perf: Entry API POC

[frankdavid]

This is a proposal for preferring iterating over Entries rather than (K, V) tuples. Entries provide lazy access to values which means that values don't need to be loaded and deserialized when the caller doesn't explicitly need them (by calling entry.value()).
As the benchmarks show, there is a considerable speed gain in scans, i.e. if some code only needs to access certain values depending on the key. If values are large / deserialization of values is slow, the speed gain can be even higher.

However, this is a breaking change.

Before:

    for (k, v) in map.range(..) {
        // Do something with k and v
    }

After:

    for entry in map.range(..) {
        // Do something with entry.key() and entry.value()
    }

Affected functions: range(), iter(), iter_upper_bound()

The backwards-compatible alternative would be introducing the API under new method names, however that would convolute the API surface.

This PR is not complete yet, tests have been disabled for the time of the discussion.

[github-actions]

canbench 🏋 (dir: .)

Significant performance change detected! ⚠️

./canbench_results.yml is up to date ✅

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

Benchmark: btreemap_insert_blob_4_1024
  total:
    instructions: 483.15 M (-0.08%) (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: 571.48 M (-0.07%) (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: 594.72 M (-0.07%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 183 pages (no change)

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

Benchmark: btreemap_insert_blob_8_1024_v2
  total:
    instructions: 687.59 M (-0.07%) (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: 676.83 M (-0.07%) (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: 761.04 M (-0.06%) (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: 712.04 M (-0.06%) (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: 799.74 M (-0.06%) (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: 980.27 M (-0.05%) (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: 1.07 B (-0.05%) (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: 1.25 B (-0.04%) (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: 1.34 B (-0.04%) (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: 1.81 B (-0.03%) (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: 1.89 B (-0.03%) (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: 2.89 B (-0.02%) (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: 2.98 B (-0.02%) (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: 4.77 B (-0.01%) (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: 4.84 B (-0.01%) (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: 4.83 B (-0.01%) (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: 4.92 B (-0.01%) (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: 4.86 B (-0.01%) (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: 4.94 B (-0.01%) (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: 4.87 B (-0.01%) (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: 4.96 B (-0.01%) (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: 4.89 B (-0.01%) (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: 4.98 B (-0.01%) (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: 4.87 B (-0.01%) (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: 4.96 B (-0.01%) (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: 4.90 B (-0.01%) (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: 4.99 B (-0.01%) (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: 4.98 B (-0.01%) (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: 5.07 B (-0.01%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 261 pages (no change)

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

Benchmark: btreemap_insert_u64_u64
  total:
    instructions: 336.18 M (-0.14%) (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: 412.07 M (-0.09%) (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: 330.63 M (-0.14%) (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: 403.46 M (-0.09%) (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: 319.64 M (-0.13%) (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: 421.61 M (-0.11%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 4 pages (no change)

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

Benchmark: btreemap_insert_10mib_values
  total:
    instructions: 81.96 M (-0.07%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 32 pages (no change)

