Java Code Examples for com.taobao.tddl.dbsync.binlog.LogBuffer#getFixString()

The following examples show how to use com.taobao.tddl.dbsync.binlog.LogBuffer#getFixString() . You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. You may check out the related API usage on the sidebar.
Example 1
Source File: RotateLogEvent.java    From canal-1.1.3 with Apache License 2.0 6 votes vote down vote up
/**
 * Creates a new <code>Rotate_log_event</code> object read normally from
 * log.
 * 
 * @throws MySQLExtractException
 */
public RotateLogEvent(LogHeader header, LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent){
    super(header);

    final int headerSize = descriptionEvent.commonHeaderLen;
    final int postHeaderLen = descriptionEvent.postHeaderLen[ROTATE_EVENT - 1];

    buffer.position(headerSize + R_POS_OFFSET);
    position = (postHeaderLen != 0) ? buffer.getLong64() : 4; // !uint8korr(buf
                                                              // +
                                                              // R_POS_OFFSET)

    final int filenameOffset = headerSize + postHeaderLen;
    int filenameLen = buffer.limit() - filenameOffset;
    if (filenameLen > FN_REFLEN - 1) filenameLen = FN_REFLEN - 1;
    buffer.position(filenameOffset);

    filename = buffer.getFixString(filenameLen);
}
 
Example 2
Source File: RotateLogEvent.java    From canal with Apache License 2.0 6 votes vote down vote up
/**
 * Creates a new <code>Rotate_log_event</code> object read normally from
 * log.
 * 
 * @throws MySQLExtractException
 */
public RotateLogEvent(LogHeader header, LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent){
    super(header);

    final int headerSize = descriptionEvent.commonHeaderLen;
    final int postHeaderLen = descriptionEvent.postHeaderLen[ROTATE_EVENT - 1];

    buffer.position(headerSize + R_POS_OFFSET);
    position = (postHeaderLen != 0) ? buffer.getLong64() : 4; // !uint8korr(buf
                                                              // +
                                                              // R_POS_OFFSET)

    final int filenameOffset = headerSize + postHeaderLen;
    int filenameLen = buffer.limit() - filenameOffset;
    if (filenameLen > FN_REFLEN - 1) filenameLen = FN_REFLEN - 1;
    buffer.position(filenameOffset);

    filename = buffer.getFixString(filenameLen);
}
 
Example 3
Source File: TableMapLogEvent.java    From canal-1.1.3 with Apache License 2.0 5 votes vote down vote up
private void parse_column_name(LogBuffer buffer, int length) {
    // stores column names extracted from field
    int limit = buffer.position() + length;
    int index = 0;
    while (buffer.hasRemaining() && buffer.position() < limit) {
        int len = (int) buffer.getPackedLong();
        columnInfo[index++].name = buffer.getFixString(len);
    }
}
 
Example 4
Source File: StartLogEventV3.java    From canal-1.1.3 with Apache License 2.0 5 votes vote down vote up
public StartLogEventV3(LogHeader header, LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent){
    super(header);

    buffer.position(descriptionEvent.commonHeaderLen);
    binlogVersion = buffer.getUint16(); // ST_BINLOG_VER_OFFSET
    serverVersion = buffer.getFixString(ST_SERVER_VER_LEN); // ST_SERVER_VER_OFFSET
}
 
Example 5
Source File: TableMapLogEvent.java    From canal with Apache License 2.0 5 votes vote down vote up
private void parse_column_name(LogBuffer buffer, int length) {
    // stores column names extracted from field
    int limit = buffer.position() + length;
    int index = 0;
    while (buffer.hasRemaining() && buffer.position() < limit) {
        int len = (int) buffer.getPackedLong();
        columnInfo[index++].name = buffer.getFixString(len);
    }
}
 
Example 6
Source File: StartLogEventV3.java    From canal with Apache License 2.0 5 votes vote down vote up
public StartLogEventV3(LogHeader header, LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent){
    super(header);

    buffer.position(descriptionEvent.commonHeaderLen);
    binlogVersion = buffer.getUint16(); // ST_BINLOG_VER_OFFSET
    serverVersion = buffer.getFixString(ST_SERVER_VER_LEN); // ST_SERVER_VER_OFFSET
}
 
