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Clean up and simplify mdb_page_search().

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Only named DBs can have DB_STALE, and they do not use MDB_PS_MODIFY.
Replace magic key values with flags.  Drop duplicated comments at
mdb_page_search_root() vs. mdb_page_search(), and rephrase.
This commit is contained in:
Hallvard Furuseth 2013-09-23 20:21:11 +02:00
parent 31cfca9316
commit 2980bd30f5
1 changed files with 29 additions and 50 deletions
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79
libraries/liblmdb/mdb.c
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@ -869,8 +869,8 @@ struct MDB_txn {
* @{
*/
#define DB_DIRTY 0x01 /**< DB was written in this txn */
#define DB_STALE 0x02 /**< DB record is older than txnID */
#define DB_NEW 0x04 /**< DB handle opened in this txn */
#define DB_STALE 0x02 /**< Named-DB record is older than txnID */
#define DB_NEW 0x04 /**< Named-DB handle opened in this txn */
#define DB_VALID 0x08 /**< DB handle is valid, see also #MDB_VALID */
/** @} */
/** In write txns, array of cursors for each DB */
@ -1056,6 +1056,8 @@ static int mdb_page_search_root(MDB_cursor *mc,
MDB_val *key, int modify);
#define MDB_PS_MODIFY 1
#define MDB_PS_ROOTONLY 2
#define MDB_PS_FIRST 4
#define MDB_PS_LAST 8
static int mdb_page_search(MDB_cursor *mc,
MDB_val *key, int flags);
static int mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst);
@ -1269,7 +1271,7 @@ static void mdb_audit(MDB_txn *txn)
txn->mt_dbs[i].md_leaf_pages +
txn->mt_dbs[i].md_overflow_pages;
if (txn->mt_dbs[i].md_flags & MDB_DUPSORT) {
mdb_page_search(&mc, NULL, 0);
mdb_page_search(&mc, NULL, MDB_PS_FIRST);
do {
unsigned j;
MDB_page *mp;
@ -2474,7 +2476,7 @@ mdb_freelist_save(MDB_txn *txn)
if (env->me_pghead) {
/* Make sure first page of freeDB is touched and on freelist */
rc = mdb_page_search(&mc, NULL, MDB_PS_MODIFY);
rc = mdb_page_search(&mc, NULL, MDB_PS_FIRST|MDB_PS_MODIFY);
if (rc && rc != MDB_NOTFOUND)
return rc;
}
@ -2502,9 +2504,7 @@ mdb_freelist_save(MDB_txn *txn)
if (freecnt < txn->mt_free_pgs[0]) {
if (!freecnt) {
/* Make sure last page of freeDB is touched and on freelist */
key.mv_size = MDB_MAXKEYSIZE+1;
key.mv_data = NULL;
rc = mdb_page_search(&mc, &key, MDB_PS_MODIFY);
rc = mdb_page_search(&mc, NULL, MDB_PS_LAST|MDB_PS_MODIFY);
if (rc && rc != MDB_NOTFOUND)
return rc;
}
@ -4579,18 +4579,11 @@ done:
return MDB_SUCCESS;
}
/** Search for the page a given key should be in.
* Pushes parent pages on the cursor stack. This function continues a
* search on a cursor that has already been initialized. (Usually by
* #mdb_page_search() but also by #mdb_node_move().)
* @param[in,out] mc the cursor for this operation.
* @param[in] key the key to search for. If NULL, search for the lowest
* page. (This is used by #mdb_cursor_first().)
* @param[in] modify If true, visited pages are updated with new page numbers.
* @return 0 on success, non-zero on failure.
/** Finish #mdb_page_search() / #mdb_page_search_lowest().
* The cursor is at the root page, set up the rest of it.
*/
static int
mdb_page_search_root(MDB_cursor *mc, MDB_val *key, int modify)
mdb_page_search_root(MDB_cursor *mc, MDB_val *key, int flags)
{
MDB_page *mp = mc->mc_pg[mc->mc_top];
int rc;
@ -4604,11 +4597,10 @@ mdb_page_search_root(MDB_cursor *mc, MDB_val *key, int modify)
assert(NUMKEYS(mp) > 1);
DPRINTF(("found index 0 to page %"Z"u", NODEPGNO(NODEPTR(mp, 0))));
if (key == NULL) /* Initialize cursor to first page. */
if (flags & (MDB_PS_FIRST|MDB_PS_LAST)) {
i = 0;
else if (key->mv_size > MDB_MAXKEYSIZE && key->mv_data == NULL) {
/* cursor to last page */
i = NUMKEYS(mp)-1;
if (flags & MDB_PS_LAST)
i = NUMKEYS(mp) - 1;
} else {
int exact;
node = mdb_node_search(mc, key, &exact);
@ -4621,10 +4613,9 @@ mdb_page_search_root(MDB_cursor *mc, MDB_val *key, int modify)
i--;
}
}
DPRINTF(("following index %u for key [%s]", i, DKEY(key)));
}
if (key)
DPRINTF(("following index %u for key [%s]", i, DKEY(key)));
assert(i < NUMKEYS(mp));
node = NODEPTR(mp, i);
@ -4635,7 +4626,7 @@ mdb_page_search_root(MDB_cursor *mc, MDB_val *key, int modify)
if ((rc = mdb_cursor_push(mc, mp)))
return rc;
if (modify) {
if (flags & MDB_PS_MODIFY) {
if ((rc = mdb_page_touch(mc)) != 0)
return rc;
mp = mc->mc_pg[mc->mc_top];
@ -4675,18 +4666,17 @@ mdb_page_search_lowest(MDB_cursor *mc)
mc->mc_ki[mc->mc_top] = 0;
if ((rc = mdb_cursor_push(mc, mp)))
return rc;
return mdb_page_search_root(mc, NULL, 0);
return mdb_page_search_root(mc, NULL, MDB_PS_FIRST);
}
/** Search for the page a given key should be in.
