scripts/tracetool/backend/__init__.py

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