Example 7
Source File: UserVarLogEvent.java    From canal-1.1.3 with Apache License 2.0 4 votes vote down vote up
public UserVarLogEvent(LogHeader header, LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent)
                                                                                                      throws IOException{
    super(header);

    /* The Post-Header is empty. The Variable Data part begins immediately. */
    buffer.position(descriptionEvent.commonHeaderLen + descriptionEvent.postHeaderLen[USER_VAR_EVENT - 1]);
    final int nameLen = (int) buffer.getUint32();
    name = buffer.getFixString(nameLen); // UV_NAME_LEN_SIZE
    isNull = (0 != buffer.getInt8());

    if (isNull) {
        type = STRING_RESULT;
        charsetNumber = 63; /* binary */
        value = null;
    } else {
        type = buffer.getInt8(); // UV_VAL_IS_NULL
        charsetNumber = (int) buffer.getUint32(); // buf + UV_VAL_TYPE_SIZE
        final int valueLen = (int) buffer.getUint32(); // buf +
                                                       // UV_CHARSET_NUMBER_SIZE
        final int limit = buffer.limit(); /* for restore */
        buffer.limit(buffer.position() + valueLen);

        /* @see User_var_log_event::print */
        switch (type) {
            case REAL_RESULT:
                value = Double.valueOf(buffer.getDouble64()); // float8get
                break;
            case INT_RESULT:
                if (valueLen == 8) value = Long.valueOf(buffer.getLong64()); // !uint8korr
                else if (valueLen == 4) value = Long.valueOf(buffer.getUint32());
                else throw new IOException("Error INT_RESULT length: " + valueLen);
                break;
            case DECIMAL_RESULT:
                final int precision = buffer.getInt8();
                final int scale = buffer.getInt8();
                value = buffer.getDecimal(precision, scale); // bin2decimal
                break;
            case STRING_RESULT:
                String charsetName = CharsetConversion.getJavaCharset(charsetNumber);
                value = buffer.getFixString(valueLen, charsetName);
                break;
            case ROW_RESULT:
                // this seems to be banned in MySQL altogether
                throw new IOException("ROW_RESULT is unsupported");
            default:
                value = null;
                break;
        }
        buffer.limit(limit);
    }
}
 
Example 8
Source File: LoadLogEvent.java    From canal-1.1.3 with Apache License 2.0 4 votes vote down vote up
/**
 * @see mysql-5.1.60/sql/log_event.cc - Load_log_event::copy_log_event
 */
protected final void copyLogEvent(LogBuffer buffer, final int bodyOffset, FormatDescriptionLogEvent descriptionEvent) {
    /* this is the beginning of the post-header */
    buffer.position(descriptionEvent.commonHeaderLen + L_EXEC_TIME_OFFSET);

    execTime = buffer.getUint32(); // L_EXEC_TIME_OFFSET
    skipLines = (int) buffer.getUint32(); // L_SKIP_LINES_OFFSET
    final int tableNameLen = buffer.getUint8(); // L_TBL_LEN_OFFSET
    final int dbLen = buffer.getUint8(); // L_DB_LEN_OFFSET
    numFields = (int) buffer.getUint32(); // L_NUM_FIELDS_OFFSET

    buffer.position(bodyOffset);
    /*
     * Sql_ex.init() on success returns the pointer to the first byte after
     * the sql_ex structure, which is the start of field lengths array.
     */
    if (header.type != LOAD_EVENT /* use_new_format */) {
        /*
         * The code below assumes that buf will not disappear from under our
         * feet during the lifetime of the event. This assumption holds true
         * in the slave thread if the log is in new format, but is not the
         * case when we have old format because we will be reusing net
         * buffer to read the actual file before we write out the
         * Create_file event.
         */
        fieldTerm = buffer.getString();
        enclosed = buffer.getString();
        lineTerm = buffer.getString();
        lineStart = buffer.getString();
        escaped = buffer.getString();
        optFlags = buffer.getInt8();
        emptyFlags = 0;
    } else {
        fieldTerm = buffer.getFixString(1);
        enclosed = buffer.getFixString(1);
        lineTerm = buffer.getFixString(1);
        lineStart = buffer.getFixString(1);
        escaped = buffer.getFixString(1);
        optFlags = buffer.getUint8();
        emptyFlags = buffer.getUint8();

