UT_IndexedHashMap.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        UT_IndexedHashMap.h ( UT Library, C++)
 *
 * COMMENTS:
 */

#ifndef __UT_IndexedHashMap__
#define __UT_IndexedHashMap__

#include "UT_API.h"
#include "UT_Array.h"
#include "UT_Assert.h"
#include "UT_ConcurrentHashMap.h"
#include "UT_ConcurrentQueue.h"
#include "UT_ConcurrentVector.h"
#include "UT_VectorTypes.h"
#include <SYS/SYS_AtomicInt.h>
#include <stddef.h>

/// Each item in the shared map is assigned a unique id
typedef int     UT_IndexedHashMapItemId;

/// @brief A thread-safe hash map which stores indexed shared items
///
/// Each item in the hash map is reference counted.  That is, if objects are
/// added multiple times, only a single object will be stored in the map.
///
/// Removing an item from the hash map (by id or key) will decrement the
/// reference count on the item.  When no longer referenced, the map will
/// delete the item.
///
/// When the map stores 'ids', each item is assigned a unique id
/// (UT_IndexedHashMapItemId).  The item can then be retrieved efficiently from
/// the map using the id (UT_IndexedHashMap::get())
///
/// Many methods on the map are thread-safe.  Some methods are not (and are
/// noted in the comments).
///
/// The KEY template parameter needs to have: @code
///     KEY(const KEY &src);                    // The copy constructor
///     uint    hash() const;                   // A hash method
///     bool    isEqual(const KEY &src) const;  // A comparison operator
/// @endcode
class UT_API UT_IndexedHashMap
{
public:
    typedef void        InternalKeyT;   // Internal key type
    typedef void        InternalItemT;  // Internal item type

protected:
    virtual uint                 hash(const InternalKeyT *key) const = 0;
    virtual bool                 areKeysEqual(const InternalKeyT *k1,
                                        const InternalKeyT *k2) const = 0;
    virtual InternalKeyT        *copyKey(const InternalKeyT *key) const = 0;
    virtual void                 deleteKey(InternalKeyT *key) const = 0;

    virtual InternalItemT       *newItem(const InternalKeyT *key) const = 0;
    virtual void                 deleteItem(InternalItemT *item) const = 0;
    virtual bool                 isItemLessThan(const InternalItemT *a,
                                        const InternalItemT *b) const = 0;

public:
    /// If @c store_ids is true, each item stored in the map will be given a
    /// unique id of type UT_IndexedHashMapItemId.  These id's can be used to
    /// perform efficient lookup of items in the map.
    ///
    /// If the @c store_ids parameter is false, then elements in the shared map
    /// will not store id's.  The ids for the elements will always be -1
    /// (invalid).  The map won't store the structures required for indexed
    /// lookup, saving some memory and allowing some operations to be slightly
    /// more efficient.  Operations which are invalid for maps that don't store
    /// id's are noted in the comments).
    UT_IndexedHashMap(bool store_ids);
    virtual ~UT_IndexedHashMap();

    /// Clear the map
    /// @note This is @b not thread-safe
    void                clear();

    /// Return the number of entries in the map.
    /// @note This is @b not thread-safe
    exint               entries() const { return myMap.size(); }

    /// Return whether the map is empty
    bool                empty() const   { return myMap.empty(); }

    /// Return approximate memory usage (not including key or item storage)
    int64               getMemoryUsage(bool inclusive) const;

    /// Return the maximum possible UT_IndexedHashMapItemId stored in the map.
    /// This returns an upper bound and is not exact.
    /// @note This is @b not thread-safe
    /// @note Not supported if id's are not stored in the map
    UT_IndexedHashMapItemId     getItemIdUpperBound() const
                                    { return SYSmax(1, getListSize())-1; }

    /// Return the "occupancy" of the map.
    /// @note This is @b not thread-safe
    /// @note Not supported if id's are not stored in the map
    fpreal              getOccupancy() const
                        {
                            exint       lsize = getListSize();
                            exint       hsize = myHoles.unsafe_size();
                            if (!lsize || !hsize)
                                return 1;       // Fully occupied
                            UT_ASSERT(lsize > hsize);
                            return (fpreal)(lsize-hsize)/(fpreal)lsize;
                        }

    /// Class used by compacting to map from the previous id to the new id.
    /// After compacting, this class stores a map of the old id's to the new
    /// id's
    class IdRemapping
    {
    public:
         IdRemapping() {}
        ~IdRemapping() {}

        /// Find the number of entries in the map
        exint   entries() const { return myIdMap.entries(); }

