text: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  """
  Generate .stp file that outputs simpletrace binary traces (DTrace with SystemTAP only).
  """
  
  __author__     = "Stefan Hajnoczi <redhat.com>"
  __copyright__  = "Copyright (C) 2014, Red Hat, Inc."
  __license__    = "GPL version 2 or (at your option) any later version"
  
  __maintainer__ = "Stefan Hajnoczi"
  __email__      = "stefanha@redhat.com"
  
  
  from tracetool import out
  from tracetool.backend.dtrace import probeprefix
  from tracetool.backend.simple import is_string
  from tracetool.format.stap import stap_escape
  
  def global_var_name(name):
      return probeprefix().replace(".", "_") + "_" + name
  
  def generate(events, backend, group):
      out('/* This file is autogenerated by tracetool, do not edit. */',
          '')
  
      for event_id, e in enumerate(events):
          if 'disable' in e.properties:
              continue
  
          out('probe %(probeprefix)s.simpletrace.%(name)s = %(probeprefix)s.%(name)s ?',
              '{',
              probeprefix=probeprefix(),
              name=e.name)
  
          # Calculate record size
          sizes = ['24'] # sizeof(TraceRecord)
          for type_, name in e.args:
              name = stap_escape(name)
              if is_string(type_):
                  out('    try {',
                      '        arg%(name)s_str = %(name)s ? user_string_n(%(name)s, 512) : "<null>"',
                      '    } catch {}',
                      '    arg%(name)s_len = strlen(arg%(name)s_str)',
                      name=name)
                  sizes.append('4 + arg%s_len' % name)
              else:
                  sizes.append('8')
          sizestr = ' + '.join(sizes)
  
          # Generate format string and value pairs for record header and arguments
          fields = [('8b', str(event_id)),
                    ('8b', 'gettimeofday_ns()'),
                    ('4b', sizestr),
                    ('4b', 'pid()')]
          for type_, name in e.args:
              name = stap_escape(name)
              if is_string(type_):
                  fields.extend([('4b', 'arg%s_len' % name),
                                 ('.*s', 'arg%s_len, arg%s_str' % (name, name))])
              else:
                  fields.append(('8b', name))
  
          # Emit the entire record in a single SystemTap printf()
          fmt_str = '%'.join(fmt for fmt, _ in fields)
          arg_str = ', '.join(arg for _, arg in fields)
          out('    printf("%%8b%%%(fmt_str)s", 1, %(arg_str)s)',
              fmt_str=fmt_str, arg_str=arg_str)
  
          out('}')
  
      out()
  