Singleton is one of the simplest patterns but the canonical anti-pattern debate. The decision to bundle single-instance guarantee with global access into one pattern causes tight coupling and test difficulty. DI is the general alternative that separates the two intents.

DIP (principle), IoC (pattern), and DI (technique) sit at different levels of abstraction. The hierarchy must be clear before framework features and design principles can be told apart.

Cache patterns split along two axes — who fills the cache on a miss, and where writes go. The five canonical patterns (cache-aside, read-through, write-through, write-back, refresh-ahead) are combinations of choices along those two axes.

How I reduced network costs and enabled instance downscaling by switching from full cache refresh to incremental refresh for campaign configuration data.

A transaction gives atomicity, a lock gives serialization — they aren’t substitutes. How pessimistic and optimistic locking cover the Lost Update that an isolation level’s plain reads don’t, and how to choose between them.

A transaction isolation level is a policy choice about which anomalies to allow. The anomalies each ANSI level prevents, and how InnoDB’s MVCC and Repeatable Read behave differently from the standard.

What each of the four ACID properties actually guarantees in an RDB transaction. A/C/D are relatively clear guarantees, but only I has ’levels’ — the gateway to the correctness vs. concurrency trade-off.

A retrospective on moving ad budget pacing from a fixed-rule scheme to a two-layer control loop — per-campaign learning sets the baseline, real-time correction absorbs drift.

A record of implementing the multithreaded HTTP server from Rust Book Chapter 20, experiencing how ownership and concurrency safety are enforced at the type level.

Two transport protocols that backend developers encounter constantly. A summary of TCP and UDP — connection establishment, reliability guarantees, flow/congestion control mechanisms, and selection criteria.