diff options
| -rw-r--r-- | src/btree/bt_debug.c | 2 | ||||
| -rw-r--r-- | src/btree/bt_split.c | 74 | ||||
| -rw-r--r-- | src/include/btmem.h | 8 | ||||
| -rw-r--r-- | src/include/btree.i | 4 | ||||
| -rw-r--r-- | src/include/extern.h | 1 |
5 files changed, 47 insertions, 42 deletions
diff --git a/src/btree/bt_debug.c b/src/btree/bt_debug.c index a89eca230fd..d664da2ebd3 100644 --- a/src/btree/bt_debug.c +++ b/src/btree/bt_debug.c @@ -699,8 +699,6 @@ __debug_page_metadata(WT_DBG *ds, WT_REF *ref) WT_RET(ds->f(ds, ", evict-lru")); if (F_ISSET_ATOMIC(page, WT_PAGE_OVERFLOW_KEYS)) WT_RET(ds->f(ds, ", overflow-keys")); - if (F_ISSET_ATOMIC(page, WT_PAGE_SPLIT_BLOCK)) - WT_RET(ds->f(ds, ", split-block")); if (F_ISSET_ATOMIC(page, WT_PAGE_SPLIT_INSERT)) WT_RET(ds->f(ds, ", split-insert")); if (F_ISSET_ATOMIC(page, WT_PAGE_UPDATE_IGNORE)) diff --git a/src/btree/bt_split.c b/src/btree/bt_split.c index 7cfcd08f931..8122d242666 100644 --- a/src/btree/bt_split.c +++ b/src/btree/bt_split.c @@ -54,6 +54,16 @@ __split_oldest_gen(WT_SESSION_IMPL *session) } /* + * __wt_split_obsolete -- + * Check if it is safe to free / evict based on split generation. + */ +bool +__wt_split_obsolete(WT_SESSION_IMPL *session, uint64_t split_gen) +{ + return (split_gen < __split_oldest_gen(session)); +} + +/* * __split_stash_add -- * Add a new entry into the session's split stash list. */ @@ -394,8 +404,8 @@ __split_ref_move(WT_SESSION_IMPL *session, WT_PAGE *from_home, * Prepare a set of WT_REFs for a move. */ static void -__split_ref_step1( - WT_SESSION_IMPL *session, WT_PAGE_INDEX *pindex, bool skip_first) +__split_ref_step1(WT_SESSION_IMPL *session, + WT_PAGE_INDEX *pindex, uint64_t split_gen, bool skip_first) { WT_PAGE *child; WT_REF *child_ref, *ref; @@ -418,30 +428,25 @@ __split_ref_step1( child = ref->page; /* - * Block eviction and splits in newly created pages. + * Block eviction in newly created pages. * * Once the split is live, newly created internal pages might be * evicted and their WT_REF structures freed. If that happened * before all threads exit the index of the page that previously * "owned" the WT_REF, a thread might see a freed WT_REF. To - * ensure that doesn't happen, the newly created page's modify - * structure has a field with a transaction ID that's checked - * before any internal page is evicted. Unfortunately, we don't - * know the correct value until we update the original page's - * index (we need a transaction ID from after that update), but - * the act of updating the original page's index is what allows - * the eviction to happen. + * ensure that doesn't happen, the newly created page contains + * the current split generation and can't be evicted until + * all readers have left the old generation. * - * Split blocking was because historic versions of the split - * code didn't update the WT_REF.home field until after the - * split was live, so the WT_REF.home fields being updated could - * split again before the update, there's a race between splits - * as to which would update them first. The current code updates - * the WT_REF.home fields before going live (in this function), - * this shouldn't be an issue, but for now splits remain turned - * off. + * Historic, we also blocked splits in newly created pages + * because we didn't update the WT_REF.home field until after + * the split was live, so the WT_REF.home fields being updated + * could split again before the update, there's a race between + * splits as to which would update them first. The current code + * updates the WT_REF.home fields before going live (in