1 files changed, 84 insertions, 0 deletions
diff --git a/lib/gitlab/process_management.rb b/lib/gitlab/process_management.rb
new file mode 100644
index 00000000000..2c2aaadb29a
--- /dev/null
+++ b/lib/gitlab/process_management.rb
@@ -0,0 +1,84 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module ProcessManagement
+    # The signals that should terminate both the master and workers.
+    TERMINATE_SIGNALS = %i(INT TERM).freeze
+
+    # The signals that should simply be forwarded to the workers.
+    FORWARD_SIGNALS = %i(TTIN USR1 USR2 HUP).freeze
+
+    # Traps the given signals and yields the block whenever these signals are
+    # received.
+    #
+    # The block is passed the name of the signal.
+    #
+    # Example:
+    #
+    #     trap_signals(%i(HUP TERM)) do |signal|
+    #       ...
+    #     end
+    def self.trap_signals(signals)
+      signals.each do |signal|
+        trap(signal) do
+          yield signal
+        end
+      end
+    end
+
+    def self.trap_terminate(&block)
+      trap_signals(TERMINATE_SIGNALS, &block)
+    end
+
+    def self.trap_forward(&block)
+      trap_signals(FORWARD_SIGNALS, &block)
+    end
+
+    def self.signal(pid, signal)
+      Process.kill(signal, pid)
+      true
+    rescue Errno::ESRCH
+      false
+    end
+
+    def self.signal_processes(pids, signal)
+      pids.each { |pid| signal(pid, signal) }
+    end
+
+    # Waits for the given process to complete using a separate thread.
+    def self.wait_async(pid)
+      Thread.new do
+        Process.wait(pid) rescue Errno::ECHILD
+      end
+    end
+
+    # Returns true if all the processes are alive.
+    def self.all_alive?(pids)
+      pids.each do |pid|
+        return false unless process_alive?(pid)
+      end
+
+      true
+    end
+
+    def self.any_alive?(pids)
+      pids_alive(pids).any?
+    end
+
+    def self.pids_alive(pids)
+      pids.select { |pid| process_alive?(pid) }
+    end
+
+    def self.process_alive?(pid)
+      # Signal 0 tests whether the process exists and we have access to send signals
+      # but is otherwise a noop (doesn't actually send a signal to the process)
+      signal(pid, 0)
+    end
+
+    def self.write_pid(path)
+      File.open(path, 'w') do |handle|
+        handle.write(Process.pid.to_s)
+      end
+    end
+  end
+end