michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /*
michael@0: ** Thread Private Data
michael@0: **
michael@0: ** There is an aribitrary limit on the number of keys that will be allocated
michael@0: ** by the runtime. It's largish, so it is intended to be a sanity check, not
michael@0: ** an impediment.
michael@0: **
michael@0: ** There is a counter, initialized to zero and incremented every time a
michael@0: ** client asks for a new key, that holds the high water mark for keys. All
michael@0: ** threads logically have the same high water mark and are permitted to
michael@0: ** ask for TPD up to that key value.
michael@0: **
michael@0: ** The vector to hold the TPD are allocated when PR_SetThreadPrivate() is
michael@0: ** called. The size of the vector will be some value greater than or equal
michael@0: ** to the current high water mark. Each thread has its own TPD length and
michael@0: ** vector.
michael@0: **
michael@0: ** Threads that get private data for keys they have not set (or perhaps
michael@0: ** don't even exist for that thread) get a NULL return. If the key is
michael@0: ** beyond the high water mark, an error will be returned.
michael@0: */
michael@0: 
michael@0: /*
michael@0: ** As of this time, BeOS has its own TPD implementation.  Integrating
michael@0: ** this standard one is a TODO for anyone with a bit of spare time on
michael@0: ** their hand.  For now, we just #ifdef out this whole file and use
michael@0: ** the routines in pr/src/btthreads/
michael@0: */
michael@0: 
michael@0: #ifndef XP_BEOS
michael@0: 
michael@0: #include "primpl.h"
michael@0: 
michael@0: #include <string.h>
michael@0: 
michael@0: #if defined(WIN95)
michael@0: /*
michael@0: ** Some local variables report warnings on Win95 because the code paths 
michael@0: ** using them are conditioned on HAVE_CUSTOME_USER_THREADS.
michael@0: ** The pragma suppresses the warning.
michael@0: ** 
michael@0: */
michael@0: #pragma warning(disable : 4101)
michael@0: #endif
michael@0: 
michael@0: #define _PR_TPD_LIMIT 128               /* arbitary limit on the TPD slots */
michael@0: static PRInt32 _pr_tpd_length = 0;      /* current length of destructor vector */
michael@0: static PRInt32 _pr_tpd_highwater = 0;   /* next TPD key to be assigned */
michael@0: static PRThreadPrivateDTOR *_pr_tpd_destructors = NULL;
michael@0:                                         /* the destructors are associated with
michael@0:                                             the keys, therefore asserting that
michael@0:                                             the TPD key depicts the data's 'type' */
michael@0: 
michael@0: /*
michael@0: ** Initialize the thread private data manipulation
michael@0: */
michael@0: void _PR_InitTPD(void)
michael@0: {
michael@0:     _pr_tpd_destructors = (PRThreadPrivateDTOR*)
michael@0:         PR_CALLOC(_PR_TPD_LIMIT * sizeof(PRThreadPrivateDTOR*));
michael@0:     PR_ASSERT(NULL != _pr_tpd_destructors);
michael@0:     _pr_tpd_length = _PR_TPD_LIMIT;
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Clean up the thread private data manipulation
michael@0: */
michael@0: void _PR_CleanupTPD(void)
michael@0: {
michael@0: }  /* _PR_CleanupTPD */
michael@0: 
michael@0: /*
michael@0: ** This routine returns a new index for per-thread-private data table. 
michael@0: ** The index is visible to all threads within a process. This index can 
michael@0: ** be used with the PR_SetThreadPrivate() and PR_GetThreadPrivate() routines 
michael@0: ** to save and retrieve data associated with the index for a thread.
michael@0: **
michael@0: ** The index independently maintains specific values for each binding thread. 
michael@0: ** A thread can only get access to its own thread-specific-data.
michael@0: **
michael@0: ** Upon a new index return the value associated with the index for all threads
michael@0: ** is NULL, and upon thread creation the value associated with all indices for 
michael@0: ** that thread is NULL. 
michael@0: **
michael@0: **     "dtor" is the destructor function to invoke when the private
michael@0: **       data is set or destroyed
michael@0: **
michael@0: ** Returns PR_FAILURE if the total number of indices will exceed the maximun 
michael@0: ** allowed.
michael@0: */
michael@0: 
michael@0: PR_IMPLEMENT(PRStatus) PR_NewThreadPrivateIndex(
michael@0:     PRUintn *newIndex, PRThreadPrivateDTOR dtor)
michael@0: {
michael@0:     PRStatus rv;
michael@0:     PRInt32 index;
michael@0: 
michael@0:     if (!_pr_initialized) _PR_ImplicitInitialization();
michael@0: 
michael@0:     PR_ASSERT(NULL != newIndex);
michael@0:     PR_ASSERT(NULL != _pr_tpd_destructors);
michael@0: 
michael@0:     index = PR_ATOMIC_INCREMENT(&_pr_tpd_highwater) - 1;  /* allocate index */
michael@0:     if (_PR_TPD_LIMIT <= index)
michael@0:     {
michael@0:         PR_SetError(PR_TPD_RANGE_ERROR, 0);
michael@0:         rv = PR_FAILURE;  /* that's just wrong */
michael@0:     }
michael@0:     else
michael@0:     {
michael@0:         _pr_tpd_destructors[index] = dtor;  /* record destructor @index */
michael@0:         *newIndex = (PRUintn)index;  /* copy into client's location */
michael@0:         rv = PR_SUCCESS;  /* that's okay */
michael@0:     }
michael@0: 
michael@0:     return rv;
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Define some per-thread-private data.
