 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 176 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_8
  total:
    instructions: 5.10 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 237 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_8_v2
  total:
    instructions: 5.49 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 178 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_16
  total:
    instructions: 5.12 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 241 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_16_v2
  total:
    instructions: 5.51 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 181 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_32
  total:
    instructions: 5.12 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 239 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_32_v2
  total:
    instructions: 5.51 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 180 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_64
  total:
    instructions: 5.16 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 250 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_64_v2
  total:
    instructions: 5.55 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 188 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_128
  total:
    instructions: 5.16 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 262 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_128_v2
  total:
    instructions: 5.55 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 196 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_256
  total:
    instructions: 5.18 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 292 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_256_v2
  total:
    instructions: 5.57 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 219 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_512
  total:
    instructions: 5.30 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 348 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_1024_512_v2
  total:
    instructions: 5.69 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 261 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_u64_u64
  total:
    instructions: 448.33 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 7 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_u64_u64_v2
  total:
    instructions: 518.61 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 6 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_u64_blob_8
  total:
    instructions: 435.86 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 7 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_u64_blob_8_v2
  total:
    instructions: 502.39 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 5 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_8_u64
  total:
    instructions: 424.33 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 6 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_blob_8_u64_v2
  total:
    instructions: 524.55 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 4 pages (no change)

---------------------------------------------------

Benchmark: btreemap_insert_10mib_values
  total:
    instructions: 145.92 M (0.08%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 32 pages (no change)

---------------------------------------------------

Benchmark: btreemap_iter_count_small_values
  total:
    instructions: 10.46 M (regressed by 2.11%)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_iter_count_10mib_values
  total:
    instructions: 525.04 K (0.72%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_4_1024
  total:
    instructions: 730.55 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_4_1024_v2
  total:
    instructions: 832.33 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_8_1024
  total:
    instructions: 958.33 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_8_1024_v2
  total:
    instructions: 1.08 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_16_1024
  total:
    instructions: 1.18 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_16_1024_v2
  total:
    instructions: 1.31 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_32_1024
  total:
    instructions: 1.26 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_32_1024_v2
  total:
    instructions: 1.40 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_64_1024
  total:
    instructions: 1.58 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_64_1024_v2
  total:
    instructions: 1.72 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_128_1024
  total:
    instructions: 1.92 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_128_1024_v2
  total:
    instructions: 2.06 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_256_1024
  total:
    instructions: 2.56 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_256_1024_v2
  total:
    instructions: 2.72 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_512_1024
  total:
    instructions: 3.93 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_512_1024_v2
  total:
    instructions: 4.08 B (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_u64_u64
  total:
    instructions: 634.57 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_u64_u64_v2
  total:
    instructions: 739.94 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_u64_blob_8
  total:
    instructions: 609.38 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_u64_blob_8_v2
  total:
    instructions: 705.69 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_8_u64
  total:
    instructions: 549.47 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_remove_blob_8_u64_v2
  total:
    instructions: 685.61 M (0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_4_1024
  total:
    instructions: 252.12 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_4_1024_v2
  total:
    instructions: 335.50 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_8_1024
  total:
    instructions: 292.70 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_8_1024_v2
  total:
    instructions: 375.37 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_16_1024
  total:
    instructions: 372.17 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_16_1024_v2
  total:
    instructions: 457.66 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_32_1024
  total:
    instructions: 419.06 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_32_1024_v2
  total:
    instructions: 504.37 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_64_1024
  total:
    instructions: 668.07 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_64_1024_v2
  total:
    instructions: 753.61 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_128_1024
  total:
    instructions: 907.60 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_128_1024_v2
  total:
    instructions: 1.01 B (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_256_1024
  total:
    instructions: 1.43 B (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_256_1024_v2
  total:
    instructions: 1.53 B (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_512_1024
  total:
    instructions: 2.46 B (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_512_1024_v2
  total:
    instructions: 2.56 B (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_u64_u64
  total:
    instructions: 241.23 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_u64_u64_v2
  total:
    instructions: 305.67 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_u64_blob_8
  total:
    instructions: 238.33 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_u64_blob_8_v2
  total:
    instructions: 297.68 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_8_u64
  total:
    instructions: 257.17 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: btreemap_get_blob_8_u64_v2
  total:
    instructions: 340.84 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: memory_manager_baseline
  total:
    instructions: 1.18 B (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 8000 pages (no change)

