scripts/tracetool/backend/__init__.py

   1 #!/usr/bin/env python
   2 # -*- coding: utf-8 -*-
   3
   4 """
   5 Backend management.
   6
   7
   8 Creating new backends
   9 ---------------------
  10
  11 A new backend named 'foo-bar' corresponds to Python module
  12 'tracetool/backend/foo_bar.py'.
  13
  14 A backend module should provide a docstring, whose first non-empty line will be
  15 considered its short description.
  16
  17 All backends must generate their contents through the 'tracetool.out' routine.
  18
  19
  20 Backend attributes
  21 ------------------
  22
  23 ========= ====================================================================
  24 Attribute Description
  25 ========= ====================================================================
  26 PUBLIC    If exists and is set to 'True', the backend is considered "public".
  27 ========= ====================================================================
  28
  29
  30 Backend functions
  31 -----------------
  32
  33 All the following functions are optional, and no output will be generated if
  34 they do not exist.
  35
  36 =============================== ==============================================
  37 Function                        Description
  38 =============================== ==============================================
  39 generate_<format>_begin(events) Generate backend- and format-specific file
  40                                 header contents.
  41 generate_<format>_end(events)   Generate backend- and format-specific file
  42                                 footer contents.
  43 generate_<format>(event)        Generate backend- and format-specific contents
  44                                 for the given event.
  45 =============================== ==============================================
  46
  47 """
  48
  49 __author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
  50 __copyright__  = "Copyright 2012-2014, Lluís Vilanova <vilanova@ac.upc.edu>"
  51 __license__    = "GPL version 2 or (at your option) any later version"
  52
  53 __maintainer__ = "Stefan Hajnoczi"
  54 __email__      = "stefanha@linux.vnet.ibm.com"
  55
  56
  57 import os
  58
  59 import tracetool
  60
  61
  62 def get_list(only_public = False):
  63     """Get a list of (name, description) pairs."""
  64     res = [("nop", "Tracing disabled.")]
  65     modnames = []
  66     for filename in os.listdir(tracetool.backend.__path__[0]):
  67         if filename.endswith('.py') and filename != '__init__.py':
  68             modnames.append(filename.rsplit('.', 1)[0])
  69     for modname in sorted(modnames):
  70         module = tracetool.try_import("tracetool.backend." + modname)
  71
  72         # just in case; should never fail unless non-module files are put there
  73         if not module[0]:
  74             continue
  75         module = module[1]
  76
  77         public = getattr(module, "PUBLIC", False)
  78         if only_public and not public:
  79             continue
  80
  81         doc = module.__doc__
  82         if doc is None:
  83             doc = ""
  84         doc = doc.strip().split("\n")[0]
  85
  86         name = modname.replace("_", "-")
  87         res.append((name, doc))
  88     return res
  89
  90
  91 def exists(name):
  92     """Return whether the given backend exists."""
  93     if len(name) == 0:
  94         return False
  95     if name == "nop":
  96         return True
  97     name = name.replace("-", "_")
  98     return tracetool.try_import("tracetool.backend." + name)[1]
  99
 100
 101 class Wrapper:
 102     def __init__(self, backends, format):
 103         self._backends = [backend.replace("-", "_") for backend in backends]
 104         self._format = format.replace("-", "_")
 105         for backend in self._backends:
 106             assert exists(backend)
 107         assert tracetool.format.exists(self._format)
 108
 109     def _run_function(self, name, *args, **kwargs):
 110         for backend in self._backends:
 111             func = tracetool.try_import("tracetool.backend." + backend,
 112                                         name % self._format, None)[1]
 113             if func is not None:
 114                 func(*args, **kwargs)
 115
 116     def generate_begin(self, events, group):
 117         self._run_function("generate_%s_begin", events, group)
 118
 119     def generate(self, event, group):
 120         self._run_function("generate_%s", event, group)
 121
 122     def generate_backend_dstate(self, event, group):
 123         self._run_function("generate_%s_backend_dstate", event, group)
 124
 125     def generate_end(self, events, group):
 126         self._run_function("generate_%s_end", events, group)