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Calculate table size of FastLRUCache more accurately #10235

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Calculate table size of FastLRUCache more accurately #10235

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94f76df
Bake load factor in CalcHashBits calculation.
Jun 22, 2022
4e52d18
Format.
Jun 22, 2022
2e48b9f
Merge branch 'main' into main
Jun 27, 2022
fe06d3e
CalcHashBits test.
Jun 27, 2022
a131b9d
Fix unused parameter.
Jun 27, 2022
adf5be2
Fix bug.
Jun 27, 2022
09cd0f9
Fix friend class issue.
Jun 27, 2022
6bf135c
Format.
Jun 27, 2022
97b3422
Fix bit shift type.
Jun 27, 2022
27289dd
Remove full namespace qualifier.
Jun 27, 2022
b09d9a1
Cleaner computation.
Jun 27, 2022
cc80c46
Remove wrong comment.
Jun 27, 2022
4900fd0
Fix comment.
Jun 27, 2022
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6 changes: 3 additions & 3 deletions cache/fast_lru_cache.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -192,8 +192,7 @@ LRUCacheShard::LRUCacheShard(size_t capacity, size_t estimated_value_size,
: capacity_(capacity),
strict_capacity_limit_(strict_capacity_limit),
table_(
CalcHashBits(capacity, estimated_value_size, metadata_charge_policy) +
static_cast<uint8_t>(ceil(log2(1.0 / kLoadFactor)))),
CalcHashBits(capacity, estimated_value_size, metadata_charge_policy)),
usage_(0),
lru_usage_(0) {
set_metadata_charge_policy(metadata_charge_policy);
Expand Down Expand Up @@ -300,7 +299,8 @@ uint8_t LRUCacheShard::CalcHashBits(
CacheMetadataChargePolicy metadata_charge_policy) {
LRUHandle h;
h.CalcTotalCharge(estimated_value_size, metadata_charge_policy);
size_t num_entries = capacity / h.total_charge;
size_t num_entries =
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static_cast<size_t>(capacity / (kLoadFactor * h.total_charge));
uint8_t num_hash_bits = 0;
while (num_entries >>= 1) {
++num_hash_bits;
Expand Down