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fix concurrency bug that cropped up when the concurrent buffer manager was used with the concurrent wrapper replacement policy. Concurrent wrapper hashes on pageid, but the buffer manager was changing the pageid out from under it

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This commit is contained in:
Sears Russell 2010-03-31 22:39:07 +00:00
parent d281282533
commit 358f037441
1 changed files with 4 additions and 14 deletions
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18
src/stasis/bufferManager/concurrentBufferManager.c
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@ -41,12 +41,6 @@ static void pageSetNode(void * page, node_t * n, void * ignore) {
p->prev = (Page *) n;
}
//static inline struct Page_s ** pagePendingPtr(Page * p) {
// return ((struct Page_s **)(&((p)->next)));
//}
//static inline intptr_t* pagePinCountPtr(Page * p) {
// return ((intptr_t*)(&((p)->queue)));
//}
static inline int needFlush(stasis_buffer_manager_t * bm) {
stasis_buffer_concurrent_hash_t *bh = bm->impl;
pageid_t count = stasis_dirty_page_table_dirty_count(bh->dpt);
@ -144,13 +138,6 @@ static inline stasis_buffer_concurrent_hash_tls_t * populateTLS(stasis_buffer_ma
assert(!tls->p->dirty);
unlock(tls->p->loadlatch);
break;
// } else if(tls->p) {
// // page is pinned or something. Oh well. Throw this one back (atomically).
// hashtable_remove_cancel(ch->ht, &h);
// // hit the page. This is safe because lru latches it. (We might be hitting some arbitrary page here, but don't care)
// ch->lru->hit(ch->lru, tmp);
// // Go around the loop again.
// tls->p = NULL;
} else {
// page is not in hashtable, but it is in LRU. getStale and hashtable remove are not atomic.
// However, we cannot observe this; the lru remove happens before the hashtable remove,
@ -179,12 +166,15 @@ static Page * chLoadPageImpl_helper(stasis_buffer_manager_t* bm, int xid, const
int succ = trywritelock(p->loadlatch, 0);
assert(succ);
// this has to happen before the page enters LRU; concurrentWrapper (and perhaps future implementations) hash on pageid.
p->id = pageid;
// this has to happen after the hashtable insertion succeeds, otherwise above, we could get a page from lru that isn't in the cache.
ch->lru->insert(ch->lru, p);
hashtable_unlock(&h);
p->id = pageid;
if(uninitialized) {
type = UNINITIALIZED_PAGE;
stasis_page_loaded(p, UNINITIALIZED_PAGE);