Remove error_logger process and add logger process

2 files changed, 147 insertions, 26 deletions

diff --git a/lib/kernel/doc/src/error_logger.xml b/lib/kernel/doc/src/error_logger.xml
index 91bf57cb91..cb6165c73e 100644
--- a/lib/kernel/doc/src/error_logger.xml
+++ b/lib/kernel/doc/src/error_logger.xml
@@ -31,6 +31,16 @@
   <module>error_logger</module>
   <modulesummary>Erlang error logger.</modulesummary>
   <description>
+
+    <note>
+      <p>In OTP-21, a new API for logging was added to Erlang/OTP. The
+	old <c>error_logger</c> module can still be used by legacy
+	code, but new code should use the new API instead.</p>
+      <p>See  <seealso marker="logger"><c>logger(3)</c></seealso> and
+	the <seealso marker="logger_chapter">Logging</seealso> chapter
+	in the user's guide for more information.</p>
+    </note>
+
     <p>The Erlang <em>error logger</em> is an event manager (see
       <seealso marker="doc/design_principles:des_princ">OTP Design Principles</seealso> and
       <seealso marker="stdlib:gen_event"><c>gen_event(3)</c></seealso>),
@@ -171,14 +181,17 @@ ok</pre>
     <func>
       <name name="get_format_depth" arity="0"/>
       <fsummary>Get the value of the Kernel application variable
-                <c>error_logger_format_depth</c>.</fsummary>
+                <c>logger_format_depth</c>.</fsummary>
       <desc>
 	<p>Returns <c>max(10, Depth)</c>, where <c>Depth</c> is the
 	value of
-	<seealso marker="kernel:kernel_app#error_logger_format_depth">
-	error_logger_format_depth</seealso>
+	<seealso marker="kernel_app#logger_format_depth">
+	logger_format_depth</seealso>
 	in the Kernel application, if Depth is an integer. Otherwise,
 	<c>unlimited</c> is returned.</p>
+	<p>For backwards compatibility, the value
+	  of <c>error_logger_format_depth</c> is used
+	  if <c>logger_format_depth</c> is not set.</p>
       </desc>
     </func>
     <func>
diff --git a/lib/kernel/doc/src/kernel_app.xml b/lib/kernel/doc/src/kernel_app.xml
index 0762cebc94..554d675383 100644
--- a/lib/kernel/doc/src/kernel_app.xml
+++ b/lib/kernel/doc/src/kernel_app.xml
@@ -51,10 +51,13 @@
   </description>
 
   <section>
-    <title>Error Logger Event Handlers</title>
-    <p>Two standard error logger event handlers are defined in
-      the Kernel application. These are described in
-      <seealso marker="error_logger"><c>error_logger(3)</c></seealso>.</p>
+    <title>Logger Handlers</title>
+    <p>Two standard logger handlers are defined in
+      the Kernel application. These are described in the
+      <seealso marker="logger_chapter">Kernel User's Guide</seealso>,
+      and in <seealso marker="logger_std_h"><c>logger_std_h(3)</c></seealso>
+      and <seealso marker="logger_disk_log_h"><c>logger_disk_log_h(3)</c>
+      </seealso>.</p>
   </section>
 
