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Clean up mdb_page_touch(), mdb_page_copy().

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When copying, round up/down to aligned sizes. Skip the unused portion,
this was not done when touching a page dirty in the parent txn.
No other change in behavior.

Simplify mdb_page_touch(), including: Drop test m3==mc, the condition
is caught below. Don't "modify" the parent's pgno into the same pgno,
when a nested txn copies a parent's page into its freelist.
This commit is contained in:
Hallvard Furuseth 2013-06-13 08:58:24 +02:00
parent 79844bd446
commit 7030ad16e2
1 changed files with 61 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

130
libraries/liblmdb/mdb.c
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@ -1563,7 +1563,7 @@ none:
return MDB_SUCCESS;
}
/** Copy a page: avoid copying unused portions of the page.
/** Copy the used portions of a non-overflow page.
* @param[in] dst page to copy into
* @param[in] src page to copy from
* @param[in] psize size of a page
@ -1571,17 +1571,19 @@ none:
static void
mdb_page_copy(MDB_page *dst, MDB_page *src, unsigned int psize)
{
dst->mp_flags = src->mp_flags | P_DIRTY;
dst->mp_pages = src->mp_pages;
enum { Align = sizeof(pgno_t) };
indx_t upper = src->mp_upper, lower = src->mp_lower, unused = upper-lower;
if (IS_LEAF2(src)) {
memcpy(dst->mp_ptrs, src->mp_ptrs, psize - PAGEHDRSZ - SIZELEFT(src));
/* If page isn't full, just copy the used portion. Adjust
* alignment so memcpy may copy words instead of bytes.
*/
if ((unused &= -Align) && !IS_LEAF2(src)) {
upper &= -Align;
memcpy(dst, src, (lower + (Align-1)) & -Align);
memcpy((pgno_t *)((char *)dst+upper), (pgno_t *)((char *)src+upper),
psize - upper);
} else {
unsigned int i, nkeys = NUMKEYS(src);
for (i=0; i<nkeys; i++)
dst->mp_ptrs[i] = src->mp_ptrs[i];
memcpy((char *)dst+src->mp_upper, (char *)src+src->mp_upper,
psize - src->mp_upper);
memcpy(dst, src, psize - unused);
}
}
@ -1592,76 +1594,36 @@ mdb_page_copy(MDB_page *dst, MDB_page *src, unsigned int psize)
static int
mdb_page_touch(MDB_cursor *mc)
{
MDB_page *mp = mc->mc_pg[mc->mc_top];
MDB_page *mp = mc->mc_pg[mc->mc_top], *np;
MDB_cursor *m2, *m3;
MDB_dbi dbi;
pgno_t pgno;
int rc;
if (!F_ISSET(mp->mp_flags, P_DIRTY)) {
MDB_page *np;
if ((rc = mdb_page_alloc(mc, 1, &np)))
return rc;
DPRINTF("touched db %u page %zu -> %zu", mc->mc_dbi, mp->mp_pgno, np->mp_pgno);
assert(mp->mp_pgno != np->mp_pgno);
mdb_midl_append(&mc->mc_txn->mt_free_pgs, mp->mp_pgno);
if (SIZELEFT(mp)) {
/* If page isn't full, just copy the used portion */
mdb_page_copy(np, mp, mc->mc_txn->mt_env->me_psize);
} else {
pgno = np->mp_pgno;
memcpy(np, mp, mc->mc_txn->mt_env->me_psize);
np->mp_pgno = pgno;
np->mp_flags |= P_DIRTY;
}
mp = np;
finish:
/* Adjust other cursors pointing to mp */
if (mc->mc_flags & C_SUB) {
MDB_cursor *m2, *m3;
MDB_dbi dbi = mc->mc_dbi-1;
