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Make dict and pool const lookup methods never rehash the hashtable #5236

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Merged
merged 2 commits into from
Aug 7, 2025
Merged

Make dict and pool const lookup methods never rehash the hashtable #5236

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cf9720e
Make const lookup methods take a lookup path that never rehashes the …
rocallahan Jul 15, 2025
4bf7c23
Make `pool` const lookup methods take a lookup path that never rehash…
rocallahan Jul 15, 2025
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56 changes: 41 additions & 15 deletions kernel/hashlib.h
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Original file line number Diff line number Diff line change
Expand Up @@ -451,16 +451,21 @@ class dict {
return 1;
}

int do_lookup(const K &key, Hasher::hash_t &hash) const
int do_lookup(const K &key, Hasher::hash_t &hash)
{
if (hashtable.empty())
return -1;

if (entries.size() * hashtable_size_trigger > hashtable.size()) {
((dict*)this)->do_rehash();
do_rehash();
hash = do_hash(key);
}

return do_lookup_internal(key, hash);
}

int do_lookup_internal(const K &key, Hasher::hash_t hash) const
{
int index = hashtable[hash];

while (index >= 0 && !ops.cmp(entries[index].udata.first, key)) {
Expand All @@ -471,6 +476,14 @@ class dict {
return index;
}

int do_lookup_no_rehash(const K &key, Hasher::hash_t hash) const
{
if (hashtable.empty())
return -1;

return do_lookup_internal(key, hash);
}

int do_insert(const K &key, Hasher::hash_t &hash)
{
if (hashtable.empty()) {
Expand Down Expand Up @@ -694,14 +707,14 @@ class dict {
int count(const K &key) const
{
Hasher::hash_t hash = do_hash(key);
int i = do_lookup(key, hash);
int i = do_lookup_no_rehash(key, hash);
return i < 0 ? 0 : 1;
}

int count(const K &key, const_iterator it) const
{
Hasher::hash_t hash = do_hash(key);
int i = do_lookup(key, hash);
int i = do_lookup_no_rehash(key, hash);
return i < 0 || i > it.index ? 0 : 1;
}

Expand All @@ -717,7 +730,7 @@ class dict {
const_iterator find(const K &key) const
{
Hasher::hash_t hash = do_hash(key);
int i = do_lookup(key, hash);
int i = do_lookup_no_rehash(key, hash);
if (i < 0)
return end();
return const_iterator(this, i);
Expand All @@ -735,7 +748,7 @@ class dict {
const T& at(const K &key) const
{
Hasher::hash_t hash = do_hash(key);
int i = do_lookup(key, hash);
int i = do_lookup_no_rehash(key, hash);
if (i < 0)
throw std::out_of_range("dict::at()");
return entries[i].udata.second;
Expand All @@ -744,7 +757,7 @@ class dict {
const T& at(const K &key, const T &defval) const
{
Hasher::hash_t hash = do_hash(key);
int i = do_lookup(key, hash);
int i = do_lookup_no_rehash(key, hash);
if (i < 0)
return defval;
return entries[i].udata.second;
Expand Down Expand Up @@ -906,16 +919,21 @@ class pool
return 1;
}

int do_lookup(const K &key, Hasher::hash_t &hash) const
int do_lookup(const K &key, Hasher::hash_t &hash)
{
if (hashtable.empty())
return -1;

if (entries.size() * hashtable_size_trigger > hashtable.size()) {
((pool*)this)->do_rehash();
do_rehash();
hash = do_hash(key);
}

return do_lookup_internal(key, hash);
}

int do_lookup_internal(const K &key, Hasher::hash_t hash) const
{
int index = hashtable[hash];

while (index >= 0 && !ops.cmp(entries[index].udata, key)) {
Expand All @@ -926,6 +944,14 @@ class pool
return index;
}

int do_lookup_no_rehash(const K &key, Hasher::hash_t hash) const
{
if (hashtable.empty())
return -1;

return do_lookup_internal(key, hash);
}

int do_insert(const K &value, Hasher::hash_t &hash)
{
if (hashtable.empty()) {
Expand Down Expand Up @@ -1087,14 +1113,14 @@ class pool
int count(const K &key) const
{
Hasher::hash_t hash = do_hash(key);
int i = do_lookup(key, hash);
int i = do_lookup_no_rehash(key, hash);
return i < 0 ? 0 : 1;
}

int count(const K &key, const_iterator it) const
{
Hasher::hash_t hash = do_hash(key);
int i = do_lookup(key, hash);
int i = do_lookup_no_rehash(key, hash);
return i < 0 || i > it.index ? 0 : 1;
}

Expand All @@ -1110,7 +1136,7 @@ class pool
const_iterator find(const K &key) const
{
Hasher::hash_t hash = do_hash(key);
int i = do_lookup(key, hash);
int i = do_lookup_no_rehash(key, hash);
if (i < 0)
return end();
return const_iterator(this, i);
Expand Down Expand Up @@ -1222,7 +1248,7 @@ class idict
int at(const K &key) const
{
Hasher::hash_t hash = database.do_hash(key);
int i = database.do_lookup(key, hash);
int i = database.do_lookup_no_rehash(key, hash);
if (i < 0)
throw std::out_of_range("idict::at()");
return i + offset;
Expand All @@ -1231,7 +1257,7 @@ class idict
int at(const K &key, int defval) const
{
Hasher::hash_t hash = database.do_hash(key);
int i = database.do_lookup(key, hash);
int i = database.do_lookup_no_rehash(key, hash);
if (i < 0)
return defval;
return i + offset;
Expand All @@ -1240,7 +1266,7 @@ class idict
int count(const K &key) const
{
Hasher::hash_t hash = database.do_hash(key);
int i = database.do_lookup(key, hash);
int i = database.do_lookup_no_rehash(key, hash);
return i < 0 ? 0 : 1;
}

Expand Down
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