From e15d4d16b6a01ef0fb249885051bbc9e0756ead1 Mon Sep 17 00:00:00 2001 From: Howard Chu Date: Fri, 19 Aug 2011 00:14:16 -0700 Subject: [PATCH] Don't alloc in cursor_push/pop --- libraries/libmdb/mdb.c | 80 +++++++++++++++--------------------------- 1 file changed, 29 insertions(+), 51 deletions(-) diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c index 85535f8..0ca8ffd 100644 --- a/libraries/libmdb/mdb.c +++ b/libraries/libmdb/mdb.c @@ -29,7 +29,6 @@ */ #include #include -#include #include #include #include @@ -231,25 +230,19 @@ static MDB_dpage *mdb_alloc_page(MDB_txn *txn, MDB_page *parent, unsigned int pa static int mdb_touch(MDB_txn *txn, MDB_pageparent *mp); typedef struct MDB_ppage { /* ordered list of pages */ - SLIST_ENTRY(MDB_ppage) mp_entry; MDB_page *mp_page; unsigned int mp_ki; /* cursor index on page */ } MDB_ppage; -SLIST_HEAD(page_stack, MDB_ppage); -/* FIXME: tree depth is mostly bounded, we should just - * use a fixed array and avoid malloc/pointer chasing - */ -#define CURSOR_EMPTY(c) SLIST_EMPTY(&(c)->mc_stack) -#define CURSOR_TOP(c) SLIST_FIRST(&(c)->mc_stack) -#define CURSOR_POP(c) SLIST_REMOVE_HEAD(&(c)->mc_stack, mp_entry) -#define CURSOR_PUSH(c,p) SLIST_INSERT_HEAD(&(c)->mc_stack, p, mp_entry) +#define CURSOR_TOP(c) (&(c)->mc_stack[(c)->mc_snum-1]) +#define CURSOR_PARENT(c) (&(c)->mc_stack[(c)->mc_snum-2]) struct MDB_xcursor; struct MDB_cursor { MDB_txn *mc_txn; - struct page_stack mc_stack; /* stack of parent pages */ + MDB_ppage mc_stack[32]; /* stack of parent pages */ + unsigned int mc_snum; /* number of pushed pages */ MDB_dbi mc_dbi; short mc_initialized; /* 1 if initialized */ short mc_eof; /* 1 if end is reached */ @@ -1542,12 +1535,12 @@ cursor_pop_page(MDB_cursor *cursor) { MDB_ppage *top; - top = CURSOR_TOP(cursor); - CURSOR_POP(cursor); - - DPRINTF("popped page %lu off cursor %p", top->mp_page->mp_pgno, (void *) cursor); + if (cursor->mc_snum) { + top = CURSOR_TOP(cursor); + cursor->mc_snum--; - free(top); + DPRINTF("popped page %lu off cursor %p", top->mp_page->mp_pgno, (void *) cursor); + } } static MDB_ppage * @@ -1557,10 +1550,9 @@ cursor_push_page(MDB_cursor *cursor, MDB_page *mp) DPRINTF("pushing page %lu on cursor %p", mp->mp_pgno, (void *) cursor); - if ((ppage = calloc(1, sizeof(MDB_ppage))) == NULL) - return NULL; + ppage = &cursor->mc_stack[cursor->mc_snum++]; ppage->mp_page = mp; - CURSOR_PUSH(cursor, ppage); + ppage->mp_ki = 0; return ppage; } @@ -1794,13 +1786,13 @@ mdb_sibling(MDB_cursor *cursor, int move_right) { int rc; MDB_node *indx; - MDB_ppage *parent, *top; + MDB_ppage *parent; MDB_page *mp; - top = CURSOR_TOP(cursor); - if ((parent = SLIST_NEXT(top, mp_entry)) == NULL) { + if (cursor->mc_snum < 2) { return MDB_NOTFOUND; /* root has no siblings */ } + parent = CURSOR_PARENT(cursor); DPRINTF("parent page is page %lu, index %u", parent->mp_page->mp_pgno, parent->mp_ki); @@ -1979,8 +1971,7 @@ mdb_cursor_set(MDB_cursor *cursor, MDB_val *key, MDB_val *data, assert(key); assert(key->mv_size > 0); - while (CURSOR_TOP(cursor) != NULL) - cursor_pop_page(cursor); + cursor->mc_snum = 0; rc = mdb_search_page(cursor->mc_txn, cursor->mc_dbi, key, cursor, 0, &mpp); if (rc != MDB_SUCCESS) @@ -2054,8 +2045,7 @@ mdb_cursor_first(MDB_cursor *cursor, MDB_val *key, MDB_val *data) MDB_pageparent mpp; MDB_node *leaf; - while (CURSOR_TOP(cursor) != NULL) - cursor_pop_page(cursor); + cursor->mc_snum = 0; rc = mdb_search_page(cursor->mc_txn, cursor->mc_dbi, NULL, cursor, 0, &mpp); if (rc != MDB_SUCCESS) @@ -2089,8 +2079,7 @@ mdb_cursor_last(MDB_cursor *cursor, MDB_val *key, MDB_val *data) MDB_node *leaf; MDB_val lkey; - while (CURSOR_TOP(cursor) != NULL) - cursor_pop_page(cursor); + cursor->mc_snum = 0; lkey.mv_size = MAXKEYSIZE+1; lkey.mv_data = NULL; @@ -2387,7 +2376,7 @@ mdb_xcursor_init0(MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx) mx->mx_dbxs[dbn+1].md_dirty = 0; mx->mx_txn.mt_numdbs = dbn+2; - SLIST_INIT(&mx->mx_cursor.mc_stack); + mx->mx_cursor.mc_snum = 0; mx->mx_cursor.mc_txn = &mx->mx_txn; mx->mx_cursor.mc_dbi = dbn+1; } @@ -2442,7 +2431,6 @@ mdb_cursor_open(MDB_txn *txn, MDB_dbi dbi, MDB_cursor **ret) size += sizeof(MDB_xcursor); if ((cursor = calloc(1, size)) != NULL) { - SLIST_INIT(&cursor->mc_stack); cursor->mc_dbi = dbi; cursor->mc_txn = txn; if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT) { @@ -2480,13 +2468,6 @@ void mdb_cursor_close(MDB_cursor *cursor) { if (cursor != NULL) { - while(!CURSOR_EMPTY(cursor)) - cursor_pop_page(cursor); - if (cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_flags & MDB_DUPSORT) { - while(!CURSOR_EMPTY(&cursor->mc_xcursor->mx_cursor)) - cursor_pop_page(&cursor->mc_xcursor->mx_cursor); - } - free(cursor); } } @@ -2852,24 +2833,21 @@ mdb_del(MDB_txn *txn, MDB_dbi dbi, unsigned int i; cursor_pop_page(&mx.mx_cursor); - top = CURSOR_TOP(&mx.mx_cursor); - if (top != NULL) { - parent = SLIST_NEXT(top, mp_entry); - while (parent != NULL) { + if (mx.mx_cursor.mc_snum) { + top = CURSOR_TOP(&mx.mx_cursor); + while (mx.mx_cursor.mc_snum > 1) { + parent = CURSOR_PARENT(&mx.mx_cursor); for (i=0; imp_page); i++) { ni = NODEPTR(top->mp_page, i); mdb_midl_insert(txn->mt_free_pgs, ni->mn_pgno); } - if (parent) { - parent->mp_ki++; - if (parent->mp_ki >= NUMKEYS(parent->mp_page)) { - cursor_pop_page(&mx.mx_cursor); - top = CURSOR_TOP(&mx.mx_cursor); - parent = SLIST_NEXT(top, mp_entry); - } else { - ni = NODEPTR(parent->mp_page, parent->mp_ki); - top->mp_page = mdb_get_page(&mx.mx_txn, ni->mn_pgno); - } + parent->mp_ki++; + if (parent->mp_ki >= NUMKEYS(parent->mp_page)) { + cursor_pop_page(&mx.mx_cursor); + top = parent; + } else { + ni = NODEPTR(parent->mp_page, parent->mp_ki); + top->mp_page = mdb_get_page(&mx.mx_txn, ni->mn_pgno); } } }