Add :ping-map-fn for shaping proc state in ping replies

Author: JarrodCTaylor

src/main/clojure/clojure/core/async/flow.clj

@@ -135,7 +135,9 @@
 
 (defn ping
   "pings all processes, returning a map of pid -> proc status and
-  state, for those procs that reply within timeout-ms (default 1000)"
+  state, for those procs that reply within timeout-ms (default 1000).
+  The value at ::flow/state is shaped by the proc's :ping-map-fn (see
+  process), defaulting to the proc's raw state."
   [g & {:keys [timeout-ms] :or {timeout-ms 1000}}]
   (g/ping g timeout-ms))
 
@@ -186,6 +188,9 @@
                    For the simple case of enumerated signal-ids, use a set,
                    e.g. #{:this/signal :that/signal}
                    If no :signal-select is provided, no signals will be received
+  :ping-map-fn - (ping-map-fn state) -> ping-map. The ping-map is
+                 placed under ::flow/state in ping/ping-proc replies.
+                 Defaults to identity.
   :workload with possible values of :mixed :io :compute.
   All entries in the describe return map are optional.
   

src/main/clojure/clojure/core/async/flow/impl.clj

@@ -244,7 +244,8 @@
   "see lib ns for docs"
   [step {:keys [workload compute-timeout-ms] :or {compute-timeout-ms 5000}}]
   (let [{:keys [params ins] :as desc} (step)
-        workload (or workload (:workload desc) :mixed)]
+        workload (or workload (:workload desc) :mixed)
+        ping-map-fn (or (:ping-map-fn desc) identity)]
     ;;(assert (or (not params) init) "must have :init if :params")
     (reify
       clojure.core.protocols/Datafiable
@@ -276,7 +277,7 @@
                                                      #::flow{:pid pid, :status status
                                                              :count count
                                                              :ins pins :outs pouts})
-                                                    ::flow/state state))))
+                                                    ::flow/state (ping-map-fn state)))))
                        handle-command (partial handle-command pid pong)
                        [nstatus nstate count read-ins]
                        (try

src/test/clojure/clojure/core/async/flow_test.clj

@@ -53,3 +53,10 @@
     (let [state-val {:a-var #'identity :a-fn inc}
           ping-state (ping-state-with (minimal-step state-val))]
       (is (= state-val ping-state) "state should be returned unchanged"))))
+
+(deftest test-ping-map-fn
+  (testing ":ping-map-fn can redact sensitive keys from state"
+    (let [ping-state (ping-state-with (minimal-step {:visible 42 :hidden "secret"}
+                                                    {:ping-map-fn #(select-keys % [:visible])}))]
+      (is (= {:visible 42} ping-state) "secret was not removed"))))
+