Merge pull request #17 from nubank/dont-run-leafs-twice

We have a tool to run a body only once, use it

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 
+## 1.14.1 / 2023-12-05
+- Fix bug that allowed a leaf body to be run multiple times in engines which used the lazy environment.
+
 ## 1.14.0 / 2023-11-30
 - Fix bug preventing nil values to the passed through channels on core-async applicative engine
 - Create a blocking tag that allows leafs and sequences to be tagged with blocking to signal that they contain a blocking IO or other expensive blocking op. Engines can choose to optimize runs with this info

project.clj

@@ -1,4 +1,4 @@
-(defproject dev.nu/nodely "1.14.0"
+(defproject dev.nu/nodely "1.14.1"
   :description "Decoupling data fetching from data dependency declaration"
   :url "https://github.com/nubank/nodely"
   :license {:name "MIT"}

src/nodely/engine/lazy_env.clj

@@ -1,6 +1,6 @@
 (ns nodely.engine.lazy-env)
 
-(deftype LazySchedulingEnvironment [env ref-map eval-fn opts]
+(deftype LazySchedulingEnvironment [env delay-map opts]
   clojure.lang.ILookup
   (valAt [this k]
     (or (.valAt this k nil)
@@ -10,23 +10,27 @@
           (throw ex))))
   (valAt [this k not-found]
     (if (find env k)
-      (let [first-read @ref-map]
-        (if (find first-read k)
-          (get first-read k)
-          (-> (dosync
-               (let [second-read @ref-map]
-                 (if-not (find second-read k)
-                   (alter ref-map assoc k (eval-fn env k this opts))
-                   second-read)))
-              (get k))))
+      @(get delay-map k)
       not-found)))
 
 (defn scheduled-nodes
   "Return the current map of nodes to applicative contexts in the
   LazySchedulingEnvironment `lazy-env`."
   [lazy-env]
-  @(.-ref-map lazy-env))
+  (reduce-kv (fn [m k v]
+               (if (realized? v)
+                 (assoc m k @v)
+                 m))
+             {}
+             (.-delay-map lazy-env)))
 
 (defn lazy-env
   [env eval-fn opts]
-  (->LazySchedulingEnvironment env (ref {}) eval-fn opts))
+  (let [this-promise (promise)
+        delay-map (reduce-kv (fn [m k _]
+                               (assoc m k (delay (eval-fn env k @this-promise opts))))
+                             {}
+                             env)
+        lookup (->LazySchedulingEnvironment env delay-map opts)]
+    (deliver this-promise lookup)
+    lookup))