From a7ca1bad3b36efea5694342c728ff702276e45e6 Mon Sep 17 00:00:00 2001
From: Matthias Andreas Benkard <code@mail.matthias.benkard.de>
Date: Sun, 19 Aug 2012 15:11:30 +0200
Subject: db: Make XA-capable.

A non-Immutant fallback is provided.
---
 resources/config.sexp.sample |  7 ++++---
 src/mulk/benki/db.clj        | 41 +++++++++++++++++++++++++++++++++++++++--
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/resources/config.sexp.sample b/resources/config.sexp.sample
index 804117d..a1e3a36 100644
--- a/resources/config.sexp.sample
+++ b/resources/config.sexp.sample
@@ -1,8 +1,9 @@
 ;;;; -*- mode: clojure; coding: utf-8 -*-
 
-{:database       {:classname "org.postgresql.Driver"
-                  :subprotocol "postgresql"
-                  :subname "//localhost:5432/benki"
+{:database       {;; NOTE: PostgreSQL is the only supported RDBMS.
+                  :host "localhost"
+                  :port 5432
+                  :database "benki"
                   :user "benki"
                   :password ""}
  :websocket-base "ws://localhost:3001"
diff --git a/src/mulk/benki/db.clj b/src/mulk/benki/db.clj
index b45ec30..95bceab 100644
--- a/src/mulk/benki/db.clj
+++ b/src/mulk/benki/db.clj
@@ -1,11 +1,48 @@
 (ns mulk.benki.db
   (:refer-clojure)
-  (:use [mulk.benki config])
+  (:use [mulk.benki config]
+        [clojure.pprint :only [cl-format]])
   (:require [clojure.java.jdbc :as sql]))
 
 
+(defn ^:private classic-db []
+  (let [{host :host, port :port, database :database,
+         user :user, password :password}
+        (:database @benki-config)]
+    {:classname "org.postgresql.Driver"
+     :subprotocol "postgresql"
+     :subname (cl-format nil "//~A:~D/~A" host port database)
+     :user user
+     :password password}))
+
+(defonce ^:private +immutant-db+ (atom nil))
+
+(defn ^:private immutant-db []
+  (if @+immutant-db+
+    {:datasource @+immutant-db+}
+    (let [{host :host, port :port, database :database,
+           user :user, password :password}
+          (:database @benki-config)]
+      (when (try
+              (require 'immutant.xa)
+              true
+              (catch Exception e
+                false))
+        (let [datasource (ns-resolve 'immutant.xa 'datasource)]
+          (reset! +immutant-db+
+                  (datasource "benkidb"
+                              {:adapter  "postgres"
+                               :host     host
+                               :port     port
+                               :database database
+                               :username user
+                               :password password
+                               :pool     1}))
+          {:datasource @+immutant-db+})))))
+
 (defn ^:private db []
-  (:database @benki-config))
+  (or (immutant-db) (classic-db)))
+
 
 (defn call-with-db [thunk]
   (sql/with-connection (db)
-- 
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