+++ /dev/null
-/*
- * 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.
- */
-
-#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; /* Function to call to free. */
-} 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
- * *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.
- */
-
-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 above 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;
-\f
-/*
- *----------------------------------------------------------------------
- *
- * TclFinalizePreserve --
- *
- * Called during exit processing to clean up the reference array.
- *
- * Results:
- * None.
- *
- * Side effects:
- * Frees the storage of the reference array.
- *
- *----------------------------------------------------------------------
- */
-
- /* ARGSUSED */
-void
-TclFinalizePreserve(void)
-{
- Tcl_MutexLock(&preserveMutex);
- if (spaceAvl != 0) {
- ckfree(refArray);
- refArray = NULL;
- inUse = 0;
- spaceAvl = 0;
- }
- Tcl_MutexUnlock(&preserveMutex);
-}
-\f
-/*
- *----------------------------------------------------------------------
- *
- * Tcl_Preserve --
- *
- * This function is used by a function 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) /* 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) {
- spaceAvl = spaceAvl ? 2*spaceAvl : INITIAL_SIZE;
- refArray = ckrealloc(refArray, spaceAvl * sizeof(Reference));
- }
-
- /*
- * 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);
-}
-\f
-/*
- *----------------------------------------------------------------------
- *
- * Tcl_Release --
- *
- * This function 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) /* Pointer to malloc'ed block of memory. */
-{
- Reference *refPtr;
- int i;
-
- 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;
- }
-
- /*
- * 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];
- }
-
- /*
- * 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);
-
- /*
- * Reference not found. This is a bug in the caller.
- */
-
- Tcl_Panic("Tcl_Release couldn't find reference for %p", clientData);
-}
-\f
-/*
- *----------------------------------------------------------------------
- *
- * 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 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;
- }
- Tcl_MutexUnlock(&preserveMutex);
-
- /*
- * No reference for this block. Free it now.
- */
-
- if (freeProc == TCL_DYNAMIC) {
- ckfree(clientData);
- } else {
- freeProc(clientData);
- }
-}
-\f
-/*
- *---------------------------------------------------------------------------
- *
- * 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(
- void *ptr) /* Pointer to an arbitrary block of memory to
- * be tracked for deletion. Must not be
- * NULL. */
-{
- HandleStruct *handlePtr = ckalloc(sizeof(HandleStruct));
-
- handlePtr->ptr = ptr;
-#ifdef TCL_MEM_DEBUG
- handlePtr->ptr2 = ptr;
-#endif
- handlePtr->refCount = 0;
- return (TclHandle) handlePtr;
-}
-\f
-/*
- *---------------------------------------------------------------------------
- *
- * 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(
- 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) {
- Tcl_Panic("using previously disposed TclHandle %p", handlePtr);
- }
- if (handlePtr->ptr2 != handlePtr->ptr) {
- Tcl_Panic("someone has changed the block referenced by the handle %p\nfrom %p to %p",
- handlePtr, handlePtr->ptr2, handlePtr->ptr);
- }
-#endif
- handlePtr->ptr = NULL;
- if (handlePtr->refCount == 0) {
- ckfree(handlePtr);
- }
-}
-\f
-/*
- *---------------------------------------------------------------------------
- *
- * 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(
- 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) {
- Tcl_Panic("using previously disposed TclHandle %p", handlePtr);
- }
- if ((handlePtr->ptr != NULL) && (handlePtr->ptr != handlePtr->ptr2)) {
- Tcl_Panic("someone has changed the block referenced by the handle %p\nfrom %p to %p",
- handlePtr, handlePtr->ptr2, handlePtr->ptr);
- }
-#endif
- handlePtr->refCount++;
-
- return handle;
-}
-\f
-/*
- *---------------------------------------------------------------------------
- *
- * TclHandleRelease --
- *
- * This function 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(
- 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) {
- Tcl_Panic("using previously disposed TclHandle %p", handlePtr);
- }
- if ((handlePtr->ptr != NULL) && (handlePtr->ptr != handlePtr->ptr2)) {
- Tcl_Panic("someone has changed the block referenced by the handle %p\nfrom %p to %p",
- handlePtr, handlePtr->ptr2, handlePtr->ptr);
- }
-#endif
- handlePtr->refCount--;
- if ((handlePtr->refCount == 0) && (handlePtr->ptr == NULL)) {
- ckfree(handlePtr);
- }
-}
-\f
-/*
- * Local Variables:
- * mode: c
- * c-basic-offset: 4
- * fill-column: 78
- * End:
- */
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