Module: Tetra::ProcessRunner

Includes:
Logging
Included in:
Bash, Git, Tar, Unzip
Defined in:
lib/tetra/facades/process_runner.rb

Overview

runs programs in subprocesses

Instance Method Summary collapse

Methods included from Logging

#log

Instance Method Details

#run(commandline, echo = false, stdin_data = nil) ⇒ Object

runs a noninteractive executable and returns its output as a string raises ExecutionFailed if the exit status is not 0 optionally echoes the executable’s output/error to standard output/error



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# File 'lib/tetra/facades/process_runner.rb', line 11

def run(commandline, echo = false, stdin_data = nil)
  log.debug "running `#{commandline}`"

  # Prepare buffers to capture output
  out_buffer = StringIO.new
  err_buffer = StringIO.new
  exit_status = nil
  # Flatten handles nested arrays, Compact removes nils
  cmd_args = Array(commandline).flatten.compact.map(&:to_s)

  Open3.popen3(*cmd_args) do |stdin, stdout, stderr, wait_thr|
    # 1. Handle Input (if any)
    stdin.write(stdin_data) if stdin_data
    stdin.close # Close stdin so the process knows input is finished

    # Use threads to read stdout and stderr simultaneously.
    readers = []

    readers << Thread.new do
      stdout.each_line do |line|
        print line if echo       # Echo to real STDOUT if requested
        out_buffer << line       # Capture to memory
      end
    end

    readers << Thread.new do
      stderr.each_line do |line|
        $stderr.print line if echo # Echo to real STDERR if requested
        err_buffer << line         # Capture to memory
      end
    end

    # Wait for reading to finish
    readers.each(&:join)

    # Get the exit code
    exit_status = wait_thr.value
  end

  # Check for failure
  unless exit_status.success?
    # Extract strings from buffers
    out = out_buffer.string
    err = err_buffer.string

    log.warn("`#{commandline}` failed with status #{exit_status.exitstatus}")

    if !out.empty? || !err.empty?
      log.warn("Output follows:")
      log.warn(out) unless out.empty?
      log.warn(err) unless err.empty?
    end

    fail ExecutionFailed.new(commandline, exit_status.exitstatus, out, err)
  end

  # Return the standard output
  out_buffer.string
end

#run_interactive(command) ⇒ Object

runs an interactive executable in a subshell



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# File 'lib/tetra/facades/process_runner.rb', line 72

def run_interactive(command)
  log.debug "running interactive `#{command}`"

  # system() passes control to the subprocess
  cmd_args = Array(command).flatten.compact.map(&:to_s)
  success = system(*cmd_args)

  log.debug "`#{command}` exited with success #{success}"

  fail ExecutionFailed.new(command, $CHILD_STATUS.exitstatus, nil, nil) unless success
end