diff options
Diffstat (limited to 'nsprpub/pr/src/threads/combined/prustack.c')
| -rw-r--r-- | nsprpub/pr/src/threads/combined/prustack.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/nsprpub/pr/src/threads/combined/prustack.c b/nsprpub/pr/src/threads/combined/prustack.c new file mode 100644 index 0000000000..3f5452c48c --- /dev/null +++ b/nsprpub/pr/src/threads/combined/prustack.c @@ -0,0 +1,175 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "primpl.h" + +/* List of free stack virtual memory chunks */ +PRLock *_pr_stackLock; +PRCList _pr_freeStacks = PR_INIT_STATIC_CLIST(&_pr_freeStacks); +PRIntn _pr_numFreeStacks; +PRIntn _pr_maxFreeStacks = 4; + +#ifdef DEBUG +/* +** A variable that can be set via the debugger... +*/ +PRBool _pr_debugStacks = PR_FALSE; +#endif + +/* How much space to leave between the stacks, at each end */ +#define REDZONE (2 << _pr_pageShift) + +#define _PR_THREAD_STACK_PTR(_qp) \ + ((PRThreadStack*) ((char*) (_qp) - offsetof(PRThreadStack,links))) + +void _PR_InitStacks(void) +{ + _pr_stackLock = PR_NewLock(); +} + +void _PR_CleanupStacks(void) +{ + if (_pr_stackLock) { + PR_DestroyLock(_pr_stackLock); + _pr_stackLock = NULL; + } +} + +/* +** Allocate a stack for a thread. +*/ +PRThreadStack *_PR_NewStack(PRUint32 stackSize) +{ + PRCList *qp; + PRThreadStack *ts; + PRThread *thr; + + /* + ** Trim the list of free stacks. Trim it backwards, tossing out the + ** oldest stack found first (this way more recent stacks have a + ** chance of being present in the data cache). + */ + PR_Lock(_pr_stackLock); + qp = _pr_freeStacks.prev; + while ((_pr_numFreeStacks > _pr_maxFreeStacks) && (qp != &_pr_freeStacks)) { + ts = _PR_THREAD_STACK_PTR(qp); + thr = _PR_THREAD_STACK_TO_PTR(ts); + qp = qp->prev; + /* + * skip stacks which are still being used + */ + if (thr->no_sched) { + continue; + } + PR_REMOVE_LINK(&ts->links); + + /* Give platform OS to clear out the stack for debugging */ + _PR_MD_CLEAR_STACK(ts); + + _pr_numFreeStacks--; + _PR_DestroySegment(ts->seg); + PR_DELETE(ts); + } + + /* + ** Find a free thread stack. This searches the list of free'd up + ** virtually mapped thread stacks. + */ + qp = _pr_freeStacks.next; + ts = 0; + while (qp != &_pr_freeStacks) { + ts = _PR_THREAD_STACK_PTR(qp); + thr = _PR_THREAD_STACK_TO_PTR(ts); + qp = qp->next; + /* + * skip stacks which are still being used + */ + if ((!(thr->no_sched)) && ((ts->allocSize - 2*REDZONE) >= stackSize)) { + /* + ** Found a stack that is not in use and is big enough. Change + ** stackSize to fit it. + */ + stackSize = ts->allocSize - 2*REDZONE; + PR_REMOVE_LINK(&ts->links); + _pr_numFreeStacks--; + ts->links.next = 0; + ts->links.prev = 0; + PR_Unlock(_pr_stackLock); + goto done; + } + ts = 0; + } + PR_Unlock(_pr_stackLock); + + if (!ts) { + /* Make a new thread stack object. */ + ts = PR_NEWZAP(PRThreadStack); + if (!ts) { + return NULL; + } + + /* + ** Assign some of the virtual space to the new stack object. We + ** may not get that piece of VM, but if nothing else we will + ** advance the pointer so we don't collide (unless the OS screws + ** up). + */ + ts->allocSize = stackSize + 2*REDZONE; + ts->seg = _PR_NewSegment(ts->allocSize, 0); + if (!ts->seg) { + PR_DELETE(ts); + return NULL; + } + } + +done: + ts->allocBase = (char*)ts->seg->vaddr; + ts->flags = _PR_STACK_MAPPED; + ts->stackSize = stackSize; + +#ifdef HAVE_STACK_GROWING_UP + ts->stackTop = ts->allocBase + REDZONE; + ts->stackBottom = ts->stackTop + stackSize; +#else + ts->stackBottom = ts->allocBase + REDZONE; + ts->stackTop = ts->stackBottom + stackSize; +#endif + + PR_LOG(_pr_thread_lm, PR_LOG_NOTICE, + ("thread stack: base=0x%x limit=0x%x bottom=0x%x top=0x%x\n", + ts->allocBase, ts->allocBase + ts->allocSize - 1, + ts->allocBase + REDZONE, + ts->allocBase + REDZONE + stackSize - 1)); + + _PR_MD_INIT_STACK(ts,REDZONE); + + return ts; +} + +/* +** Free the stack for the current thread +*/ +void _PR_FreeStack(PRThreadStack *ts) +{ + if (!ts) { + return; + } + if (ts->flags & _PR_STACK_PRIMORDIAL) { + PR_DELETE(ts); + return; + } + + /* + ** Put the stack on the free list. This is done because we are still + ** using the stack. Next time a thread is created we will trim the + ** list down; it's safe to do it then because we will have had to + ** context switch to a live stack before another thread can be + ** created. + */ + PR_Lock(_pr_stackLock); + PR_APPEND_LINK(&ts->links, _pr_freeStacks.prev); + _pr_numFreeStacks++; + PR_Unlock(_pr_stackLock); +} |