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B-trees and CPU Caches

B-tree Indexes and CPU Caches by Goetz Graefe and Per-Åke Larson

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

Summary of book "Clean Architecture" by Robert C. Martin

Uncle Bob, the well known author of Clean Code, is coming back to us with a new book called Clean Architecture which wants to take a larger view on how to create software.

Even if Clean Code is one of the major book around OOP and code design (mainly by presenting the SOLID principles), I was not totally impressed by the book.

Clean Architecture leaves me with the same feeling, even if it's pushing the development world to do better, has some good stories and present robust principles to build software.

The book is build around 34 chapters organised in chapters.

Code is clean if it can be understood easily – by everyone on the team. Clean code can be read and enhanced by a developer other than its original author. With understandability comes readability, changeability, extensibility and maintainability.

General rules

Follow standard conventions.
Keep it simple stupid. Simpler is always better. Reduce complexity as much as possible.
Boy scout rule. Leave the campground cleaner than you found it.
Always find root cause. Always look for the root cause of a problem.

Design rules

macOS Keyboard Shortcuts You Should Know

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Activation Key:

UX394X3HLT-eyJsaWNlbnNlSWQiOiJVWDM5NFgzSExUIiwibGljZW5zZWVOYW1lIjoiSG9uZ2lrIFVuaXZlcnNpdHntmY3snbXrjIDtlZnqtZAiLCJsaWNlbnNlZVR5cGUiOiJDTEFTU1JPT00iLCJhc3NpZ25lZU5hbWUiOiLkvJfliJvkupEg5bel5L2c5a6kIiwiYXNzaWduZWVFbWFpbCI6ImhhbmF6YXdhbWl0b0BnbWFpbC5jb20iLCJsaWNlbnNlUmVzdHJpY3Rpb24iOiJG

	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

	/* The world's smallest Brainfuck interpreter in C, by Kang Seonghoon
	* http://j.mearie.org/post/1181041789/brainfuck-interpreter-in-2-lines-of-c */
	s[99],r=s,d,c;main(a,b){charv=1[d=b];for(;c=v++%93;)for(b=c&2,b=c%7?a&&(c&17
	?c&1?(r+=b-1):(r+=b-1):syscall(4-!b,b,r,1),0):v;b&&c\|a*r;v=d)main(!c,&a);d=v;}

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