156 lines
3.5 KiB
C++
156 lines
3.5 KiB
C++
/*
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* Copyright (c) 2018 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2024-11-16
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#pragma once
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#include <maxscale/ccdefs.hh>
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#include <list>
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#include <maxscale/buffer.hh>
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#include <maxscale/utils.hh>
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#include <maxscale/modutil.hh>
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// A transaction
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class Trx
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{
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public:
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// A log of executed queries, for transaction replay
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typedef std::list<mxs::Buffer> TrxLog;
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Trx()
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: m_size(0)
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{
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}
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/**
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* Add a statement to the transaction
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*
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* @param buf Statement to add
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*/
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void add_stmt(GWBUF* buf)
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{
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mxb_assert_message(buf, "Trx::add_stmt: Buffer must not be empty");
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if (mxs_log_is_priority_enabled(LOG_INFO))
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{
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MXS_INFO("Adding to trx: %s", mxs::extract_sql(buf, 512).c_str());
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}
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m_size += gwbuf_length(buf);
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m_log.emplace_back(buf);
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}
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/**
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* Add a result to the transaction
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*
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* The result is used to update the checksum.
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*
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* @param buf Result to add
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*/
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void add_result(GWBUF* buf)
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{
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m_checksum.update(buf);
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}
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/**
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* Releases the oldest statement in this transaction
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*
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* This reduces the size of the transaction by one and should only be used
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* to replay a transaction.
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*
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* @return The oldest statement in this transaction
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*/
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GWBUF* pop_stmt()
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{
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mxb_assert(!m_log.empty());
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GWBUF* rval = m_log.front().release();
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m_log.pop_front();
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return rval;
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}
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/**
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* Finalize the transaction
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*
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* This function marks the transaction as completed be that by a COMMIT
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* or by a failure of the current server where the transaction was being
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* executed.
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*/
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void finalize()
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{
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m_checksum.finalize();
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}
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/**
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* Check if transaction has statements
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*
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* @return True if transaction has statements
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*
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* @note This function should only be used when checking whether a transaction
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* that is being replayed has ended. The empty() method can be used
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* to check whether statements were added to the transaction.
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*/
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bool have_stmts() const
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{
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return !m_log.empty();
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}
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/**
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* Check whether the transaction is empty
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*
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* @return True if no statements have been added to the transaction
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*/
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bool empty() const
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{
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return m_size == 0;
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}
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/**
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* Get transaction size in bytes
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*
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* @return Size of the transaction in bytes
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*/
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size_t size() const
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{
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return m_size;
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}
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/**
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* Close the transaction
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*
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* This clears out the stored statements and resets the checksum state.
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*/
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void close()
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{
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m_checksum.reset();
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m_log.clear();
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m_size = 0;
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}
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/**
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* Return the current checksum
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*
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* finalize() must be called before the return value of this function is used.
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*
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* @return The checksum of the transaction
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*/
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const mxs::SHA1Checksum& checksum() const
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{
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return m_checksum;
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}
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private:
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mxs::SHA1Checksum m_checksum; /**< Checksum of the transaction */
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TrxLog m_log; /**< The transaction contents */
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size_t m_size; /**< Transaction size in bytes */
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};
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