diff options
Diffstat (limited to 'src/clj')
| -rw-r--r-- | src/clj/clojure/core.clj | 89 | ||||
| -rw-r--r-- | src/clj/clojure/core_print.clj | 8 |
2 files changed, 87 insertions, 10 deletions
diff --git a/src/clj/clojure/core.clj b/src/clj/clojure/core.clj index 245c3643..c253fc1b 100644 --- a/src/clj/clojure/core.clj +++ b/src/clj/clojure/core.clj @@ -1329,14 +1329,29 @@ :validator validate-fn + :error-handler handler-fn + + :error-mode mode-keyword + If metadata-map is supplied, it will be come the metadata on the agent. validate-fn must be nil or a side-effect-free fn of one argument, which will be passed the intended new state on any state change. If the new state is unacceptable, the validate-fn should - return false or throw an exception." - ([state] (new clojure.lang.Agent state)) + return false or throw an exception. handler-fn is called if an + action throws an exception or if validate-fn rejects a new state -- + see set-error-handler! for details. The mode-keyword may be either + :continue (the default if an error-handler is given) or :fail (the + default if no error-handler is given) -- see set-error-mode! for + details." ([state & options] - (setup-reference (agent state) options))) + (let [a (new clojure.lang.Agent state) + opts (apply hash-map options)] + (setup-reference a options) + (when (:error-handler opts) + (.setErrorHandler a (:error-handler opts))) + (.setErrorMode a (or (:error-mode opts) + (if (:error-handler opts) :continue :fail))) + a))) (defn send "Dispatch an action to an agent. Returns the agent immediately. @@ -1388,16 +1403,73 @@ [#^clojure.lang.IRef reference key] (.removeWatch reference key)) +(defn agent-error + "Returns the exception thrown during an asynchronous action of the + agent if the agent is failed. Returns nil if the agent is not + failed." + [#^clojure.lang.Agent a] (.getError a)) + +(defn restart-agent + "When an agent is failed, changes the agent state to new-state and + then un-fails the agent so that sends are allowed again. If + a :clear-actions true option is given, any actions queued on the + agent that were being held while it was failed will be discarded, + otherwise those held actions will proceed. The new-state must pass + the validator if any, or restart will throw an exception and the + agent will remain failed with its old state and error. Watchers, if + any, will NOT be notified of the new state. Throws an exception if + the agent is not failed." + [#^clojure.lang.Agent a, new-state & options] + (let [opts (apply hash-map options)] + (.restart a new-state (if (:clear-actions opts) true false)))) + +(defn set-error-handler! + "Sets the error-handler of agent a to handler-fn. If an action + being run by the agent throws an exception or doesn't pass the + validator fn, handler-fn will be called with two arguments: the + agent and the exception." + [#^clojure.lang.Agent a, handler-fn] + (.setErrorHandler a handler-fn)) + +(defn error-handler + "Returns the error-handler of agent a, or nil if there is none. + See set-error-handler!" + [#^clojure.lang.Agent a] + (.getErrorHandler a)) + +(defn set-error-mode! + "Sets the error-mode of agent a to mode-keyword, which must be + either :fail or :continue. If an action being run by the agent + throws an exception or doesn't pass the validator fn, an + error-handler may be called (see set-error-handler!), after which, + if the mode is :continue, the agent will continue as if neither the + action that caused the error nor the error itself ever happened. + + If the mode is :fail, the agent will become failed and will stop + accepting new 'send' and 'send-off' actions, and any previously + queued actions will be held until a 'restart-agent'. Deref will + still work, returning the state of the agent before the error." + [#^clojure.lang.Agent a, mode-keyword] + (.setErrorMode a mode-keyword)) + +(defn error-mode + "Returns the error-mode of agent a. See set-error-mode!" + [#^clojure.lang.Agent a] + (.getErrorMode a)) (defn agent-errors - "Returns a sequence of the exceptions thrown during asynchronous + "DEPRECATED: Use 'agent-error' instead. + Returns a sequence of the exceptions thrown during asynchronous actions of the agent." - [#^clojure.lang.Agent a] (. a (getErrors))) + [a] + (when-let [e (agent-error a)] + (list e))) (defn clear-agent-errors - "Clears any exceptions thrown during asynchronous actions of the + "DEPRECATED: Use 'restart-agent' instead. + Clears any exceptions thrown during asynchronous actions of the agent, allowing subsequent actions to occur." - [#^clojure.lang.Agent a] (. a (clearErrors))) + [#^clojure.lang.Agent a] (restart-agent a (.deref a))) (defn shutdown-agents "Initiates a shutdown of the thread pools that back the agent @@ -2104,7 +2176,8 @@ (defn await "Blocks the current thread (indefinitely!) until all actions dispatched thus far, from this thread or agent, to the agent(s) have - occurred." + occurred. Will block on failed agents. Will never return if + a failed agent is restarted with :clear-actions true." [& agents] (io! "await in transaction" (when *agent* diff --git a/src/clj/clojure/core_print.clj b/src/clj/clojure/core_print.clj index d2b1612e..0ab1ee52 100644 --- a/src/clj/clojure/core_print.clj +++ b/src/clj/clojure/core_print.clj @@ -309,9 +309,13 @@ (.write w ")")) (defmethod print-method clojure.lang.IDeref [o #^Writer w] - (print-sequential (format "#<%s@%x: " + (print-sequential (format "#<%s@%x%s: " (.getSimpleName (class o)) - (System/identityHashCode o)) + (System/identityHashCode o) + (if (and (instance? clojure.lang.Agent o) + (agent-error o)) + " FAILED" + "")) pr-on, "", ">", (list (if (and (future? o) (not (future-done? o))) :pending @o)), w)) (def #^{:private true} print-initialized true) |