        /// Query the new id associated with the previous id
        UT_IndexedHashMapItemId newId(UT_IndexedHashMapItemId prev) const
                                {
                                    if (prev >= 0 && prev < myIdMap.entries())
                                        return myIdMap(prev);
                                    return -1;
                                }

        /// @private Used by UT_IndexedHashMap::compactIds()
        void    prepare(exint size)
                {
                    myIdMap.entries(size);      // Grow to expected size
                    myIdMap.constant(-1);               // Initialize to -1
                }
        /// @private Used by UT_IndexedHashMap::compactIds()
        void    setId(UT_IndexedHashMapItemId prev, UT_IndexedHashMapItemId curr)
                {
                    UT_ASSERT(myIdMap(prev) == -1);
                    myIdMap(prev) = curr;
                }
    private:
        UT_Array<exint>         myIdMap;
    };

    /// Compact the list.  This fills out the integer map of old id's and their
    /// new id's.  If no compaction was done, the function returns false.
    /// @note This is @b not thread-safe
    /// @note This is a no-op if id's are not stored in the map
    bool                compactIds(IdRemapping &remapping);

    /// Sort the list of ids based on the comparator.  This method only works
    /// if the table has been compacted.  Returns false if there are no ids or
    /// the list is not compacted.
    /// @note This is @b not thread-safe
    /// @note This is a no-op if id's are not stored in the map
    bool                sortItems();

    exint               getReferenceCount(UT_IndexedHashMapItemId id) const;

protected:
    /// @{
    /// Internal implementation using internal types rather than exposed types.
    /// None of these methods use the template types and thus are only generated
    /// one time (outlined).
    void                 _replace(const UT_IndexedHashMap &src);
    InternalItemT       *_add(const InternalKeyT *key,
                                InternalItemT *item=NULL,
                                UT_IndexedHashMapItemId *id=NULL);
    InternalItemT       *_addReference(UT_IndexedHashMapItemId id, int inc);
    InternalItemT       *_addReference(UT_IndexedHashMapItemId id)
                            { return _addReference(id, 1); }

    InternalItemT       *_find(const InternalKeyT *key) const
                         {
                            UT_IndexedHashMapItemId id;
                            return _findItemAndId(key, id);
                         }
    exint               _findId(const InternalKeyT *key) const
                        {
                            UT_IndexedHashMapItemId hid;
                            if (!_findItemAndId(key, hid))
                                hid = -1;
                            return hid;
                        }
    InternalItemT       *_findItemAndId(const InternalKeyT *key,
                                UT_IndexedHashMapItemId &id) const;
    InternalItemT       *_get(UT_IndexedHashMapItemId id) const;
    const InternalKeyT  *_getKey(UT_IndexedHashMapItemId id) const;
    InternalItemT       *_getOrderedItem(exint index,
                                    UT_IndexedHashMapItemId *id) const;
    bool                _remove(const InternalKeyT *key);
    bool                _remove(UT_IndexedHashMapItemId id);
    UT_IndexedHashMapItemId     _replaceItem(UT_IndexedHashMapItemId id,
                                            const InternalKeyT *key,
                                            InternalItemT *new_item=NULL);
    exint               _extractItems(
                                UT_Array<UT_IndexedHashMapItemId> &ids,
                                UT_Array<InternalItemT *> &items,
                                exint maxitems
                            ) const;
    exint               _extractItems(
                                UT_Array<UT_IndexedHashMapItemId> &ids,
                                UT_Array<InternalItemT *> &items
                            ) const;
    exint               _extractItems(
                                UT_Array<InternalItemT *> &items
                            ) const;
    /// @}


    // These classes need to be defined for the iterator
    // Class to store reference counted items in the map
    friend class        itemContainer;
    class itemContainer
    {
    public:
        itemContainer(const UT_IndexedHashMap &map,
                        InternalItemT *item,
                        exint id)
            : myMap(map)
            , myItem(item)
            , myId(id)
            , myRefCount(0)
        {}
        ~itemContainer()
        {
            myMap.deleteItem(myItem);
        }

        InternalItemT   *getItem() const        { return myItem; }
        exint            getId() const          { return myId; }
        void             setId(exint id)        { myId = id; }
        exint            getRef() const { return myRefCount; }
        void             setRef(int d)          { myRefCount = d; }
        int              bumpRef(int d)
                         {
                            myRefCount += d;
                            return myRefCount;
                         }

    private:
        const UT_IndexedHashMap &myMap;
        InternalItemT           *myItem;
        exint                    myId;
        int                      myRefCount;
    };

