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[IDX-7033] Remove boost::hana in favor of concepts #41

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5c96dbf
Remove `boost::hana`
dalloriam May 14, 2026
c5450ee
Improve concepts ergonomics
dalloriam May 15, 2026
3229d5b
Address misc. comments
dalloriam May 21, 2026
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124 changes: 68 additions & 56 deletions include/cachemere/cache.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@
#include <boost/accumulators/accumulators.hpp>
#include <boost/accumulators/statistics/rolling_mean.hpp>
#include <boost/accumulators/statistics/stats.hpp>
#include <boost/hana.hpp>

#ifdef _WIN32
# pragma warning(pop)
Expand Down Expand Up @@ -95,7 +94,7 @@ class Cache
/// If the provided container has `size()` and `reserve()` methods, `collect_into` will reserve
/// the appropriate amount of space in the container before inserting.
/// @param container The container in which to insert the items.
template<typename C> void collect_into(C& container) const;
template<detail::traits::CacheContainer<Key, Value> C> void collect_into(C& container) const;

/// @brief Insert a key/value pair in the cache.
/// @details If the key is new, the key/value pair will be inserted.
Expand Down Expand Up @@ -340,28 +339,26 @@ template<class K,
class SK,
class KH,
bool TS>
template<class Container>
template<detail::traits::CacheContainer<K, V> Container>
void Cache<K, V, I, E, C, SV, SK, KH, TS>::collect_into(Container& container) const
{
using namespace detail;

// Use emplace_back if container is a sequence container, or emplace if container is an associative container.
constexpr auto emplace_fn = boost::hana::if_(
traits::stl::has_emplace_back<Container, K, V>,
[](auto& seq_container, const auto& key, const auto& item) { seq_container.emplace_back(key, item.m_value); },
[](auto& assoc_container, const auto& key, const auto& item) { assoc_container.emplace(key, item.m_value); });

LockGuard guard(lock());

// Reserve space if the container has a reserve() method and a size method().
boost::hana::if_(
boost::hana::and_(traits::stl::has_reserve<Container>, traits::stl::has_size<Container>),
[&](auto& c) { c.reserve(c.size() + m_data.size()); },
[](auto&) {})(container);
if constexpr (traits::ReservableContainer<Container>) {
container.reserve(container.size() + m_data.size());
}

// Copy the cache contents to the container.
for (const auto& [key, cached_item] : m_data) {
emplace_fn(container, key, cached_item);
// Use emplace_back if container is a sequence container, or emplace if container is an associative container.
if constexpr (traits::SequenceContainer<Container, K, V>) {
container.emplace_back(key, cached_item.m_value);
} else {
container.emplace(key, cached_item.m_value);
}
}
}

Expand Down Expand Up @@ -518,8 +515,8 @@ void Cache<K, V, I, E, C, SV, SK, KH, TS>::swap(CacheType& other) noexcept
swap(m_hit_rate_acc, other.m_hit_rate_acc);
swap(m_byte_hit_rate_acc, other.m_byte_hit_rate_acc);
} catch (const std::system_error& e) {
// The only exception that can sensibly be thrown in the above block is a `system_error` when acquiring the mutexes of both caches (if the caches are
// running in thread-safe mode).
// The only exception that can sensibly be thrown in the above block is a `system_error` when acquiring the mutexes of both caches (if the caches
// are running in thread-safe mode).
//
// According to the [reference for std mutexes](https://en.cppreference.com/w/cpp/named_req/Mutex), this exception can be thrown for one of two
// reasons:
Expand Down Expand Up @@ -949,14 +946,14 @@ template<class K,
bool TS>
void Cache<K, V, I, E, C, SV, SK, KH, TS>::remove_popped_victim(DataMapIt it)
{
boost::hana::if_(
detail::traits::event::has_on_evict<K, KH, V, I>,
[&](auto& x) { return x.on_evict(it->first, it->second); },
[](auto&) {})(*m_insertion_policy);
boost::hana::if_(
detail::traits::event::has_on_evict<K, KH, V, C>,
[&](auto& x) { return x.on_evict(it->first, it->second); },
[](auto&) {})(*m_constraint_policy);
if constexpr (detail::traits::event::HasOnEvict<K, KH, V, I>) {
m_eviction_policy->on_evict(it->first, it->second);
Comment thread
dalloriam marked this conversation as resolved.
}

if constexpr (detail::traits::event::HasOnEvict<K, KH, V, C>) {
m_constraint_policy->on_evict(it->first, it->second);
}