michael@0: **     "index" is an index into the per-thread private data table
michael@0: **     "priv" is the per-thread-private data 
michael@0: **
michael@0: ** If the per-thread private data table has a previously registered
michael@0: ** destructor function and a non-NULL per-thread-private data value,
michael@0: ** the destructor function is invoked.
michael@0: **
michael@0: ** This can return PR_FAILURE if index is invalid (ie., beyond the current
michael@0: ** high water mark) or memory is insufficient to allocate an exanded vector.
michael@0: */
michael@0: 
michael@0: PR_IMPLEMENT(PRStatus) PR_SetThreadPrivate(PRUintn index, void *priv)
michael@0: {
michael@0:     PRThread *self = PR_GetCurrentThread();
michael@0: 
michael@0:     /*
michael@0:     ** The index being set might not have a sufficient vector in this
michael@0:     ** thread. But if the index has been allocated, it's okay to go
michael@0:     ** ahead and extend this one now.
michael@0:     */
michael@0:     if ((index >= _PR_TPD_LIMIT) || (index >= _pr_tpd_highwater))
michael@0:     {
michael@0:         PR_SetError(PR_TPD_RANGE_ERROR, 0);
michael@0:         return PR_FAILURE;
michael@0:     }
michael@0: 
michael@0:     PR_ASSERT(((NULL == self->privateData) && (0 == self->tpdLength))
michael@0:         || ((NULL != self->privateData) && (0 != self->tpdLength)));
michael@0: 
michael@0:     if ((NULL == self->privateData) || (self->tpdLength <= index))
michael@0:     {
michael@0:         void *extension = PR_CALLOC(_pr_tpd_length * sizeof(void*));
michael@0:         if (NULL == extension)
michael@0:         {
michael@0:             PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
michael@0:             return PR_FAILURE;
michael@0:         }
michael@0:         if (self->privateData) {
michael@0:             (void)memcpy(
michael@0:                 extension, self->privateData,
michael@0:                 self->tpdLength * sizeof(void*));
michael@0:             PR_DELETE(self->privateData);
michael@0:         }
michael@0:         self->tpdLength = _pr_tpd_length;
michael@0:         self->privateData = (void**)extension;
michael@0:     }
michael@0:     /*
michael@0:     ** There wasn't much chance of having to call the destructor
michael@0:     ** unless the slot already existed.
michael@0:     */
michael@0:     else if (self->privateData[index] && _pr_tpd_destructors[index])
michael@0:     {
michael@0:         void *data = self->privateData[index];
michael@0:         self->privateData[index] = NULL;
michael@0:         (*_pr_tpd_destructors[index])(data);
michael@0:     }
michael@0: 
michael@0:     PR_ASSERT(index < self->tpdLength);
michael@0:     self->privateData[index] = priv;
michael@0: 
michael@0:     return PR_SUCCESS;
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Recover the per-thread-private data for the current thread. "index" is
michael@0: ** the index into the per-thread private data table. 
michael@0: **
michael@0: ** The returned value may be NULL which is indistinguishable from an error 
michael@0: ** condition.
michael@0: **
michael@0: */
michael@0: 
michael@0: PR_IMPLEMENT(void*) PR_GetThreadPrivate(PRUintn index)
michael@0: {
michael@0:     PRThread *self = PR_GetCurrentThread();
michael@0:     void *tpd = ((NULL == self->privateData) || (index >= self->tpdLength)) ?
michael@0:         NULL : self->privateData[index];
michael@0: 
michael@0:     return tpd;
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Destroy the thread's private data, if any exists. This is called at
michael@0: ** thread termination time only. There should be no threading issues
michael@0: ** since this is being called by the thread itself.
michael@0: */
michael@0: void _PR_DestroyThreadPrivate(PRThread* self)
michael@0: {
michael@0: #define _PR_TPD_DESTRUCTOR_ITERATIONS 4
michael@0: 
michael@0:     if (NULL != self->privateData)  /* we have some */
michael@0:     {
michael@0:         PRBool clean;
michael@0:         PRUint32 index;
michael@0:         PRInt32 passes = _PR_TPD_DESTRUCTOR_ITERATIONS;
michael@0:         PR_ASSERT(0 != self->tpdLength);
michael@0:         do
michael@0:         {
michael@0:             clean = PR_TRUE;
michael@0:             for (index = 0; index < self->tpdLength; ++index)
michael@0:             {
michael@0:                 void *priv = self->privateData[index];  /* extract */
michael@0:                 if (NULL != priv)  /* we have data at this index */
michael@0:                 {
michael@0:                     if (NULL != _pr_tpd_destructors[index])
michael@0:                     {
michael@0:                         self->privateData[index] = NULL;  /* precondition */
michael@0:                         (*_pr_tpd_destructors[index])(priv);  /* destroy */
michael@0:                         clean = PR_FALSE;  /* unknown side effects */
michael@0:                     }
michael@0:                 }
michael@0:             }
michael@0:         } while ((--passes > 0) && !clean);  /* limit # of passes */
michael@0:         /*
michael@0:         ** We give up after a fixed number of passes. Any non-NULL
michael@0:         ** thread-private data value with a registered destructor
michael@0:         ** function is not destroyed.
michael@0:         */
michael@0:         memset(self->privateData, 0, self->tpdLength * sizeof(void*));
michael@0:     }
michael@0: }  /* _PR_DestroyThreadPrivate */
michael@0: 
michael@0: #endif /* !XP_BEOS */