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authorLukas Larsson <[email protected]>2018-05-02 17:14:26 +0200
committerLukas Larsson <[email protected]>2018-05-02 18:17:05 +0200
commit65cd0e43158e38a3c42b00e7f591723226d235fb (patch)
treef53b1160da0ef0f0a1f50d90b68140528fcb0391 /lib/kernel/doc
parent6e729eb3d4edf2a2f5f0d7b0a0d36f7e3d031a40 (diff)
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kernel: Use formatter in simple logger example
Diffstat (limited to 'lib/kernel/doc')
-rw-r--r--lib/kernel/doc/src/logger_chapter.xml37
1 files changed, 7 insertions, 30 deletions
diff --git a/lib/kernel/doc/src/logger_chapter.xml b/lib/kernel/doc/src/logger_chapter.xml
index 0bc3b37476..88dcfbe8d9 100644
--- a/lib/kernel/doc/src/logger_chapter.xml
+++ b/lib/kernel/doc/src/logger_chapter.xml
@@ -539,12 +539,8 @@ changing_config(logger:handler_id(),logger:config(),logger:config()) -> {ok,logg
-module(myhandler).
-export([log/2]).
-log(#{msg:={report,R}},_) ->
- io:format("~p~n",[R]);
-log(#{msg:={string,S}},_) ->
- io:put_chars(S);
-log(#{msg:={F,A}},_) ->
- io:format(F,A).
+log(Log,#{formatter:={FModule,FConfig}) ->
+ io:put_chars(FModule:format(Log,FConfig)).
</code>
<p>A simple handler which prints to file could be implemented like
@@ -562,18 +558,13 @@ removing_handler(Id,#{myhandler_fd:=Fd}) ->
_ = file:close(Fd),
ok.
-log(#{msg:={report,R}},#{myhandler_fd:=Fd}) ->
- io:format(Fd,"~p~n",[R]);
-log(#{msg:={string,S}},#{myhandler_fd:=Fd}) ->
- io:put_chars(Fd,S);
-log(#{msg:={F,A}},#{myhandler_fd:=Fd}) ->
- io:format(Fd,F,A).
+log(Log,#{myhandler_fd:=Fd,formatter:={FModule,FConfig}}) ->
+ io:put_chars(Fd,FModule:format(Log,FConfig)).
</code>
- <p>Note that none of the above handlers have any overload
+ <note><p>The above handlers do not have any overload
protection, and all log events are printed directly from the
- client process. Neither do the handlers use the formatter or
- in any way add time or other metadata to the printed events.</p>
+ client process.</p></note>
<p>For examples of overload protection, please refer to the
implementation
@@ -582,14 +573,7 @@ log(#{msg:={F,A}},#{myhandler_fd:=Fd}) ->
</seealso>.</p>
<p>Below is a simpler example of a handler which logs through one
- single process, and uses the default formatter to gain a common
- look of the log events.</p>
- <p>It also uses the metadata field <c>report_cb</c>, if it exists,
- to print reports in the way the event issuer suggests. The
- formatter will normally do this, but if the handler either has
- an own default (as in this example) or if the
- given <c>report_cb</c> should not be used at all, then the
- handler must take care of this itself.</p>
+ single process.</p>
<code>
-module(myhandler).
-export([adding_handler/2, removing_handler/1, log/2]).
@@ -620,16 +604,9 @@ terminate(Reason,#{fd:=Fd}) ->
_ = file:close(Fd),
ok.
-do_log(Fd,#{msg:={report,R}} = Log, Config) ->
- Fun = maps:get(report_cb,Config,fun my_report_cb/1,
- {F,A} = Fun(R),
- do_log(Fd,Log#{msg=>{F,A},Config);
do_log(Fd,Log,#{formatter:={FModule,FConfig}}) ->
String = FModule:format(Log,FConfig),
io:put_chars(Fd,String).
-
-my_report_cb(R) ->
- {"~p",[R]}.
</code>
</section>