add documentation

backend/v3/storage/database/database.go

@@ -4,15 +4,7 @@ import (
 	"context"
 )
 
-var (
-	db *database
-)
-
-type database struct {
-	connector Connector
-	pool      Pool
-}
-
+// Pool is a connection pool. e.g. pgxpool
 type Pool interface {
 	Beginner
 	QueryExecutor
@@ -21,6 +13,7 @@ type Pool interface {
 	Close(ctx context.Context) error
 }
 
+// Client is a single database connection which can be released back to the pool.
 type Client interface {
 	Beginner
 	QueryExecutor
@@ -28,33 +21,37 @@ type Client interface {
 	Release(ctx context.Context) error
 }
 
+// Querier is a database client that can execute queries and return rows.
 type Querier interface {
 	Query(ctx context.Context, stmt string, args ...any) (Rows, error)
 	QueryRow(ctx context.Context, stmt string, args ...any) Row
 }
 
+// Executor is a database client that can execute statements.
 type Executor interface {
 	Exec(ctx context.Context, stmt string, args ...any) error
 }
 
+// QueryExecutor is a database client that can execute queries and statements.
 type QueryExecutor interface {
 	Querier
 	Executor
 }
 
+// Scanner scans a single row of data into the destination.
 type Scanner interface {
 	Scan(dest ...any) error
 }
 
+// Row is an abstraction of sql.Row.
 type Row interface {
 	Scanner
 }
 
+// Rows is an abstraction of sql.Rows.
 type Rows interface {
 	Row
 	Next() bool
 	Close() error
 	Err() error
 }
-
-type Query[T any] func(querier Querier) (result T, err error)