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1.2.0

1.2.0 permalink

per-thread-singleton

Returns a per-thread singleton function. f is a function of no
arguments that creates and returns some object. The singleton
function will call f only once for each thread, and cache its value
for subsequent calls from the same thread. This allows you to
safely and lazily initialize shared objects on a per-thread basis.

Warning: due to a bug in JDK 5, it may not be safe to use a
per-thread-singleton in the initialization function for another
per-thread-singleton. See
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5025230

0 Examples top

Source clojure/contrib/singleton.clj:41 top

(defn per-thread-singleton
  "Returns a per-thread singleton function.  f is a function of no
  arguments that creates and returns some object.  The singleton
  function will call f only once for each thread, and cache its value
  for subsequent calls from the same thread.  This allows you to
  safely and lazily initialize shared objects on a per-thread basis.

  Warning: due to a bug in JDK 5, it may not be safe to use a
  per-thread-singleton in the initialization function for another
  per-thread-singleton.  See
  http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5025230"
  [f]
  (let [thread-local (proxy [ThreadLocal] [] (initialValue [] (f)))]
    (fn [] (.get thread-local))))

Vars in clojure.contrib.singleton/per-thread-singleton: defn fn let

Used in 0 other vars

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per-thread-singleton

clojure.contrib.singleton

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See Also top

Source clojure/contrib/singleton.clj:41 top

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