for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
m3 = &m2->mc_xcursor->mx_cursor;
if (m3 == mc) continue;
if (m3->mc_snum < mc->mc_snum) continue;
if (m3->mc_pg[mc->mc_top] == mc->mc_pg[mc->mc_top]) {
m3->mc_pg[mc->mc_top] = mp;
}
}
DPRINTF("touched db %u page %zu -> %zu", mc->mc_dbi,mp->mp_pgno,pgno);
assert(mp->mp_pgno != pgno);
mdb_midl_append(&mc->mc_txn->mt_free_pgs, mp->mp_pgno);
/* Update the parent page, if any, to point to the new page */
if (mc->mc_top) {
MDB_page *parent = mc->mc_pg[mc->mc_top-1];
MDB_node *node = NODEPTR(parent, mc->mc_ki[mc->mc_top-1]);
SETPGNO(node, pgno);
} else {
MDB_cursor *m2;
for (m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2; m2=m2->mc_next) {
if (m2 == mc || m2->mc_snum < mc->mc_snum) continue;
if (m2->mc_pg[mc->mc_top] == mc->mc_pg[mc->mc_top]) {
m2->mc_pg[mc->mc_top] = mp;
if ((mc->mc_db->md_flags & MDB_DUPSORT) &&
m2->mc_ki[mc->mc_top] == mc->mc_ki[mc->mc_top]) {
MDB_node *leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
if (!(leaf->mn_flags & F_SUBDATA)) {
m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
mc->mc_db->md_root = pgno;
}
}
}
}
}
mc->mc_pg[mc->mc_top] = mp;
/** If this page has a parent, update the parent to point to
* this new page.
*/
if (mc->mc_top)
SETPGNO(NODEPTR(mc->mc_pg[mc->mc_top-1], mc->mc_ki[mc->mc_top-1]), mp->mp_pgno);
else
mc->mc_db->md_root = mp->mp_pgno;
} else if (mc->mc_txn->mt_parent && !(mp->mp_flags & P_SUBP)) {
MDB_page *np;
MDB_ID2 mid, *dl = mc->mc_txn->mt_u.dirty_list;
pgno = mp->mp_pgno;
/* If txn has a parent, make sure the page is in our
* dirty list.
*/
if (dl[0].mid) {
unsigned x = mdb_mid2l_search(dl, mp->mp_pgno);
if (x <= dl[0].mid && dl[x].mid == mp->mp_pgno) {
unsigned x = mdb_mid2l_search(dl, pgno);
if (x <= dl[0].mid && dl[x].mid == pgno) {
np = dl[x].mptr;
if (mp != np)
mc->mc_pg[mc->mc_top] = np;
@ -1673,12 +1635,42 @@ finish:
np = mdb_page_malloc(mc, 1);
if (!np)
return ENOMEM;
memcpy(np, mp, mc->mc_txn->mt_env->me_psize);
mid.mid = np->mp_pgno;
mid.mid = pgno;
mid.mptr = np;
mdb_mid2l_insert(dl, &mid);
mp = np;
goto finish;
} else {
return 0;
}
mdb_page_copy(np, mp, mc->mc_txn->mt_env->me_psize);
np->mp_pgno = pgno;
np->mp_flags |= P_DIRTY;
/* Adjust cursors pointing to mp */
mc->mc_pg[mc->mc_top] = np;
dbi = mc->mc_dbi;
if (mc->mc_flags & C_SUB) {
dbi--;
for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
m3 = &m2->mc_xcursor->mx_cursor;
if (m3->mc_snum < mc->mc_snum) continue;
if (m3->mc_pg[mc->mc_top] == mp)
m3->mc_pg[mc->mc_top] = np;
}
} else {
for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
if (m2->mc_snum < mc->mc_snum) continue;
if (m2->mc_pg[mc->mc_top] == mp) {
m2->mc_pg[mc->mc_top] = np;
if ((mc->mc_db->md_flags & MDB_DUPSORT) &&
m2->mc_ki[mc->mc_top] == mc->mc_ki[mc->mc_top])
{
MDB_node *leaf = NODEPTR(np, mc->mc_ki[mc->mc_top]);
if (!(leaf->mn_flags & F_SUBDATA))
m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
}
}
}
}
return 0;
}