FEX-Emu/robin-map
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Fix issue #23. The 'distance_type' used to store the distance of a value in a bucket from its ideal bucket could overflow when a lot of collisions happened and the load_factor() stayed below REHASH_ON_HIGH_NB_PROBES__MIN_LOAD_FACTOR. We now rehash no matter the load factor if the distance becomes too high.

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This commit is contained in:
Tessil 2019-09-25 20:27:26 +02:00
parent 8d650f9a01
commit 73959d62e3
1 changed files with 6 additions and 7 deletions
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13
include/tsl/robin_hash.h
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@ -293,6 +293,11 @@ private:
tsl_rh_assert(!empty());
value().~value_type();
}
public:
static const distance_type DIST_FROM_IDEAL_BUCKET_LIMIT = 512;
static_assert(DIST_FROM_IDEAL_BUCKET_LIMIT <= std::numeric_limits<distance_type>::max() - 1,
"DIST_FROM_IDEAL_BUCKET_LIMIT must be <= std::numeric_limits<distance_type>::max() - 1.");
private:
using storage = typename std::aligned_storage<sizeof(value_type), alignof(value_type)>::type;
@ -1266,9 +1271,7 @@ private:
while(!m_buckets[ibucket].empty()) {
if(dist_from_ideal_bucket > m_buckets[ibucket].dist_from_ideal_bucket()) {
if(dist_from_ideal_bucket >= REHASH_ON_HIGH_NB_PROBES__NPROBES &&
load_factor() >= REHASH_ON_HIGH_NB_PROBES__MIN_LOAD_FACTOR)
{
if(dist_from_ideal_bucket >= bucket_entry::DIST_FROM_IDEAL_BUCKET_LIMIT) {
/**
* The number of probes is really high, rehash the map on the next insert.
* Difficult to do now as rehash may throw an exception.
@ -1376,10 +1379,6 @@ public:
"MAXIMUM_MIN_LOAD_FACTOR should be < MINIMUM_MAX_LOAD_FACTOR");
private:
static const distance_type REHASH_ON_HIGH_NB_PROBES__NPROBES = 128;
static constexpr float REHASH_ON_HIGH_NB_PROBES__MIN_LOAD_FACTOR = 0.15f;
/**
* Return an always valid pointer to an static empty bucket_entry with last_bucket() == true.
*/