        if ((emptyFlags & FIELD_TERM_EMPTY) != 0) fieldTerm = null;
        if ((emptyFlags & ENCLOSED_EMPTY) != 0) enclosed = null;
        if ((emptyFlags & LINE_TERM_EMPTY) != 0) lineTerm = null;
        if ((emptyFlags & LINE_START_EMPTY) != 0) lineStart = null;
        if ((emptyFlags & ESCAPED_EMPTY) != 0) escaped = null;
    }

    final int fieldLenPos = buffer.position();
    buffer.forward(numFields);
    fields = new String[numFields];
    for (int i = 0; i < numFields; i++) {
        final int fieldLen = buffer.getUint8(fieldLenPos + i);
        fields[i] = buffer.getFixString(fieldLen + 1);
    }

    table = buffer.getFixString(tableNameLen + 1);
    db = buffer.getFixString(dbLen + 1);

    // null termination is accomplished by the caller
    final int from = buffer.position();
    final int end = from + buffer.limit();
    int found = from;
    for (; (found < end) && buffer.getInt8(found) != '\0'; found++)
        /* empty loop */;
    fname = buffer.getString(found);
    buffer.forward(1); // The + 1 is for \0 terminating fname
}
 
Example 9
Source File: LogHeader.java    From canal-1.1.3 with Apache License 2.0 4 votes vote down vote up
public LogHeader(LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent){
    when = buffer.getUint32();
    type = buffer.getUint8(); // LogEvent.EVENT_TYPE_OFFSET;
    serverId = buffer.getUint32(); // LogEvent.SERVER_ID_OFFSET;
    eventLen = (int) buffer.getUint32(); // LogEvent.EVENT_LEN_OFFSET;

    if (descriptionEvent.binlogVersion == 1) {
        logPos = 0;
        flags = 0;
        return;
    }

    /* 4.0 or newer */
    logPos = buffer.getUint32(); // LogEvent.LOG_POS_OFFSET
    /*
     * If the log is 4.0 (so here it can only be a 4.0 relay log read by the
     * SQL thread or a 4.0 master binlog read by the I/O thread), log_pos is
     * the beginning of the event: we transform it into the end of the
     * event, which is more useful. But how do you know that the log is 4.0:
     * you know it if description_event is version 3 *and* you are not
     * reading a Format_desc (remember that mysqlbinlog starts by assuming
     * that 5.0 logs are in 4.0 format, until it finds a Format_desc).
     */
    if (descriptionEvent.binlogVersion == 3 && type < LogEvent.FORMAT_DESCRIPTION_EVENT && logPos != 0) {
        /*
         * If log_pos=0, don't change it. log_pos==0 is a marker to mean
         * "don't change rli->group_master_log_pos" (see
         * inc_group_relay_log_pos()). As it is unreal log_pos, adding the
         * event len's is nonsense. For example, a fake Rotate event should
         * not have its log_pos (which is 0) changed or it will modify
         * Exec_master_log_pos in SHOW SLAVE STATUS, displaying a nonsense
         * value of (a non-zero offset which does not exist in the master's
         * binlog, so which will cause problems if the user uses this value
         * in CHANGE MASTER).
         */
        logPos += eventLen; /* purecov: inspected */
    }

    flags = buffer.getUint16(); // LogEvent.FLAGS_OFFSET
    if ((type == LogEvent.FORMAT_DESCRIPTION_EVENT) || (type == LogEvent.ROTATE_EVENT)) {
        /*
         * These events always have a header which stops here (i.e. their
         * header is FROZEN).
         */
        /*
         * Initialization to zero of all other Log_event members as they're
         * not specified. Currently there are no such members; in the future
         * there will be an event UID (but Format_description and Rotate
         * don't need this UID, as they are not propagated through
         * --log-slave-updates (remember the UID is used to not play a query
         * twice when you have two masters which are slaves of a 3rd
         * master). Then we are done.
         */

