shared_source/c_tcl_base_7_5_w_mods/tclpreserve.c

/* $Header$ */
/* 
 * tclPreserve.c --
 *
 *      This file contains a collection of procedures that are used
 *      to make sure that widget records and other data structures
 *      aren't reallocated when there are nested procedures that
 *      depend on their existence.
 *
 * Copyright (c) 1991-1994 The Regents of the University of California.
 * Copyright (c) 1994-1998 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclpreserve.c,v 1.1.1.1 2001/06/13 04:45:15 dtashley Exp $
 */

#include "tclInt.h"

/*
 * The following data structure is used to keep track of all the
 * Tcl_Preserve calls that are still in effect.  It grows as needed
 * to accommodate any number of calls in effect.
 */

typedef struct {
    ClientData clientData;      /* Address of preserved block. */
    int refCount;               /* Number of Tcl_Preserve calls in effect
                                 * for block. */
    int mustFree;               /* Non-zero means Tcl_EventuallyFree was
                                 * called while a Tcl_Preserve call was in
                                 * effect, so the structure must be freed
                                 * when refCount becomes zero. */
    Tcl_FreeProc *freeProc;     /* Procedure to call to free. */
} Reference;

static Reference *refArray;     /* First in array of references. */
static int spaceAvl = 0;        /* Total number of structures available
                                 * at *firstRefPtr. */
static int inUse = 0;           /* Count of structures currently in use
                                 * in refArray. */
#define INITIAL_SIZE 2
TCL_DECLARE_MUTEX(preserveMutex)/* To protect the above statics */

/*
 * The following data structure is used to keep track of whether an
 * arbitrary block of memory has been deleted.  This is used by the
 * TclHandle code to avoid the more time-expensive algorithm of
 * Tcl_Preserve().  This mechanism is mainly used when we have lots of
 * references to a few big, expensive objects that we don't want to live
 * any longer than necessary.
 */

typedef struct HandleStruct {
    VOID *ptr;                  /* Pointer to the memory block being
                                 * tracked.  This field will become NULL when
                                 * the memory block is deleted.  This field
                                 * must be the first in the structure. */
#ifdef TCL_MEM_DEBUG
    VOID *ptr2;                 /* Backup copy of the abpve pointer used to
                                 * ensure that the contents of the handle are
                                 * not changed by anyone else. */
#endif
    int refCount;               /* Number of TclHandlePreserve() calls in
                                 * effect on this handle. */
} HandleStruct;


/*
 * Static routines in this file:
 */

static void     PreserveExitProc _ANSI_ARGS_((ClientData clientData));


/*
 *----------------------------------------------------------------------
 *
 * PreserveExitProc --
 *
 *      Called during exit processing to clean up the reference array.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Frees the storage of the reference array.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
static void
PreserveExitProc(clientData)
    ClientData clientData;              /* NULL -Unused. */
{
    Tcl_MutexLock(&preserveMutex);
    if (spaceAvl != 0) {
        ckfree((char *) refArray);
        refArray = (Reference *) NULL;
        inUse = 0;
        spaceAvl = 0;
    }
    Tcl_MutexUnlock(&preserveMutex);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Preserve --
 *
 *      This procedure is used by a procedure to declare its interest
 *      in a particular block of memory, so that the block will not be
 *      reallocated until a matching call to Tcl_Release has been made.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Information is retained so that the block of memory will
 *      not be freed until at least the matching call to Tcl_Release.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_Preserve(clientData)
    ClientData clientData;      /* Pointer to malloc'ed block of memory. */
{
    Reference *refPtr;
    int i;

    /*
     * See if there is already a reference for this pointer.  If so,
     * just increment its reference count.
     */

    Tcl_MutexLock(&preserveMutex);
    for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
        if (refPtr->clientData == clientData) {
            refPtr->refCount++;
            Tcl_MutexUnlock(&preserveMutex);
            return;
        }
    }

