Remove column for wait event names in wait_event_names.txt

This file is now made of two columns, removing the column listing the
user-visible strings used in the system views and the documentation:
- Enum definitions for each class without the prefix "WAIT_EVENT_", so
as this information can be grepped in the code and wait_event_names.txt
at the same time.
- Description in the documentation.

The wait event names are now generated from the enum objects in
CamelCase, with the underscores removed.  The data generated for wait
events is consistent with what was produced by 414f6c0.

This has the advantage to remove WAIT_EVENT_DOCONLY, which was a
placeholder for the wait event types Lock and LWLock as these two only
require the generation of the documentation.

Reviewed-by: Bertrand Drouvot
Discussion: https://postgr.es/m/ZOxVHQwEC/9X/p/z@paquier.xyz

Author: michaelpq

src/backend/utils/activity/generate-wait_event_types.pl

@@ -65,29 +65,45 @@
 	push(@lines, $section_name . "\t" . $_);
 }
 
-# Sort the lines based on the third column.
+# Sort the lines based on the second column.
 # uc() is being used to force the comparison to be case-insensitive.
 my @lines_sorted =
-  sort { uc((split(/\t/, $a))[2]) cmp uc((split(/\t/, $b))[2]) } @lines;
+  sort { uc((split(/\t/, $a))[1]) cmp uc((split(/\t/, $b))[1]) } @lines;
 
 # Read the sorted lines and populate the hash table
 foreach my $line (@lines_sorted)
 {
 	die "unable to parse wait_event_names.txt for line $line\n"
-	  unless $line =~ /^(\w+)\t+(\w+)\t+(\w+)\t+("\w.*\.")$/;
+	  unless $line =~ /^(\w+)\t+(\w+)\t+("\w.*\.")$/;
 
-	(   my $waitclassname,
-		my $waiteventenumname,
-		my $waiteventdescription,
-		my $waitevendocsentence) = split(/\t/, $line);
+	(my $waitclassname, my $waiteventname, my $waitevendocsentence) =
+	  split(/\t/, $line);
 
+	# Generate the element name for the enums based on the
+	# description.  The C symbols are prefixed with "WAIT_EVENT_".
+	my $waiteventenumname = "WAIT_EVENT_$waiteventname";
+
+	# Build the descriptions.  These are in camel-case.
+	# LWLock and Lock classes do not need any modifications.
+	my $waiteventdescription = '';
+	if (   $waitclassname eq 'WaitEventLWLock'
+		|| $waitclassname eq 'WaitEventLock')
+	{
+		$waiteventdescription = $waiteventname;
+	}
+	else
+	{
+		my @waiteventparts = split("_", $waiteventname);
+		foreach my $waiteventpart (@waiteventparts)
+		{
+			$waiteventdescription .= substr($waiteventpart, 0, 1)
+			  . lc(substr($waiteventpart, 1, length($waiteventpart)));
+		}
+	}
+
+	# Store the event into the list for each class.
 	my @waiteventlist =
 	  [ $waiteventenumname, $waiteventdescription, $waitevendocsentence ];
-	my $trimmedwaiteventname = $waiteventenumname;
-	$trimmedwaiteventname =~ s/^WAIT_EVENT_//;
-
-	die "wait event names must start with 'WAIT_EVENT_'"
-	  if ($trimmedwaiteventname eq $waiteventenumname);
 	push(@{ $hashwe{$waitclassname} }, @waiteventlist);
 }