Changeset 275482 in webkit

Timestamp:

Apr 5, 2021 7:46:54 PM (3 years ago)

Author:

commit-queue@webkit.org

Message:

Document how to use logging in WebKit
​https://bugs.webkit.org/show_bug.cgi?id=224152

Patch by Tyler Wilcock <Tyler Wilcock> on 2021-04-05
Reviewed by Simon Fraser.

Add documentation about how to use logging in WebKit.

• Introduction.md:

Location:

trunk

Files:

• ChangeLog (modified) (1 diff)
• Introduction.md (modified) (1 diff)

trunk/ChangeLog

@@ +1 @@
+2021-04-05  Tyler Wilcock  <twilco.o@protonmail.com>
+
+        Document how to use logging in WebKit
+        https://bugs.webkit.org/show_bug.cgi?id=224152
+
+        Reviewed by Simon Fraser.
+
+        Add documentation about how to use logging in WebKit.
+
+        * Introduction.md:
+
 2021-03-28  David Kilzer  <ddkilzer@apple.com>
 

trunk/Introduction.md

@@ -1345 +1345 @@
 # Logging in WebKit
 
-FIXME: Write this.
-
+Some places in WebKit use a macro called `LOG_WITH_STREAM`. Here's an example invocation:
+
+```
+LOG_WITH_STREAM(Scrolling, stream << "ScrollingTree::commitTreeState - removing unvisited node " << nodeID);
+```
+
+The first argument is the _log channel_ and the second is the _log content_. By default, this logging is enabled in
+debug builds and disabled in release builds (see definition of `LOG_DISABLED`).
+
+The only logs that will be printed are those whose channels you have enabled. You can specify the channels you want to
+enable by constructing a comma-separated list with the following syntax:
+
+* `ChannelName` to enable logging for this channel
+* `all` to enable logging for all channels
+* `-ChannelName` to disable logging for this channel
+
+Where you specify this list depends on the platform you are running WebKit on.
+
+### Linux
+
+Set the `WEBKIT_DEBUG` environment variable.
+
+```
+WEBKIT_DEBUG=Scrolling Tools/Scripts/run-minibrowser --gtk --debug
+```
+
+### Mac
+
+Set a value for the `WebCoreLogging` key in [standardUserDefaults](https://developer.apple.com/documentation/foundation/nsuserdefaults/1416603-standarduserdefaults).
+
+You may also pass this key and value as an argument:
+
+```
+Tools/Scripts/run-minibrowser --debug -WebCoreLogging Scrolling
+```
+
+or set the key and value on the [NSGlobalDomain](https://developer.apple.com/documentation/foundation/nsglobaldomain).
+
+```
+defaults write NSGlobalDomain  WebCoreLogging -string Scrolling
+Tools/Scripts/run-minibrowser --debug
+```
+
+### Windows
+
+Set the `WebCoreLogging` environment variable.