    /*
     * Make a reference array if it doesn't already exist, or make it
     * bigger if it is full.
     */

    if (inUse == spaceAvl) {
        if (spaceAvl == 0) {
            Tcl_CreateExitHandler((Tcl_ExitProc *) PreserveExitProc,
                    (ClientData) NULL);
            refArray = (Reference *) ckalloc((unsigned)
                    (INITIAL_SIZE*sizeof(Reference)));
            spaceAvl = INITIAL_SIZE;
        } else {
            Reference *new;

            new = (Reference *) ckalloc((unsigned)
                    (2*spaceAvl*sizeof(Reference)));
            memcpy((VOID *) new, (VOID *) refArray,
                    spaceAvl*sizeof(Reference));
            ckfree((char *) refArray);
            refArray = new;
            spaceAvl *= 2;
        }
    }

    /*
     * Make a new entry for the new reference.
     */

    refPtr = &refArray[inUse];
    refPtr->clientData = clientData;
    refPtr->refCount = 1;
    refPtr->mustFree = 0;
    refPtr->freeProc = TCL_STATIC;
    inUse += 1;
    Tcl_MutexUnlock(&preserveMutex);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Release --
 *
 *      This procedure is called to cancel a previous call to
 *      Tcl_Preserve, thereby allowing a block of memory to be
 *      freed (if no one else cares about it).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If Tcl_EventuallyFree has been called for clientData, and if
 *      no other call to Tcl_Preserve is still in effect, the block of
 *      memory is freed.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_Release(clientData)
    ClientData clientData;      /* Pointer to malloc'ed block of memory. */
{
    Reference *refPtr;
    int mustFree;
    Tcl_FreeProc *freeProc;
    int i;

    Tcl_MutexLock(&preserveMutex);
    for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
        if (refPtr->clientData != clientData) {
            continue;
        }
        refPtr->refCount--;
        if (refPtr->refCount == 0) {

            /*
             * Must remove information from the slot before calling freeProc
             * to avoid reentrancy problems if the freeProc calls Tcl_Preserve
             * on the same clientData. Copy down the last reference in the
             * array to overwrite the current slot.
             */

            freeProc = refPtr->freeProc;
            mustFree = refPtr->mustFree;
            inUse--;
            if (i < inUse) {
                refArray[i] = refArray[inUse];
            }
            if (mustFree) {
                if ((freeProc == TCL_DYNAMIC) ||
                        (freeProc == (Tcl_FreeProc *) free)) {
                    ckfree((char *) clientData);
                } else {
                    Tcl_MutexUnlock(&preserveMutex);
                    (*freeProc)((char *) clientData);
                    return;
                }
            }
        }
        Tcl_MutexUnlock(&preserveMutex);
        return;
    }
    Tcl_MutexUnlock(&preserveMutex);

    /*
     * Reference not found.  This is a bug in the caller.
     */

    panic("Tcl_Release couldn't find reference for 0x%x", clientData);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_EventuallyFree --
 *
 *      Free up a block of memory, unless a call to Tcl_Preserve is in
 *      effect for that block.  In this case, defer the free until all
 *      calls to Tcl_Preserve have been undone by matching calls to
 *      Tcl_Release.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Ptr may be released by calling free().
 *
 *----------------------------------------------------------------------
 */

void
Tcl_EventuallyFree(clientData, freeProc)
    ClientData clientData;      /* Pointer to malloc'ed block of memory. */
    Tcl_FreeProc *freeProc;     /* Procedure to actually do free. */
{
    Reference *refPtr;
    int i;

    /*
     * See if there is a reference for this pointer.  If so, set its
     * "mustFree" flag (the flag had better not be set already!).
     */

    Tcl_MutexLock(&preserveMutex);
    for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
        if (refPtr->clientData != clientData) {
            continue;
        }
        if (refPtr->mustFree) {
            panic("Tcl_EventuallyFree called twice for 0x%x\n", clientData);
        }
        refPtr->mustFree = 1;
        refPtr->freeProc = freeProc;
        Tcl_MutexUnlock(&preserveMutex);
        return;
    }
    Tcl_MutexUnlock(&preserveMutex);

    /*
     * No reference for this block.  Free it now.
     */

    if ((freeProc == TCL_DYNAMIC)
            || (freeProc == (Tcl_FreeProc *) free)) {
        ckfree((char *) clientData);
    } else {
        (*freeProc)((char *)clientData);
    }
}