    // Class to search for items in the map
    friend class keyContainer;
    class keyContainer
    {
    public:
        // Here, we just hold a reference to the key rather than duplicating
        // the key.
        explicit keyContainer(const UT_IndexedHashMap &map,
                                const InternalKeyT *key)
            : myMap(map)
            , myKey(key)
            , myOwn(false)
        {}
        keyContainer(const keyContainer &src)
            : myMap(src.myMap)
            , myKey(src.myKey ? src.myMap.copyKey(src.myKey) : NULL)
            , myOwn(true)
        {}
        ~keyContainer()
        {
            if (myOwn)
                myMap.deleteKey(const_cast<InternalKeyT *>(myKey));
        }
        keyContainer    &operator=(const keyContainer &src)
                        {
                            UT_ASSERT(0);
                            if (myKey != src.myKey)
                            {
                                if (myOwn)
                                    myMap.deleteKey(const_cast<InternalKeyT *>(myKey));
                                // Make a hard copy
                                myKey = src.myKey ?
                                        src.myMap.copyKey(src.myKey) : NULL;
                            }
                            return *this;
                        }
        const InternalKeyT      *getKey() const
                                {
                                    UT_ASSERT(myOwn);
                                    return myKey;
                                }
        uint            hash() const
                        {
                            UT_ASSERT(myKey);
                            return myMap.hash(myKey);
                        }
        bool            isEqual(const keyContainer &b) const
                        {
                            UT_ASSERT(myKey && b.myKey);
                            return myMap.areKeysEqual(myKey, b.myKey);
                        }
    private:
        const UT_IndexedHashMap &myMap;
        const InternalKeyT      *myKey;
        bool                     myOwn;
    };

    // Class to store items in the indexed list
    class listContainer
    {
    public:
        listContainer()
            : myItem(NULL)
            , myKey(NULL)
        {}
        listContainer(itemContainer *i, const InternalKeyT *k)
            : myItem(i)
            , myKey(k)
        {}
        listContainer(const listContainer &src)
            : myItem(src.myItem)
            , myKey(src.myKey)
        {}
        listContainer   &operator=(const listContainer &src)
                        {
                            myItem = src.myItem;
                            myKey = src.myKey;
                            return *this;
                        }
        bool            isValid() const { return myItem; }

        InternalItemT           *getItem() const
                                 {
                                     return myItem ? myItem->getItem() : NULL;
                                 }
        const InternalKeyT      *getKey() const { return myKey; }

        void                     setId(exint id) { myItem->setId(id); }
        exint                    getId() const { return myItem->getId(); }
        exint                    getRef() const
                                    { return myItem ? myItem->getRef() : -1; }

        itemContainer           *getItemContainer() { return myItem; }

    private:
        itemContainer           *myItem;
        const InternalKeyT      *myKey;
    };

    // Comparison class for hash map
    class keyCompare
    {
    public:
        static size_t   hash(const keyContainer &key)
                        {
                            return key.hash();
                        }
        static bool     equal(const keyContainer &a, const keyContainer &b)
                        {
                            return a.isEqual(b);
                        }
    };

    // Class used to sort items
    friend class itemCompare;
    class itemCompare
    {
    public:
        itemCompare(const UT_IndexedHashMap &map)
            : myMap(map)
        {}
        bool    operator()(const listContainer &a, const listContainer &b) const
                {
                    return myMap.isItemLessThan(a.getItem(), b.getItem());
                }
    private:
        const UT_IndexedHashMap &myMap;
    };

    typedef UT_ConcurrentHashMap<keyContainer, itemContainer *, keyCompare>
                                                UT_IndexedHashMapTable;
    typedef UT_ConcurrentVector<listContainer>  UT_IndexedHashMapVector;
    typedef UT_ConcurrentQueue<UT_IndexedHashMapItemId>
                                                UT_IndexedHashMapHoleQueue;

public:
    /// Iterate over items in the list - this is in the order they are stored
    /// in the map (i.e. by id).
    class UT_API unsafe_listiterator
    {
        unsafe_listiterator()
            : myMap(NULL)
            , myIterator()
            , mySize(0)
            , myCurr(0)
        { }

