[GR-18163] Caching Process.pid in constant

PullRequest: truffleruby/3663

Author: horakivo

CHANGELOG.md

@@ -85,6 +85,7 @@ Performance:
 
 * Marking of native structures wrapped in objects is now done on C call exit to reduce memory overhead (@aardvark179).
 * Splitting (copying) of call targets has been optimized by implementing `cloneUninitialized()` (@andrykonchin, @eregon).
+* `Process.pid` is now cached per process like `$$` (#2882, @horakivo)
 
 Changes:
 

lib/gems/gems/rbs-2.7.0/core/global_variables.rbs

@@ -5,7 +5,7 @@ $!: Exception | nil
 $": Array[String]
 
 # The process number of the Ruby running this script. Same as Process.pid.
-$$: Integer
+$$: Integer | nil
 
 # The string matched by the last successful match.
 $&: String | nil

src/main/ruby/truffleruby/core/post.rb

@@ -86,7 +86,7 @@ def p(*a)
 end
 
 Truffle::Boot.delay do
-  $$ = Process.pid if Truffle::POSIX::NATIVE
+  $$ = Truffle::POSIX::NATIVE ? Truffle::POSIX.getpid : nil
 
   ARGV.concat(Truffle::Boot.original_argv)
 end

src/main/ruby/truffleruby/core/process.rb

@@ -343,7 +343,7 @@ def getpgrp
   end
 
   def pid
-    Truffle::POSIX.getpid
+    $$ or raise SecurityError, 'native access is not allowed'
   end
 
   def ppid