/*
 *---------------------------------------------------------------------------
 *
 * TclHandleCreate --
 *
 *      Allocate a handle that contains enough information to determine
 *      if an arbitrary malloc'd block has been deleted.  This is 
 *      used to avoid the more time-expensive algorithm of Tcl_Preserve().
 *
 * Results:
 *      The return value is a TclHandle that refers to the given malloc'd
 *      block.  Doubly dereferencing the returned handle will give
 *      back the pointer to the block, or will give NULL if the block has
 *      been deleted.
 *
 * Side effects:
 *      The caller must keep track of this handle (generally by storing
 *      it in a field in the malloc'd block) and call TclHandleFree()
 *      on this handle when the block is deleted.  Everything else that
 *      wishes to keep track of whether the malloc'd block has been deleted
 *      should use calls to TclHandlePreserve() and TclHandleRelease()
 *      on the associated handle.
 *
 *---------------------------------------------------------------------------
 */

TclHandle
TclHandleCreate(ptr)
    VOID *ptr;                  /* Pointer to an arbitrary block of memory
                                 * to be tracked for deletion.  Must not be
                                 * NULL. */
{
    HandleStruct *handlePtr;

    handlePtr = (HandleStruct *) ckalloc(sizeof(HandleStruct));
    handlePtr->ptr = ptr;
#ifdef TCL_MEM_DEBUG
    handlePtr->ptr2 = ptr;
#endif
    handlePtr->refCount = 0;
    return (TclHandle) handlePtr;
}

/*
 *---------------------------------------------------------------------------
 *
 * TclHandleFree --
 *
 *      Called when the arbitrary malloc'd block associated with the
 *      handle is being deleted.  Modifies the handle so that doubly
 *      dereferencing it will give NULL.  This informs any user of the
 *      handle that the block of memory formerly referenced by the
 *      handle has been freed.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If nothing is referring to the handle, the handle will be reclaimed.
 *
 *---------------------------------------------------------------------------
 */

void
TclHandleFree(handle)
    TclHandle handle;           /* Previously created handle associated
                                 * with a malloc'd block that is being
                                 * deleted.  The handle is modified so that
                                 * doubly dereferencing it will give NULL. */
{
    HandleStruct *handlePtr;

    handlePtr = (HandleStruct *) handle;
#ifdef TCL_MEM_DEBUG
    if (handlePtr->refCount == 0x61616161) {
        panic("using previously disposed TclHandle %x", handlePtr);
    }
    if (handlePtr->ptr2 != handlePtr->ptr) {
        panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
                handlePtr, handlePtr->ptr2, handlePtr->ptr);
    }
#endif
    handlePtr->ptr = NULL;
    if (handlePtr->refCount == 0) {
        ckfree((char *) handlePtr);
    }
}

/*
 *---------------------------------------------------------------------------
 *
 * TclHandlePreserve --
 *
 *      Declare an interest in the arbitrary malloc'd block associated
 *      with the handle.  
 *
 * Results:
 *      The return value is the handle argument, with its ref count
 *      incremented.
 *
 * Side effects:
 *      For each call to TclHandlePreserve(), there should be a matching
 *      call to TclHandleRelease() when the caller is no longer interested
 *      in the malloc'd block associated with the handle.
 *
 *---------------------------------------------------------------------------
 */

TclHandle
TclHandlePreserve(handle)
    TclHandle handle;           /* Declare an interest in the block of
                                 * memory referenced by this handle. */
{
    HandleStruct *handlePtr;

    handlePtr = (HandleStruct *) handle;
#ifdef TCL_MEM_DEBUG
    if (handlePtr->refCount == 0x61616161) {
        panic("using previously disposed TclHandle %x", handlePtr);
    }
    if ((handlePtr->ptr != NULL)
            && (handlePtr->ptr != handlePtr->ptr2)) {
        panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
                handlePtr, handlePtr->ptr2, handlePtr->ptr);
    }
#endif
    handlePtr->refCount++;

    return handle;
}

/*
 *---------------------------------------------------------------------------
 *
 * TclHandleRelease --
 *
 *      This procedure is called to release an interest in the malloc'd
 *      block associated with the handle.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The ref count of the handle is decremented.  If the malloc'd block
 *      has been freed and if no one is using the handle any more, the
 *      handle will be reclaimed.
 *
 *---------------------------------------------------------------------------
 */
 