this + * function), this isn't an issue. */ - F_SET_ATOMIC(child, WT_PAGE_SPLIT_BLOCK); + child->pg_intl_split_gen = split_gen; /* * We use a page flag to prevent the child from splitting from @@ -473,7 +478,6 @@ __split_ref_step2( WT_SESSION_IMPL *session, WT_PAGE_INDEX *pindex, bool skip_first) { WT_DECL_RET; - WT_PAGE *child; WT_REF *ref; uint32_t i; @@ -503,14 +507,9 @@ __split_ref_step2( continue; WT_ERR(ret); - child = ref->page; - - /* The child can now be evicted or split. */ - F_CLR_ATOMIC(child, WT_PAGE_SPLIT_BLOCK); - #ifdef HAVE_DIAGNOSTIC WT_WITH_PAGE_INDEX(session, - __split_verify_intl_key_order(session, child)); + __split_verify_intl_key_order(session, ref->page)); #endif WT_ERR(__wt_hazard_clear(session, ref)); @@ -653,8 +652,12 @@ __split_root(WT_SESSION_IMPL *session, WT_PAGE *root) /* Start making real changes to the tree, errors are fatal. */ complete = WT_ERR_PANIC; + /* Get a generation for this split, mark the root page. */ + split_gen = __wt_atomic_addv64(&S2C(session)->split_gen, 1); + root->pg_intl_split_gen = split_gen; + /* Prepare the WT_REFs for the move. */ - __split_ref_step1(session, alloc_index, false); + __split_ref_step1(session, alloc_index, split_gen, false); /* * Confirm the root page's index hasn't moved, then update it, which @@ -686,7 +689,6 @@ __split_root(WT_SESSION_IMPL *session, WT_PAGE *root) * fails, we don't roll back that change, because threads may already * be using the new index. */ - split_gen = __wt_atomic_addv64(&S2C(session)->split_gen, 1); size = sizeof(WT_PAGE_INDEX) + pindex->entries * sizeof(WT_REF *); WT_TRET(__split_safe_free(session, split_gen, false, pindex, size)); root_decr += size; @@ -838,6 +840,10 @@ __split_parent(WT_SESSION_IMPL *session, WT_REF *ref, WT_REF **ref_new, /* Start making real changes to the tree, errors are fatal. */ complete = WT_ERR_PANIC; + /* Get a generation for this split, mark the parent page. */ + split_gen = __wt_atomic_addv64(&S2C(session)->split_gen, 1); + parent->pg_intl_split_gen = split_gen; + /* * Confirm the parent page's index hasn't moved then update it, which * makes the split visible to threads descending the tree. @@ -908,7 +914,6 @@ __split_parent(WT_SESSION_IMPL *session, WT_REF *ref, WT_REF **ref_new, * * Acquire a new split generation. */ - split_gen = __wt_atomic_addv64(&S2C(session)->split_gen, 1); for (i = 0, deleted_refs = scr->mem; i < deleted_entries; ++i) { next_ref = pindex->index[deleted_refs[i]]; WT_ASSERT(session, next_ref->state == WT_REF_SPLIT); @@ -1160,8 +1165,12 @@ __split_internal(WT_SESSION_IMPL *session, WT_PAGE *parent, WT_PAGE *page) /* Start making real changes to the tree, errors are fatal. */ complete = WT_ERR_PANIC; + /* Get a generation for this split, mark the page. */ + split_gen = __wt_atomic_addv64(&S2C(session)->split_gen, 1); + page->pg_intl_split_gen = split_gen; + /* Prepare the WT_REFs for the move. */ - __split_ref_step1(session, alloc_index, true); + __split_ref_step1(session, alloc_index, split_gen, true); /* Split into the parent. */ WT_ERR(__split_parent(session, page_ref, alloc_index->index, @@ -1207,7 +1216,6 @@ __split_internal(WT_SESSION_IMPL *session, WT_PAGE *parent, WT_PAGE *page) * back that change, because threads may already be using the new parent * page. */ - split_gen = __wt_atomic_addv64(&S2C(session)->split_gen, 1); size = sizeof(WT_PAGE_INDEX) + pindex->entries * sizeof(WT_REF *); WT_TRET(__split_safe_free(session, split_gen, false, pindex, size)); page_decr += size; @@ -1284,10 +1292,6 @@ __split_internal_lock(WT_SESSION_IMPL *session, WT_REF *ref, bool