refactoring by skill

private/database.rkt

@@ -26,6 +26,12 @@
 ;; Supporting functions
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; goal   : Check whether PostgreSQL settings have been saved.
+; pre    : config is a wiki-config value.
+; post   : The settings path has only been inspected.
+; result : #t when database.rktd exists, otherwise #f.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (define (database-settings-exist? config)
   (file-exists? (database-config-path config)))
 
@@ -45,12 +51,24 @@
                      (hash-ref value 'password "")
                      (hash-ref value 'ssl 'no)))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; goal   : Read the saved PostgreSQL connection settings.
+; pre    : config is a wiki-config value.
+; post   : The settings file, when present, has only been read.
+; result : A database-settings value, or #f when no settings file exists.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (define (read-database-settings config)
   (and (database-settings-exist? config)
        (call-with-input-file (database-config-path config)
          (λ (in)
            (datum->settings (read in))))))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; goal   : Persist PostgreSQL connection settings.
+; pre    : config and settings are wiki-config and database-settings values.
+; post   : database.rktd contains settings and is private where supported.
+; result : void.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (define (write-database-settings! config settings)
   (make-directory* (wiki-config-data-dir config))
   (call-with-output-file (database-config-path config)
@@ -63,24 +81,30 @@
   (void))
 
 (define (connect settings)
-  (define password
-    (if (string=? (database-settings-password settings) "")
-        #f
-        (database-settings-password settings)))
-  (postgresql-connect #:server (database-settings-server settings)
-                      #:port (database-settings-port settings)
-                      #:database (database-settings-database settings)
-                      #:user (database-settings-user settings)
-                      #:password password
-                      #:ssl (database-settings-ssl settings)))
+  (let ((password
+         (if (string=? (database-settings-password settings) "")
+             #f
+             (database-settings-password settings))))
+    (postgresql-connect #:server (database-settings-server settings)
+                        #:port (database-settings-port settings)
+                        #:database (database-settings-database settings)
+                        #:user (database-settings-user settings)
+                        #:password password
+                        #:ssl (database-settings-ssl settings))))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; goal   : Verify that supplied PostgreSQL settings can execute a query.
+; pre    : settings is a database-settings value for a reachable database.
+; post   : The temporary connection is closed on success or failure.
+; result : void, or a database exception when validation fails.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (define (test-database-settings! settings)
-  (define db (connect settings))
-  (dynamic-wind
-   void
-   (λ () (query-value db "SELECT 1"))
-   (λ () (disconnect db)))
-  (void))
+  (let ((db (connect settings)))
+    (dynamic-wind
+     void
+     (λ () (query-value db "SELECT 1"))
+     (λ () (disconnect db)))
+    (void)))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; goal   : Run a procedure with a fresh PostgreSQL connection.
@@ -89,26 +113,32 @@
 ; result : The value returned by proc.
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (define (call-with-wiki-database config proc)
-  (define settings (read-database-settings config))
-  (unless settings
-    (error 'call-with-wiki-database "PostgreSQL is not configured"))
-  (define db (connect settings))
-  (dynamic-wind
-   void
-   (λ () (proc db))
-   (λ () (disconnect db))))
+  (let ((settings (read-database-settings config)))
+    (unless settings
+      (error 'call-with-wiki-database "PostgreSQL is not configured"))
+    (let ((db (connect settings)))
+      (dynamic-wind
+       void
+       (λ () (proc db))
+       (λ () (disconnect db))))))
 
 (define (initialize-on-connection! db config)
   (migrate-database! db config)
   (query-exec db "DELETE FROM sessions WHERE expires_at <= $1" (current-seconds))
   (void))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; goal   : Initialize the wiki schema using explicit PostgreSQL settings.
+; pre    : settings can connect to a writable PostgreSQL database.
+; post   : Migrations are complete, expired sessions are removed and the connection is closed.
+; result : void.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (define (initialize-database-with-settings! settings config)
-  (define db (connect settings))
-  (dynamic-wind
-   void
-   (λ () (initialize-on-connection! db config))
-   (λ () (disconnect db))))
+  (let ((db (connect settings)))
+    (dynamic-wind
+     void
+     (λ () (initialize-on-connection! db config))
+     (λ () (disconnect db)))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; goal   : Initialize the PostgreSQL schema used by racket-wiki.
@@ -122,6 +152,12 @@
    (λ (db)
      (initialize-on-connection! db config))))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+; goal   : Check whether the configured database has the required core tables.
+; pre    : config is a wiki-config value.
+; post   : The database is unchanged and every temporary connection is closed.
+; result : #t when settings and core tables are available, otherwise #f.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (define (database-ready? config)
   (and (database-settings-exist? config)
        (with-handlers ((exn:fail? (λ (_e) #f)))