void
TclHandleRelease(handle)
    TclHandle handle;           /* Unregister interest in the block of
                                 * memory referenced by this handle. */
{
    HandleStruct *handlePtr;

    handlePtr = (HandleStruct *) handle;
#ifdef TCL_MEM_DEBUG
    if (handlePtr->refCount == 0x61616161) {
        panic("using previously disposed TclHandle %x", handlePtr);
    }
    if ((handlePtr->ptr != NULL)
            && (handlePtr->ptr != handlePtr->ptr2)) {
        panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
                handlePtr, handlePtr->ptr2, handlePtr->ptr);
    }
#endif
    handlePtr->refCount--;
    if ((handlePtr->refCount == 0) && (handlePtr->ptr == NULL)) {
        ckfree((char *) handlePtr);
    }
}
    
/* End of tclpreserve.c */
1	/* $Header$ */
2	/*
3	* tclPreserve.c --
4	*
5	* This file contains a collection of procedures that are used
6	* to make sure that widget records and other data structures
7	* aren't reallocated when there are nested procedures that
8	* depend on their existence.
9	*
10	* Copyright (c) 1991-1994 The Regents of the University of California.
11	* Copyright (c) 1994-1998 Sun Microsystems, Inc.
12	*
13	* See the file "license.terms" for information on usage and redistribution
14	* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
15	*
16	* RCS: @(#) $Id: tclpreserve.c,v 1.1.1.1 2001/06/13 04:45:15 dtashley Exp $
17	*/
18
19	#include "tclInt.h"
20
21	/*
22	* The following data structure is used to keep track of all the
23	* Tcl_Preserve calls that are still in effect. It grows as needed
24	* to accommodate any number of calls in effect.
25	*/
26
27	typedef struct {
28	ClientData clientData; /* Address of preserved block. */
29	int refCount; /* Number of Tcl_Preserve calls in effect
30	* for block. */
31	int mustFree; /* Non-zero means Tcl_EventuallyFree was
32	* called while a Tcl_Preserve call was in
33	* effect, so the structure must be freed
34	* when refCount becomes zero. */
35	Tcl_FreeProc freeProc; / Procedure to call to free. */
36	} Reference;
37
38	static Reference refArray; / First in array of references. */
39	static int spaceAvl = 0; /* Total number of structures available
40	* at firstRefPtr. /
41	static int inUse = 0; /* Count of structures currently in use
42	* in refArray. */
43	#define INITIAL_SIZE 2
44	TCL_DECLARE_MUTEX(preserveMutex)/* To protect the above statics */
45
46	/*
47	* The following data structure is used to keep track of whether an
48	* arbitrary block of memory has been deleted. This is used by the
49	* TclHandle code to avoid the more time-expensive algorithm of
50	* Tcl_Preserve(). This mechanism is mainly used when we have lots of
51	* references to a few big, expensive objects that we don't want to live
52	* any longer than necessary.
53	*/
54
55	typedef struct HandleStruct {
56	VOID ptr; / Pointer to the memory block being
57	* tracked. This field will become NULL when
58	* the memory block is deleted. This field
59	* must be the first in the structure. */
60	#ifdef TCL_MEM_DEBUG
61	VOID ptr2; / Backup copy of the abpve pointer used to
62	* ensure that the contents of the handle are
63	* not changed by anyone else. */
64	#endif
65	int refCount; /* Number of TclHandlePreserve() calls in
66	* effect on this handle. */
67	} HandleStruct;
68
69
70	/*
71	* Static routines in this file:
72	*/
73
74	static void PreserveExitProc _ANSI_ARGS_((ClientData clientData));
75
76
77	/*
78	*----------------------------------------------------------------------
79	*
80	* PreserveExitProc --
81	*
82	* Called during exit processing to clean up the reference array.
83	*
84	* Results:
85	* None.
86	*
87	* Side effects:
88	* Frees the storage of the reference array.
89	*
90	*----------------------------------------------------------------------