m_data.erase(it);
}

Expand All @@ -972,11 +969,17 @@ template<class K,
void Cache<K, V, I, E, C, SV, SK, KH, TS>::on_insert(const K& key, const CacheItem& item) const
{
// Call event handler iif the method is defined in the policy.
boost::hana::if_(detail::traits::event::has_on_insert<K, KH, V, I>, [&](auto& x) { return x.on_insert(key, item); }, [](auto&) {})(*m_insertion_policy);
if constexpr (detail::traits::event::HasOnInsert<K, KH, V, I>) {
m_insertion_policy->on_insert(key, item);
}

boost::hana::if_(detail::traits::event::has_on_insert<K, KH, V, E>, [&](auto& x) { return x.on_insert(key, item); }, [](auto&) {})(*m_eviction_policy);
if constexpr (detail::traits::event::HasOnInsert<K, KH, V, E>) {
m_eviction_policy->on_insert(key, item);
}

boost::hana::if_(detail::traits::event::has_on_insert<K, KH, V, C>, [&](auto& x) { return x.on_insert(key, item); }, [](auto&) {})(*m_constraint_policy);
if constexpr (detail::traits::event::HasOnInsert<K, KH, V, C>) {
m_constraint_policy->on_insert(key, item);
}
}

template<class K,
Expand All @@ -991,20 +994,17 @@ template<class K,
void Cache<K, V, I, E, C, SV, SK, KH, TS>::on_update(const K& key, const CacheItem& old_item, const CacheItem& new_item) const
{
// Call event handler iif the method is defined in the policy.
boost::hana::if_(
detail::traits::event::has_on_update<K, KH, V, I>,
[&](auto& x) { return x.on_update(key, old_item, new_item); },
[](auto&) {})(*m_insertion_policy);

boost::hana::if_(
detail::traits::event::has_on_update<K, KH, V, E>,
[&](auto& x) { return x.on_update(key, old_item, new_item); },
[](auto&) {})(*m_eviction_policy);

boost::hana::if_(
detail::traits::event::has_on_update<K, KH, V, C>,
[&](auto& x) { return x.on_update(key, old_item, new_item); },
[](auto&) {})(*m_constraint_policy);
if constexpr (detail::traits::event::HasOnUpdate<K, KH, V, I>) {
m_insertion_policy->on_update(key, old_item, new_item);
}

if constexpr (detail::traits::event::HasOnUpdate<K, KH, V, E>) {
m_eviction_policy->on_update(key, old_item, new_item);
}

if constexpr (detail::traits::event::HasOnUpdate<K, KH, V, C>) {
m_constraint_policy->on_update(key, old_item, new_item);
}
}

template<class K,
Expand All @@ -1023,17 +1023,17 @@ void Cache<K, V, I, E, C, SV, SK, KH, TS>::on_cache_hit(const K& key, const Cach
m_byte_hit_rate_acc(static_cast<uint32_t>(item.m_value_size));

// Call event handler iif the method is defined in the policy.
boost::hana::if_(
detail::traits::event::has_on_cachehit<K, KH, V, I>,
[&](auto& x) { return x.on_cache_hit(key, item); },
[](auto&) {})(*m_insertion_policy);
if constexpr (detail::traits::event::HasOnCacheHit<K, KH, V, I>) {
m_insertion_policy->on_cache_hit(key, item);
}

boost::hana::if_(detail::traits::event::has_on_cachehit<K, KH, V, E>, [&](auto& x) { return x.on_cache_hit(key, item); }, [](auto&) {})(*m_eviction_policy);
if constexpr (detail::traits::event::HasOnCacheHit<K, KH, V, E>) {
m_eviction_policy->on_cache_hit(key, item);
}

boost::hana::if_(
detail::traits::event::has_on_cachehit<K, KH, V, C>,
[&](auto& x) { return x.on_cache_hit(key, item); },
[](auto&) {})(*m_constraint_policy);
if constexpr (detail::traits::event::HasOnCacheHit<K, KH, V, C>) {
m_constraint_policy->on_cache_hit(key, item);
}
}

template<class K,
Expand All @@ -1053,11 +1053,17 @@ void Cache<K, V, I, E, C, SV, SK, KH, TS>::on_cache_miss(const KeyView& key) con
m_byte_hit_rate_acc(0);