trylock, for (;;) { parent = ref->home; - /* Skip pages that aren't ready to split. */ - if (F_ISSET_ATOMIC(parent, WT_PAGE_SPLIT_BLOCK)) - return (EBUSY); - if (trylock) WT_RET(__wt_try_writelock(session, &parent->page_lock)); else diff --git a/src/include/btmem.h b/src/include/btmem.h index 43c1a309d52..39ca223aebf 100644 --- a/src/include/btmem.h +++ b/src/include/btmem.h @@ -483,6 +483,7 @@ struct __wt_page { */ struct { WT_REF *parent_ref; /* Parent reference */ + uint64_t split_gen; /* Generation of last split */ struct __wt_page_index { uint32_t entries; @@ -492,6 +493,8 @@ struct __wt_page { } intl; #undef pg_intl_parent_ref #define pg_intl_parent_ref u.intl.parent_ref +#undef pg_intl_split_gen +#define pg_intl_split_gen u.intl.split_gen /* * Macros to copy/set the index because the name is obscured to ensure @@ -593,9 +596,8 @@ struct __wt_page { #define WT_PAGE_DISK_MAPPED 0x04 /* Disk image in mapped memory */ #define WT_PAGE_EVICT_LRU 0x08 /* Page is on the LRU queue */ #define WT_PAGE_OVERFLOW_KEYS 0x10 /* Page has overflow keys */ -#define WT_PAGE_SPLIT_BLOCK 0x20 /* Split blocking eviction and splits */ -#define WT_PAGE_SPLIT_INSERT 0x40 /* A leaf page was split for append */ -#define WT_PAGE_UPDATE_IGNORE 0x80 /* Ignore updates on page discard */ +#define WT_PAGE_SPLIT_INSERT 0x20 /* A leaf page was split for append */ +#define WT_PAGE_UPDATE_IGNORE 0x40 /* Ignore updates on page discard */ uint8_t flags_atomic; /* Atomic flags, use F_*_ATOMIC */ uint8_t unused[2]; /* Unused padding */ diff --git a/src/include/btree.i b/src/include/btree.i index 378d93dd2ee..315efa86fa6 100644 --- a/src/include/btree.i +++ b/src/include/btree.i @@ -1348,8 +1348,8 @@ __wt_page_can_evict( * discards its WT_REF array, and a thread traversing the original * parent page index might see a freed WT_REF. */ - if (WT_PAGE_IS_INTERNAL(page) && - F_ISSET_ATOMIC(page, WT_PAGE_SPLIT_BLOCK)) + if (WT_PAGE_IS_INTERNAL(page) && !__wt_split_obsolete( + session, page->pg_intl_split_gen)) return (false); /* diff --git a/src/include/extern.h b/src/include/extern.h index 863d2a02861..836a7cb1ae6 100644 --- a/src/include/extern.h +++ b/src/include/extern.h @@ -160,6 +160,7 @@ __wt_page_in_func(WT_SESSION_IMPL *session, WT_REF *ref, uint32_t flags extern int __wt_bt_rebalance(WT_SESSION_IMPL *session, const char *cfg[]) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result)) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("hidden"))); extern int __wt_kv_return(WT_SESSION_IMPL *session, WT_CURSOR_BTREE *cbt, WT_UPDATE *upd) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result)) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("hidden"))); extern int __wt_bt_salvage(WT_SESSION_IMPL *session, WT_CKPT *ckptbase, const char *cfg[]) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result)) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("hidden"))); +extern bool __wt_split_obsolete(WT_SESSION_IMPL *session, uint64_t split_gen) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("hidden"))); extern void __wt_split_stash_discard(WT_SESSION_IMPL *session) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("hidden"))); extern void __wt_split_stash_discard_all( WT_SESSION_IMPL *session_safe, WT_SESSION_IMPL *session) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("hidden"))); extern int __wt_multi_to_ref(WT_SESSION_IMPL *session, WT_PAGE *page, WT_MULTI *multi, WT_REF **refp, size_t *incrp, bool closing) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result)) WT_GCC_FUNC_DECL_ATTRIBUTE((visibility("hidden"))); |