diff options
Diffstat (limited to 'generic/tclPreserve.c')
| -rw-r--r-- | generic/tclPreserve.c | 431 |
1 files changed, 314 insertions, 117 deletions
diff --git a/generic/tclPreserve.c b/generic/tclPreserve.c index ce20445..0bd8f93 100644 --- a/generic/tclPreserve.c +++ b/generic/tclPreserve.c @@ -1,57 +1,76 @@ -/* +/* * 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. + * 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) 1994-1995 Sun Microsystems, Inc. - * - * See the file "license.terms" for information on usage and redistribution - * of this file, and for a DISCLAIMER OF ALL WARRANTIES. + * Copyright (c) 1994-1998 Sun Microsystems, Inc. * - * RCS: @(#) $Id: tclPreserve.c,v 1.2 1998/09/14 18:40:02 stanton Exp $ + * 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. + * 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 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. */ + * effect, so the structure must be freed when + * refCount becomes zero. */ + Tcl_FreeProc *freeProc; /* Function 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 - /* - * Static routines in this file: + * Global data structures used to hold the list of preserved data references. + * These variables are protected by "preserveMutex". */ -static void PreserveExitProc _ANSI_ARGS_((ClientData clientData)); +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; /* *---------------------------------------------------------------------- * - * PreserveExitProc -- + * TclFinalizePreserve -- * * Called during exit processing to clean up the reference array. * @@ -65,16 +84,17 @@ static void PreserveExitProc _ANSI_ARGS_((ClientData clientData)); */ /* ARGSUSED */ -static void -PreserveExitProc(clientData) - ClientData clientData; /* NULL -Unused. */ +void +TclFinalizePreserve(void) { + Tcl_MutexLock(&preserveMutex); if (spaceAvl != 0) { - ckfree((char *) refArray); - refArray = (Reference *) NULL; - inUse = 0; - spaceAvl = 0; + ckfree(refArray); + refArray = NULL; + inUse = 0; + spaceAvl = 0; } + Tcl_MutexUnlock(&preserveMutex); } /* @@ -82,62 +102,49 @@ PreserveExitProc(clientData) * * 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. + * 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. + * 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. */ +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. + * See if there is already a reference for this pointer. If so, just + * increment its reference count. */ - for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) { + 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. + * 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; - } + spaceAvl = spaceAvl ? 2*spaceAvl : INITIAL_SIZE; + refArray = ckrealloc(refArray, spaceAvl * sizeof(Reference)); } /* @@ -150,6 +157,7 @@ Tcl_Preserve(clientData) refPtr->mustFree = 0; refPtr->freeProc = TCL_STATIC; inUse += 1; + Tcl_MutexUnlock(&preserveMutex); } /* @@ -157,67 +165,79 @@ Tcl_Preserve(clientData) * * 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). + * 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. + * 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. */ +Tcl_Release( + ClientData clientData) /* Pointer to malloc'ed block of memory. */ { Reference *refPtr; - int mustFree; - Tcl_FreeProc *freeProc; int i; - for (i = 0, refPtr = refArray; i < inUse; i++, refPtr++) { + Tcl_MutexLock(&preserveMutex); + for (i=0, refPtr=refArray ; i<inUse ; i++, refPtr++) { + int mustFree; + Tcl_FreeProc *freeProc; + 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 { - (*freeProc)((char *) clientData); - } + + 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. + * Reference not found. This is a bug in the caller. */ - panic("Tcl_Release couldn't find reference for 0x%x", clientData); + Tcl_Panic("Tcl_Release couldn't find reference for %p", clientData); } /* @@ -225,10 +245,9 @@ Tcl_Release(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. + * 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. @@ -240,38 +259,216 @@ Tcl_Release(clientData) */ void -Tcl_EventuallyFree(clientData, freeProc) - ClientData clientData; /* Pointer to malloc'ed block of memory. */ - Tcl_FreeProc *freeProc; /* Procedure to actually do free. */ +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!). + * 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; + Tcl_Panic("Tcl_EventuallyFree called twice for %p", clientData); + } + refPtr->mustFree = 1; refPtr->freeProc = freeProc; - return; + 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); + if (freeProc == TCL_DYNAMIC) { + ckfree(clientData); } else { - (*freeProc)((char *)clientData); + freeProc(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( + 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; +} + +/* + *--------------------------------------------------------------------------- + * + * 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); + } +} + +/* + *--------------------------------------------------------------------------- + * + * 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; +} + +/* + *--------------------------------------------------------------------------- + * + * 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); + } +} + +/* + * Local Variables: + * mode: c + * c-basic-offset: 4 + * fill-column: 78 + * End: + */ |