* Pushes parent pages on the cursor stack. This function just sets up
* the search; it finds the root page for \b mc's database and sets this
* as the root of the cursor's stack. Then #mdb_page_search_root() is
* called to complete the search.
* Push it and its parent pages on the cursor stack.
* @param[in,out] mc the cursor for this operation.
* @param[in] key the key to search for. If NULL, search for the lowest
* page. (This is used by #mdb_cursor_first().)
* @param[in] flags If MDB_PS_MODIFY set, visited pages are updated with new page numbers.
* @param[in] key the key to search for, or NULL for first/last page.
* @param[in] flags If MDB_PS_MODIFY is set, visited pages in the DB
* are touched (updated with new page numbers).
* If MDB_PS_FIRST or MDB_PS_LAST is set, find first or last leaf.
* This is used by #mdb_cursor_first() and #mdb_cursor_last().
* If MDB_PS_ROOTONLY set, just fetch root node, no further lookups.
* @return 0 on success, non-zero on failure.
*/
@ -4697,23 +4687,20 @@ mdb_page_search(MDB_cursor *mc, MDB_val *key, int flags)
pgno_t root;
/* Make sure the txn is still viable, then find the root from
* the txn's db table.
* the txn's db table and set it as the root of the cursor's stack.
*/
if (F_ISSET(mc->mc_txn->mt_flags, MDB_TXN_ERROR)) {
DPUTS("transaction has failed, must abort");
return MDB_BAD_TXN;
} else {
/* Make sure we're using an up-to-date root */
if (mc->mc_dbi > MAIN_DBI) {
if ((*mc->mc_dbflag & DB_STALE) ||
((flags & MDB_PS_MODIFY) && !(*mc->mc_dbflag & DB_DIRTY))) {
if (*mc->mc_dbflag & DB_STALE) {
MDB_cursor mc2;
unsigned char dbflag = 0;
mdb_cursor_init(&mc2, mc->mc_txn, MAIN_DBI, NULL);
rc = mdb_page_search(&mc2, &mc->mc_dbx->md_name, flags & MDB_PS_MODIFY);
rc = mdb_page_search(&mc2, &mc->mc_dbx->md_name, 0);
if (rc)
return rc;
if (*mc->mc_dbflag & DB_STALE) {
{
MDB_val data;
int exact = 0;
uint16_t flags;
@ -4733,11 +4720,7 @@ mdb_page_search(MDB_cursor *mc, MDB_val *key, int flags)
return MDB_INCOMPATIBLE;
memcpy(mc->mc_db, data.mv_data, sizeof(MDB_db));
}
if (flags & MDB_PS_MODIFY)
dbflag = DB_DIRTY;
*mc->mc_dbflag &= ~DB_STALE;
*mc->mc_dbflag |= dbflag;
}
}
root = mc->mc_db->md_root;
@ -5310,7 +5293,7 @@ mdb_cursor_first(MDB_cursor *mc, MDB_val *key, MDB_val *data)
mc->mc_xcursor->mx_cursor.mc_flags &= ~(C_INITIALIZED|C_EOF);
if (!(mc->mc_flags & C_INITIALIZED) || mc->mc_top) {
rc = mdb_page_search(mc, NULL, 0);
rc = mdb_page_search(mc, NULL, MDB_PS_FIRST);
if (rc != MDB_SUCCESS)
return rc;
}
@ -5356,11 +5339,7 @@ mdb_cursor_last(MDB_cursor *mc, MDB_val *key, MDB_val *data)
if (!(mc->mc_flags & C_EOF)) {
if (!(mc->mc_flags & C_INITIALIZED) || mc->mc_top) {
MDB_val lkey;
lkey.mv_size = MDB_MAXKEYSIZE+1;
lkey.mv_data = NULL;
rc = mdb_page_search(mc, &lkey, 0);
rc = mdb_page_search(mc, NULL, MDB_PS_LAST);
if (rc != MDB_SUCCESS)
return rc;
}
@ -8056,7 +8035,7 @@ mdb_drop0(MDB_cursor *mc, int subs)
{
int rc;
rc = mdb_page_search(mc, NULL, 0);
rc = mdb_page_search(mc, NULL, MDB_PS_FIRST);
if (rc == MDB_SUCCESS) {
MDB_txn *txn = mc->mc_txn;
MDB_node *ni;