// Call event handler iif the method is defined in the policy.
boost::hana::if_(detail::traits::event::has_on_cachemiss<K, KH, V, I>, [&](auto& x) { return x.on_cache_miss(key); }, [](auto&) {})(*m_insertion_policy);
if constexpr (detail::traits::event::HasOnCacheMiss<K, KH, V, I>) {
m_insertion_policy->on_cache_miss(key);
}

boost::hana::if_(detail::traits::event::has_on_cachemiss<K, KH, V, E>, [&](auto& x) { return x.on_cache_miss(key); }, [](auto&) {})(*m_eviction_policy);
if constexpr (detail::traits::event::HasOnCacheMiss<K, KH, V, E>) {
m_eviction_policy->on_cache_miss(key);
}

boost::hana::if_(detail::traits::event::has_on_cachemiss<K, KH, V, C>, [&](auto& x) { return x.on_cache_miss(key); }, [](auto&) {})(*m_constraint_policy);
if constexpr (detail::traits::event::HasOnCacheMiss<K, KH, V, C>) {
m_constraint_policy->on_cache_miss(key);
}
}

template<class K,
Expand All @@ -1072,11 +1078,17 @@ template<class K,
void Cache<K, V, I, E, C, SV, SK, KH, TS>::on_evict(const K& key, const CacheItem& item) const
{
// Call event handler iif the method is defined in the policy.
boost::hana::if_(detail::traits::event::has_on_evict<K, KH, V, I>, [&](auto& x) { return x.on_evict(key, item); }, [](auto&) {})(*m_insertion_policy);
if constexpr (detail::traits::event::HasOnEvict<K, KH, V, I>) {
m_insertion_policy->on_evict(key, item);
}

boost::hana::if_(detail::traits::event::has_on_evict<K, KH, V, E>, [&](auto& x) { return x.on_evict(key, item); }, [](auto&) {})(*m_eviction_policy);
if constexpr (detail::traits::event::HasOnEvict<K, KH, V, E>) {
m_eviction_policy->on_evict(key, item);
}

boost::hana::if_(detail::traits::event::has_on_evict<K, KH, V, C>, [&](auto& x) { return x.on_evict(key, item); }, [](auto&) {})(*m_constraint_policy);
if constexpr (detail::traits::event::HasOnEvict<K, KH, V, C>) {
m_constraint_policy->on_evict(key, item);
}
}

template<class K,
Expand Down
63 changes: 31 additions & 32 deletions include/cachemere/detail/traits.h
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Original file line number Diff line number Diff line change
@@ -1,59 +1,58 @@
#pragma once

#include <boost/hana.hpp>
#include <concepts>
#include <utility>

#include <cachemere/item.h>

namespace cachemere::detail::traits {

// Traits for STL types.
namespace stl {

template<typename T>
constexpr auto has_reserve =
boost::hana::is_valid([](auto& t) -> decltype(boost::hana::traits::declval(t).reserve(std::declval<size_t>())) {})(boost::hana::type_c<T>);
template<typename T, typename... Args>
concept SequenceContainer = requires(T t, Args... args) {
{ t.emplace_back(args...) };
};

template<typename T>
constexpr auto has_size = boost::hana::is_valid([](auto& t) -> decltype(boost::hana::traits::declval(t).size()) {})(boost::hana::type_c<T>);
template<typename T, typename... Args>
concept AssociativeContainer = requires(T t, Args... args) {
{ t.emplace(args...) };
};

template<typename T, typename... Args>
constexpr auto has_emplace_back =
boost::hana::is_valid([](auto& t) -> decltype(boost::hana::traits::declval(t).emplace_back(std::declval<Args>()...)) {})(boost::hana::type_c<T>);
concept CacheContainer = SequenceContainer<T, Args...> || AssociativeContainer<T, Args...>;

} // namespace stl
template<typename T>
concept ReservableContainer = requires(T t) {
{ t.reserve(std::declval<size_t>()) };
{ t.size() } -> std::convertible_to<size_t>;
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};

// Traits for cache event handlers.
namespace event {

template<typename K, typename KH, typename V, template<class, class, class> typename P>
constexpr auto has_on_insert = boost::hana::is_valid(
[](auto& policy_t, auto& key_t, auto& item_t) -> decltype(boost::hana::traits::declval(policy_t).on_insert(boost::hana::traits::declval(key_t),
boost::hana::traits::declval(item_t))) {
})(boost::hana::type_c<P<K, KH, V>>, boost::hana::type_c<K>, boost::hana::type_c<Item<V>>);
concept HasOnInsert = requires(P<K, KH, V> policy, K key, Item<V> item) {
{ policy.on_insert(key, item) };
};

