[GR-20446] Implement Process::Status.wait

PullRequest: truffleruby/2736

CHANGELOG.md

@@ -8,6 +8,7 @@ Bug fixes:
 
 Compatibility:
 
+* Implement `Process::Status.wait` (#2378).
 
 Performance:
 

spec/ruby/core/process/status/wait_spec.rb

@@ -0,0 +1,103 @@
+require_relative '../../../spec_helper'
+require_relative '../fixtures/common'
+
+ruby_version_is "3.0" do
+  describe "Process::Status.wait" do
+    ProcessSpecs.use_system_ruby(self)
+
+    before :all do
+      begin
+        leaked = Process.waitall
+        # Ruby-space should not see PIDs used by mjit
+        raise "subprocesses leaked before wait specs: #{leaked}" unless leaked.empty?
+      rescue NotImplementedError
+      end
+    end
+
+    it "returns a status with pid -1 if there are no child processes" do
+      Process::Status.wait.pid.should == -1
+    end
+
+    platform_is_not :windows do
+      it "returns a status with its child pid" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        status = Process::Status.wait
+        status.should be_an_instance_of(Process::Status)
+        status.pid.should == pid
+      end
+
+      it "should not set $? to the Process::Status" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        status = Process::Status.wait
+        $?.should_not equal(status)
+      end
+
+      it "should not change the value of $?" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        Process.wait
+        status = $?
+        Process::Status.wait
+        status.should equal($?)
+      end
+
+      it "waits for any child process if no pid is given" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        Process::Status.wait.pid.should == pid
+        -> { Process.kill(0, pid) }.should raise_error(Errno::ESRCH)
+      end
+
+      it "waits for a specific child if a pid is given" do
+        pid1 = Process.spawn(ruby_cmd('exit'))
+        pid2 = Process.spawn(ruby_cmd('exit'))
+        Process::Status.wait(pid2).pid.should == pid2
+        Process::Status.wait(pid1).pid.should == pid1
+        -> { Process.kill(0, pid1) }.should raise_error(Errno::ESRCH)
+        -> { Process.kill(0, pid2) }.should raise_error(Errno::ESRCH)
+      end
+
+      it "coerces the pid to an Integer" do
+        pid1 = Process.spawn(ruby_cmd('exit'))
+        Process::Status.wait(mock_int(pid1)).pid.should == pid1
+        -> { Process.kill(0, pid1) }.should raise_error(Errno::ESRCH)
+      end
+
+      # This spec is probably system-dependent.
+      it "waits for a child whose process group ID is that of the calling process" do
+        pid1 = Process.spawn(ruby_cmd('exit'), pgroup: true)
+        pid2 = Process.spawn(ruby_cmd('exit'))
+
+        Process::Status.wait(0).pid.should == pid2
+        Process::Status.wait.pid.should == pid1
+      end
+
+      # This spec is probably system-dependent.
+      it "doesn't block if no child is available when WNOHANG is used" do
+        read, write = IO.pipe
+        pid = Process.fork do
+          read.close
+          Signal.trap("TERM") { Process.exit! }
+          write << 1
+          write.close
+          sleep
+        end
+
+        Process::Status.wait(pid, Process::WNOHANG).should be_nil
+
+        # wait for the child to setup its TERM handler
+        write.close
+        read.read(1)
+        read.close
+
+        Process.kill("TERM", pid)
+        Process::Status.wait.pid.should == pid
+      end
+
+      it "always accepts flags=0" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        Process::Status.wait(-1, 0).pid.should == pid
+        -> { Process.kill(0, pid) }.should raise_error(Errno::ESRCH)
+      end
+    end
+  end
+end
+

spec/tags/core/process/status/wait_tags.txt

@@ -0,0 +1 @@
+fails:Process::Status.wait doesn't block if no child is available when WNOHANG is used

spec/truffleruby.mspec

@@ -95,6 +95,7 @@ class MSpecScript
   set :next, %w[
     spec/ruby/core/mutex/owned_spec.rb
     spec/ruby/core/fiber/raise_spec.rb
+    spec/ruby/core/process/status/wait_spec.rb
   ]
 
   set :tags_patterns, [

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

@@ -601,26 +601,8 @@ def self.last_status
   # TODO: Support other options such as WUNTRACED? --rue
   #
   def self.wait2(input_pid=-1, flags=nil)
-    input_pid = Truffle::Type.coerce_to input_pid, Integer, :to_int
-    flags ||= 0
-
-    FFI::MemoryPointer.new(:int, 4) do |ptr|
-      pid = Truffle::POSIX.truffleposix_waitpid(input_pid, flags, ptr)
-      if pid == 0
-        return nil
-      elsif pid == -1
-        Errno.handle "No child process: #{input_pid}"
-      else
-        ints = ptr.read_array_of_int(4)
-        exitcode, termsig, stopsig, = ints.map { |e| e == -1000 ? nil : e }
-        raw_status = ints.last
-
-        status = Process::Status.new(pid, exitcode, termsig, stopsig, raw_status)
-        Primitive.thread_set_return_code status
-
-        [pid, status]
-      end
-    end
+    status = Truffle::ProcessOperations.wait(input_pid, flags, true, true)
+    [status.pid, status]
   end
 
   #
@@ -650,8 +632,7 @@ def self.waitall
   end
 
   def self.wait(pid=-1, flags=nil)
-    pid, _status = Process.wait2(pid, flags)
-    pid
+    Truffle::ProcessOperations.wait(pid, flags, true, true)&.pid
   end
 
   class << self
@@ -781,6 +762,10 @@ def to_s
     def inspect
       "#<Process::Status: #{self}>"
     end
+
+    def self.wait(pid=-1, flags=nil)
+      Truffle::ProcessOperations.wait(pid, flags, false, false)
+    end
   end
 
   module Sys

src/main/ruby/truffleruby/core/truffle/process_operations.rb

@@ -87,6 +87,29 @@ def self.spawn(*args)
       end
     end
 
+    def self.wait(input_pid, flags, set_status, raise_on_error)
+      input_pid = Truffle::Type.coerce_to input_pid, Integer, :to_int
+      flags ||= 0
+
+      FFI::MemoryPointer.new(:int, 4) do |ptr|
+        pid = Truffle::POSIX.truffleposix_waitpid(input_pid, flags, ptr)
+        if pid == 0
+          return nil
+        elsif raise_on_error && pid == -1
+          Errno.handle "No child process: #{input_pid}"
+        else
+          ints = ptr.read_array_of_int(4)
+          exitcode, termsig, stopsig, = ints.map { |e| e == -1000 ? nil : e }
+          raw_status = ints.last
+
+          status = Process::Status.new(pid, exitcode, termsig, stopsig, raw_status)
+          Primitive.thread_set_return_code status if set_status
+
+          status
+        end
+      end
+    end
+
     class Execute
       def initialize
         @options = {}