        /// @{
        /// Get information about the current item
        const InternalKeyT      *getKey() const
                                    { return myIterator->getKey(); }
        InternalItemT           *getItem() const
                                    { return myIterator->getItem(); }
        UT_IndexedHashMapItemId  getItemId() const
                                    { return myIterator->getId(); }
        exint                    getItemShareCount() const
                                    { return myIterator->getRef(); }
        template <typename T> const T   *keyAs() const
                                { return static_cast<const T *>(getKey()); }
        template <typename T> const T   *itemAs() const
                                { return static_cast<const T *>(getItem()); }
        /// @}

        /// @{
        /// Implementation of iterator interface
        bool            atEnd() const   { return myCurr >= mySize; }
        void            advance()
                        {
                            do
                            {
                                myCurr++;
                                myIterator++;
                            } while (myCurr < mySize && !myIterator->isValid());
                        }
        unsafe_listiterator     &operator++()   { advance(); return *this; }
        bool            operator==(const unsafe_listiterator &it) const
                        {
                            if (atEnd() && it.atEnd())
                                return true;
                            return myMap == it.myMap &&
                                    mySize == it.mySize &&
                                    myCurr == it.myCurr;
                        }
        bool            operator!=(const unsafe_listiterator &it)
                            { return !(*this == it); }
        /// @}
    private:
        unsafe_listiterator(const UT_IndexedHashMap &map)
            : myMap(&map)
            , myIterator(map.myList.begin())
            , myCurr(0)
            , mySize(map.entries())
        {
        }
        const UT_IndexedHashMap                 *myMap;
        UT_IndexedHashMapVector::const_iterator  myIterator;
        exint                                    mySize, myCurr;
        friend class UT_IndexedHashMap;
    };
    /// Iterate over items in the map - this is arbitrary order
    class UT_API unsafe_iterator
    {
    public:
        unsafe_iterator()
            : myMap(NULL)
            , myIterator()
            , mySize(0)
            , myCurr(0)
        {}

        /// @{
        /// Get information about the current item
        const InternalKeyT      *getKey() const
                                    { return myIterator->first.getKey(); }
        InternalItemT           *getItem() const
                                    { return myIterator->second->getItem(); }
        UT_IndexedHashMapItemId  getItemId() const
                                    { return myMap->_findId(getKey()); }
        exint                    getItemShareCount() const
                                    { return myIterator->second->getRef();}

        template <typename T> const T   *keyAs() const
                                { return static_cast<const T *>(getKey()); }
        template <typename T> const T   *itemAs() const
                                { return static_cast<const T *>(getItem()); }
        /// @}

        /// @{
        /// Implementation of iterator interface
        bool            atEnd() const           { return myCurr >= mySize; }
        void            advance()
                        {
                            ++myCurr;           // Move my count
                            ++myIterator;       // Move my iterator
                            // Assert that the iterator doesn't terminate early
                            UT_ASSERT(myCurr >= mySize ||
                                        myIterator != myMap->myMap.end());
                        }
        unsafe_iterator &operator++()           { advance(); return *this; }
        // No post increment as it is dangerous.
        bool            operator==(const unsafe_iterator &it) const
                        {
                            if (atEnd() && it.atEnd())
                                return true;
                            return myMap == it.myMap &&
                                    mySize == it.mySize &&
                                    myCurr == it.myCurr;
                        }
        bool            operator!=(const unsafe_iterator &it)
                            { return !(*this == it); }
        /// @}
    private:
        unsafe_iterator(const UT_IndexedHashMap &map)
            : myMap(&map)
            , myIterator(map.myMap.begin())
            , myCurr(0)
            , mySize(map.entries())
        {
        }
        const UT_IndexedHashMap                 *myMap;
        UT_IndexedHashMapTable::const_iterator   myIterator;
        exint                                    mySize, myCurr;
        friend class UT_IndexedHashMap;
    };
    unsafe_iterator     begin() const
                            { return unsafe_iterator(*this); }
    unsafe_iterator     end() const
                            { return unsafe_iterator(); }
    unsafe_listiterator beginList() const
                            { return unsafe_listiterator(*this); }
    unsafe_listiterator endList() const
                            { return unsafe_listiterator(); }

private:
    UT_IndexedHashMapItemId     storeItemInList(itemContainer *item,
                                        const InternalKeyT *key);

    int                 getListSize() const
                            { return myListSize.relaxedLoad(); }
    bool                isValidId(UT_IndexedHashMapItemId id) const
                            { return id >= 0 && id < getListSize(); }

    UT_IndexedHashMapTable      myMap;
    UT_IndexedHashMapVector     myList;
    UT_IndexedHashMapHoleQueue  myHoles;
    SYS_AtomicInt32             myListSize;
    bool                        myStoreIds;
};

#endif