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

Benchmark: btreemap_read_keys_from_range
  total:
    instructions: 13.85 M (improved by 83.21%)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_read_every_third_value_from_range
  total:
    instructions: 36.52 M (improved by 55.73%)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_iter_small_values
  total:
    instructions: 14.09 M (regressed by 4.82%)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_iter_rev_small_values
  total:
    instructions: 14.08 M (regressed by 4.79%)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_iter_10mib_values
  total:
    instructions: 11.39 M (0.06%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_iter_rev_10mib_values
  total:
    instructions: 11.37 M (-0.11%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_keys_small_values
  total:
    instructions: 9.10 M (improved by 3.69%)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_keys_rev_small_values
  total:
    instructions: 9.14 M (improved by 5.66%)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_keys_10mib_values
  total:
    instructions: 458.69 K (-0.59%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_keys_rev_10mib_values
  total:
    instructions: 455.89 K (-1.50%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_values_small_values
  total:
    instructions: 13.52 M (improved by 7.58%)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_values_rev_small_values
  total:
    instructions: 13.49 M (improved by 8.04%)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_values_10mib_values
  total:
    instructions: 11.39 M (-0.20%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_values_rev_10mib_values
  total:
    instructions: 11.38 M (-0.22%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_iter_count_small_values
  total:
    instructions: 9.13 M (-1.98%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_iter_count_10mib_values
  total:
    instructions: 473.14 K (0.13%) (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: 469.24 M (-0.11%) (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: 573.77 M (-0.10%) (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: 619.16 M (-0.11%) (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: 740.45 M (-0.10%) (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: 784.55 M (-0.10%) (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: 909.48 M (-0.09%) (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: 847.89 M (-0.10%) (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: 974.71 M (-0.09%) (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: 1.18 B (-0.07%) (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: 1.30 B (-0.07%) (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: 1.51 B (-0.06%) (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: 1.64 B (-0.06%) (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: 2.15 B (-0.04%) (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: 2.27 B (-0.04%) (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: 3.49 B (-0.03%) (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: 3.61 B (-0.03%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_remove_u64_u64
  total:
    instructions: 482.29 M (-0.18%) (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: 597.03 M (-0.12%) (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: 469.46 M (-0.18%) (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: 574.92 M (-0.13%) (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: 419.18 M (-0.17%) (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: 557.28 M (-0.14%) (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: 178.03 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: 256.54 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_blob_8_1024
  total:
    instructions: 209.55 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: 285.97 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_blob_16_1024
  total:
    instructions: 288.61 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: 357.15 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_blob_32_1024
  total:
    instructions: 318.96 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: 390.39 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_blob_64_1024
  total:
    instructions: 568.57 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: 642.03 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_blob_128_1024
  total:
    instructions: 816.92 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: 891.56 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_blob_256_1024
  total:
    instructions: 1.32 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: 1.40 B (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_blob_512_1024
  total:
    instructions: 2.33 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: 2.40 B (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_u64_u64
  total:
    instructions: 176.02 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_u64_u64_v2
  total:
    instructions: 251.38 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_u64_blob_8
  total:
    instructions: 175.23 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: 244.59 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: btreemap_get_blob_8_u64
  total:
    instructions: 193.33 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: 284.36 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: 349.80 M (0.05%) (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: 3.33 M (-0.60%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: vec_insert_blob_8
  total:
    instructions: 3.36 M (-0.59%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 1 pages (no change)

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

Benchmark: vec_insert_blob_16
  total:
    instructions: 3.42 M (-0.58%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 2 pages (no change)

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

Benchmark: vec_insert_blob_32
  total:
    instructions: 3.54 M (-0.56%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 5 pages (no change)

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

Benchmark: vec_insert_blob_64
  total:
    instructions: 3.78 M (-0.53%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 9 pages (no change)

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

Benchmark: vec_insert_blob_128
  total:
    instructions: 4.25 M (-0.47%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 19 pages (no change)

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

Benchmark: vec_insert_u64
  total:
    instructions: 5.64 M (-0.18%) (change within noise threshold)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 1 pages (no change)

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

Benchmark: vec_get_blob_4
  total:
    instructions: 4.72 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: vec_get_blob_8
  total:
    instructions: 5.43 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: vec_get_blob_16
  total:
    instructions: 7.78 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: vec_get_blob_32
  total:
    instructions: 8.41 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: vec_get_blob_64
  total:
    instructions: 12.78 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: vec_get_blob_128
  total:
    instructions: 17.78 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

Benchmark: vec_get_u64
  total:
    instructions: 5.24 M (no change)
    heap_increase: 0 pages (no change)
    stable_memory_increase: 0 pages (no change)

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

[berestovskyy]

Should we maintain backward compatibility by adding a new function like entry_range to create an iterator over the range or entries?

[frankdavid]

I'm concerned that it'd make the API quite convoluted:
iter() would need iter_entries() or entry_iter()
range() would need entry_range()
iter_upper_bound() would need entry_iter_upper_bound()

Every time we add a new function which returns an iterator, we'd need to duplicate it (not even mentioning variants corresponding to keys() and values()).

I was considering a single iterator API with iterator transformers, like
iter().as_key_value_tuples() or range(...).as_key_value_tuples() (bad naming, only for illustration)

[berestovskyy]

Hey David, we've discussed this internally, and we're in favor of adopting this approach, as it clearly brings a significant performance improvement. Do you think it makes sense to discuss the new API with a wider group of developers?