        if (type == LogEvent.FORMAT_DESCRIPTION_EVENT) {
            int commonHeaderLen = buffer.getUint8(FormatDescriptionLogEvent.LOG_EVENT_MINIMAL_HEADER_LEN
                                                  + FormatDescriptionLogEvent.ST_COMMON_HEADER_LEN_OFFSET);
            buffer.position(commonHeaderLen + FormatDescriptionLogEvent.ST_SERVER_VER_OFFSET);
            String serverVersion = buffer.getFixString(FormatDescriptionLogEvent.ST_SERVER_VER_LEN); // ST_SERVER_VER_OFFSET
            int versionSplit[] = new int[] { 0, 0, 0 };
            FormatDescriptionLogEvent.doServerVersionSplit(serverVersion, versionSplit);
            checksumAlg = LogEvent.BINLOG_CHECKSUM_ALG_UNDEF;
            if (FormatDescriptionLogEvent.versionProduct(versionSplit) >= FormatDescriptionLogEvent.checksumVersionProduct) {
                buffer.position(eventLen - LogEvent.BINLOG_CHECKSUM_LEN - LogEvent.BINLOG_CHECKSUM_ALG_DESC_LEN);
                checksumAlg = buffer.getUint8();
            }

            processCheckSum(buffer);
        }
        return;
    }

    /*
     * CRC verification by SQL and Show-Binlog-Events master side. The
     * caller has to provide @description_event->checksum_alg to be the last
     * seen FD's (A) descriptor. If event is FD the descriptor is in it.
     * Notice, FD of the binlog can be only in one instance and therefore
     * Show-Binlog-Events executing master side thread needs just to know
     * the only FD's (A) value - whereas RL can contain more. In the RL
     * case, the alg is kept in FD_e (@description_event) which is reset to
     * the newer read-out event after its execution with possibly new alg
     * descriptor. Therefore in a typical sequence of RL: {FD_s^0, FD_m,
     * E_m^1} E_m^1 will be verified with (A) of FD_m. See legends
     * definition on MYSQL_BIN_LOG::relay_log_checksum_alg docs lines
     * (log.h). Notice, a pre-checksum FD version forces alg :=
     * BINLOG_CHECKSUM_ALG_UNDEF.
     */
    checksumAlg = descriptionEvent.getHeader().checksumAlg; // fetch
                                                            // checksum alg
    processCheckSum(buffer);
    /* otherwise, go on with reading the header from buf (nothing now) */
}
 
Example 10
Source File: UserVarLogEvent.java    From canal with Apache License 2.0 4 votes vote down vote up
public UserVarLogEvent(LogHeader header, LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent)
                                                                                                      throws IOException{
    super(header);

    /* The Post-Header is empty. The Variable Data part begins immediately. */
    buffer.position(descriptionEvent.commonHeaderLen + descriptionEvent.postHeaderLen[USER_VAR_EVENT - 1]);
    final int nameLen = (int) buffer.getUint32();
    name = buffer.getFixString(nameLen); // UV_NAME_LEN_SIZE
    isNull = (0 != buffer.getInt8());

    if (isNull) {
        type = STRING_RESULT;
        charsetNumber = 63; /* binary */
        value = null;
    } else {
        type = buffer.getInt8(); // UV_VAL_IS_NULL
        charsetNumber = (int) buffer.getUint32(); // buf + UV_VAL_TYPE_SIZE
        final int valueLen = (int) buffer.getUint32(); // buf +
                                                       // UV_CHARSET_NUMBER_SIZE
        final int limit = buffer.limit(); /* for restore */
        buffer.limit(buffer.position() + valueLen);

        /* @see User_var_log_event::print */
        switch (type) {
            case REAL_RESULT:
                value = Double.valueOf(buffer.getDouble64()); // float8get
                break;
            case INT_RESULT:
                if (valueLen == 8) value = Long.valueOf(buffer.getLong64()); // !uint8korr
                else if (valueLen == 4) value = Long.valueOf(buffer.getUint32());
                else throw new IOException("Error INT_RESULT length: " + valueLen);
                break;
            case DECIMAL_RESULT:
                final int precision = buffer.getInt8();
                final int scale = buffer.getInt8();
                value = buffer.getDecimal(precision, scale); // bin2decimal
                break;
            case STRING_RESULT:
                String charsetName = CharsetConversion.getJavaCharset(charsetNumber);
                value = buffer.getFixString(valueLen, charsetName);
                break;
            case ROW_RESULT:
                // this seems to be banned in MySQL altogether
                throw new IOException("ROW_RESULT is unsupported");
            default:
                value = null;
                break;
        }
        buffer.limit(limit);
    }
}
 
