[misc] Add with-lock macro

src/orchard/clojuredocs.clj

@@ -6,14 +6,15 @@
    [clojure.edn :as edn]
    [clojure.java.io :as io]
    [clojure.string :as string]
+   [orchard.misc :refer [with-lock]]
    [orchard.util.os :as os])
   (:import
    (java.net URI)
    (javax.net.ssl HttpsURLConnection)
    (java.util.concurrent.locks ReentrantLock)))
 
 (def cache (atom {}))
-(def ^:private ^ReentrantLock lock
+(def ^:private lock
   "Lock to prevent concurrent loading and parsing of Clojuredocs data and writing
   it into cache. This lock provides only efficiency benefits and is not
   necessary for correct behavior as accessing atom that contains immutable data
@@ -66,14 +67,13 @@
   {:added "0.5"}
   []
   ;; Prevent multiple threads from trying to load the cache simultaneously.
-  (.lock lock)
-  (try (when (empty? @cache)
-         (let [cache-file (io/file cache-file-name)]
-           (load-cache-file!
-            (if (.exists cache-file)
-              cache-file
-              (io/resource "clojuredocs/export.edn")))))
-       (finally (.unlock lock))))
+  (with-lock lock
+    (when (empty? @cache)
+      (let [cache-file (io/file cache-file-name)]
+        (load-cache-file!
+         (if (.exists cache-file)
+           cache-file
+           (io/resource "clojuredocs/export.edn")))))))
 
 (defn update-cache!
   "Load exported docs file from ClojureDocs, and store it as a cache.
@@ -84,10 +84,9 @@
    (update-cache! default-edn-file-url))
   ([export-edn-url]
    (let [cache-file (io/file cache-file-name)]
-     (.lock lock)
-     (try (write-cache-file! export-edn-url)
-          (load-cache-file! cache-file)
-          (finally (.unlock lock))))))
+     (with-lock lock
+       (write-cache-file! export-edn-url)
+       (load-cache-file! cache-file)))))
 
 (defn clean-cache!
   "Clean the cached ClojureDocs export file and the in memory cache."

src/orchard/java/parser_next.clj

@@ -28,6 +28,7 @@
    (com.sun.source.doctree BlockTagTree DocCommentTree EndElementTree
                            LinkTree LiteralTree ParamTree ReturnTree
                            StartElementTree TextTree ThrowsTree)
+   (java.util.concurrent.locks ReentrantLock)
    (javax.lang.model.element Element ElementKind ExecutableElement TypeElement VariableElement)
    (javax.lang.model.type ArrayType TypeKind TypeVariable)
    (jdk.javadoc.doclet DocletEnvironment)))
@@ -298,7 +299,7 @@
   (parse-info* [o env]
     (parse-variable-element o env)))
 
-(def lock (Object.))
+(def ^:private lock (ReentrantLock.))
 
 (defn source-info
   "If the source for the Java class is available on the classpath, parse it
@@ -307,7 +308,7 @@
   same structure as that of `orchard.java/reflect-info`."
   [klass]
   {:pre [(symbol? klass)]}
-  (locking lock ;; the jdk.javadoc.doclet classes aren't meant for concurrent modification/access.
+  (misc/with-lock lock ;; the jdk.javadoc.doclet classes aren't meant for concurrent modification/access.
     (when-let [path (source-path klass)]
       (when-let [^DocletEnvironment root (parse-java path (module-name klass))]
         (try

src/orchard/misc.clj

@@ -4,7 +4,9 @@
   (:require
    [clojure.java.io :as io]
    [clojure.string :as string]
-   [orchard.util.io :as util.io]))
+   [orchard.util.io :as util.io])
+  (:import
+   (java.util.concurrent.locks ReentrantLock)))
 
 (defn os-windows? []
   (.startsWith (System/getProperty "os.name") "Windows"))
@@ -68,6 +70,14 @@
     (as-sym n)
     sym))
 
+(defmacro with-lock
+  "Like `clojure.core/locking`, but for java.util.concurrent.locks.Lock."
+  [lock & body]
+  `(let [^ReentrantLock l# ~lock]
+     (.lock l#)
+     (try ~@body
+          (finally (.unlock l#)))))
+
 (defn update-vals
   "Update the values of map `m` via the function `f`."
   [f m]