Commit edf78694 authored by Howard Chu's avatar Howard Chu
Browse files

Add cursor_prev

parent cc56ba04
......@@ -362,6 +362,8 @@ static int mdb_set_key(MDB_node *node, MDB_val *key);
static int mdb_sibling(MDB_cursor *cursor, int move_right);
static int mdb_cursor_next(MDB_cursor *cursor,
MDB_val *key, MDB_val *data);
static int mdb_cursor_prev(MDB_cursor *cursor,
MDB_val *key, MDB_val *data);
static int mdb_cursor_set(MDB_cursor *cursor,
MDB_val *key, MDB_val *data, int *exactp);
static int mdb_cursor_first(MDB_cursor *cursor,
......@@ -1753,6 +1755,46 @@ mdb_cursor_next(MDB_cursor *cursor, MDB_val *key, MDB_val *data)
return mdb_set_key(leaf, key);
}
static int
mdb_cursor_prev(MDB_cursor *cursor, MDB_val *key, MDB_val *data)
{
MDB_ppage *top;
MDB_page *mp;
MDB_node *leaf;
assert(cursor->mc_initialized);
top = CURSOR_TOP(cursor);
mp = top->mp_page;
DPRINTF("cursor_prev: top page is %lu in cursor %p", mp->mp_pgno, (void *) cursor);
if (top->mp_ki == 0) {
DPRINTF("=====> move to prev sibling page");
if (mdb_sibling(cursor, 0) != MDB_SUCCESS) {
return ENOENT;
}
top = CURSOR_TOP(cursor);
mp = top->mp_page;
top->mp_ki = NUMKEYS(mp) - 1;
DPRINTF("prev page is %lu, key index %u", mp->mp_pgno, top->mp_ki);
} else
top->mp_ki--;
cursor->mc_eof = 0;
DPRINTF("==> cursor points to page %lu with %u keys, key index %u",
mp->mp_pgno, NUMKEYS(mp), top->mp_ki);
assert(IS_LEAF(mp));
leaf = NODEPTR(mp, top->mp_ki);
if (data && mdb_read_data(cursor->mc_txn->mt_env, leaf, data) != MDB_SUCCESS)
return MDB_FAIL;
return mdb_set_key(leaf, key);
}
static int
mdb_cursor_set(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
int *exactp)
......@@ -1831,6 +1873,7 @@ static int
mdb_cursor_last(MDB_cursor *cursor, MDB_val *key, MDB_val *data)
{
int rc;
MDB_ppage *top;
MDB_pageparent mpp;
MDB_node *leaf;
MDB_val lkey;
......@@ -1845,7 +1888,10 @@ mdb_cursor_last(MDB_cursor *cursor, MDB_val *key, MDB_val *data)
leaf = NODEPTR(mpp.mp_page, NUMKEYS(mpp.mp_page)-1);
cursor->mc_initialized = 1;
cursor->mc_eof = 1;
cursor->mc_eof = 0;
top = CURSOR_TOP(cursor);
top->mp_ki = NUMKEYS(top->mp_page) - 1;
if (data && (rc = mdb_read_data(cursor->mc_txn->mt_env, leaf, data)) != MDB_SUCCESS)
return rc;
......@@ -1880,6 +1926,14 @@ mdb_cursor_get(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
else
rc = mdb_cursor_next(cursor, key, data);
break;
case MDB_PREV:
if (!cursor->mc_initialized || cursor->mc_eof) {
while (CURSOR_TOP(cursor) != NULL)
cursor_pop_page(cursor);
rc = mdb_cursor_last(cursor, key, data);
} else
rc = mdb_cursor_prev(cursor, key, data);
break;
case MDB_FIRST:
while (CURSOR_TOP(cursor) != NULL)
cursor_pop_page(cursor);
......
......@@ -58,7 +58,7 @@ typedef enum MDB_cursor_op { /* cursor operations */
MDB_FIRST,
MDB_NEXT,
MDB_LAST,
MDB_PREV, /* not implemented */
MDB_PREV,
MDB_GET_BOTH, /* position at key/data */
MDB_GET_BOTH_RANGE /* position at key, nearest data */
} MDB_cursor_op;
......
......@@ -91,11 +91,18 @@ int main(int argc,char * argv[])
rc = mdbenv_stat(env, &mst);
rc = mdb_txn_begin(env, 1, &txn);
rc = mdb_cursor_open(txn, dbi, &cursor);
printf("Cursor next\n");
while ((rc = mdb_cursor_get(cursor, &key, &data, MDB_NEXT)) == 0) {
printf("key: %.*s, data: %.*s\n",
(int) key.mv_size, (char *) key.mv_data,
(int) data.mv_size, (char *) data.mv_data);
}
printf("Cursor prev\n");
while ((rc = mdb_cursor_get(cursor, &key, &data, MDB_PREV)) == 0) {
printf("key: %.*s, data: %.*s\n",
(int) key.mv_size, (char *) key.mv_data,
(int) data.mv_size, (char *) data.mv_data);
}
#if 0
/* write ops aren't coordinated with cursors,
* this stuff all breaks
......
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