Example 11
Source File: LoadLogEvent.java    From canal with Apache License 2.0 4 votes vote down vote up
/**
 * @see mysql-5.1.60/sql/log_event.cc - Load_log_event::copy_log_event
 */
protected final void copyLogEvent(LogBuffer buffer, final int bodyOffset, FormatDescriptionLogEvent descriptionEvent) {
    /* this is the beginning of the post-header */
    buffer.position(descriptionEvent.commonHeaderLen + L_EXEC_TIME_OFFSET);

    execTime = buffer.getUint32(); // L_EXEC_TIME_OFFSET
    skipLines = (int) buffer.getUint32(); // L_SKIP_LINES_OFFSET
    final int tableNameLen = buffer.getUint8(); // L_TBL_LEN_OFFSET
    final int dbLen = buffer.getUint8(); // L_DB_LEN_OFFSET
    numFields = (int) buffer.getUint32(); // L_NUM_FIELDS_OFFSET

    buffer.position(bodyOffset);
    /*
     * Sql_ex.init() on success returns the pointer to the first byte after
     * the sql_ex structure, which is the start of field lengths array.
     */
    if (header.type != LOAD_EVENT /* use_new_format */) {
        /*
         * The code below assumes that buf will not disappear from under our
         * feet during the lifetime of the event. This assumption holds true
         * in the slave thread if the log is in new format, but is not the
         * case when we have old format because we will be reusing net
         * buffer to read the actual file before we write out the
         * Create_file event.
         */
        fieldTerm = buffer.getString();
        enclosed = buffer.getString();
        lineTerm = buffer.getString();
        lineStart = buffer.getString();
        escaped = buffer.getString();
        optFlags = buffer.getInt8();
        emptyFlags = 0;
    } else {
        fieldTerm = buffer.getFixString(1);
        enclosed = buffer.getFixString(1);
        lineTerm = buffer.getFixString(1);
        lineStart = buffer.getFixString(1);
        escaped = buffer.getFixString(1);
        optFlags = buffer.getUint8();
        emptyFlags = buffer.getUint8();

        if ((emptyFlags & FIELD_TERM_EMPTY) != 0) fieldTerm = null;
        if ((emptyFlags & ENCLOSED_EMPTY) != 0) enclosed = null;
        if ((emptyFlags & LINE_TERM_EMPTY) != 0) lineTerm = null;
        if ((emptyFlags & LINE_START_EMPTY) != 0) lineStart = null;
        if ((emptyFlags & ESCAPED_EMPTY) != 0) escaped = null;
    }

    final int fieldLenPos = buffer.position();
    buffer.forward(numFields);
    fields = new String[numFields];
    for (int i = 0; i < numFields; i++) {
        final int fieldLen = buffer.getUint8(fieldLenPos + i);
        fields[i] = buffer.getFixString(fieldLen + 1);
    }

    table = buffer.getFixString(tableNameLen + 1);
    db = buffer.getFixString(dbLen + 1);

    // null termination is accomplished by the caller
    final int from = buffer.position();
    final int end = from + buffer.limit();
    int found = from;
    for (; (found < end) && buffer.getInt8(found) != '\0'; found++)
        /* empty loop */;
    fname = buffer.getString(found);
    buffer.forward(1); // The + 1 is for \0 terminating fname
}
 
Example 12
Source File: LogHeader.java    From canal with Apache License 2.0 4 votes vote down vote up
public LogHeader(LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent){
    when = buffer.getUint32();
    type = buffer.getUint8(); // LogEvent.EVENT_TYPE_OFFSET;
    serverId = buffer.getUint32(); // LogEvent.SERVER_ID_OFFSET;
    eventLen = (int) buffer.getUint32(); // LogEvent.EVENT_LEN_OFFSET;

    if (descriptionEvent.binlogVersion == 1) {
        logPos = 0;
        flags = 0;
        return;
    }

