(PDB-3059) Add memoize-resource-identity-hashes opt

Add a boolean memoize-resource-identity-hashes option to the developer
config section that defaults to false, disabling the resource hash
memoization (for the whole JVM).  The previous behavior can be restored
by setting the value to true.

project.clj

@@ -1,4 +1,4 @@
-(def pdb-version "4.1.2")
+(def pdb-version "4.1.2-hotfix-3059")
 
 (defn deploy-info
   "Generate deployment information from the URL supplied and the username and

src/puppetlabs/puppetdb/cli/services.clj

@@ -61,6 +61,7 @@
             [puppetlabs.puppetdb.query-eng :as qeng]
             [puppetlabs.puppetdb.query.population :as pop]
             [puppetlabs.puppetdb.scf.migrate :refer [migrate! indexes!]]
+            [puppetlabs.puppetdb.scf.hash :as scf-hash]
             [puppetlabs.puppetdb.scf.storage :as scf-store]
             [puppetlabs.puppetdb.scf.storage-utils :as sutils]
             [puppetlabs.puppetdb.time :refer [to-seconds to-millis parse-period
@@ -256,6 +257,9 @@
     (when-let [v (version/version)]
       (log/infof "PuppetDB version %s" v))
 
+    (reset! scf-hash/memoize-resource-identity-hashes?
+            (:memoize-resource-identity-hashes developer))
+
     (init-with-db database config)
 
     (let [population-registry (get-in metrics/metrics-registries [:population :registry])]

src/puppetlabs/puppetdb/config.clj

@@ -178,10 +178,12 @@
 
 (def developer-config-in
   (all-optional
-    {:pretty-print (pls/defaulted-maybe String "false")}))
+   {:pretty-print (pls/defaulted-maybe String "false")
+    :memoize-resource-identity-hashes (pls/defaulted-maybe String "false")}))
 
 (def developer-config-out
-  {:pretty-print Boolean})
+  {:pretty-print Boolean
+   :memoize-resource-identity-hashes Boolean})
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;; Database config

src/puppetlabs/puppetdb/scf/hash.clj

@@ -50,6 +50,8 @@
 ;; "medium" site persona
 (def memoized-resource-identity-hash* (kitchensink/bounded-memoize resource-identity-hash* 40000))
 
+(def memoize-resource-identity-hashes? (atom true))
+
 (defn resource-identity-hash
   "Compute a hash for a given resource that will uniquely identify it
   _for storage deduplication only_.
@@ -60,7 +62,9 @@
   [{:keys [type title parameters] :as resource}]
   {:pre  [(map? resource)]
    :post [(string? %)]}
-  (memoized-resource-identity-hash* type title parameters))
+  (if @memoize-resource-identity-hashes?
+    (memoized-resource-identity-hash* type title parameters)
+    (resource-identity-hash* type title parameters)))
 
 (defn catalog-resource-identity-format
   "Narrow `resource` to only contain the needed key/values for computing the hash of