1 files changed, 111 insertions, 0 deletions
diff --git a/scripts/tracetool/backend/__init__.py b/scripts/tracetool/backend/__init__.py
new file mode 100644
index 0000000000..34b7ed8081
--- /dev/null
+++ b/scripts/tracetool/backend/__init__.py
@@ -0,0 +1,111 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Backend management.
+
+
+Creating new backends
+---------------------
+
+A new backend named 'foo-bar' corresponds to Python module
+'tracetool/backend/foo_bar.py'.
+
+A backend module should provide a docstring, whose first non-empty line will be
+considered its short description.
+
+All backends must generate their contents through the 'tracetool.out' routine.
+
+
+Backend functions
+-----------------
+
+======== =======================================================================
+Function Description
+======== =======================================================================
+<format> Called to generate the format- and backend-specific code for each of
+         the specified events. If the function does not exist, the backend is
+         considered not compatible with the given format.
+======== =======================================================================
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012, Lluís Vilanova <vilanova@ac.upc.edu>"
+__license__    = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__      = "stefanha@linux.vnet.ibm.com"
+
+
+import pkgutil
+
+import tracetool
+
+
+def get_list():
+    """Get a list of (name, description) pairs."""
+    res = [("nop", "Tracing disabled.")]
+    for _, modname, _ in pkgutil.iter_modules(tracetool.backend.__path__):
+        module = tracetool.try_import("tracetool.backend." + modname)
+
+        # just in case; should never fail unless non-module files are put there
+        if not module[0]:
+            continue
+        module = module[1]
+
+        doc = module.__doc__
+        if doc is None:
+            doc = ""
+        doc = doc.strip().split("\n")[0]
+
+        name = modname.replace("_", "-")
+        res.append((name, doc))
+    return res
+
+
+def exists(name):
+    """Return whether the given backend exists."""
+    if len(name) == 0:
+        return False
+    if name == "nop":
+        return True
+    name = name.replace("-", "_")
+    return tracetool.try_import("tracetool.backend." + name)[1]
+
+
+def compatible(backend, format):
+    """Whether a backend is compatible with the given format."""
+    if not exists(backend):
+        raise ValueError("unknown backend: %s" % backend)
+
+    backend = backend.replace("-", "_")
+    format = format.replace("-", "_")
+
+    if backend == "nop":
+        return True
+    else:
+        func = tracetool.try_import("tracetool.backend." + backend,
+                                    format, None)[1]
+        return func is not None
+
+
+def _empty(events):
+    pass
+
+def generate(backend, format, events):
+    """Generate the per-event output for the given (backend, format) pair."""
+    if not compatible(backend, format):
+        raise ValueError("backend '%s' not compatible with format '%s'" %
+                         (backend, format))
+
+    backend = backend.replace("-", "_")
+    format = format.replace("-", "_")
+
+    if backend == "nop":
+        func = tracetool.try_import("tracetool.format." + format,
+                                    "nop", _empty)[1]
+    else:
+        func = tracetool.try_import("tracetool.backend." + backend,
+                                    format, None)[1]
+
+    func(events)