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Boostcon 2011

From Just in Time

This page will contain my notes taken during Boostcon 2011

Library in a Week

Review tools

  • Code Collaborator
  • Crucible (Crubicle?)

Boost.Asio

Chris Kohlhoff

fundamental concepts that went into the library. Use them in your programs.

One key criterium: should not be a framework, but a toolkit. This gives you more freedom.

io_service
"your channel into the operationg system"

Challenges of asynchronous programming:

  • Object lifetimes
  • Thinking asynchronously
  • Threads
  • ?

Object lifetimes

handlers and buffers are taken by value, a copy is made. Buffers are shallow.

Arguments taken by non-const reference: caller needs to guarantee lifetime. this-pointer should outlive operation. Newby problem: providing a buffer that goes out of scope (local variable for instance).

Use shared_ptr and shared_from_this to automatically manage object lifetime.

Thinking Asynchronously

Wrong:

if (socket.connected())
{   
    socket.write();
}

Threading

  • First: single threaded
  • Use other thread to handle long running task. Uset post to give the result back to the main thread. Take care to tell the service that there is still work pending while the background thread is working. use 'asio::ioservice::work.
  • multiple io_services. Tip: If you want to make handlers wait for some event triggered by another async op, use a timer that will never expire.
  • one io_service, multiple threads. Use strands.

"Difficulty with reactor pattern is that it is hard to create [higher order abstractions] based on it"

Manage Complexity

Approaches

  • Pass the buck
    • create composed operations
  • the buck stops here