SIP4 python bindings generator for TQt
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sip4-tqt/siplib/objmap.c

283 lines
7.7 KiB

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