mirror of https://github.com/status-im/timbre.git
308 lines
15 KiB
Markdown
308 lines
15 KiB
Markdown
**[API docs][]** | **[CHANGELOG][]** | [other Clojure libs][] | [Twitter][] | [contact/contrib](#contact--contributing) | current [Break Version][]:
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```clojure
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[com.taoensso/timbre "3.3.1"]
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```
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v3 is a **major, backwards-compatible release**. Please see the [CHANGELOG][] for details. Appender authors: please see [here](https://github.com/ptaoussanis/timbre/issues/41) about migrating Timbre 2.x appenders to 3.x's recommended style.
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# Timbre, a (sane) Clojure logging & profiling library
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Logging with Java can be maddeningly, unnecessarily hard. Particularly if all you want is something *simple that works out-the-box*. Timbre brings functional, Clojure-y goodness to all your logging needs. **No XML!**
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## What's in the box™?
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* [Logs as Clojure values](https://github.com/ptaoussanis/timbre/tree/dev#redis-carmine-appender-v3) (v3+).
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* Small, uncomplicated **all-Clojure** library.
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* **Super-simple map-based config**: no arcane XML or properties files!
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* **Low overhead** with dynamic logging level.
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* **No overhead** with compile-time logging level. (v2.6+)
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* Flexible **fn-centric appender model** with **middleware**.
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* Sensible built-in appenders including simple **email appender**.
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* Tunable **rate limit** and **asynchronous** logging support.
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* Robust **namespace filtering**.
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* [tools.logging](https://github.com/clojure/tools.logging) support (optional, useful when integrating with legacy logging systems).
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* Dead-simple, logging-level-aware **logging profiler**.
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## 3rd-party tools, appenders, etc.
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* [log-config](https://github.com/palletops/log-config) by [Hugo Duncan](https://github.com/hugoduncan) - library to help manage Timbre logging config.
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* Suggestions welcome!
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## Getting started
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### Dependencies
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Add the necessary dependency to your [Leiningen][] `project.clj` and use the supplied ns-import helper:
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```clojure
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[com.taoensso/timbre "3.3.1"] ; project.clj
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(ns my-app (:require [taoensso.timbre :as timbre])) ; Your ns
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(timbre/refer-timbre) ; Provides useful Timbre aliases in this ns
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```
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The `refer-timbre` call is a convenience fn that executes:
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```clojure
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(require '[taoensso.timbre :as timbre
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:refer (log trace debug info warn error fatal report
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logf tracef debugf infof warnf errorf fatalf reportf
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spy logged-future with-log-level with-logging-config
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sometimes)])
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(require '[taoensso.timbre.profiling :as profiling
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:refer (pspy pspy* profile defnp p p*)])
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```
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### Logging
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By default, Timbre gives you basic print output to `*out*`/`*err*` at a `debug` logging level:
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```clojure
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(info "This will print") => nil
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%> 2012-May-28 17:26:11:444 +0700 localhost INFO [my-app] - This will print
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(spy :info (* 5 4 3 2 1)) => 120
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%> 2012-May-28 17:26:14:138 +0700 localhost INFO [my-app] - (* 5 4 3 2 1) 120
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(trace "This won't print due to insufficient logging level") => nil
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```
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First-argument exceptions generate a nicely cleaned-up stack trace using [io.aviso.exception](https://github.com/AvisoNovate/pretty):
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```clojure
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(info (Exception. "Oh noes") "arg1" "arg2")
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%> 2012-May-28 17:35:16:132 +0700 localhost INFO [my-app] - arg1 arg2
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java.lang.Exception: Oh noes
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NO_SOURCE_FILE:1 my-app/eval6409
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Compiler.java:6511 clojure.lang.Compiler.eval
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<...>
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```
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### Configuration
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This is the biggest win over Java logging utilities IMO. Here's `timbre/example-config` (also Timbre's default config):
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```clojure
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(def example-config
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"APPENDERS
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An appender is a map with keys:
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:doc ; (Optional) string.
