Import QEMU upstream snapshot d2e570c

Upstream: https://gitlab.com/qemu-project/qemu.git

Upstream-Commit: d2e570cc0f97b936902a5b1b86b73c0f5998b475

scripts/tracetool/backend/__init__.py

@@ -0,0 +1,140 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+"""
+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 attributes
+------------------
+
+=========================== ====================================================
+Attribute                   Description
+=========================== ====================================================
+PUBLIC                      If exists and is set to 'True', the backend is
+                            considered "public".
+CHECK_TRACE_EVENT_GET_STATE If exists and is set to 'True', the backend-specific
+                            code inside the tracepoint is emitted within an
+                            ``if trace_event_get_state()`` conditional.
+=========================== ====================================================
+
+
+Backend functions
+-----------------
+
+All the following functions are optional, and no output will be generated if
+they do not exist.
+
+=============================== ==============================================
+Function                        Description
+=============================== ==============================================
+generate_<format>_begin(events) Generate backend- and format-specific file
+                                header contents.
+generate_<format>_end(events)   Generate backend- and format-specific file
+                                footer contents.
+generate_<format>(event)        Generate backend- and format-specific contents
+                                for the given event.
+=============================== ==============================================
+
+"""
+
+__author__     = "Lluís Vilanova <[email protected]>"
+__copyright__  = "Copyright 2012-2014, Lluís Vilanova <[email protected]>"
+__license__    = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__      = "[email protected]"
+
+
+import os
+
+import tracetool
+
+
+def get_list(only_public = False):
+    """Get a list of (name, description) pairs."""
+    res = [("nop", "Tracing disabled.")]
+    modnames = []
+    for filename in os.listdir(tracetool.backend.__path__[0]):
+        if filename.endswith('.py') and filename != '__init__.py':
+            modnames.append(filename.rsplit('.', 1)[0])
+    for modname in sorted(modnames):
+        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]
+
+        public = getattr(module, "PUBLIC", False)
+        if only_public and not public:
+            continue
+
+        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)[0]
+
+
+class Wrapper:
+    def __init__(self, backends, format):
+        self._backends = [backend.replace("-", "_") for backend in backends]
+        self._format = format.replace("-", "_")
+        self.check_trace_event_get_state = False
+        for backend in self._backends:
+            assert exists(backend)
+        assert tracetool.format.exists(self._format)
+        for backend in self.backend_modules():
+            check_trace_event_get_state = getattr(backend, "CHECK_TRACE_EVENT_GET_STATE", False)
+            self.check_trace_event_get_state = self.check_trace_event_get_state or check_trace_event_get_state
+
+    def backend_modules(self):
+        for backend in self._backends:
+             module = tracetool.try_import("tracetool.backend." + backend)[1]
+             if module is not None:
+                 yield module
+
+    def _run_function(self, name, *args, check_trace_event_get_state=None, **kwargs):
+        for backend in self.backend_modules():
+            func = getattr(backend, name % self._format, None)
+            if func is not None and \
+                (check_trace_event_get_state is None or
+                 check_trace_event_get_state == getattr(backend, 'CHECK_TRACE_EVENT_GET_STATE', False)):
+                    func(*args, **kwargs)
+
+    def generate_begin(self, events, group):
+        self._run_function("generate_%s_begin", events, group)
+
+    def generate(self, event, group, check_trace_event_get_state=None):
+        self._run_function("generate_%s", event, group, check_trace_event_get_state=check_trace_event_get_state)
+
+    def generate_backend_dstate(self, event, group):
+        self._run_function("generate_%s_backend_dstate", event, group)
+
+    def generate_end(self, events, group):
+        self._run_function("generate_%s_end", events, group)