Hashtable.cpp

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/*
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Germany nor the names of its contributors may be used to endorse
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#include "StdAfx.h"
#ifdef PAYMENT
#include "Hashtable.hpp"
#include "CAMsg.hpp"
#include "CAUtil.hpp"
 
// Every entry in the hashtable is embedded in this structure
 
struct Entry
{
  struct Entry *e_Next;
  void   *e_Key;
  void   *e_Value;
};
 
 
 
/************************** Hashtable **************************/
// #pragma mark -
 
 
CAMutex *Hashtable::getMutex()
{
  return m_pMutex;
}
 
 
/* Hashtable - a general purpose hash table
 * Erzeugt einen neuen Hashtable nach den Vorgaben des
 *  Benutzers.
 *
 *  @param capacity die Anfangskapazitt des Hashtables. Sie wird zwar bei
 *    Bedarf vergroessert, aber das kann dann etwas laenger dauern, da der Hashtable
 *    dann komplett neu aufgebaut werden muss Voreingestellt sind 100 Eintrge.
 *  @param loadFactor die gewueschte maximale Auslastung des Hashtables.
 *    Bei kleinen Werten muss der Hashtable haeufiger neu aufgebaut werden und belegt
 *    mehr Speicher, ist aber schnell. Bei groessen Werten wird das Beschreiben und
 *    Auslesen langsamer. Voreingestellt ist 0.75f.
 * 
**/
Hashtable::Hashtable(UINT32 (*hashFunc)(void *), SINT32 (*compareFunc)(void *,void *), SINT32 capacity, float loadFactor)
{
  m_pMutex = new CAMutex();
  
  if (capacity < 0 || loadFactor <= 0)
  {
    return;
  }
 
  if (!capacity)
  {
    capacity = 1;
  } 
  
  m_table = new Entry*[capacity];
  for (SINT32 i = 0; i < capacity; i++)
  {
    m_table[i] = NULL;
  }
  
  m_threshold = (UINT32)(capacity * loadFactor);
  m_modCount = 0;
  m_count = 0;
  m_loadFactor = loadFactor;
  m_capacity = capacity;
 
  //m_hashFunc = (UINT32 (*)(void *))stringHash;
  m_hashFunc = hashFunc;
  //m_compareFunc = (SINT32 (*)(void *,void *))stringCompare;
  m_compareFunc = compareFunc;
}
 
 
Hashtable::~Hashtable()
{
  m_pMutex->lock();
  
  for(SINT32 index = 0; index < m_capacity; index++)
  {
    struct Entry *e,*next;
 
    for(e = m_table[index]; e; e = next)
    {
      next = e->e_Next;
      delete e;
      e = NULL;
    }
    m_table[index] = NULL;
  }
  delete m_table;
  m_table = NULL;
  m_capacity = 0;
  m_count = 0;
  m_threshold = 0;
  m_loadFactor = 0;
  m_modCount = 0;
  m_hashFunc = NULL;
  m_compareFunc = NULL;
  
  m_pMutex->unlock();
  
  delete m_pMutex;
  m_pMutex = NULL;
}
 
 
 
 
bool Hashtable::isEmpty()
{
  return m_count == 0;
}
 
 
bool Hashtable::containsKey(void *key)
{
  return getHashEntry(key) ? true : false;
}
 
 
void *Hashtable::getValue(void *key)
{   
  struct Entry *e = getHashEntry(key);
 
  return e ? e->e_Value : NULL;
}
 
 
void* Hashtable::put(void *key, void *value)
{
  //CAMsg::printMsg(LOG_INFO, "Hashtable: Putting key.\n");
  
  if (!key || !value || !m_table)
  {
    return NULL;
  }
  
  struct Entry *oldEntry = NULL;
  struct Entry *newEntry = NULL;
  UINT32 hash = m_hashFunc(key);
  UINT32 index = hash % m_capacity;
  
  m_count++;
  if (m_count >= m_threshold)
  {   
    rehash();
  }
  
  index = hash % m_capacity;
  
  newEntry = new Entry;
  newEntry->e_Key = key;
  newEntry->e_Value = value;
  newEntry->e_Next = NULL;
  
  oldEntry = m_table[index];
  if (!oldEntry)
  {
    m_table[index] = newEntry;
  }
  else
  {
    struct Entry *prevEntry = NULL;
    for(; oldEntry; oldEntry = oldEntry->e_Next)
    {     
      if (m_hashFunc(oldEntry->e_Key) == hash && !m_compareFunc(oldEntry->e_Key,key))
      {
        // found the same entry
        newEntry->e_Next = oldEntry->e_Next;
        break;
      }
      prevEntry = oldEntry;
    }
    if (prevEntry)
    {
      prevEntry->e_Next = newEntry;
    }
    else
    {
      m_table[index] = newEntry;
    }
  }
  
  return oldEntry;
}
 
 
void *Hashtable::remove(void *key)
{
  //CAMsg::printMsg(LOG_INFO, "Hashtable: Removing key.\n");
  
  if (!key || !m_table)
  {
    return NULL;
  }
  
  struct Entry *e,*prev;
  UINT32 hash = m_hashFunc(key);
  
  for(e = m_table[hash % m_capacity], prev = NULL; e; e = e->e_Next)
  {     
    if (m_hashFunc(e->e_Key) == hash && !m_compareFunc(e->e_Key,key))
    {
      void *value;
 