template<typename K, typename KH, typename V, template<class, class, class> typename P>
constexpr auto has_on_update = boost::hana::is_valid(
[](auto& policy_t, auto& key_t, auto& item_t) -> decltype(boost::hana::traits::declval(policy_t).on_update(boost::hana::traits::declval(key_t),
boost::hana::traits::declval(item_t),
boost::hana::traits::declval(item_t))) {
})(boost::hana::type_c<P<K, KH, V>>, boost::hana::type_c<K>, boost::hana::type_c<Item<V>>);
concept HasOnUpdate = requires(P<K, KH, V> policy, K key, Item<V> old_item, Item<V> new_item) {
{ policy.on_update(key, old_item, new_item) };
};

template<typename K, typename KH, typename V, template<class, class, class> typename P>
constexpr auto has_on_cachehit = boost::hana::is_valid(
[](auto& policy_t, auto& key_t, auto& item_t) -> decltype(boost::hana::traits::declval(policy_t).on_cache_hit(boost::hana::traits::declval(key_t),
boost::hana::traits::declval(item_t))) {
})(boost::hana::type_c<P<K, KH, V>>, boost::hana::type_c<K>, boost::hana::type_c<Item<V>>);
concept HasOnCacheHit = requires(P<K, KH, V> policy, K key, Item<V> item) {
{ policy.on_cache_hit(key, item) };
};

template<typename K, typename KH, typename V, template<class, class, class> typename P>
constexpr auto has_on_cachemiss = boost::hana::is_valid(
[](auto& policy_t, auto& item_t) -> decltype(boost::hana::traits::declval(policy_t).on_cache_miss(boost::hana::traits::declval(item_t))) {
})(boost::hana::type_c<P<K, KH, V>>, boost::hana::type_c<K>);
concept HasOnCacheMiss = requires(P<K, KH, V> policy, K key) {
{ policy.on_cache_miss(key) };
};

template<typename K, typename KH, typename V, template<class, class, class> typename P>
constexpr auto has_on_evict = boost::hana::is_valid(
[](auto& policy_t, auto& key_t, auto& value_t) -> decltype(boost::hana::traits::declval(policy_t).on_evict(boost::hana::traits::declval(key_t),
boost::hana::traits::declval(value_t))) {
})(boost::hana::type_c<P<K, KH, V>>, boost::hana::type_c<K>, boost::hana::type_c<Item<V>>);
concept HasOnEvict = requires(P<K, KH, V> policy, K key, Item<V> item) {
{ policy.on_evict(key, item) };
};

} // namespace event

Expand Down
86 changes: 36 additions & 50 deletions vcpkg.json
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,53 +1,39 @@
{
"name": "cachemere",
"version-semver": "0.3.0",
"dependencies": [
{
"name": "abseil",
"version>=": "20220623.1",
"features": [
"cxx17"
]
"name": "cachemere",
"version-semver": "0.3.0",
"dependencies": [
{
"name": "abseil",
"version>=": "20220623.1",
"features": ["cxx17"]
},
{
"name": "vcpkg-cmake",
"version>=": "2021-02-28",
"host": true,
"$comment": "This transitive dependency needs to be specified explicitly."
},
{
"name": "vcpkg-cmake-config",
"version>=": "2021-02-26",
"host": true,
"$comment": "This transitive dependency needs to be specified explicitly."
}
],
"default-features": ["boost"],
"features": {
"boost": {
"description": "Use boost from vcpkg",
"dependencies": ["boost-accumulators", "boost-dynamic-bitset"]
},
"tests": {
"description": "The unit tests",
"dependencies": ["gtest"]
},
"benchmarks": {
"description": "The accuracy and performance benchmarks",
"dependencies": ["benchmark", "gtest", "tbb"]
}
},
{
"name": "vcpkg-cmake",
"version>=": "2021-02-28",
"host": true,
"$comment": "This transitive dependency needs to be specified explicitly."
},
{
"name": "vcpkg-cmake-config",
"version>=": "2021-02-26",
"host": true,
"$comment": "This transitive dependency needs to be specified explicitly."
}
],
"default-features": [
"boost"
],
"features": {
"boost": {
"description": "Use boost from vcpkg",
"dependencies": [
"boost-accumulators",
"boost-dynamic-bitset",
"boost-hana"
]
},
"tests": {
"description": "The unit tests",
"dependencies": [
"gtest"
]
},
"benchmarks": {
"description": "The accuracy and performance benchmarks",
"dependencies": [
"benchmark",
"gtest",
"tbb"
]
}
},
"builtin-baseline": "3304e4ed22ae8e2a586ec4399c7d933f09475331"
"builtin-baseline": "3304e4ed22ae8e2a586ec4399c7d933f09475331"
}
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