vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

jboner

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

hellerbarde

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

mgreensmith

Solarized
#FDF6E3,#EEE8D5,#93A1A1,#FDF6E3,#EEE8D5,#657B83,#2AA198,#DC322F

Solarized Dark
#073642,#002B36,#B58900,#FDF6E3,#CB4B16,#FDF6E3,#2AA198,#DC322F

invictus-ir

"Initial Access","Execution","Persistence","Privilege Escalation","Defense Evasion","Credential Access","Discovery","Lateral Movement","Exfiltration","Impact"
ConsoleLogin,StartInstance,CreateAccessKey,CreateGroup,StopLogging,GetSecretValue,ListUsers,AssumeRole,CreateSnapShot,PutBucketVersioning
PasswordRecoveryRequested,StartInstances,CreateUser,CreateRole,DeleteTrail,GetPasswordData,ListRoles,SwitchRole,ModifySnapshotAttributes ,RunInstances
,Invoke,CreateNetworkAclEntry,UpdateAccessKey,UpdateTrail,RequestCertificate,ListIdentities,,ModifyImageAttribute,DeleteAccountPublicAccessBlock 
,SendCommand,CreateRoute,PutGroupPolicy,PutEventSelectors,UpdateAssumeRolePolicy,ListAccessKeys,,SharedSnapshotCopyInitiated,
,,CreateLoginProfile,PutRolePolicy,DeleteFlowLogs,,ListServiceQuotas,,SharedSnapshotVolumeCreated,
,,AuthorizeSecurityGroupEgress,PutUserPolicy,DeleteDetector,,ListInstanceProfiles,,ModifyDBSnapshotAttribute,
,,AuthorizeSecurityGroupIngress,AddRoleToInstanceProfile,DeleteMembers,,ListBuckets,,PutBucketP

watson

[
  "😁",
  "😂",
  "😃",
  "😄",
  "😅",
  "😆",
  "😉",
  "😊",
  "😋",

lelandbatey

Description

This simple script will take a picture of a whiteboard and use parts of the ImageMagick library with sane defaults to clean it up tremendously.

The script is here:

#!/bin/bash
convert "$1" -morphology Convolve DoG:15,100,0 -negate -normalize -blur 0x1 -channel RBG -level 60%,91%,0.1 "$2"

Results

spullara

#!/bin/bash
TOKEN=< OpenAI token from https://platform.openai.com/account/api-keys >
PROMPT="You are the best at writing shell commands. Assume the OS is Ubuntu. I want you to respond with only the shell commands separated by semicolons and no commentary. Here is what I want to do: $@"
RESULT=`curl -s https://api.openai.com/v1/chat/completions \
  -H 'Content-Type: application/json' \
  -H "Authorization: Bearer $TOKEN" \
  -d "{
  \"model\": \"gpt-3.5-turbo\",
  \"messages\": [{\"role\": \"user\", \"content\": \"$PROMPT\"}]
}" | jq '.choices[] | .message.content' -r`

l15n

# Credit http://stackoverflow.com/a/2514279
for branch in `git branch -r | grep -v HEAD`;do echo -e `git show --format="%ai %ar by %an" $branch | head -n 1` \\t$branch; done | sort -r

jrom

    if ($request_uri = /) { 
      set $test  A; 
    } 
  
    if ($host ~* teambox.com) { 
      set $test  "${test}B"; 
    } 
  
    if ($http_cookie !~* "auth_token") { 
      set $test  "${test}C";