From 3cef0524e4332ebf547180ec0d0feafe0a559b5c Mon Sep 17 00:00:00 2001
From: Siri Hansen <siri@erlang.org>
Date: Wed, 2 May 2018 19:20:27 +0200
Subject: Add logger:update_process_metadata/1

---
 lib/kernel/doc/src/logger.xml    | 22 ++++++++++++++++++----
 lib/kernel/src/logger.erl        | 17 +++++++++++++++--
 lib/kernel/test/logger_SUITE.erl |  3 +++
 3 files changed, 36 insertions(+), 6 deletions(-)

(limited to 'lib/kernel')

diff --git a/lib/kernel/doc/src/logger.xml b/lib/kernel/doc/src/logger.xml
index 2beefd1240..2f7feb5eef 100644
--- a/lib/kernel/doc/src/logger.xml
+++ b/lib/kernel/doc/src/logger.xml
@@ -471,10 +471,9 @@ Current logger configuration:
       <name name="set_process_metadata" arity="1"/>
       <fsummary>Set metadata to use when logging from current process.</fsummary>
       <desc>
-        <p>Set metadata which <c>logger</c> automatically inserts it
-          in all log events produced on the current
-          process. Subsequent calls will overwrite previous data set
-          by this function.</p>
+        <p>Set metadata which <c>logger</c> automatically inserts in
+          all log events produced on the current process. Subsequent
+          calls will overwrite previous data set by this function.</p>
 	<p>When logging, location data produced by the log macros,
 	  and/or metadata given as argument to the log call (API
 	  function or macro), will be merged with the process
@@ -485,6 +484,21 @@ Current logger configuration:
       </desc>
     </func>
 
+    <func>
+      <name name="update_process_metadata" arity="1"/>
+      <fsummary>Update metadata to use when logging from current process.</fsummary>
+      <desc>
+	<p>Update metadata to use when logging from current process</p>
+	<p>This function behaves as if it was implemented as follows:</p>
+	<code type="erl">
+logger:set_process_metadata(maps:merge(logger:get_process_metadata(),Meta))
+	</code>
+	<p>If no process metadata exists, the function behaves as
+	  <seealso marker="#set_process_metadata-1"><c>set_process_metadata/1</c>
+	  </seealso>.</p>
+      </desc>
+    </func>
+
     <func>
       <name name="get_process_metadata" arity="0"/>
       <fsummary>Retrieve data set with set_process_metadata/1.</fsummary>
diff --git a/lib/kernel/src/logger.erl b/lib/kernel/src/logger.erl
index 943ef8c2d1..5562764204 100644
--- a/lib/kernel/src/logger.erl
+++ b/lib/kernel/src/logger.erl
@@ -44,8 +44,8 @@
 
 %% Misc
 -export([compare_levels/2]).
--export([set_process_metadata/1, unset_process_metadata/0,
-         get_process_metadata/0]).
+-export([set_process_metadata/1, update_process_metadata/1,
+         unset_process_metadata/0, get_process_metadata/0]).
 -export([i/0, i/1]).
 -export([setup_standard_handler/0, replace_simple_handler/3]).
 -export([limit_term/1, get_format_depth/0, get_max_size/0, get_utc_config/0]).
@@ -390,6 +390,19 @@ set_process_metadata(Meta) when is_map(Meta) ->
 set_process_metadata(Meta) ->
     erlang:error(badarg,[Meta]).
 
+-spec update_process_metadata(Meta) -> ok when
+      Meta :: metadata().
+update_process_metadata(Meta) when is_map(Meta) ->
+    case get_process_metadata() of
+        undefined ->
+            set_process_metadata(Meta);
+        Meta0 when is_map(Meta0) ->
+            set_process_metadata(maps:merge(Meta0,Meta)),
+            ok
+    end;
+update_process_metadata(Meta) ->
+    erlang:error(badarg,[Meta]).
+
 -spec get_process_metadata() -> Meta | undefined when
       Meta :: metadata().
 get_process_metadata() ->
diff --git a/lib/kernel/test/logger_SUITE.erl b/lib/kernel/test/logger_SUITE.erl
index 0edce3e34c..94fd87bdb0 100644
--- a/lib/kernel/test/logger_SUITE.erl
+++ b/lib/kernel/test/logger_SUITE.erl
@@ -666,6 +666,9 @@ process_metadata(_Config) ->
     check_logged(info,S3,#{time=>Time,line=>0,custom=>func}),
 
     ProcMeta = logger:get_process_metadata(),
+    ok = logger:update_process_metadata(#{custom=>changed,custom2=>added}),
+    Expected = ProcMeta#{custom:=changed,custom2=>added},
+    Expected = logger:get_process_metadata(),
     ok = logger:unset_process_metadata(),
     undefined = logger:get_process_metadata(),
 
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