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tag/Pool: use doubly-linked list 

This adds some memory overhead but eliminates the linear search from
tag_pool_put_item().
This commit is contained in:
Max Kellermann 2023-09-06 15:56:10 +02:00
parent b896711fc6
commit 44beae519d
1 changed files with 7 additions and 40 deletions
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47
src/tag/Pool.cxx
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@ -4,7 +4,7 @@
#include "Pool.hxx"
#include "Item.hxx"
#include "util/Cast.hxx"
#include "util/IntrusiveForwardList.hxx"
#include "util/IntrusiveList.hxx"
#include "util/VarSize.hxx"
#include <array>
@ -18,7 +18,7 @@
Mutex tag_pool_lock;
struct TagPoolSlot {
IntrusiveForwardListHook list_hook;
IntrusiveListHook<IntrusiveHookMode::NORMAL> list_hook;
uint8_t ref = 1;
TagItem item;
@ -45,8 +45,8 @@ TagPoolSlot::Create(TagType type,
value);
}
static std::array<IntrusiveForwardList<TagPoolSlot,
IntrusiveForwardListMemberHookTraits<&TagPoolSlot::list_hook>>,
static std::array<IntrusiveList<TagPoolSlot,
IntrusiveListMemberHookTraits<&TagPoolSlot::list_hook>>,
16127> slots;
static inline unsigned
@ -60,19 +60,6 @@ calc_hash(TagType type, std::string_view p) noexcept
return hash ^ type;
}
static inline unsigned
calc_hash(TagType type, const char *p) noexcept
{
unsigned hash = 5381;
assert(p != nullptr);
while (*p != 0)
hash = (hash << 5) + hash + *p++;
return hash ^ type;
}
static constexpr TagPoolSlot *
tag_item_to_slot(TagItem *item) noexcept
{
@ -85,20 +72,12 @@ tag_value_list(TagType type, std::string_view value) noexcept
return slots[calc_hash(type, value) % slots.size()];
}
static inline auto &
tag_value_list(TagType type, const char *value) noexcept
{
return slots[calc_hash(type, value) % slots.size()];
}
TagItem *
tag_pool_get_item(TagType type, std::string_view value) noexcept
{
auto &list = tag_value_list(type, value);
for (auto i = list.before_begin(), n = std::next(i); n != list.end(); i = n) {
auto &slot = *n++;
for (auto &slot : list) {
if (slot.item.type == type &&
value == slot.item.value &&
slot.ref < TagPoolSlot::MAX_REF) {
@ -141,18 +120,6 @@ tag_pool_put_item(TagItem *item) noexcept
if (slot->ref > 0)
return;
auto &list = tag_value_list(item->type, item->value);
for (auto i = list.before_begin();;) {
const auto n = std::next(i);
auto &s = *n;
assert(i != list.end());
if (&s == slot) {
list.erase_after(i);
DeleteVarSize(slot);
return;
}
i = n;
}
slot->list_hook.unlink();
DeleteVarSize(slot);
}