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:min-level ; (Optional) keyword, or nil (no minimum level).
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:enabled? ; (Optional).
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:async? ; (Optional) dispatch using agent (good for slow appenders).
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:rate-limit ; (Optional) [ncalls-limit window-ms].
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:fmt-output-opts ; (Optional) extra opts passed to `fmt-output-fn`.
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:fn ; (fn [appender-args-map]), with keys described below.
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An appender's fn takes a single map with keys:
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:level ; Keyword.
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:error? ; Is level an 'error' level?.
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:throwable ; java.lang.Throwable.
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:args ; Raw logging macro args (as given to `info`, etc.).
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:message ; Stringified logging macro args, or nil.
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:output ; Output of `fmt-output-fn`, used by built-in appenders
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; as final, formatted appender output. Appenders may (but
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; are not obligated to) use this as their output.
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:ap-config ; Contents of config's :shared-appender-config key.
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:profile-stats ; From `profile` macro.
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:instant ; java.util.Date.
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:timestamp ; String generated from :timestamp-pattern, :timestamp-locale.
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:hostname ; String.
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:ns ; String.
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;; Waiting on http://dev.clojure.org/jira/browse/CLJ-865:
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:file ; String.
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:line ; Integer.
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MIDDLEWARE
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Middleware are fns (applied right-to-left) that transform the map
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dispatched to appender fns. If any middleware returns nil, no dispatching
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will occur (i.e. the event will be filtered).
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The `example-config` code contains further settings and details.
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See also `set-config!`, `merge-config!`, `set-level!`."
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{;;; Control log filtering by namespace patterns (e.g. ["my-app.*"]).
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;;; Useful for turning off logging in noisy libraries, etc.
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:ns-whitelist []
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:ns-blacklist []
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;; Fns (applied right-to-left) to transform/filter appender fn args.
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;; Useful for obfuscating credentials, pattern filtering, etc.
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:middleware []
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;;; Control :timestamp format
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:timestamp-pattern "yyyy-MMM-dd HH:mm:ss ZZ" ; SimpleDateFormat pattern
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:timestamp-locale nil ; A Locale object, or nil
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;; Output formatter used by built-in appenders. Custom appenders may (but are
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;; not required to use) its output (:output). Extra per-appender opts can be
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;; supplied as an optional second (map) arg.
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:fmt-output-fn
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(fn [{:keys [level throwable message timestamp hostname ns]}
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;; Any extra appender-specific opts:
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& [{:keys [nofonts?] :as appender-fmt-output-opts}]]
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;; <timestamp> <hostname> <LEVEL> [<ns>] - <message> <throwable>
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(format "%s %s %s [%s] - %s%s"
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timestamp hostname (-> level name str/upper-case) ns (or message "")
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(or (stacktrace throwable "\n" (when nofonts? {})) "")))
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:shared-appender-config {} ; Provided to all appenders via :ap-config key
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:appenders
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{:standard-out
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{:doc "Prints to *out*/*err*. Enabled by default."
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:min-level nil :enabled? true :async? false :rate-limit nil
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:fn (fn [{:keys [error? output]}] ; Use any appender args
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(binding [*out* (if error? *err* *out*)]
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(str-println output)))}
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:spit
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{:doc "Spits to `(:spit-filename :shared-appender-config)` file."
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:min-level nil :enabled? false :async? false :rate-limit nil
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:fn (fn [{:keys [ap-config output]}] ; Use any appender args
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(when-let [filename (:spit-filename ap-config)]
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(try (spit filename output :append true)
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(catch java.io.IOException _))))}}})
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```
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A few things to note:
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* Appenders are trivial to write & configure - **they're just fns**. It's Timbre's job to dispatch useful args to appenders when appropriate, it's their job to do something interesting with them.
