diff options
Diffstat (limited to 'src/include/serial.i')
| -rw-r--r-- | src/include/serial.i | 109 |
1 files changed, 73 insertions, 36 deletions
diff --git a/src/include/serial.i b/src/include/serial.i index 9e6b0f7916c..9e5acde9616 100644 --- a/src/include/serial.i +++ b/src/include/serial.i @@ -30,6 +30,32 @@ __page_write_gen_wrapped_check(WT_PAGE *page) } /* + * __insert_simple_func -- + * Worker function to add a WT_INSERT entry to the middle of a skiplist. + */ +static inline int +__insert_simple_func(WT_SESSION_IMPL *session, + WT_INSERT ***ins_stack, WT_INSERT *new_ins, u_int skipdepth) +{ + u_int i; + + WT_UNUSED(session); + + /* + * Update the skiplist elements referencing the new WT_INSERT item. + * If we fail connecting one of the upper levels in the skiplist, + * return success: the levels we updated are correct and sufficient. + * Even though we don't get the benefit of the memory we allocated, + * we can't roll back. + */ + for (i = 0; i < skipdepth; i++) + if (!WT_ATOMIC_CAS8(*ins_stack[i], new_ins->next[i], new_ins)) + return (i == 0 ? WT_RESTART : 0); + + return (0); +} + +/* * __insert_serial_func -- * Worker function to add a WT_INSERT entry to a skiplist. */ @@ -42,31 +68,20 @@ __insert_serial_func(WT_SESSION_IMPL *session, WT_INSERT_HEAD *ins_head, WT_UNUSED(session); /* - * Confirm we are still in the expected position, and no item has been - * added where our insert belongs. Take extra care at the beginning - * and end of the list (at each level): retry if we race there. + * Update the skiplist elements referencing the new WT_INSERT item. * - * !!! - * Note the test for ins_stack[0] == NULL: that's the test for an - * uninitialized cursor, ins_stack[0] is cleared as part of - * initializing a cursor for a search. + * Confirm we are still in the expected position, and no item has been + * added where our insert belongs. If we fail connecting one of the + * upper levels in the skiplist, return success: the levels we updated + * are correct and sufficient. Even though we don't get the benefit of + * the memory we allocated, we can't roll back. */ for (i = 0; i < skipdepth; i++) { - if (ins_stack[i] == NULL || - *ins_stack[i] != new_ins->next[i]) - return (WT_RESTART); - if (new_ins->next[i] == NULL && - ins_head->tail[i] != NULL && - ins_stack[i] != &ins_head->tail[i]->next[i]) - return (WT_RESTART); - } - - /* Update the skiplist elements referencing the new WT_INSERT item. */ - for (i = 0; i < skipdepth; i++) { + if (!WT_ATOMIC_CAS8(*ins_stack[i], new_ins->next[i], new_ins)) + return (i == 0 ? WT_RESTART : 0); if (ins_head->tail[i] == NULL || ins_stack[i] == &ins_head->tail[i]->next[i]) ins_head->tail[i] = new_ins; - *ins_stack[i] = new_ins; } return (0); @@ -128,12 +143,19 @@ __wt_col_append_serial(WT_SESSION_IMPL *session, WT_PAGE *page, WT_INSERT *new_ins = *new_insp; WT_DECL_RET; - /* Clear references to memory we now own. */ - *new_insp = NULL; + /* !!! + * Test for an uninitialized cursor, ins_stack[0] is cleared as part of + * initializing a cursor for a search. + */ + if (ins_stack[0] == NULL) + return (WT_RESTART); /* Check for page write generation wrap. */ WT_RET(__page_write_gen_wrapped_check(page)); + /* Clear references to memory we now own and must free on error. */ + *new_insp = NULL; + /* Acquire the page's spinlock, call the worker function. */ WT_PAGE_LOCK(session, page); ret = __col_append_serial_func( @@ -171,21 +193,39 @@ __wt_insert_serial(WT_SESSION_IMPL *session, WT_PAGE *page, { WT_INSERT *new_ins = *new_insp; WT_DECL_RET; + int simple; + u_int i; - /* Clear references to memory we now own. */ - *new_insp = NULL; + /* !!! + * Test for an uninitialized cursor, ins_stack[0] is cleared as part of + * initializing a cursor for a search. + */ + if (ins_stack[0] == NULL) + return (WT_RESTART); /* Check for page write generation wrap. */ WT_RET(__page_write_gen_wrapped_check(page)); - /* Acquire the page's spinlock, call the worker function. */ - WT_PAGE_LOCK(session, page); - ret = __insert_serial_func( - session, ins_head, ins_stack, new_ins, skipdepth); - WT_PAGE_UNLOCK(session, page); + /* Clear references to memory we now own and must free on error. */ + *new_insp = NULL; + + simple = 1; + for (i = 0; i < skipdepth; i++) + if (new_ins->next[i] == NULL) + simple = 0; + + if (simple) + ret = __insert_simple_func( + session, ins_stack, new_ins, skipdepth); + else { + WT_PAGE_LOCK(session, page); + ret = __insert_serial_func( + session, ins_head, ins_stack, new_ins, skipdepth); + WT_PAGE_UNLOCK(session, page); + } - /* Free unused memory on error. */ if (ret != 0) { + /* Free unused memory on error. */ __wt_free(session, new_ins); return (ret); } @@ -215,17 +255,15 @@ __wt_update_serial(WT_SESSION_IMPL *session, WT_PAGE *page, WT_DECL_RET; WT_UPDATE *obsolete, *upd = *updp; - /* Clear references to memory we now own. */ - *updp = NULL; - /* Check for page write generation wrap. */ WT_RET(__page_write_gen_wrapped_check(page)); + /* Clear references to memory we now own and must free on error. */ + *updp = NULL; + /* * Swap the update into place. If that fails, a new update was added - * after our search, we raced. Check if our update is still permitted, - * and if it is, do a full-barrier to ensure the update's next pointer - * is set before we update the linked list and try again. + * after our search, we raced. Check if our update is still permitted. */ while (!WT_ATOMIC_CAS8(*srch_upd, upd->next, upd)) { if ((ret = __wt_txn_update_check( @@ -234,7 +272,6 @@ __wt_update_serial(WT_SESSION_IMPL *session, WT_PAGE *page, __wt_free(session, upd); return (ret); } - WT_WRITE_BARRIER(); } /* |