sphrak

sqlite3 stable pagination with uuid

based on https://morningcoffee.io/stable-pagination.html.

In order for this to work I had to use uuidgen -t to generate time-based uuids otherwise the ordering would be messed up after 2-3 pages in.

create db

sqlite3 pagination.db

sphrak

@Composable
fun ParallaxScreen(modifier: Modifier = Modifier) {
    val context = LocalContext.current
    val scope = rememberCoroutineScope()

    var data by remember { mutableStateOf<SensorData?>(null) }

    DisposableEffect(Unit) {
        val dataManager = SensorDataManager(context)
        dataManager.init()

sphrak

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

sphrak

class MainActivity : AppCompatActivity(R.layout.activity_main) {

    @Inject
    lateinit var viewModel: MainActivityViewModel

    private var isInitialised: Boolean = false

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

sphrak

class MainActivity : AppCompatActivity(R.layout.activity_main) {

    @Inject
    lateinit var viewModel: MainActivityViewModel

    @Inject
    lateinit eventChannel: ConflatedBroadcastChannel<MainActivityView.Event>

    private var isInitialised: Boolean = false

sphrak

Kotlin Snippets

A tiny collection of Kotlin snippets that I find useful.

Measure Execution time

Keep in mind this is not an end all be all measurement since the jvm has indeterministic garbage collection but it can give you a general idea of whats taking time.

With return value

sphrak

#!/bin/bash

# Usage
# chmod +x semverdiff.sh
# Get diff between 1.0.0..1.0.1
# ./semverdiff 1.0.1 

get_diff() {
    sed -n "/^## \[$1\]/,/^## /p" CHANGELOG.md | egrep "^(-|\s+)"
}

sphrak

import android.support.annotation.StringDef
import android.text.Editable
import android.text.TextWatcher
import android.widget.EditText

@StringDef(PHONE_9_MASK, PHONE_8_MASK, CPF_MASK, ZIP_CODE_PT_BR, MONTH_YEAR, CREDIT_CARD)
@Retention(AnnotationRetention.SOURCE)
annotation class MaskType

const val PHONE_9_MASK = "(##) #####-####"

sphrak

#!/bin/bash

# Simple bash script runs adb to measure startup time of android apps

trap ctrl_c INT

time=()

function ctrl_c() {
    total=0

sphrak

Useful unix commands

recursively search files matching *.fileExt for pattern in current directory

grep --color -inr --include \*.kt 'SDK_INT' .

Detect how many gradle daemons are running