Common Transactions

1
Common Transactions

• Jim Johnson
• Microsoft

2
Introduction

• Transacted memory is a great idea
• Helps application simplicity and reliability
• Helps with concurrency control
• Based on a concept they already use
• Makes adoption easier
• Requires that we consider how to integrate
  it(not really green field)

3
An application today

• using (TransactionScope sc new TransactionScope
  ())
• using (SqlConnection cn new SqlConnection
  ())
• string sql "INSERT INTO "
• SqlCommand cmd new SqlCommand(sql, cn)
• cn.Open()
• cmd.ExecuteNonQuery()
• cn.Close()
• sc.Complete ()

4
An application tomorrow

• It will start with the application today, and add
  memory state as a transacted resource.
• Developers will expect the collection to just
  work
• cn.Close()
• hash key val // Update with insertion data
• sc.Complete ()

5
Implications

• Transactions will
• Do I/O to databases, queues, and network
• Incorporate more than one thread or process
• Range from very short, so several seconds in time
• Rollback, both planned and unplanned
• Threads will
• Span more than one active transaction
  simultaneously

6
Thoughts

• Need to treat memory as a participant in a
  normal transaction
• Can hardware leverage any of the semantics we
  know about the transaction (e.g. isolation
  levels)?
• Can hardware provide acceleration for a
  transaction manager, especially if the
  transaction is volatile?