pditommaso

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

pditommaso

Latency Comparison Numbers
--------------------------
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
Send 1K bytes over 1 Gbps network        10,000   ns    0.01 ms
Read 4K randomly from SSD*              150,000   ns    0.15 ms

pditommaso

CSS Circle Hover Animations

Nice looking hover animations made out of pure CSS. Some cool projects on Dribbble featured within.

By Mary Lou on Codrops: http://bit.ly/codropsmarylou

A Pen by Paolo Di Tommaso on CodePen.

License.

pditommaso

I used to think that

ssh -X [email protected]

"just bloody worked". However this might not work - ssh must play ball on both sides of the link. On the remote (ssh server, X client) sshd must sit behind some port, tell Xlib to send X11 requests to it and then forward them back to you the X server (where the ssh client is). If the remote box is locked down to prevent this, you will get:

X11 forwarding request failed on channel 0

as part of an otherwise working login. As it happens, I am the admin of the remote box in question, so I followed the ArchWiki and went to /etc/ssh/sshd_config and uncommented

pditommaso

import org.codehaus.groovy.antlr.*
import org.codehaus.groovy.antlr.parser.*
import static org.codehaus.groovy.antlr.parser.GroovyTokenTypes.*

def code = '''
// useful functions
def myFunc1(String arg) {
    println("Hello " + arg)
}

pditommaso

import org.codehaus.groovy.control.*
import org.codehaus.groovy.antlr.*
import org.codehaus.groovy.syntax.*


class SourceModifierParserPlugin extends AntlrParserPlugin {
    Reduction parseCST(SourceUnit sourceUnit, Reader reader) throws CompilationFailedException {
        def text = addCommas(reader.text)
        StringReader stringReader = new StringReader(text)
        super.parseCST(sourceUnit, stringReader)

pditommaso

@Grab('com.xlson.groovycsv:groovycsv:1.0')
import com.xlson.groovycsv.CsvParser

// a normally parsed csv can only be searched through ONCE
// this is used to create a "re-searchable" object (List of Maps)
List<Map> csv2List( String filePath, boolean shouldTrim = true ) {
    new File( filePath ).withReader { r ->
        new CsvParser().parse( r ).with { csv ->
            return csv.collect { line ->
                line.columns.collectEntries { c, v ->

pditommaso

@Grab( 'com.bloidonia:groovy-common-extensions:0.5.5' )
@Grab('com.xlson.groovycsv:groovycsv:1.0')
import static com.xlson.groovycsv.CsvParser.parseCsv
import groovy.transform.*

// A bufferedReader with some output
@InheritConstructors
class SpinnerReader extends BufferedReader {
    private String output = '/-\\|'
    private int offset = 0

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apply plugin: 'groovy'

repositories {
    mavenCentral()
}

configurations {
    patch
    [compile, testCompile]*.exclude module: 'jersey-server'
}

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@Grab('org.slf4j:slf4j-api:1.6.1')
@Grab('ch.qos.logback:logback-classic:0.9.28')
import org.slf4j.*
import groovy.transform.*

trait Loggable {
    @Memoized getLog() {
        LoggerFactory.getLogger( this.getClass() )
    }
}