Changeset 002cf5f for iknow-api/Program.cs

Timestamp:

09/16/26 22:59:59 (7 days ago)

Author:

Boris Gjorgjievski <boris@…>

Branches:

master

Children:

0496e6e

Parents:

1b20b22

Message:

Phase 8: connection pooling and concurrent-enrolment handling

Two enrolments for the same semester sent at once both pass the
"already enrolled" check, because each transaction reads the state from
before the other one wrote. UNIQUE (user_id, semester_id) is what
settles it, so EnrollAsync now catches the 23505 and returns the same
sentence instead of a 500.

Sizes the connection pool in the connection string (max 10, min 1)
rather than taking Npgsql's default of 100 - every physical connection
is one more channel through the SSH tunnel - and switches to
AddDbContextPool, which AppDbContext qualifies for since its only
constructor takes DbContextOptions.

docs/Ph8.md is the wiki page: the three transactional scenarios, the
isolation level and what it does not cover, and the pool settings with
the measured connection counts.

File:

• iknow-api/Program.cs (modified) (1 diff)

iknow-api/Program.cs

@@ -66 +66 @@
 // Postgres type by name; PgEnumLabels covers the members whose label is not
 // simply the lowercased member name.
-builder.Services.AddDbContext<AppDbContext>(options =>
+// AddDbContextPool reuses the DbContext instances themselves; the connections
+// underneath them are pooled separately by Npgsql, sized in the connection
+// string. Both matter here because every physical connection is one more
+// channel through the SSH tunnel.
+builder.Services.AddDbContextPool<AppDbContext>(options =>
     options.UseNpgsql(
         builder.Configuration.GetConnectionString("DefaultConnection"),