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283 lines
7.7 KiB
283 lines
7.7 KiB
/*
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* This module implements a hash table class for mapping C/C++ addresses to the
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* corresponding wrapped Python object.
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*
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* Copyright (c) 2010 Riverbank Computing Limited <info@riverbankcomputing.com>
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*
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* This file is part of SIP-TQt.
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*
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* This copy of SIP-TQt is licensed for use under the terms of the SIP License
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* Agreement. See the file LICENSE for more details.
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*
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* This copy of SIP-TQt may also used under the terms of the GNU General Public
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* License v2 or v3 as published by the Free Software Foundation which can be
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* found in the files LICENSE-GPL2 and LICENSE-GPL3 included in this package.
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*
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* SIP-TQt is supplied WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#include <string.h>
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#include "sip-tqt.h"
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#include "sipint.h"
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#define hash_1(k,s) (((unsigned long)(k)) % (s))
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#define hash_2(k,s) ((s) - 2 - (hash_1((k),(s)) % ((s) - 2)))
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/* Prime numbers to use as hash table sizes. */
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static unsigned long hash_primes[] = {
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521, 1031, 2053, 4099,
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8209, 16411, 32771, 65537, 131101, 262147,
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524309, 1048583, 2097169, 4194319, 8388617, 16777259,
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33554467, 67108879, 134217757, 268435459, 536870923, 1073741827,
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2147483659U,0
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};
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static sipHashEntry *newHashTable(unsigned long);
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static sipHashEntry *findHashEntry(sipObjectMap *,void *);
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static void reorganiseMap(sipObjectMap *om);
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/*
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* Initialise an object map.
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*/
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void sipOMInit(sipObjectMap *om)
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{
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om -> primeIdx = 0;
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om -> unused = om -> size = hash_primes[om -> primeIdx];
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om -> stale = 0;
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om -> hash_array = newHashTable(om -> size);
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}
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/*
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* Finalise an object map.
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*/
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void sipOMFinalise(sipObjectMap *om)
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{
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sip_api_free(om -> hash_array);
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}
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/*
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* Allocate and initialise a new hash table.
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*/
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static sipHashEntry *newHashTable(unsigned long size)
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{
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size_t nbytes;
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sipHashEntry *hashtab;
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nbytes = sizeof (sipHashEntry) * size;
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if ((hashtab = (sipHashEntry *)sip_api_malloc(nbytes)) != NULL)
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memset(hashtab,0,nbytes);
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return hashtab;
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}
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/*
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* Return a pointer to the hash entry that is used, or should be used, for the
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* given C/C++ address.
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*/
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static sipHashEntry *findHashEntry(sipObjectMap *om,void *key)
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{
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unsigned long hash, inc;
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void *hek;
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hash = hash_1(key,om -> size);
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inc = hash_2(key,om -> size);
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while ((hek = om -> hash_array[hash].key) != NULL && hek != key)
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hash = (hash + inc) % om -> size;
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return &om -> hash_array[hash];
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}
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/*
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* Return the wrapped Python object of a specific type for a C/C++ address or
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* NULL if it wasn't found.
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*/
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sipSimpleWrapper *sipOMFindObject(sipObjectMap *om, void *key,
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const sipTypeDef *td)
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{
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sipHashEntry *he = findHashEntry(om, key);
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sipSimpleWrapper *sw;
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PyTypeObject *py_type = sipTypeAsPyTypeObject(td);
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/* Go through each wrapped object at this address. */
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for (sw = he->first; sw != NULL; sw = sw->next)
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{
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/*
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* If the reference count is 0 then it is in the process of being
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* deleted, so ignore it. It's not completely clear how this can
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* happen (but it can) because it implies that the garbage collection
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* code is being re-entered (and there are guards in place to prevent
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* this).
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*/
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if (Py_REFCNT(sw) == 0)
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continue;
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/*
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* If this wrapped object is of the given type, or a sub-type of it,
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* then we assume it is the same C++ object.
