class ShopifyCli::ProcessSupervision

ProcessSupervision wraps a running process spawned by exec and keeps track if its pid and keeps a log file for it as well

• Attributes
• Class Methods
  • run_dir
  • for_ident
  • start
  • stop
  • running?
• Instance Methods
  • stop
  • alive?
  • write

Attributes

• identifier a string or a symbol to identify this process by

• pid process ID for the running process

• time starttime of the process

• pid_path filepath to the pidfile for this process

• log_path filepath to the logfile for this process

Class Methods

run_dir

run_dir()

see source

# File lib/shopify-cli/process_supervision.rb, line 20
def run_dir
  # is the directory where the pid and logfile are kept
  File.join(ShopifyCli.cache_dir, "sv")
end

---

for_ident

for_ident(identifier) Will find and create a new instance of ProcessSupervision for a running process if it is currently running. It will return nil if the process is not running.

Parameters

• identifier - a string or a symbol that a process was started with

Returns

• process - ProcessSupervision instance if the process is running this will be nil if the process is not running.

see source

# File lib/shopify-cli/process_supervision.rb, line 38
def for_ident(identifier)
  pid, time = File.read(File.join(ShopifyCli::ProcessSupervision.run_dir, "#{identifier}.pid")).split(":")
  new(identifier, pid: Integer(pid), time: time)
rescue Errno::ENOENT
  nil
end

---

start

start(identifier, args) will fork and spawn a new process that is separate from the current process. This process will keep running beyond the command running so be careful!

Parameters

• identifier - a string or symbol to identify the new process by.
• args - a command to run, either a string or array of strings

Returns

• process - ProcessSupervision instance if the process is running, this will be nil if the process did not start.

see source

# File lib/shopify-cli/process_supervision.rb, line 59
def start(identifier, args)
  return for_ident(identifier) if running?(identifier)

  # Windows doesn't support forking process without extra gems, so we resort to spawning a new child process -
  # that means that it dies along with the original process if it is interrupted. On UNIX, we fork the process so
  # that it doesn't have to be restarted on every run.
  if Context.new.windows?
    pid_file = new(identifier)

    # Make sure the file exists and is empty, otherwise Windows fails
    File.open(pid_file.log_path, "w") {}
    pid = Process.spawn(
      *args,
      out: pid_file.log_path,
      err: pid_file.log_path,
      in: Context.new.windows? ? "nul" : "/dev/null",
    )
    pid_file.pid = pid
    pid_file.write

    Process.detach(pid)
  else
    fork do
      pid_file = new(identifier, pid: Process.pid)
      pid_file.write
      STDOUT.reopen(pid_file.log_path, "w")
      STDERR.reopen(pid_file.log_path, "w")
      STDIN.reopen("/dev/null", "r")
      Process.setsid
      exec(*args)
    end
  end

  sleep(0.1)
  for_ident(identifier)
end

---

stop

stop(identifier) will attempt to shutdown a running process

Parameters

• identifier - a string or symbol to identify the new process by.

Returns

• stopped - [true, false]

see source

# File lib/shopify-cli/process_supervision.rb, line 107
def stop(identifier)
  process = for_ident(identifier)
  return false unless process
  process.stop
end

---

running?

running?(identifier) will help identify if your process is still running in the background.

Parameters

• identifier - a string or symbol to identify the new process by.

Returns

• running - [true, false]

see source

# File lib/shopify-cli/process_supervision.rb, line 124
def running?(identifier)
  process = for_ident(identifier)
  return false unless process
  process.alive?
end

---

Instance Methods

stop

stop() will attempt to shutdown a running process

Parameters

• ctx - the context of this command

Returns

• stopped - [true, false]

see source

# File lib/shopify-cli/process_supervision.rb, line 151
def stop
  kill_proc
  unlink
  true
rescue
  false
end

---

alive?

alive?() will help identify if your process is still running in the background.

Returns

• alive - [true, false]

see source

# File lib/shopify-cli/process_supervision.rb, line 166
def alive?
  stat(pid)
end

---

write

write() persists the pidfile

see source

# File lib/shopify-cli/process_supervision.rb, line 173
def write
  FileUtils.mkdir_p(File.dirname(pid_path))
  File.write(pid_path, "#{pid}:#{time}")
end

---