| 1 | # SPDX-License-Identifier: GPL-2.0-or-later |
| 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 |
| 26 | considered "public". |
| 27 | CHECK_TRACE_EVENT_GET_STATE If exists and is set to 'True', the backend-specific |
| 28 | code inside the tracepoint is emitted within an |
| 29 | ``if trace_event_get_state()`` conditional. |
| 30 | =========================== ==================================================== |
| 31 | |
| 32 | |
| 33 | Backend functions |
| 34 | ----------------- |
| 35 | |
| 36 | All the following functions are optional, and no output will be generated if |
| 37 | they do not exist. |
| 38 | |
| 39 | =============================== ============================================== |
| 40 | Function Description |
| 41 | =============================== ============================================== |
| 42 | generate_<format>_begin(events) Generate backend- and format-specific file |
| 43 | header contents. |
| 44 | generate_<format>_end(events) Generate backend- and format-specific file |
| 45 | footer contents. |
| 46 | generate_<format>(event) Generate backend- and format-specific contents |
| 47 | for the given event. |
| 48 | =============================== ============================================== |
| 49 | |
| 50 | """ |
| 51 | |
| 52 | __author__ = "Lluís Vilanova <vilanova@ac.upc.edu>" |
| 53 | __copyright__ = "Copyright 2012-2014, Lluís Vilanova <vilanova@ac.upc.edu>" |
| 54 | __license__ = "GPL version 2 or (at your option) any later version" |
| 55 | |
| 56 | __maintainer__ = "Stefan Hajnoczi" |
| 57 | __email__ = "stefanha@redhat.com" |
| 58 | |
| 59 | |
| 60 | import os |
| 61 | |
| 62 | import tracetool |
| 63 | |
| 64 | |
| 65 | def get_list(only_public = False): |
| 66 | """Get a list of (name, description) pairs.""" |
| 67 | res = [("nop", "Tracing disabled.")] |
| 68 | modnames = [] |
| 69 | for filename in os.listdir(tracetool.backend.__path__[0]): |
| 70 | if filename.endswith('.py') and filename != '__init__.py': |
| 71 | modnames.append(filename.rsplit('.', 1)[0]) |
| 72 | for modname in sorted(modnames): |
| 73 | module = tracetool.try_import("tracetool.backend." + modname) |
| 74 | |
| 75 | # just in case; should never fail unless non-module files are put there |
| 76 | if not module[0]: |
| 77 | continue |
| 78 | module = module[1] |
| 79 | |
| 80 | public = getattr(module, "PUBLIC", False) |
| 81 | if only_public and not public: |
| 82 | continue |
| 83 | |
| 84 | doc = module.__doc__ |
| 85 | if doc is None: |
| 86 | doc = "" |
| 87 | doc = doc.strip().split("\n")[0] |
| 88 | |
| 89 | name = modname.replace("_", "-") |
| 90 | res.append((name, doc)) |
| 91 | return res |
| 92 | |
| 93 | |
| 94 | def exists(name): |
| 95 | """Return whether the given backend exists.""" |
| 96 | if len(name) == 0: |
| 97 | return False |
| 98 | if name == "nop": |
| 99 | return True |
| 100 | name = name.replace("-", "_") |
| 101 | return tracetool.try_import("tracetool.backend." + name)[0] |
| 102 | |
| 103 | |
| 104 | class Wrapper: |
| 105 | def __init__(self, backends, format): |
| 106 | self._backends = [backend.replace("-", "_") for backend in backends] |
| 107 | self._format = format.replace("-", "_") |
| 108 | self.check_trace_event_get_state = False |
| 109 | for backend in self._backends: |
| 110 | assert exists(backend) |
| 111 | assert tracetool.format.exists(self._format) |
| 112 | for backend in self.backend_modules(): |
| 113 | check_trace_event_get_state = getattr(backend, "CHECK_TRACE_EVENT_GET_STATE", False) |
| 114 | self.check_trace_event_get_state = self.check_trace_event_get_state or check_trace_event_get_state |
| 115 | |
| 116 | def backend_modules(self): |
| 117 | for backend in self._backends: |
| 118 | module = tracetool.try_import("tracetool.backend." + backend)[1] |
| 119 | if module is not None: |
| 120 | yield module |
| 121 | |
| 122 | def _run_function(self, name, *args, check_trace_event_get_state=None, **kwargs): |
| 123 | for backend in self.backend_modules(): |
| 124 | func = getattr(backend, name % self._format, None) |
| 125 | if func is not None and \ |
| 126 | (check_trace_event_get_state is None or |
| 127 | check_trace_event_get_state == getattr(backend, 'CHECK_TRACE_EVENT_GET_STATE', False)): |
| 128 | func(*args, **kwargs) |
| 129 | |
| 130 | def generate_begin(self, events, group): |
| 131 | self._run_function("generate_%s_begin", events, group) |
| 132 | |
| 133 | def generate(self, event, group, check_trace_event_get_state=None): |
| 134 | self._run_function("generate_%s", event, group, check_trace_event_get_state=check_trace_event_get_state) |
| 135 | |
| 136 | def generate_backend_dstate(self, event, group): |
| 137 | self._run_function("generate_%s_backend_dstate", event, group) |
| 138 | |
| 139 | def generate_end(self, events, group): |
| 140 | self._run_function("generate_%s_end", events, group) |