trikitrok

lost(arg, function(err, result) {
    if(err) return console.log(err);
    In(result, function(err, result) {
        if(err) return console.log(err);
        callback(result, function(err, result) {
            if(err) return console.log(err);
            hell(result);
        });
    });
});

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Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

trikitrok

References from my talk 'Without Resilience, Nothing Else Matters'

• Drift into Failure
• How Complex Systems Fail
• Antifragile: Things That Gain from Disorder
• Leverage Points: Places to Intervene in a System
• Going Solid: A Model of System Dynamics and Consequences for Patient Safety
• Resilience in Complex Adaptive Systems: Operating at the Edge of Failure
• Puppies! Now that I’ve got your attention, Complexity Theory
• [Towards Resilient Architectures: Biology

trikitrok

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Get all gists from the user santisbon.
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trikitrok

class BankAccount {
  public void Spend(double amount) { ... }
}

/* ---- */
class OneClient {
  ...
    bankAccount.Spend(amount);
  ...
}

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Budget {
  public double CalculateTotal() { ... }
}

/* ---- */
OneClient {
  ...
    budget.CalculateTotal();
  ...
}

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package server;

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.Date;
import java.util.Properties;
import java.util.Vector;

import javax.mail.*;
import javax.mail.internet.*;

trikitrok

Working Effectively with Legacy Code

Notes by Jeremy W. Sherman, October 2013, based on:

Feathers, Michael. Working Effectively with Legacy Code. Sixth printing, July 2007.

Foreword:

• Software systems degrade into a mess.
• Requirements ALWAYS change.
• Your goal as a software developer: Create designs that tolerate change.

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Modern Legacy Systems

Presented by Robert Annett at QCon London, 14 Sep 2012.

Notes by Jeremy W. Sherman, 2013–10–13.

“Legacy”

What is legacy?

• Often an insult, but how odd, not like that in normal English (cf. inheritance).
• Also perhaps defined as “as opposed to its alternatives, it’s the software that actually works”.

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Working Effectively with Legacy Code

Michael C. Feathers

Notes by Jeremy W. Sherman, 14 Oct 2013.

Chapter 11: I need to make a change. What methods should I test?

Use effect sketches to figure out where to target your characterization tests prior to making changes. Big fan-in means a big bang for your test-writing buck.

• Prior to changing, write characterization tests to pin down existing behavior.
• Characterization test: A test that characterizes the actual behavior of a piece of code (186).