91	*/
92
93	/* ARGSUSED */
94	static void
95	PreserveExitProc(clientData)
96	ClientData clientData; /* NULL -Unused. */
97	{
98	Tcl_MutexLock(&preserveMutex);
99	if (spaceAvl != 0) {
100	ckfree((char *) refArray);
101	refArray = (Reference *) NULL;
102	inUse = 0;
103	spaceAvl = 0;
104	}
105	Tcl_MutexUnlock(&preserveMutex);
106	}
107
108	/*
109	*----------------------------------------------------------------------
110	*
111	* Tcl_Preserve --
112	*
113	* This procedure is used by a procedure to declare its interest
114	* in a particular block of memory, so that the block will not be
115	* reallocated until a matching call to Tcl_Release has been made.
116	*
117	* Results:
118	* None.
119	*
120	* Side effects:
121	* Information is retained so that the block of memory will
122	* not be freed until at least the matching call to Tcl_Release.
123	*
124	*----------------------------------------------------------------------
125	*/
126
127	void
128	Tcl_Preserve(clientData)
129	ClientData clientData; /* Pointer to malloc'ed block of memory. */
130	{
131	Reference *refPtr;
132	int i;
133
134	/*
135	* See if there is already a reference for this pointer. If so,
136	* just increment its reference count.
137	*/
138
139	Tcl_MutexLock(&preserveMutex);
140	for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
141	if (refPtr->clientData == clientData) {
142	refPtr->refCount++;
143	Tcl_MutexUnlock(&preserveMutex);
144	return;
145	}
146	}
147
148	/*
149	* Make a reference array if it doesn't already exist, or make it
150	* bigger if it is full.
151	*/
152
153	if (inUse == spaceAvl) {
154	if (spaceAvl == 0) {
155	Tcl_CreateExitHandler((Tcl_ExitProc *) PreserveExitProc,
156	(ClientData) NULL);
157	refArray = (Reference *) ckalloc((unsigned)
158	(INITIAL_SIZE*sizeof(Reference)));
159	spaceAvl = INITIAL_SIZE;
160	} else {
161	Reference *new;
162
163	new = (Reference *) ckalloc((unsigned)
164	(2spaceAvlsizeof(Reference)));
165	memcpy((VOID ) new, (VOID ) refArray,
166	spaceAvl*sizeof(Reference));
167	ckfree((char *) refArray);
168	refArray = new;
169	spaceAvl *= 2;
170	}
171	}
172
173	/*
174	* Make a new entry for the new reference.
175	*/
176
177	refPtr = &refArray[inUse];
178	refPtr->clientData = clientData;
179	refPtr->refCount = 1;
180	refPtr->mustFree = 0;
181	refPtr->freeProc = TCL_STATIC;
182	inUse += 1;
183	Tcl_MutexUnlock(&preserveMutex);
184	}
185
186	/*
187	*----------------------------------------------------------------------
188	*
189	* Tcl_Release --
190	*
191	* This procedure is called to cancel a previous call to
192	* Tcl_Preserve, thereby allowing a block of memory to be
193	* freed (if no one else cares about it).
194	*
195	* Results:
196	* None.
197	*
198	* Side effects:
199	* If Tcl_EventuallyFree has been called for clientData, and if
200	* no other call to Tcl_Preserve is still in effect, the block of
201	* memory is freed.
202	*
203	*----------------------------------------------------------------------
204	*/
205
206	void
207	Tcl_Release(clientData)
208	ClientData clientData; /* Pointer to malloc'ed block of memory. */
209	{
210	Reference *refPtr;
211	int mustFree;
212	Tcl_FreeProc *freeProc;
213	int i;
214
215	Tcl_MutexLock(&preserveMutex);
216	for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
217	if (refPtr->clientData != clientData) {
218	continue;
219	}
220	refPtr->refCount--;
221	if (refPtr->refCount == 0) {
222
223	/*
224	* Must remove information from the slot before calling freeProc
225	* to avoid reentrancy problems if the freeProc calls Tcl_Preserve
226	* on the same clientData. Copy down the last reference in the
227	* array to overwrite the current slot.
228	*/
229
230	freeProc = refPtr->freeProc;
231	mustFree = refPtr->mustFree;
232	inUse--;
233	if (i < inUse) {
234	refArray[i] = refArray[inUse];
235	}
