/// <summary>备份单表数据，抽取数据和写入文件双线程</summary>
/// <remarks>
/// 最大支持21亿行
/// </remarks>
/// <param name="table">数据表</param>
/// <param name="stream">目标数据流</param>
/// <returns></returns>
public virtual Int32 Backup(IDataTable table, Stream stream)
{
using var span = Tracer?.NewSpan("db:Backup", table.Name);
// 并行写入文件，提升吞吐
var writeFile = new WriteFileActor
{
Stream = stream,
// 最多同时堆积数
BoundedCapacity = 4,
TracerParent = span,
Tracer = Tracer,
Log = Log,
};
var tableName = Dal.Db.FormatName(table);
var sb = new SelectBuilder {
Table = tableName
};
var connName = Dal.ConnName;
var extracer = GetExtracter(table);
// 总行数
writeFile.Total = Dal.SelectCount(sb);
WriteLog("备份[{0}/{1}]开始，共[{2:n0}]行，抽取器{3}", table, connName, writeFile.Total, extracer);
// 临时关闭日志
var old = Dal.Db.ShowSQL;
Dal.Db.ShowSQL = false;
Dal.Session.ShowSQL = false;
var total = 0;
var sw = Stopwatch.StartNew();
try
{
foreach (var dt in extracer.Fetch())
{
var row = extracer.Row;
var count = dt.Rows.Count;
WriteLog("备份[{0}/{1}]数据 {2:n0} + {3:n0}", table, connName, row, count);
if (count == 0)
{
break;
}
// 字段名更换为属性名
for (var i = 0; i < dt.Columns.Length; i++)
{
var dc = table.GetColumn(dt.Columns[i]);
if (dc != null)
{
dt.Columns[i] = dc.Name;
}
}
// 进度报告、消费数据
OnProcess(table, row, dt, writeFile);
total += count;
}
// 通知写入完成
writeFile.Stop(-1);
}
catch (Exception ex)
{
span?.SetError(ex, table);
throw;
}
finally
{
Dal.Db.ShowSQL = old;
Dal.Session.ShowSQL = old;
}
sw.Stop();
var ms = sw.Elapsed.TotalMilliseconds;
WriteLog("备份[{0}/{1}]完成，共[{2:n0}]行，耗时{3:n0}ms，速度{4:n0}tps", table, connName, total, ms, total * 1000L / ms);
// 返回总行数
return(total);
}
