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/*
* tclPreserve.c --
*
* This file contains a collection of functions that are used to make
* sure that widget records and other data structures aren't reallocated
* when there are nested functions 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.
*
*
* === NOVEM EXPERIMENT ===
* Replace the dynamic var-sized array of References with a
* hashtable. Faster lookup, no linear search.
*
* Current disadvantage - Possible higher memory churn as individual
* Reference structures get allocated and freed.
*
* Could be fixable by using a list-based stack of free/reusable Reference
* structures.
* === NOVEM EXPERIMENT ===
*/
#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
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} Reference;
/*
* Global data structures used to hold the list of preserved data references.
* These variables are protected by "preserveMutex".
*/
static Reference *refArray = NULL; /* First in array of references. */
static int spaceAvl = 0; /* Total number of structures available at
static Tcl_HashTable* refTable;
* *firstRefPtr. */
static int inUse = 0; /* Count of structures currently in use in
* refArray. */
TCL_DECLARE_MUTEX(preserveMutex)/* To protect the above statics */
#define INITIAL_SIZE 2 /* Initial number of reference slots to make */
/*
* 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.
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*/
/* ARGSUSED */
void
TclFinalizePreserve(void)
{
Tcl_MutexLock(&preserveMutex);
if (spaceAvl != 0) {
ckfree(refArray);
refArray = NULL;
inUse = 0;
if (refTable) {
for (;;) {
Reference* refPtr;
Tcl_HashSearch s;
Tcl_HashEntry* hEntry;
hEntry = Tcl_FirstHashEntry (refTable, &s);
if (!hEntry) break;
refPtr = Tcl_GetHashValue (hEntry);
Tcl_DeleteHashEntry (hEntry);
ckfree (refPtr);
}
Tcl_DeleteHashTable (refTable);
refTable = 0;
spaceAvl = 0;
}
Tcl_MutexUnlock(&preserveMutex);
}
/*
*----------------------------------------------------------------------
*
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*/
void
Tcl_Preserve(
ClientData clientData) /* Pointer to malloc'ed block of memory. */
{
Reference *refPtr;
int i;
int isnew;
Tcl_HashEntry* hEntry;
/*
* 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;
}
if (!refTable) {
refTable = ckalloc (sizeof (Tcl_HashTable));
Tcl_InitHashTable (refTable, TCL_ONE_WORD_KEYS);
}
/*
* Make a reference array if it doesn't already exist, or make it bigger
* if it is full.
hEntry = Tcl_FindHashEntry (refTable, clientData);
if (hEntry) {
*/
refPtr = Tcl_GetHashValue (hEntry);
refPtr->refCount++;
if (inUse == spaceAvl) {
spaceAvl = spaceAvl ? 2*spaceAvl : INITIAL_SIZE;
refArray = ckrealloc(refArray, spaceAvl * sizeof(Reference));
Tcl_MutexUnlock(&preserveMutex);
return;
}
/*
* Make a new entry for the new reference.
*/
refPtr = &refArray[inUse];
refPtr = ckalloc (sizeof (Reference));
refPtr->clientData = clientData;
refPtr->refCount = 1;
refPtr->mustFree = 0;
refPtr->freeProc = TCL_STATIC;
inUse += 1;
hEntry = Tcl_CreateHashEntry (refTable, clientData, &isnew);
Tcl_SetHashValue (hEntry, refPtr);
Tcl_MutexUnlock(&preserveMutex);
}
/*
*----------------------------------------------------------------------
*
* Tcl_Release --
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*/
void
Tcl_Release(
ClientData clientData) /* Pointer to malloc'ed block of memory. */
{
Reference *refPtr;
Tcl_HashEntry* hEntry;
int i;
int mustFree;
Tcl_FreeProc *freeProc;
Tcl_MutexLock(&preserveMutex);
for (i=0, refPtr=refArray ; i<inUse ; i++, refPtr++) {
int mustFree;
Tcl_FreeProc *freeProc;
if (refPtr->clientData != clientData) {
continue;
}
if (--refPtr->refCount != 0) {
Tcl_MutexUnlock(&preserveMutex);
return;
}
if (!refTable) {
refTable = ckalloc (sizeof (Tcl_HashTable));
Tcl_InitHashTable (refTable, TCL_ONE_WORD_KEYS);
}
hEntry = Tcl_FindHashEntry (refTable, clientData);
if (!hEntry) {
Tcl_MutexUnlock(&preserveMutex);
/*
* Reference not found. This is a bug in the caller.
*/
Tcl_Panic("Tcl_Release couldn't find reference for %p", clientData);
}
refPtr = Tcl_GetHashValue (hEntry);
if (--refPtr->refCount != 0) {
Tcl_MutexUnlock(&preserveMutex);
return;
}
/*
* 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
/*
* Must remove information from the slot before calling freeProc to
* avoid reentrancy problems if the freeProc calls Tcl_Preserve on the
* same clientData.
* overwrite the current slot.
*/
*/
freeProc = refPtr->freeProc;
mustFree = refPtr->mustFree;
freeProc = refPtr->freeProc;
mustFree = refPtr->mustFree;
inUse--;
if (i < inUse) {
refArray[i] = refArray[inUse];
}
Tcl_DeleteHashEntry (hEntry);
ckfree (refPtr);
/*
* Now committed to disposing the data. But first, we've patched up
* all the global data structures so we should release the mutex now.
* Only then should we dabble around with potentially-slow memory
* managers...
*/
/*
* Now committed to disposing the data. But first, we've patched up
* all the global data structures so we should release the mutex now.
* Only then should we dabble around with potentially-slow memory
* managers...
*/
Tcl_MutexUnlock(&preserveMutex);
if (mustFree) {
if (freeProc == TCL_DYNAMIC) {
ckfree(clientData);
} else {
freeProc(clientData);
}
}
return;
Tcl_MutexUnlock(&preserveMutex);
if (mustFree) {
if (freeProc == TCL_DYNAMIC) {
ckfree(clientData);
} else {
freeProc(clientData);
}
}
return;
}
Tcl_MutexUnlock(&preserveMutex);
/*
* Reference not found. This is a bug in the caller.
*/
Tcl_Panic("Tcl_Release couldn't find reference for %p", clientData);
}
/*
*----------------------------------------------------------------------
*
* Tcl_EventuallyFree --
*
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void
Tcl_EventuallyFree(
ClientData clientData, /* Pointer to malloc'ed block of memory. */
Tcl_FreeProc *freeProc) /* Function 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) {
Tcl_Panic("Tcl_EventuallyFree called twice for %p", clientData);
}
refPtr->mustFree = 1;
refPtr->freeProc = freeProc;
Tcl_MutexUnlock(&preserveMutex);
return;
}
if (refTable) {
Tcl_HashEntry* hEntry;
hEntry = Tcl_FindHashEntry (refTable, clientData);
if (hEntry) {
refPtr = Tcl_GetHashValue (hEntry);
if (refPtr->mustFree) {
Tcl_Panic("Tcl_EventuallyFree called twice for %p", 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) {
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