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*/
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if (PyObject_TypeCheck(sw, py_type))
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return sw;
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}
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return NULL;
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}
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/*
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* Add a C/C++ address and the corresponding wrapped Python object to the map.
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*/
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void sipOMAddObject(sipObjectMap *om, sipSimpleWrapper *val)
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{
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sipHashEntry *he = findHashEntry(om, val->u.cppPtr);
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/*
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* If the bucket is in use then we appear to have several objects at the
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* same address.
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*/
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if (he -> first != NULL)
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{
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/*
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* This can happen for three reasons. A variable of one class can be
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* declared at the start of another class. Therefore there are two
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* objects, of different classes, with the same address. The second
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* reason is that the old C/C++ object has been deleted by C/C++ but we
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* didn't get to find out for some reason, and a new C/C++ instance has
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* been created at the same address. The third reason is if we are in
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* the process of deleting a Python object but the C++ object gets
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* wrapped again because the C++ dtor called a method that has been
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* re-implemented in Python. The absence of the SIP_SHARE_MAP flag
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* tells us that a new C++ instance has just been created and so we
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* know the second reason is the correct one so we mark the old
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* pointers as invalid and reuse the entry. Otherwise we just add this
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* one to the existing list of objects at this address.
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*/
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if (!(val->flags & SIP_SHARE_MAP))
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{
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sipSimpleWrapper *sw = he->first;
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he->first = NULL;
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while (sw != NULL)
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{
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sipSimpleWrapper *next = sw->next;
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/* We are removing it from the map here. */
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sipSetNotInMap(sw);
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sip_api_common_dtor(sw);
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sw = next;
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}
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}
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val->next = he->first;
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he->first = val;
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return;
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}
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/* See if the bucket was unused or stale. */
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if (he->key == NULL)
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{
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he->key = val -> u.cppPtr;
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om->unused--;
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}
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else
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om->stale--;
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/* Add the rest of the new value. */
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he->first = val;
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val->next = NULL;
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reorganiseMap(om);
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}
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/*
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* Reorganise a map if it is running short of space.
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*/
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static void reorganiseMap(sipObjectMap *om)
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{
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unsigned long old_size, i;
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sipHashEntry *ohe, *old_tab;
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/* Don't bother if it still has more than 12% available. */
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if (om -> unused > om -> size >> 3)
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return;
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/*
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* If reorganising (ie. making the stale buckets unused) using the same
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* sized table would make 25% available then do that. Otherwise use a
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* bigger table (if possible).
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*/
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if (om -> unused + om -> stale < om -> size >> 2 && hash_primes[om -> primeIdx + 1] != 0)
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om -> primeIdx++;
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old_size = om -> size;
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old_tab = om -> hash_array;
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om -> unused = om -> size = hash_primes[om -> primeIdx];
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om -> stale = 0;
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om -> hash_array = newHashTable(om -> size);
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/* Transfer the entries from the old table to the new one. */
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ohe = old_tab;
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for (i = 0; i < old_size; ++i)
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{
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if (ohe -> key != NULL && ohe -> first != NULL)
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{
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*findHashEntry(om,ohe -> key) = *ohe;
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om -> unused--;
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}
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++ohe;
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}
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sip_api_free(old_tab);
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}
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/*
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* Remove a C/C++ object from the table. Return 0 if it was removed
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* successfully.
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*/
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int sipOMRemoveObject(sipObjectMap *om, sipSimpleWrapper *val)
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{
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sipHashEntry *he = findHashEntry(om, val->u.cppPtr);
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sipSimpleWrapper **swp;
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for (swp = &he->first; *swp != NULL; swp = &(*swp)->next)
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if (*swp == val)
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{
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*swp = val->next;
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/*
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* If the bucket is now empty then count it as stale. Note that we
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* do not NULL the key and count it as unused because that might
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* throw out the search for another entry that wanted to go here,
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* found it already occupied, and was put somewhere else. In other
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* words, searches must be repeatable until we reorganise the
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* table.
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*/
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if (he->first == NULL)
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om->stale++;
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return 0;
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}
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return -1;
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}
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