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/*
* tclThreadStorage.c --
*
* This file implements platform independent thread storage operations.
*
* Copyright (c) 2003-2004 by Joe Mistachkin
* Copyright (c) 2008 by George Peter Staplin
*
* The primary idea is that we create one platform-specific TSD slot, and
* use it for storing a table pointer.
*
* Each Tcl_ThreadDataKey has an offset into the table of TSD values.
*
* We don't use more than 1 platform-specific TSD slot, because there is
* a hard limit on the number of TSD slots.
*
* Valid key offsets are > 0. 0 is for the initialized Tcl_ThreadDataKey.
*
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
* RCS: @(#) $Id: tclThreadStorage.c,v 1.16 2008/05/09 04:58:54 georgeps Exp $
*/
#include "tclInt.h"
#include <signal.h>
#if defined(TCL_THREADS)
static void *tclTsdKey = NULL;
static Tcl_Mutex tclTsdMutex;
static sig_atomic_t tclTsdCounter = 0;
typedef struct TSDTable {
sig_atomic_t allocated;
void **table;
} TSDTable;
typedef union {
void *ptr;
volatile sig_atomic_t offset;
} TSDUnion;
static TSDTable *TSDTableCreate(void);
static void TSDTableDelete(TSDTable *t);
static void TSDTableGrow(TSDTable *t, sig_atomic_t atLeast);
static TSDTable *
TSDTableCreate(void) {
TSDTable *t;
sig_atomic_t i;
t = TclpSysAlloc(sizeof *t, 0);
if (NULL == t) {
Tcl_Panic("unable to allocate TSDTable");
}
t->allocated = 8;
t->table = TclpSysAlloc(sizeof (*(t->table)) * t->allocated, 0);
if (NULL == t->table) {
Tcl_Panic("unable to allocate TSDTable");
}
for (i = 0; i < t->allocated; ++i) {
t->table[i] = NULL;
}
return t;
}
static void
TSDTableDelete(TSDTable *t) {
TclpSysFree(t->table);
TclpSysFree(t);
}
/*
*----------------------------------------------------------------------
*
* TSDTableGrow --
*
* This procedure makes the passed TSDTable grow to fit the atLeast value.
*
* Side effects: The table is enlarged.
*
*----------------------------------------------------------------------
*/
static void
TSDTableGrow(TSDTable *t, sig_atomic_t atLeast) {
sig_atomic_t newAllocated = t->allocated * 2;
void **newTablePtr;
sig_atomic_t i;
if (newAllocated <= atLeast) {
newAllocated = atLeast + 10;
}
newTablePtr = TclpSysRealloc(t->table, sizeof (*newTablePtr) * newAllocated);
if (NULL == newTablePtr) {
Tcl_Panic("unable to reallocate TSDTable");
}
for (i = t->allocated; i < newAllocated; ++i) {
newTablePtr[i] = NULL;
}
t->allocated = newAllocated;
t->table = newTablePtr;
}
/*
*----------------------------------------------------------------------
*
* TclThreadStorageKeyGet --
*
* This procedure gets the value associated with the passed key.
*
* Results: A pointer value associated with the Tcl_ThreadDataKey or NULL.
*
*----------------------------------------------------------------------
*/
void *
TclThreadStorageKeyGet(Tcl_ThreadDataKey *dataKeyPtr) {
TSDTable *t = TclpThreadGetMasterTSD(tclTsdKey);
void *resultPtr = NULL;
TSDUnion *keyPtr = (TSDUnion *)dataKeyPtr;
sig_atomic_t offset = keyPtr->offset;
if (t == NULL) {
return NULL;
}
if (offset && offset > 0 && offset < t->allocated) {
resultPtr = t->table[offset];
}
return resultPtr;
}
/*
*----------------------------------------------------------------------
*
* TclThreadStorageKeySet --
*
* This procedure set an association of value with the key passed.
* The associated value may be retrieved with TclThreadDataKeyGet().
*
* Side effects: The thread-specific table may be created or reallocated.
*
*----------------------------------------------------------------------
*/
void
TclThreadStorageKeySet(Tcl_ThreadDataKey *dataKeyPtr, void *value) {
TSDTable *t = TclpThreadGetMasterTSD(tclTsdKey);
TSDUnion *keyPtr = (TSDUnion *)dataKeyPtr;
if (NULL == t) {
t = TSDTableCreate();
TclpThreadSetMasterTSD(tclTsdKey, t);
}
Tcl_MutexLock(&tclTsdMutex);
if (0 == keyPtr->offset) {
/*
* The Tcl_ThreadDataKey hasn't been used yet.
*/
++tclTsdCounter;
if (tclTsdCounter >= t->allocated) {
TSDTableGrow(t, tclTsdCounter);
}
keyPtr->offset = tclTsdCounter;
t->table[tclTsdCounter] = value;
} else {
if (keyPtr->offset >= t->allocated) {
/*
* This is the first time this Tcl_ThreadDataKey has been
* used with the current thread.
*/
TSDTableGrow(t, keyPtr->offset);
}
t->table[keyPtr->offset] = value;
}
Tcl_MutexUnlock(&tclTsdMutex);
}
/*
*----------------------------------------------------------------------
*
* TclFinalizeThreadDataThread --
*
* This procedure finalizes the data for a single thread.
*
*
* Side effects: The TSDTable is deleted/freed.
*----------------------------------------------------------------------
*/
void
TclFinalizeThreadDataThread(void) {
TSDTable *t = TclpThreadGetMasterTSD(tclTsdKey);
if (NULL == t) {
return;
}
TSDTableDelete(t);
TclpThreadSetMasterTSD(tclTsdKey, NULL);
}
/*
*----------------------------------------------------------------------
*
* TclInitializeThreadStorage --
*
* This procedure initializes the TSD subsystem with per-platform
* code. This should be called before any Tcl threads are created.
*
*----------------------------------------------------------------------
*/
void
TclInitThreadStorage(void) {
tclTsdKey = TclpThreadCreateKey();
}
/*
*----------------------------------------------------------------------
*
* TclFinalizeThreadStorage --
*
* This procedure cleans up the thread storage data key for all
* threads.
*
* IMPORTANT: All Tcl threads must be finalized before calling this!
*
* Results:
* None.
*
* Side effects:
* Releases the thread data key.
*
*----------------------------------------------------------------------
*/
void
TclFinalizeThreadStorage(void) {
TclpThreadDeleteKey(tclTsdKey);
tclTsdKey = NULL;
}
#else /* !defined(TCL_THREADS) */
/*
* Stub functions for non-threaded builds
*/
void
TclInitThreadStorage(void)
{
}
void
TclFinalizeThreadDataThread(void)
{
}
void
TclFinalizeThreadStorage(void)
{
}
#endif /* defined(TCL_THREADS) && defined(USE_THREAD_STORAGE) */
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/
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