236	if (mustFree) {
237	if ((freeProc == TCL_DYNAMIC) \|\|
238	(freeProc == (Tcl_FreeProc *) free)) {
239	ckfree((char *) clientData);
240	} else {
241	Tcl_MutexUnlock(&preserveMutex);
242	(freeProc)((char ) clientData);
243	return;
244	}
245	}
246	}
247	Tcl_MutexUnlock(&preserveMutex);
248	return;
249	}
250	Tcl_MutexUnlock(&preserveMutex);
251
252	/*
253	* Reference not found. This is a bug in the caller.
254	*/
255
256	panic("Tcl_Release couldn't find reference for 0x%x", clientData);
257	}
258
259	/*
260	*----------------------------------------------------------------------
261	*
262	* Tcl_EventuallyFree --
263	*
264	* Free up a block of memory, unless a call to Tcl_Preserve is in
265	* effect for that block. In this case, defer the free until all
266	* calls to Tcl_Preserve have been undone by matching calls to
267	* Tcl_Release.
268	*
269	* Results:
270	* None.
271	*
272	* Side effects:
273	* Ptr may be released by calling free().
274	*
275	*----------------------------------------------------------------------
276	*/
277
278	void
279	Tcl_EventuallyFree(clientData, freeProc)
280	ClientData clientData; /* Pointer to malloc'ed block of memory. */
281	Tcl_FreeProc freeProc; / Procedure to actually do free. */
282	{
283	Reference *refPtr;
284	int i;
285
286	/*
287	* See if there is a reference for this pointer. If so, set its
288	* "mustFree" flag (the flag had better not be set already!).
289	*/
290
291	Tcl_MutexLock(&preserveMutex);
292	for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) {
293	if (refPtr->clientData != clientData) {
294	continue;
295	}
296	if (refPtr->mustFree) {
297	panic("Tcl_EventuallyFree called twice for 0x%x\n", clientData);
298	}
299	refPtr->mustFree = 1;
300	refPtr->freeProc = freeProc;
301	Tcl_MutexUnlock(&preserveMutex);
302	return;
303	}
304	Tcl_MutexUnlock(&preserveMutex);
305
306	/*
307	* No reference for this block. Free it now.
308	*/
309
310	if ((freeProc == TCL_DYNAMIC)
311	\|\| (freeProc == (Tcl_FreeProc *) free)) {
312	ckfree((char *) clientData);
313	} else {
314	(freeProc)((char )clientData);
315	}
316	}
317
318	/*
319	*---------------------------------------------------------------------------
320	*
321	* TclHandleCreate --
322	*
323	* Allocate a handle that contains enough information to determine
324	* if an arbitrary malloc'd block has been deleted. This is
325	* used to avoid the more time-expensive algorithm of Tcl_Preserve().
326	*
327	* Results:
328	* The return value is a TclHandle that refers to the given malloc'd
329	* block. Doubly dereferencing the returned handle will give
330	* back the pointer to the block, or will give NULL if the block has
331	* been deleted.
332	*
333	* Side effects:
334	* The caller must keep track of this handle (generally by storing
335	* it in a field in the malloc'd block) and call TclHandleFree()
336	* on this handle when the block is deleted. Everything else that
337	* wishes to keep track of whether the malloc'd block has been deleted
338	* should use calls to TclHandlePreserve() and TclHandleRelease()
339	* on the associated handle.
340	*
341	*---------------------------------------------------------------------------
342	*/
343
344	TclHandle
345	TclHandleCreate(ptr)
346	VOID ptr; / Pointer to an arbitrary block of memory
347	* to be tracked for deletion. Must not be
348	* NULL. */
349	{
350	HandleStruct *handlePtr;
351
352	handlePtr = (HandleStruct *) ckalloc(sizeof(HandleStruct));
353	handlePtr->ptr = ptr;
354	#ifdef TCL_MEM_DEBUG
355	handlePtr->ptr2 = ptr;
356	#endif
357	handlePtr->refCount = 0;
358	return (TclHandle) handlePtr;
359	}
360
361	/*
362	*---------------------------------------------------------------------------
363	*
364	* TclHandleFree --
365	*
366	* Called when the arbitrary malloc'd block associated with the