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* Being 'just fns', appenders have basically limitless potential: write to your database, send a message over the network, check some other state (e.g. environment config) before making a choice, etc.
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The **logging level** may be set:
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* At compile-time: (`TIMBRE_LOG_LEVEL` environment variable).
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* Via an atom: `(timbre/set-level! <level>)`. (Usual method).
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* Via dynamic thread-level binding: `(timbre/with-log-level <level> ...)`.
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A compile-time level offers _zero-overhead_ performance since it'll cause insufficient logging calls to disappear completely at compile-time. Usually you won't need/want to bother: Timbre offers very decent performance with runtime level checks (~15msecs/10k checks on my Macbook Air).
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For common-case ease-of-use, **all logging utils use a global atom for their config**. This is configurable with `timbre/set-config!`, `timbre/merge-config!`. The lower-level `log` and `logf` macros also take an optional first-arg config map for greater flexibility (e.g. **during testing**).
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### Built-in appenders
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#### Redis ([Carmine](https://github.com/ptaoussanis/carmine)) appender (v3+)
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```clojure
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;; [com.taoensso/carmine "2.4.0"] ; Add to project.clj deps
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;; (:require [taoensso.timbre.appenders (:carmine :as car-appender)]) ; Add to ns
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(timbre/set-config! [:appenders :carmine] (postal-appenders/make-carmine-appender))
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```
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This gives us a high-performance Redis appender:
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* **All raw logging args are preserved** in serialized form (**even Throwables!**).
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* Only the most recent instance of each **unique entry** is kept (hash fn used to determine uniqueness is configurable).
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* Configurable number of entries to keep per logging level.
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* **Log is just a value**: a vector of Clojure maps: **query+manipulate with standard seq fns**: group-by hostname, sort/filter by ns & severity, explore exception stacktraces, filter by raw arguments, etc. **Datomic and `core.logic`** also offer interesting opportunities here.
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A simple query utility is provided: `car-appender/query-entries`.
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#### Email ([Postal](https://github.com/drewr/postal)) appender
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```clojure
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;; [com.draines/postal "1.9.2"] ; Add to project.clj deps
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;; (:require [taoensso.timbre.appenders (postal :as postal-appender)]) ; Add to ns
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(timbre/set-config! [:appenders :postal]
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(postal-appender/make-postal-appender
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{:enabled? true
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:rate-limit [1 60000] ; 1 msg / 60,000 msecs (1 min)
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:async? true ; Don't block waiting for email to send
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}
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{:postal-config
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^{:host "mail.isp.net" :user "jsmith" :pass "sekrat!!1"}
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{:from "me@draines.com" :to "foo@example.com"}}))
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```
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#### File appender
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```clojure
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(timbre/set-config! [:appenders :spit :enabled?] true)
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(timbre/set-config! [:shared-appender-config :spit-filename] "/path/my-file.log")
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```
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#### Other included appenders
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A number of 3rd-party appenders are included out-the-box for: Android, IRC, sockets, MongoDB, and rotating files. These are all located in the `taoensso.timbre.appenders.x` namespaces - **please see the relevant docstrings for details**.
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Thanks to their respective authors! Just give me a shout if you've got an appender you'd like to have added.
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## Profiling
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The usual recommendation for Clojure profiling is: use a good **JVM profiler** like [YourKit](http://www.yourkit.com/), [JProfiler](http://www.ej-technologies.com/products/jprofiler/overview.html), or [VisualVM](http://docs.oracle.com/javase/6/docs/technotes/guides/visualvm/index.html).
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And these certainly do the job. But as with many Java tools, they can be a little hairy and often heavy-handed - especially when applied to Clojure. Timbre includes an alternative.