---------------------------------------------------

Benchmark: memory_manager_overhead
  total:
    instructions: 1.18 B (-0.00%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 8320 pages (no change)

---------------------------------------------------

Benchmark: memory_manager_grow
  total:
    instructions: 351.69 M (-0.33%) (change within noise threshold)
    heap_increase: 2 pages (no change)
    stable_memory_increase: 32.00 K pages (no change)

---------------------------------------------------

Benchmark: vec_insert_blob_4
  total:
    instructions: 3.98 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: vec_insert_blob_8
  total:
    instructions: 4.01 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 1 pages (no change)

---------------------------------------------------

Benchmark: vec_insert_blob_16
  total:
    instructions: 4.07 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 2 pages (no change)

---------------------------------------------------

Benchmark: vec_insert_blob_32
  total:
    instructions: 4.19 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 5 pages (no change)

---------------------------------------------------

Benchmark: vec_insert_blob_64
  total:
    instructions: 4.43 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 9 pages (no change)

---------------------------------------------------

Benchmark: vec_insert_blob_128
  total:
    instructions: 4.90 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 19 pages (no change)

---------------------------------------------------

Benchmark: vec_insert_u64
  total:
    instructions: 6.11 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 1 pages (no change)

---------------------------------------------------

Benchmark: vec_get_blob_4
  total:
    instructions: 5.89 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: vec_get_blob_8
  total:
    instructions: 7.15 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: vec_get_blob_16
  total:
    instructions: 9.95 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: vec_get_blob_32
  total:
    instructions: 10.86 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: vec_get_blob_64
  total:
    instructions: 15.71 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: vec_get_blob_128
  total:
    instructions: 21.62 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: vec_get_u64
  total:
    instructions: 6.43 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

[dsarlis]

Let's add a short description of what the changes are trying to accomplish.

I also notice a non-negligible performance regression for insert operations. Do you have an idea why that might be?

[hpeebles]

Let's add a short description of what the changes are trying to accomplish.

I also notice a non-negligible performance regression for insert operations. Do you have an idea why that might be?

I'm surprised by the performance regression around inserts since I should have only affected reading and iterating over the map. I'll have a look into it tomorrow though.

[dsarlis]

Let's add a short description of what the changes are trying to accomplish.
I also notice a non-negligible performance regression for insert operations. Do you have an idea why that might be?

I'm surprised by the performance regression around inserts since I should have only affected reading and iterating over the map. I'll have a look into it tomorrow though.

insert also needs to navigate the map to find the point where the value should be inserted, so if your change affects iteration (in more general terms "navigation" in the map), it's not completely unexpected to affect insert I think.

[dsarlis]

Let's add a short description of what the changes are trying to accomplish.
I also notice a non-negligible performance regression for insert operations. Do you have an idea why that might be?

I'm surprised by the performance regression around inserts since I should have only affected reading and iterating over the map. I'll have a look into it tomorrow though.

insert also needs to navigate the map to find the point where the value should be inserted, so if your change affects iteration (in more general terms "navigation" in the map), it's not completely unexpected to affect insert I think.

Actually, I think we might be seeing a race condition here because around the same time, Islam bumped the canbench version used. By visually comparing the numbers, I think you get pretty much the same after that PR. Yeah, the bot edited the results at some point but not the summary of the comment (still says significant change detected but all results are now within noise, this is a separate issue that we should fix I guess).