    /* 4.0 or newer */
    logPos = buffer.getUint32(); // LogEvent.LOG_POS_OFFSET
    /*
     * If the log is 4.0 (so here it can only be a 4.0 relay log read by the
     * SQL thread or a 4.0 master binlog read by the I/O thread), log_pos is
     * the beginning of the event: we transform it into the end of the
     * event, which is more useful. But how do you know that the log is 4.0:
     * you know it if description_event is version 3 *and* you are not
     * reading a Format_desc (remember that mysqlbinlog starts by assuming
     * that 5.0 logs are in 4.0 format, until it finds a Format_desc).
     */
    if (descriptionEvent.binlogVersion == 3 && type < LogEvent.FORMAT_DESCRIPTION_EVENT && logPos != 0) {
        /*
         * If log_pos=0, don't change it. log_pos==0 is a marker to mean
         * "don't change rli->group_master_log_pos" (see
         * inc_group_relay_log_pos()). As it is unreal log_pos, adding the
         * event len's is nonsense. For example, a fake Rotate event should
         * not have its log_pos (which is 0) changed or it will modify
         * Exec_master_log_pos in SHOW SLAVE STATUS, displaying a nonsense
         * value of (a non-zero offset which does not exist in the master's
         * binlog, so which will cause problems if the user uses this value
         * in CHANGE MASTER).
         */
        logPos += eventLen; /* purecov: inspected */
    }

    flags = buffer.getUint16(); // LogEvent.FLAGS_OFFSET
    if ((type == LogEvent.FORMAT_DESCRIPTION_EVENT) || (type == LogEvent.ROTATE_EVENT)) {
        /*
         * These events always have a header which stops here (i.e. their
         * header is FROZEN).
         */
        /*
         * Initialization to zero of all other Log_event members as they're
         * not specified. Currently there are no such members; in the future
         * there will be an event UID (but Format_description and Rotate
         * don't need this UID, as they are not propagated through
         * --log-slave-updates (remember the UID is used to not play a query
         * twice when you have two masters which are slaves of a 3rd
         * master). Then we are done.
         */

        if (type == LogEvent.FORMAT_DESCRIPTION_EVENT) {
            int commonHeaderLen = buffer.getUint8(FormatDescriptionLogEvent.LOG_EVENT_MINIMAL_HEADER_LEN
                                                  + FormatDescriptionLogEvent.ST_COMMON_HEADER_LEN_OFFSET);
            buffer.position(commonHeaderLen + FormatDescriptionLogEvent.ST_SERVER_VER_OFFSET);
            String serverVersion = buffer.getFixString(FormatDescriptionLogEvent.ST_SERVER_VER_LEN); // ST_SERVER_VER_OFFSET
            int versionSplit[] = new int[] { 0, 0, 0 };
            FormatDescriptionLogEvent.doServerVersionSplit(serverVersion, versionSplit);
            checksumAlg = LogEvent.BINLOG_CHECKSUM_ALG_UNDEF;
            if (FormatDescriptionLogEvent.versionProduct(versionSplit) >= FormatDescriptionLogEvent.checksumVersionProduct) {
                buffer.position(eventLen - LogEvent.BINLOG_CHECKSUM_LEN - LogEvent.BINLOG_CHECKSUM_ALG_DESC_LEN);
                checksumAlg = buffer.getUint8();
            }

            processCheckSum(buffer);
        }
        return;
    }

    /*
     * CRC verification by SQL and Show-Binlog-Events master side. The
     * caller has to provide @description_event->checksum_alg to be the last
     * seen FD's (A) descriptor. If event is FD the descriptor is in it.
     * Notice, FD of the binlog can be only in one instance and therefore
     * Show-Binlog-Events executing master side thread needs just to know
     * the only FD's (A) value - whereas RL can contain more. In the RL
     * case, the alg is kept in FD_e (@description_event) which is reset to
     * the newer read-out event after its execution with possibly new alg
     * descriptor. Therefore in a typical sequence of RL: {FD_s^0, FD_m,
     * E_m^1} E_m^1 will be verified with (A) of FD_m. See legends
     * definition on MYSQL_BIN_LOG::relay_log_checksum_alg docs lines
     * (log.h). Notice, a pre-checksum FD version forces alg :=
     * BINLOG_CHECKSUM_ALG_UNDEF.
     */
    checksumAlg = descriptionEvent.getHeader().checksumAlg; // fetch
                                                            // checksum alg
    processCheckSum(buffer);
    /* otherwise, go on with reading the header from buf (nothing now) */
}