System design URL shortener: Spring Boot 4.1.1, base62 ids, Redis cache-aside, Redis Lua token bucket, 24 tests and live transcripts

2026-10-22 08:13:35 +00:00
commit aa61ed8786
51 changed files with 1717 additions and 0 deletions
@@ -0,0 +1,24 @@
+--- instance A: three links
+ id |  code   | len 
+----+---------+-----
+  1 | 6MelkkB |   7
+  2 | 7qqChen |   7
+  3 | J4Wn4LP |   7
+(3 rows)
+
+--- instance A stopped and restarted (ids 4..100 of its first block are never used)
+ id  |  code   | len 
+-----+---------+-----
+   1 | 6MelkkB |   7
+   2 | 7qqChen |   7
+   3 | J4Wn4LP |   7
+ 101 | IZKi2wO |   7
+(4 rows)
+
+--- two instances running at once never overlap: B starts while A is alive
+ id  |  code   
+-----+---------
+ 102 | DDCfjej
+ 201 | Globq13
+(2 rows)
+