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#pragma once
#include <util/generic/hash.h>
#include <util/system/spinlock.h>
#include <array>
template <typename K, typename V, size_t BucketCount = 64, typename L = TAdaptiveLock>
class TConcurrentHashMap {
public:
using TActualMap = THashMap<K, V>;
using TLock = L;
struct TBucket {
friend class TConcurrentHashMap;
private:
TActualMap Map;
mutable TLock Mutex;
public:
TLock& GetMutex() const {
return Mutex;
}
TActualMap& GetMap() {
return Map;
}
const TActualMap& GetMap() const {
return Map;
}
const V& GetUnsafe(const K& key) const {
typename TActualMap::const_iterator it = Map.find(key);
Y_VERIFY(it != Map.end(), "not found by key");
return it->second;
}
V& GetUnsafe(const K& key) {
typename TActualMap::iterator it = Map.find(key);
Y_VERIFY(it != Map.end(), "not found by key");
return it->second;
}
V RemoveUnsafe(const K& key) {
typename TActualMap::iterator it = Map.find(key);
Y_VERIFY(it != Map.end(), "removing non-existent key");
V r = std::move(it->second);
Map.erase(it);
return r;
}
bool HasUnsafe(const K& key) const {
typename TActualMap::const_iterator it = Map.find(key);
return (it != Map.end());
}
const V* TryGetUnsafe(const K& key) const {
typename TActualMap::const_iterator it = Map.find(key);
return it == Map.end() ? nullptr : &it->second;
}
V* TryGetUnsafe(const K& key) {
typename TActualMap::iterator it = Map.find(key);
return it == Map.end() ? nullptr : &it->second;
}
};
std::array<TBucket, BucketCount> Buckets;
public:
TBucket& GetBucketForKey(const K& key) {
return Buckets[THash<K>()(key) % BucketCount];
}
const TBucket& GetBucketForKey(const K& key) const {
return Buckets[THash<K>()(key) % BucketCount];
}
void Insert(const K& key, const V& value) {
TBucket& bucket = GetBucketForKey(key);
TGuard<TLock> guard(bucket.Mutex);
bucket.Map[key] = value;
}
void InsertUnique(const K& key, const V& value) {
TBucket& bucket = GetBucketForKey(key);
TGuard<TLock> guard(bucket.Mutex);
if (!bucket.Map.insert(std::make_pair(key, value)).second) {
Y_FAIL("non-unique key");
}
}
V& InsertIfAbsent(const K& key, const V& value) {
TBucket& bucket = GetBucketForKey(key);
TGuard<TLock> guard(bucket.Mutex);
return bucket.Map.insert(std::make_pair(key, value)).first->second;
}
template <typename TKey, typename... Args>
V& EmplaceIfAbsent(TKey&& key, Args&&... args) {
TBucket& bucket = GetBucketForKey(key);
TGuard<TLock> guard(bucket.Mutex);
if (V* value = bucket.TryGetUnsafe(key)) {
return *value;
}
return bucket.Map.emplace(
std::piecewise_construct,
std::forward_as_tuple(std::forward<TKey>(key)),
std::forward_as_tuple(std::forward<Args>(args)...)
).first->second;
}
template <typename Callable>
V& InsertIfAbsentWithInit(const K& key, Callable initFunc) {
TBucket& bucket = GetBucketForKey(key);
TGuard<TLock> guard(bucket.Mutex);
if (V* value = bucket.TryGetUnsafe(key)) {
return *value;
}
return bucket.Map.insert(std::make_pair(key, initFunc())).first->second;
}
V Get(const K& key) const {
const TBucket& bucket = GetBucketForKey(key);
TGuard<TLock> guard(bucket.Mutex);
return bucket.GetUnsafe(key);
}
bool Get(const K& key, V& result) const {
const TBucket& bucket = GetBucketForKey(key);
TGuard<TLock> guard(bucket.Mutex);
if (const V* value = bucket.TryGetUnsafe(key)) {
result = *value;
return true;
}
return false;
}
V Remove(const K& key) {
TBucket& bucket = GetBucketForKey(key);
TGuard<TLock> guard(bucket.Mutex);
return bucket.RemoveUnsafe(key);
}
bool Has(const K& key) const {
const TBucket& bucket = GetBucketForKey(key);
TGuard<TLock> guard(bucket.Mutex);
return bucket.HasUnsafe(key);
}
};
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