/*
- * Copyright 2015 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
/*
* AtomicHashMap --
*
- * A high performance concurrent hash map with int32 or int64 keys. Supports
+ * A high-performance concurrent hash map with int32 or int64 keys. Supports
* insert, find(key), findAt(index), erase(key), size, and more. Memory cannot
* be freed or reclaimed by erase. Can grow to a maximum of about 18 times the
* initial capacity, but performance degrades linearly with growth. Can also be
* internal storage (retrieved with iterator::getIndex()).
*
* Advantages:
- * - High performance (~2-4x tbb::concurrent_hash_map in heavily
+ * - High-performance (~2-4x tbb::concurrent_hash_map in heavily
* multi-threaded environments).
* - Efficient memory usage if initial capacity is not over estimated
* (especially for small keys and values).
* faster because of reduced data indirection.
*
* AHMap is a wrapper around AHArray sub-maps that allows growth and provides
- * an interface closer to the stl UnorderedAssociativeContainer concept. These
+ * an interface closer to the STL UnorderedAssociativeContainer concept. These
* sub-maps are allocated on the fly and are processed in series, so the more
* there are (from growing past initial capacity), the worse the performance.
*
*
*/
-#ifndef FOLLY_ATOMICHASHMAP_H_
+#pragma once
#define FOLLY_ATOMICHASHMAP_H_
#include <boost/iterator/iterator_facade.hpp>
{}
};
-template<class KeyT, class ValueT,
- class HashFcn, class EqualFcn, class Allocator>
+template<class KeyT, class ValueT, class HashFcn, class EqualFcn,
+ class Allocator, class ProbeFcn, class KeyConvertFcn>
class AtomicHashMap : boost::noncopyable {
- typedef AtomicHashArray<KeyT, ValueT, HashFcn, EqualFcn, Allocator> SubMap;
+typedef AtomicHashArray<KeyT, ValueT, HashFcn, EqualFcn,
+ Allocator, ProbeFcn, KeyConvertFcn>
+ SubMap;
public:
typedef KeyT key_type;
typedef std::pair<const KeyT, ValueT> value_type;
typedef HashFcn hasher;
typedef EqualFcn key_equal;
+ typedef KeyConvertFcn key_convert;
typedef value_type* pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
explicit AtomicHashMap(size_t finalSizeEst, const Config& c = Config());
~AtomicHashMap() {
- const int numMaps = numMapsAllocated_.load(std::memory_order_relaxed);
+ const unsigned int numMaps =
+ numMapsAllocated_.load(std::memory_order_relaxed);
FOR_EACH_RANGE (i, 0, numMaps) {
SubMap* thisMap = subMaps_[i].load(std::memory_order_relaxed);
DCHECK(thisMap);
*
* Same contract as insert(), but performs in-place construction
* of the value type using the specified arguments.
+ *
+ * Also, like find(), this method optionally allows 'key_in' to have a type
+ * different from that stored in the table; see find(). If and only if no
+ * equal key is already present, this method converts 'key_in' to a key of
+ * type KeyT using the provided LookupKeyToKeyFcn.
*/
- template <typename... ArgTs>
- std::pair<iterator,bool> emplace(key_type k, ArgTs&&... vCtorArg);
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal,
+ typename LookupKeyToKeyFcn = key_convert,
+ typename... ArgTs>
+ std::pair<iterator,bool> emplace(LookupKeyT k, ArgTs&&... vCtorArg);
/*
* find --
*
- * Returns an iterator into the map.
+ * Returns the iterator to the element if found, otherwise end().
+ *
+ * As an optional feature, the type of the key to look up (LookupKeyT) is
+ * allowed to be different from the type of keys actually stored (KeyT).
*
- * If the key is not found, returns end().
+ * This enables use cases where materializing the key is costly and usually
+ * redudant, e.g., canonicalizing/interning a set of strings and being able
+ * to look up by StringPiece. To use this feature, LookupHashFcn must take
+ * a LookupKeyT, and LookupEqualFcn must take KeyT and LookupKeyT as first
+ * and second parameter, respectively.
+ *
+ * See folly/test/ArrayHashMapTest.cpp for sample usage.
*/
- iterator find(key_type k);
- const_iterator find(key_type k) const;
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal>
+ iterator find(LookupKeyT k);
+
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal>
+ const_iterator find(LookupKeyT k) const;
/*
* erase --
SimpleRetT() = default;
};
- template <typename... ArgTs>
- SimpleRetT insertInternal(KeyT key, ArgTs&&... value);
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal,
+ typename LookupKeyToKeyFcn = key_convert,
+ typename... ArgTs>
+ SimpleRetT insertInternal(LookupKeyT key, ArgTs&&... value);
- SimpleRetT findInternal(const KeyT k) const;
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal>
+ SimpleRetT findInternal(const LookupKeyT k) const;
SimpleRetT findAtInternal(uint32_t idx) const;
std::atomic<SubMap*> subMaps_[kNumSubMaps_];
std::atomic<uint32_t> numMapsAllocated_;
- inline bool tryLockMap(int idx) {
+ inline bool tryLockMap(unsigned int idx) {
SubMap* val = nullptr;
return subMaps_[idx].compare_exchange_strong(val, (SubMap*)kLockedPtr_,
std::memory_order_acquire);
}; // AtomicHashMap
+template <class KeyT,
+ class ValueT,
+ class HashFcn = std::hash<KeyT>,
+ class EqualFcn = std::equal_to<KeyT>,
+ class Allocator = std::allocator<char>>
+using QuadraticProbingAtomicHashMap =
+ AtomicHashMap<KeyT,
+ ValueT,
+ HashFcn,
+ EqualFcn,
+ Allocator,
+ AtomicHashArrayQuadraticProbeFcn>;
} // namespace folly
#include <folly/AtomicHashMap-inl.h>
-
-#endif // FOLLY_ATOMICHASHMAP_H_
projects / folly.git / blobdiff