mariadb/storage/tokudb/ft-index/ft/le-cursor.cc
Sergei Golubchik b91432b4a4 tokudb 7.5.0
2014-09-23 22:03:35 +02:00

191 lines
7.4 KiB
C++

/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
#ident "$Id$"
/*
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COPYRIGHT NOTICE:
TokuFT, Tokutek Fractal Tree Indexing Library.
Copyright (C) 2007-2013 Tokutek, Inc.
DISCLAIMER:
This program is distributed in the hope that it will be useful, but
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UNIVERSITY PATENT NOTICE:
The technology is licensed by the Massachusetts Institute of
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Foundation of State University of New York at Stony Brook under
United States of America Serial No. 11/760379 and to the patents
and/or patent applications resulting from it.
PATENT MARKING NOTICE:
This software is covered by US Patent No. 8,185,551.
This software is covered by US Patent No. 8,489,638.
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*/
#ident "Copyright (c) 2010-2013 Tokutek Inc. All rights reserved."
#ident "The technology is licensed by the Massachusetts Institute of Technology, Rutgers State University of New Jersey, and the Research Foundation of State University of New York at Stony Brook under United States of America Serial No. 11/760379 and to the patents and/or patent applications resulting from it."
#include "ft/ft.h"
#include "ft/ft-internal.h"
#include "ft/le-cursor.h"
#include "ft/cursor.h"
// A LE_CURSOR is a special purpose FT_CURSOR that:
// - enables prefetching
// - does not perform snapshot reads. it reads everything, including uncommitted.
//
// A LE_CURSOR is good for scanning a FT from beginning to end. Useful for hot indexing.
struct le_cursor {
FT_CURSOR ft_cursor;
bool neg_infinity; // true when the le cursor is positioned at -infinity (initial setting)
bool pos_infinity; // true when the le cursor is positioned at +infinity (when _next returns DB_NOTFOUND)
};
int
toku_le_cursor_create(LE_CURSOR *le_cursor_result, FT_HANDLE ft_handle, TOKUTXN txn) {
int result = 0;
LE_CURSOR MALLOC(le_cursor);
if (le_cursor == NULL) {
result = get_error_errno();
}
else {
result = toku_ft_cursor(ft_handle, &le_cursor->ft_cursor, txn, false, false);
if (result == 0) {
// TODO move the leaf mode to the ft cursor constructor
toku_ft_cursor_set_leaf_mode(le_cursor->ft_cursor);
le_cursor->neg_infinity = false;
le_cursor->pos_infinity = true;
}
}
if (result == 0) {
*le_cursor_result = le_cursor;
} else {
toku_free(le_cursor);
}
return result;
}
void toku_le_cursor_close(LE_CURSOR le_cursor) {
toku_ft_cursor_close(le_cursor->ft_cursor);
toku_free(le_cursor);
}
// Move to the next leaf entry under the LE_CURSOR
// Success: returns zero, calls the getf callback with the getf_v parameter
// Failure: returns a non-zero error number
int
toku_le_cursor_next(LE_CURSOR le_cursor, FT_GET_CALLBACK_FUNCTION getf, void *getf_v) {
int result;
if (le_cursor->neg_infinity) {
result = DB_NOTFOUND;
} else {
le_cursor->pos_infinity = false;
// TODO replace this with a non deprecated function. Which?
result = toku_ft_cursor_get(le_cursor->ft_cursor, NULL, getf, getf_v, DB_PREV);
if (result == DB_NOTFOUND) {
le_cursor->neg_infinity = true;
}
}
return result;
}
bool
toku_le_cursor_is_key_greater_or_equal(LE_CURSOR le_cursor, const DBT *key) {
bool result;
if (le_cursor->neg_infinity) {
result = true; // all keys are greater than -infinity
} else if (le_cursor->pos_infinity) {
result = false; // all keys are less than +infinity
} else {
FT ft = le_cursor->ft_cursor->ft_handle->ft;
// get the current position from the cursor and compare it to the given key.
int r = ft->cmp(&le_cursor->ft_cursor->key, key);
if (r <= 0) {
result = true; // key is right of the cursor key
} else {
result = false; // key is at or left of the cursor key
}
}
return result;
}
void
toku_le_cursor_update_estimate(LE_CURSOR le_cursor, DBT* estimate) {
// don't handle these edge cases, not worth it.
// estimate stays same
if (le_cursor->pos_infinity || le_cursor->neg_infinity) {
return;
}
DBT *cursor_key = &le_cursor->ft_cursor->key;
estimate->data = toku_xrealloc(estimate->data, cursor_key->size);
memcpy(estimate->data, cursor_key->data, cursor_key->size);
estimate->size = cursor_key->size;
estimate->flags = DB_DBT_REALLOC;
}