diff options
Diffstat (limited to 'lib/kernel/doc/src/logger_std_h.xml')
| -rw-r--r-- | lib/kernel/doc/src/logger_std_h.xml | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/lib/kernel/doc/src/logger_std_h.xml b/lib/kernel/doc/src/logger_std_h.xml new file mode 100644 index 0000000000..e156f5719b --- /dev/null +++ b/lib/kernel/doc/src/logger_std_h.xml @@ -0,0 +1,141 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE erlref SYSTEM "erlref.dtd"> + +<erlref> + <header> + <copyright> + <year>2017</year><year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>logger_std_h</title> + <prepared></prepared> + <responsible></responsible> + <docno></docno> + <approved></approved> + <checked></checked> + <date></date> + <rev>A</rev> + <file>logger_std_h.xml</file> + </header> + <module>logger_std_h</module> + <modulesummary>Standard handler for Logger.</modulesummary> + + <description> + <p>This is the standard handler for Logger. + Multiple instances of this handler can be added to + Logger, and each instance prints logs to <c>standard_io</c>, + <c>standard_error</c>, or to file.</p> + <p>The handler has an overload protection mechanism that keeps the handler + process and the Kernel application alive during high loads of log + events. How overload protection works, and how to configure it, is + described in the + <seealso marker="logger_chapter#overload_protection"><c>User's Guide</c> + </seealso>.</p> + <p>To add a new instance of the standard handler, use + <seealso marker="logger#add_handler-3"><c>logger:add_handler/3</c> + </seealso>. The handler configuration argument is a map which can contain + general configuration parameters, as documented in the + <seealso marker="logger_chapter#handler_configuration"><c>User's Guide</c> + </seealso>, and handler specific parameters. The specific data + is stored in a sub map with the key <c>config</c>, and can contain the + following parameters:</p> + <taglist> + <tag><marker id="type"/><c>type</c></tag> + <item> + <p>This has the value <c>standard_io</c>, <c>standard_error</c>, + <c>{file,LogFileName}</c>, or <c>{file,LogFileName,LogFileOpts}</c>.</p> + <p>If <c>LogFileOpts</c> is specified, it replaces the default + list of options used when opening the log file. The default + list is <c>[raw,append,delayed_write]</c>. One reason to do + so can be to change <c>append</c> to, for + example, <c>write</c>, ensuring that the old log is + truncated when a node is restarted. See the reference manual + for <seealso marker="file#open-2"><c>file:open/2</c></seealso> + for more information about file options.</p> + <p>Log files are always UTF-8 encoded. The encoding can not be + changed by setting the option <c>{encoding,Encoding}</c> + in <c>LogFileOpts</c>.</p> + <p>Notice that the standard handler does not have support for + circular logging. Use the disk_log handler, + <seealso marker="logger_disk_log_h"><c>logger_disk_log_h</c></seealso>, + for this.</p> + <p>The value is set when the handler is added, and it can not + be changed in runtime.</p> + <p>Defaults to <c>standard_io</c>.</p> + </item> + <tag><c>filesync_repeat_interval</c></tag> + <item> + <p>This value, in milliseconds, specifies how often the handler does + a file sync operation to write buffered data to disk. The handler attempts + the operation repeatedly, but only performs a new sync if something has + actually been logged.</p> + <p>If <c>no_repeat</c> is set as value, the repeated file sync operation + is disabled, and it is the operating system settings that determine + how quickly or slowly data is written to disk. The user can also call + the <seealso marker="logger_std_h#filesync-1"><c>filesync/1</c></seealso> + function to perform a file sync.</p> + <p>Defaults to <c>5000</c> milliseconds.</p> + </item> + </taglist> + <p>Other configuration parameters exist, to be used for customizing + the overload protection behaviour. The same parameters are used both in the + standard handler and the disk_log handler, and are documented in the + <seealso marker="logger_chapter#overload_protection"><c>User's Guide</c> + </seealso>.</p> + <p>Notice that if changing the configuration of the handler in runtime, + the <c>type</c> parameter must not be modified.</p> + <p>Example of adding a standard handler:</p> + <code type="none"> +logger:add_handler(my_standard_h, logger_std_h, + #{config => #{type => {file,"./system_info.log"}, + filesync_repeat_interval => 1000}}). + </code> + <p>To set the default handler, that starts initially with + the Kernel application, to log to file instead of <c>standard_io</c>, + change the Kernel default logger configuration. Example:</p> + <code type="none"> +erl -kernel logger '[{handler,default,logger_std_h, + #{config => #{type => {file,"./log.log"}}}}]' + </code> + <p>An example of how to replace the standard handler with a disk_log handler + at startup is found in the + <seealso marker="logger_disk_log_h"><c>logger_disk_log_h</c></seealso> + manual.</p> + </description> + + <funcs> + + <func> + <name name="filesync" arity="1" clause_i="1"/> + <fsummary>Writes buffered data to disk.</fsummary> + <desc> + <p>Write buffered data to disk.</p> + </desc> + </func> + + </funcs> + + <section> + <title>See Also</title> + <p><seealso marker="logger"><c>logger(3)</c></seealso>, + <seealso marker="logger_disk_log_h"> + <c>logger_disk_log_h(3)</c></seealso></p> + </section> +</erlref> + + |