   <section>
@@ -113,6 +116,7 @@
   </section>
 
   <section>
+    <marker id="configuration"/>
     <title>Configuration</title>
     <p>The following configuration parameters are defined for the Kernel
       application. For more information about configuration parameters,
@@ -176,34 +180,105 @@
         <p>Permissions are described in
 	  <seealso marker="application#permit/2"><c>application:permit/2</c></seealso>.</p>
       </item>
-      <tag><c>error_logger = Value</c></tag>
+      <tag><c>logger_dest = Value</c></tag>
       <item>
         <p><c>Value</c> is one of:</p>
         <taglist>
           <tag><c>tty</c></tag>
-          <item><p>Installs the standard event handler, which prints error
-           reports to <c>stdio</c>. This is the default option.</p></item>
+          <item><p>Installs the standard handler, <seealso marker="logger_std_h">
+	   <c>logger_std_h(3)</c></seealso>, with <c>type</c> set
+           to <c>standard_io</c>. This is the default
+           option.</p></item>
           <tag><c>{file, FileName}</c></tag>
-          <item><p>Installs the standard event handler, which prints error
-           reports to file <c>FileName</c>, where <c>FileName</c>
+          <item><p>Installs the standard handler, <seealso marker="logger_std_h">
+	   <c>logger_std_h(3)</c></seealso>, with <c>type</c> set
+           to <c>{file, FileName}</c>, where <c>FileName</c>
            is a string. The file is opened with encoding UTF-8.</p></item>
+          <tag><c>{disk_log, FileName}</c></tag>
+          <item><p>Installs the disk_log handler, <seealso marker="logger_disk_log_h">
+	   <c>logger_disk_log_h(3)</c></seealso>, with <c>file</c> set
+           to <c>FileName</c> (a string), and possibly other disk_log
+           parameters set by the environment variables
+	   <c>logger_disk_log_type</c>, <c>logger_disk_log_maxfiles</c> and
+	   <c>logger_disk_log_maxbytes</c>,
+           see <seealso marker="#disk_log_vars">below</seealso>. The
+           file is opened with encoding UTF-8.</p></item>
           <tag><c>false</c></tag>
           <item>
-            <p>No standard event handler is installed, but
-              the initial, primitive event handler is kept, printing
+            <p>No standard handler is installed, but
+              the initial, primitive handler is kept, printing
               raw event messages to <c>tty</c>.</p>
           </item>
           <tag><c>silent</c></tag>
           <item>
-            <p>Error logging is turned off.</p>
+            <p>No standard handler is started, and the initial,
+              primitive handler is removed.</p>
           </item>
         </taglist>
       </item>
-      <tag><c>error_logger_format_depth = Depth</c></tag>
+      <tag><c>logger_level = Level</c></tag>
+      <item>
+        <p><c>Value = emergency | alert | critical | error | warning |
+	    notice | info | debug</c></p>
+	  <p>This parameter specifies which log levels to log. The
+	    specified level, and all levels that are more severe, will
+	    be logged.</p>
+	  <p>This configuration parameter is used both for the global
+	    logger level, and for the standard handler started by
+	    the Kernel application (see <c>logger_dest</c> variable above).</p>
+	  <p>The default value is <c>info</c></p>
+      </item>
+      <tag><marker id="disk_log_vars"/>
+	<c>logger_disk_log_type = halt | wrap</c></tag>
+      <item/>
+      <tag><c>logger_disk_log_maxfiles = integer()</c></tag>
+      <item/>
+      <tag><c>logger_disk_log_maxbytes = integer()</c></tag>
+      <item>
+	<p>If <c>logger_dest</c> is set to {disk_log,File}, then these
+	  parameters specify the configuration to use when opening the
+	  disk log file. They specify the type of disk log, the
+	  maximum number of files (if the type is wrap) and the
+	  maximum size of each file, respectively.</p>
+	<p>The default values are:</p>
+	<code>
+logger_disk_log_type = wrap
+logger_disk_log_maxfiles = 10
+logger_disk_log_maxbytes = 1048576</code>
+      </item>
+      <tag><marker id="logger_sasl_compatible"/>
+	<c>logger_sasl_compatible = boolean()</c></tag>
+      <item>
+	<p>If this parameter is set to true, then the logger handler
+	  started by kernel will not log any progress-, crash-, or
+	  supervisor reports. If the SASL application is starated,
+	  these log events will be sent to a second handler instance
+	  named sasl_h, according to values of the SASL environment
+	  variables <c>sasl_error_logger</c>
+	  and <c>sasl_errlog_type</c>, see
+	  <seealso marker="sasl:sasl_app#configuration">SASL(6)
+	</seealso></p>
+	<p>The default value is <c>false</c></p>
+	<p>See chapter <seealso marker="logger_chapter#compatibility">Backwards
+	  compatibility with error_logger</seealso> for more
+	  information about handling of the so called SASL reports.</p>
+      </item>
+      <tag><marker id="logger_log_progress"/>
+	<c>logger_log_progress = boolean()</c></tag>
+      <item>
+	<p>If <c>logger_sasl_compatible = false</c>,
+	  then <c>logger_log_progress</c> specifies if progress
+	  reports from <c>supervisor</c>
+	  and <c>application_controller</c> shall be logged or
+	  not.</p>
+	<p>If <c>logger_sasl_compatible = false</c>,
+	  then <c>logger_log_progress</c> is ignored.</p>
+      </item>
+      <tag><marker id="logger_format_depth"/>
+	<c>logger_format_depth = Depth</c></tag>
       <item>
-        <marker id="error_logger_format_depth"></marker>
 	<p>Can be used to limit the size of the
-	formatted output from the error logger event handlers.</p>
+	formatted output from the logger handlers.</p>
 