367	* handle is being deleted. Modifies the handle so that doubly
368	* dereferencing it will give NULL. This informs any user of the
369	* handle that the block of memory formerly referenced by the
370	* handle has been freed.
371	*
372	* Results:
373	* None.
374	*
375	* Side effects:
376	* If nothing is referring to the handle, the handle will be reclaimed.
377	*
378	*---------------------------------------------------------------------------
379	*/
380
381	void
382	TclHandleFree(handle)
383	TclHandle handle; /* Previously created handle associated
384	* with a malloc'd block that is being
385	* deleted. The handle is modified so that
386	* doubly dereferencing it will give NULL. */
387	{
388	HandleStruct *handlePtr;
389
390	handlePtr = (HandleStruct *) handle;
391	#ifdef TCL_MEM_DEBUG
392	if (handlePtr->refCount == 0x61616161) {
393	panic("using previously disposed TclHandle %x", handlePtr);
394	}
395	if (handlePtr->ptr2 != handlePtr->ptr) {
396	panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
397	handlePtr, handlePtr->ptr2, handlePtr->ptr);
398	}
399	#endif
400	handlePtr->ptr = NULL;
401	if (handlePtr->refCount == 0) {
402	ckfree((char *) handlePtr);
403	}
404	}
405
406	/*
407	*---------------------------------------------------------------------------
408	*
409	* TclHandlePreserve --
410	*
411	* Declare an interest in the arbitrary malloc'd block associated
412	* with the handle.
413	*
414	* Results:
415	* The return value is the handle argument, with its ref count
416	* incremented.
417	*
418	* Side effects:
419	* For each call to TclHandlePreserve(), there should be a matching
420	* call to TclHandleRelease() when the caller is no longer interested
421	* in the malloc'd block associated with the handle.
422	*
423	*---------------------------------------------------------------------------
424	*/
425
426	TclHandle
427	TclHandlePreserve(handle)
428	TclHandle handle; /* Declare an interest in the block of
429	* memory referenced by this handle. */
430	{
431	HandleStruct *handlePtr;
432
433	handlePtr = (HandleStruct *) handle;
434	#ifdef TCL_MEM_DEBUG
435	if (handlePtr->refCount == 0x61616161) {
436	panic("using previously disposed TclHandle %x", handlePtr);
437	}
438	if ((handlePtr->ptr != NULL)
439	&& (handlePtr->ptr != handlePtr->ptr2)) {
440	panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
441	handlePtr, handlePtr->ptr2, handlePtr->ptr);
442	}
443	#endif
444	handlePtr->refCount++;
445
446	return handle;
447	}
448
449	/*
450	*---------------------------------------------------------------------------
451	*
452	* TclHandleRelease --
453	*
454	* This procedure is called to release an interest in the malloc'd
455	* block associated with the handle.
456	*
457	* Results:
458	* None.
459	*
460	* Side effects:
461	* The ref count of the handle is decremented. If the malloc'd block
462	* has been freed and if no one is using the handle any more, the
463	* handle will be reclaimed.
464	*
465	*---------------------------------------------------------------------------
466	*/
467
468	void
469	TclHandleRelease(handle)
470	TclHandle handle; /* Unregister interest in the block of
471	* memory referenced by this handle. */
472	{
473	HandleStruct *handlePtr;
474
475	handlePtr = (HandleStruct *) handle;
476	#ifdef TCL_MEM_DEBUG
477	if (handlePtr->refCount == 0x61616161) {
478	panic("using previously disposed TclHandle %x", handlePtr);
479	}
480	if ((handlePtr->ptr != NULL)
481	&& (handlePtr->ptr != handlePtr->ptr2)) {
482	panic("someone has changed the block referenced by the handle %x\nfrom %x to %x",
483	handlePtr, handlePtr->ptr2, handlePtr->ptr);
484	}
485	#endif
486	handlePtr->refCount--;
487	if ((handlePtr->refCount == 0) && (handlePtr->ptr == NULL)) {
488	ckfree((char *) handlePtr);
489	}
490	}
491
492	/* End of tclpreserve.c */