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Wrap forms that you'd like to profile with the `p` macro and give them a name:
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```clojure
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(defn my-fn
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[]
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(let [nums (vec (range 1000))]
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(+ (p :fast-sleep (Thread/sleep 1) 10)
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(p :slow-sleep (Thread/sleep 2) 32)
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(p :add (reduce + nums))
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(p :sub (reduce - nums))
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(p :mult (reduce * nums))
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(p :div (reduce / nums)))))
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(my-fn) => 42
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```
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The `profile` macro can now be used to log times for any wrapped forms:
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```clojure
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(profile :info :Arithmetic (dotimes [n 100] (my-fn))) => "Done!"
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%> 2012-Jul-03 20:46:17 +0700 localhost INFO [my-app] - Profiling my-app/Arithmetic
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Name Calls Min Max MAD Mean Total% Total
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my-app/slow-sleep 100 2ms 2ms 31μs 2ms 57 231ms
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my-app/fast-sleep 100 1ms 1ms 27μs 1ms 29 118ms
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my-app/add 100 44μs 2ms 46μs 100μs 2 10ms
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my-app/sub 100 42μs 564μs 26μs 72μs 2 7ms
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my-app/div 100 54μs 191μs 17μs 71μs 2 7ms
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my-app/mult 100 31μs 165μs 11μs 44μs 1 4ms
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Unaccounted 6 26ms
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Total 100 405ms
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```
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You can also use the `defnp` macro to conveniently wrap whole fns.
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It's important to note that Timbre profiling is fully **logging-level aware**: if the level is insufficient, you *won't pay for profiling* (there is a minimal dynamic-var deref cost). Likewise, normal namespace filtering applies. (Performance characteristics for both checks are inherited from Timbre itself).
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And since `p` and `profile` **always return their body's result** regardless of whether profiling actually happens or not, it becomes feasible to use profiling more often as part of your normal workflow: just *leave profiling code in production as you do for logging code*.
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A simple **sampling profiler** is also available: `taoensso.timbre.profiling/sampling-profile`.
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## This project supports the CDS and  goals
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* [CDS][], the **Clojure Documentation Site**, is a **contributer-friendly** community project aimed at producing top-notch, **beginner-friendly** Clojure tutorials and documentation. Awesome resource.
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* [ClojureWerkz][] is a growing collection of open-source, **batteries-included Clojure libraries** that emphasise modern targets, great documentation, and thorough testing. They've got a ton of great stuff, check 'em out!
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## Contact & contributing
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`lein start-dev` to get a (headless) development repl that you can connect to with [Cider][] (emacs) or your IDE.
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Please use the project's GitHub [issues page][] for project questions/comments/suggestions/whatever **(pull requests welcome!)**. Am very open to ideas if you have any!
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Otherwise reach me (Peter Taoussanis) at [taoensso.com][] or on [Twitter][]. Cheers!
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## License
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Copyright © 2012-2014 Peter Taoussanis. Distributed under the [Eclipse Public License][], the same as Clojure.
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[API docs]: <http://ptaoussanis.github.io/timbre/>
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[CHANGELOG_]: <https://github.com/ptaoussanis/timbre/blob/master/CHANGELOG.md>
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[CHANGELOG]: <https://github.com/ptaoussanis/timbre/releases>
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[other Clojure libs]: <https://www.taoensso.com/clojure-libraries>
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[Twitter]: <https://twitter.com/ptaoussanis>
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[SemVer]: <http://semver.org/>
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[Break Version]: <https://github.com/ptaoussanis/encore/blob/master/BREAK-VERSIONING.md>
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[Leiningen]: <http://leiningen.org/>
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[CDS]: <http://clojure-doc.org/>
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[ClojureWerkz]: <http://clojurewerkz.org/>
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[issues page]: <https://github.com/ptaoussanis/timbre/issues>
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[Cider]: <https://github.com/clojure-emacs/cider>
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[commit history]: <https://github.com/ptaoussanis/timbre/commits/master>
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[taoensso.com]: <https://www.taoensso.com>
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[Eclipse Public License]: <https://raw2.github.com/ptaoussanis/timbre/master/LICENSE>
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