 	<note><p>This configuration parameter was introduced in OTP 18.1
 	and is experimental. Based on user feedback, it
@@ -214,16 +289,16 @@
 	useless.</p></note>
 
         <p><c>Depth</c> is a positive integer representing the maximum
-        depth to which terms are printed by the error logger event
+        depth to which terms are printed by the logger
         handlers included in OTP. This
-        configuration parameter is used by the two event handlers
-        defined by the Kernel application and the two event
-        handlers in the SASL application.
-	(If you have implemented your own error handlers, this configuration
-	parameter has no effect on them.)</p>
+        configuration parameter is used by the default formatter,
+	<seealso marker="logger_formatter"><c>logger_formatter(3)</c></seealso>,
+	unless the formatter's <c>depth</c> parameter is explicitly set.
+	(If you have implemented your own formatter, this configuration
+	parameter has no effect on that.)</p>
 
 	<p><c>Depth</c> is used as follows: Format strings
-	passed to the event handlers are rewritten.
+	received by the formatter are rewritten.
 	The format controls <c>~p</c> and <c>~w</c> are replaced with
 	<c>~P</c> and <c>~W</c>, respectively, and <c>Depth</c> is
 	used as the depth parameter. For details, see
@@ -234,7 +309,20 @@
 	<c>30</c>. We recommend to test crashing various processes in your
 	application, examine the logs from the crashes, and then
 	increase or decrease the value.</p></note>
-     </item>
+      </item>
+      <tag><c>logger_max_size = integer() | unlimited</c></tag>
+      <item>
+	<p>This parameter specifies the maximum size (bytes) each
+	  log event can have when printed by the standard logger
+	  handler. If the resulting string after formatting an event
+	  is bigger than this, it will be truncated before printed
+	  to the handler's destination.</p>
+      </item>
+      <tag><c>logger_utc = boolean()</c></tag>
+      <item>
+	<p>If set to <c>true</c>, the default formatter will display
+	  all dates in Universal Coordinated Time.</p>
+      </item>
       <tag><c>global_groups = [GroupTuple]</c></tag>
       <item>
         <marker id="global_groups"></marker>
@@ -497,6 +585,26 @@ MaxT = TickTime + TickTime / 4</code>
   </section>
 
   <section>
+    <title>Deprecated Configuration Parameters</title>
+    <p>In OTP-21, a new API for logging was added to Erlang/OTP. The
+      old <c>error_logger</c> event manager, and event handlers
+      running on this manager, will still work, but they are not used
+      by default.</p>
+    <p>The following application environment variables can still be
+      set, but they will only be used if the corresponding new logger
+      variables are not set.</p>
+    <taglist>
+      <tag><c>error_logger</c></tag>
+      <item>Replaced by <c>logger_dest</c></item>
+      <tag><c>error_logger_format_depth</c></tag>
+      <item>Replaced by <c>logger_format_depth</c></item>
+    </taglist>
+    <p>See <seealso marker="logger_chapter#compatibility">Backwards
+	compatibility with error_logger</seealso> for more
+      information.</p>
+  </section>
+
+  <section>
     <title>See Also</title>
     <p><seealso marker="app"><c>app(4)</c></seealso>,
       <seealso marker="application"><c>application(3)</c></seealso>,