      //m_modCount++;
      if (prev)
      {
        prev->e_Next = e->e_Next;
      }
      else
      {
        m_table[hash % m_capacity] = e->e_Next;
      }
      
      m_count--;
      value = e->e_Value;
      e->e_Value = NULL;
      e->e_Key = NULL;
      e->e_Next = NULL;
      delete e;
      e = NULL;
 
      return value;
    }
    prev = e;
  }
  
  return NULL;
}
 
 
void Hashtable::clear(SINT8 keyMode,SINT8 valueMode)
{ 
  if (!m_table)
  {
    return;
  }
  
  //CAMsg::printMsg(LOG_INFO, "Hashtable: Clearing...\n");
 
  for(SINT32 index = 0; index < m_capacity; index++)
  {
    struct Entry *e,*next;
 
    for(e = m_table[index]; e; e = next)
    {
      switch(keyMode)
      {
        case HASH_EMPTY_DELETE:
          if (e->e_Key)
          {
            delete e->e_Key;
            e->e_Key = NULL;
          }
          break;
//        case HASH_EMPTY_FREE:
//          free(e->e_Key);
        default:
          e->e_Key = NULL;    
      }
      switch(valueMode)
      {
        case HASH_EMPTY_DELETE:
          if (e->e_Value)
          {
            delete e->e_Value;
            e->e_Value = NULL;
          }
          break;
//        case HASH_EMPTY_FREE:
//          free(e->e_Value);
        default:
          e->e_Value = NULL;
      }
      next = e->e_Next;
      delete e;
      e = NULL;
    }
    m_table[index] = NULL;
  }
  m_count = 0;
  
  //CAMsg::printMsg(LOG_INFO, "Hashtable: Has been cleared!\n");
}
 
UINT32 Hashtable::getSize()
{
  return m_count;
}
 
UINT32 Hashtable::getCapacity()
{
  return m_capacity;
}
 
 
bool Hashtable::rehash()
{
  if (!m_table)
  {
    return false;
  }
  
  CAMsg::printMsg(LOG_INFO, "Hashtable: Rehashing.\n");
  
  UINT32 (*hashCode)(void *) = m_hashFunc;
  struct Entry **oldtable = m_table,**newtable;
  SINT32 oldCapacity = m_capacity;
  UINT32 newCapacity;
 
  newCapacity = oldCapacity * 2 + 1;
  newtable = new Entry*[newCapacity];
  for (UINT32 i = 0; i < newCapacity; i++)
  {
    newtable[i] = NULL;
  }
 
  m_modCount++;
  if (m_modCount > 10)
  {
    CAMsg::printMsg(LOG_INFO, "Hashtable: Too many rehash operations! Please adapt hashtable capacity to at least %d.\n", newCapacity);
  }
  
  m_threshold = (UINT32)(newCapacity * m_loadFactor);
  m_table = newtable;
  m_capacity = newCapacity;
 
  for(SINT32 i = 0; i < oldCapacity; i++)
  {
    struct Entry *nextEntry, *e = NULL;
    UINT32 index;
    
    for (nextEntry = oldtable[i]; nextEntry;)
    {
      e = nextEntry;  
      // save the previous next entry, as it will be deleted later
      nextEntry = nextEntry->e_Next;
            
      index = hashCode(e->e_Key) % newCapacity;
      /* If there has been another entry before, replace it.
       * Delete the previous next entry in the same step.
       */
      e->e_Next = newtable[index]; 
      newtable[index] = e;
    }
  }
  delete oldtable;
  oldtable = NULL;
  
  CAMsg::printMsg(LOG_INFO, "Hashtable: Rehashing complete.\n");
  
  return true;
}
 
 
struct Entry *Hashtable::getHashEntry(void *key)
{ 
  if (!key || !m_table)
  {
    return NULL;
  }
  
  struct Entry *e;
  UINT32 hash = m_hashFunc(key);
  
  for(e = m_table[hash % m_capacity]; e; e = e->e_Next)
  {   
    if (m_hashFunc(e->e_Key) == hash && !m_compareFunc(e->e_Key,key))
    {
      return e;
    }
  }
  
  return NULL;
}
 
#endif //define PAYMENT