API for logging
Logging macros which delegate to a specific logging implementation. At
runtime a specific implementation is selected from, in order, Apache
commons-logging, log4j, and finally java.util.logging.
Logging levels are specified by clojure keywords corresponding to the
values used in log4j and commons-logging:
:trace, :debug, :info, :warn, :error, :fatal
Logging occurs with the log macro, or the level-specific convenience macros,
which write either directly or via an agent. For performance reasons, direct
logging is enabled by default, but setting the *allow-direct-logging* boolean
atom to false will disable it. If logging is invoked within a transaction it
will always use an agent.
The log macros will not evaluate their 'message' unless the specific logging
level is in effect. Alternately, you can use the spy macro when you have code
that needs to be evaluated, and also want to output the code and its result to
the debug log.
Unless otherwise specified, the current namespace (as identified by *ns*) will
be used as the log-ns (similar to how the java class name is usually used).
Note: your log configuration should display the name that was passed to the
logging implementation, and not perform stack-inspection, otherwise you'll see
something like "fn__72$impl_write_BANG__39__auto____81" in your logs.
Use the enabled? macro to write conditional code against the logging level
(beyond simply whether or not to call log, which is handled automatically).
You can redirect all java writes of System.out and System.err to the log
system by calling log-capture!. To rebind *out* and *err* to the log system
invoke with-logs. In both cases a log-ns (e.g., "com.example.captured")
needs to be specified to namespace the output.
Public Variables and Functions
A boolean indicating whether direct logging (as opposed to via an agent) is
allowed when not operating from within a transaction. Defaults to true.
The name of the logging implementation used.
The default agent used for performing logging durng a transaction or when
direct logging is disabled.
Usage: (debug message)
(debug message throwable)
Logs a message at the debug level.
Usage: (enabled? level)
(enabled? level log-ns)
Returns true if the specific logging level is enabled. Use of this function
should only be necessary if one needs to execute alternate code paths beyond
whether the log should be written to.
Usage: (error message)
(error message throwable)
Logs a message at the error level.
Usage: (fatal message)
(fatal message throwable)
Logs a message at the fatal level.
Implementation-specific check if a particular level is enabled. End-users
should not need to call this.
Returns an implementation-specific log by string namespace. End-users should
not need to call this.
Implementation-specific write of a log message. End-users should not need to
Usage: (info message)
(info message throwable)
Logs a message at the info level.
Usage: (log level message)
(log level message throwable)
(log level message throwable log-ns)
Logs a message, either directly or via an agent. Also see the level-specific
Usage: (log-capture! log-ns)
Captures System.out and System.err, redirecting all writes of those streams
to :info and :error logging, respectively. The specified log-ns value will
be used to namespace all redirected logging. NOTE: this will not redirect
output of *out* or *err*; for that, use with-logs.
Usage: (log-stream level log-ns)
Creates a PrintStream that will output to the log. End-users should not need
to invoke this.
Restores System.out and System.err to their original values.
Usage: (spy expr)
Evaluates expr and outputs the form and its result to the debug log; returns
the result of expr.
Usage: (trace message)
(trace message throwable)
Logs a message at the trace level.
Usage: (warn message)
(warn message throwable)
Logs a message at the warn level.
Usage: (with-logs log-ns & body)
Evaluates exprs in a context in which *out* and *err* are bound to :info and
:error logging, respectively. The specified log-ns value will be used to
namespace all redirected logging.