91 lines
3.1 KiB
C++
91 lines
3.1 KiB
C++
/* Copyright (c) 2005, 2024, Oracle and/or its affiliates.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is designed to work with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have either included with
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the program or referenced in the documentation.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#ifndef _sql_cursor_h_
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#define _sql_cursor_h_
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#include <stddef.h>
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#include <sys/types.h>
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#include <new>
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#include "sql/sql_class.h" /* Query_arena */
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class Query_result;
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struct MEM_ROOT;
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/**
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@file
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Declarations for implementation of server side cursors. Only
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read-only non-scrollable cursors are currently implemented.
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*/
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/**
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Server_side_cursor -- an interface for materialized
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implementation of cursors. All cursors are self-contained
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(created in their own memory root). For that reason they must
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be deleted only using a pointer to Server_side_cursor, not to
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its base class.
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*/
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class Server_side_cursor {
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public:
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/**
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For allocation of Handler objects for the temporary table. The prepared
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statement's mem_root cannot be used, since the handler may be created and
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deleted several times. The execution mem_root cannot be used since
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creation of and retrieval from a cursor are in different executions.
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*/
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MEM_ROOT mem_root{key_memory_TABLE, 1024};
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protected:
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Query_arena m_arena;
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/** Row destination used for fetch */
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Query_result *m_result;
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public:
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Server_side_cursor(Query_result *result_arg)
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: m_arena(&mem_root, Query_arena::STMT_INITIALIZED),
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m_result(result_arg) {}
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virtual bool is_open() const = 0;
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virtual bool open(THD *thd) = 0;
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virtual bool fetch(ulong num_rows) = 0;
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virtual void close() = 0;
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virtual ~Server_side_cursor() { mem_root.Clear(); }
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static void *operator new(size_t size, MEM_ROOT *mem_root,
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const std::nothrow_t & = std::nothrow) noexcept {
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return mem_root->Alloc(size);
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}
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static void operator delete(void *, size_t) {}
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static void operator delete(
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void *, MEM_ROOT *, const std::nothrow_t &) noexcept { /* never called */
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}
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};
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Query_result *new_cursor_result(MEM_ROOT *mem_root, Query_result *result);
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bool mysql_open_cursor(THD *thd, Query_result *result,
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Server_side_cursor **res);
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#endif /* _sql_cursor_h_ */
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