src/python.c

   1 #include <Python.h>
   2 #include <structmember.h>
   3
   4 #include "collectd.h"
   5 #include "common.h"
   6
   7 typedef struct cpy_callback_s {
   8         char *name;
   9         PyObject *callback;
  10         PyObject *data;
  11         struct cpy_callback_s *next;
  12 } cpy_callback_t;
  13
  14 /* This is our global thread state. Python saves some stuff in thread-local
  15  * storage. So if we allow the interpreter to run in the background
  16  * (the scriptwriters might have created some threads from python), we have
  17  * to save the state so we can resume it later from a different thread.
  18
  19  * Technically the Global Interpreter Lock (GIL) and thread states can be
  20  * manipulated independently. But to keep stuff from getting too complex
  21  * we'll just use PyEval_SaveTread and PyEval_RestoreThreas which takes
  22  * care of the thread states as well as the GIL. */
  23
  24 static PyThreadState *state;
  25
  26 static cpy_callback_t *cpy_config_callbacks;
  27 static cpy_callback_t *cpy_init_callbacks;
  28 static cpy_callback_t *cpy_shutdown_callbacks;
  29
  30 typedef struct {
  31         PyObject_HEAD      /* No semicolon! */
  32         PyObject *parent;
  33         PyObject *key;
  34         PyObject *values;
  35         PyObject *children;
  36 } Config;
  37
  38 static void Config_dealloc(PyObject *s) {
  39         Config *self = (Config *) s;
  40
  41         Py_XDECREF(self->parent);
  42         Py_XDECREF(self->key);
  43         Py_XDECREF(self->values);
  44         Py_XDECREF(self->children);
  45         self->ob_type->tp_free(s);
  46 }
  47
  48 static PyObject *Config_new(PyTypeObject *type, PyObject *args, PyObject *kwds) {
  49         Config *self;
  50
  51         self = (Config *) type->tp_alloc(type, 0);
  52         if (self == NULL)
  53                 return NULL;
  54
  55         self->parent = NULL;
  56         self->key = NULL;
  57         self->values = NULL;
  58         self->children = NULL;
  59         return (PyObject *) self;
  60 }
  61
  62 static int Config_init(PyObject *s, PyObject *args, PyObject *kwds) {
  63         PyObject *key = NULL, *parent = NULL, *values = NULL, *children = NULL, *tmp;
  64         Config *self = (Config *) s;
  65         static char *kwlist[] = {"key", "parent", "values", "children", NULL};
  66
  67         if (!PyArg_ParseTupleAndKeywords(args, kwds, "S|OOO", kwlist,
  68                         &key, &parent, &values, &children))
  69                 return -1;
  70
  71         if (values == NULL) {
  72                 values = PyTuple_New(0);
  73                 PyErr_Clear();
  74         }
  75         if (children == NULL) {
  76                 children = PyTuple_New(0);
  77                 PyErr_Clear();
  78         }
  79         tmp = self->key;
  80         Py_INCREF(key);
  81         self->key = key;
  82         Py_XDECREF(tmp);
  83         if (parent != NULL) {
  84                 tmp = self->parent;
  85                 Py_INCREF(parent);
  86                 self->parent = parent;
  87                 Py_XDECREF(tmp);
  88         }
  89         if (values != NULL) {
  90                 tmp = self->values;
  91                 Py_INCREF(values);
  92                 self->values = values;
  93                 Py_XDECREF(tmp);
  94         }
  95         if (children != NULL) {
  96                 tmp = self->children;
  97                 Py_INCREF(children);
  98                 self->children = children;
  99                 Py_XDECREF(tmp);
 100         }
 101         return 0;
 102 }
 103
 104 static PyMemberDef Config_members[] = {
 105     {"Parent", T_OBJECT, offsetof(Config, parent), 0, "Parent node"},
 106     {"Key", T_OBJECT_EX, offsetof(Config, key), 0, "Keyword of this node"},
 107     {"Values", T_OBJECT_EX, offsetof(Config, values), 0, "Values after the key"},
 108     {"Children", T_OBJECT_EX, offsetof(Config, children), 0, "Childnodes of this node"},
 109     {NULL}
 110 };
 111
 112 static PyTypeObject ConfigType = {
 113     PyObject_HEAD_INIT(NULL)
 114     0,                         /* Always 0 */
 115     "collectd.Config",         /* tp_name */
 116     sizeof(Config),            /* tp_basicsize */
 117     0,                         /* Will be filled in later */
 118     Config_dealloc,            /* tp_dealloc */
 119     0,                         /* tp_print */
 120     0,                         /* tp_getattr */
 121     0,                         /* tp_setattr */
 122     0,                         /* tp_compare */
 123     0,                         /* tp_repr */
 124     0,                         /* tp_as_number */
 125     0,                         /* tp_as_sequence */
 126     0,                         /* tp_as_mapping */
 127     0,                         /* tp_hash */
 128     0,                         /* tp_call */
 129     0,                         /* tp_str */
 130     0,                         /* tp_getattro */
 131     0,                         /* tp_setattro */
 132     0,                         /* tp_as_buffer */
 133     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
 134     "Cool help text later",    /* tp_doc */
 135     0,                         /* tp_traverse */
 136     0,                         /* tp_clear */
 137     0,                         /* tp_richcompare */
 138     0,                         /* tp_weaklistoffset */
 139     0,                         /* tp_iter */
 140     0,                         /* tp_iternext */
 141     0,                         /* tp_methods */
 142     Config_members,            /* tp_members */
 143     0,                         /* tp_getset */
 144     0,                         /* tp_base */
 145     0,                         /* tp_dict */
 146     0,                         /* tp_descr_get */
 147     0,                         /* tp_descr_set */
 148     0,                         /* tp_dictoffset */
 149     Config_init,               /* tp_init */
 150     0,                         /* tp_alloc */
 151     Config_new                 /* tp_new */
 152 };
 153
 154 static PyObject *cpy_register_generic(cpy_callback_t **list_head, PyObject *args, PyObject *kwds) {
 155         cpy_callback_t *c;
 156         const char *name = NULL;
 157         PyObject *callback = NULL, *data = NULL;
 158         static char *kwlist[] = {"callback", "data", "name", NULL};
 159
 160         if (PyArg_ParseTupleAndKeywords(args, kwds, "O|Oz", kwlist, &callback, &data, &name) == 0) return NULL;
 161         if (PyCallable_Check(callback) == 0) {
 162                 PyErr_SetString(PyExc_TypeError, "callback needs a be a callable object.");
 163                 return NULL;
 164         }
 165         if (name == NULL) {
 166                 PyObject *mod;
 167
 168                 mod = PyObject_GetAttrString(callback, "__module__");
 169                 if (mod != NULL) name = PyString_AsString(mod);
 170                 if (name == NULL) {
 171                         PyErr_SetString(PyExc_ValueError, "No module name specified and "
 172                                 "callback function does not have a \"__module__\" attribute.");
 173                         return NULL;
 174                 }
 175         }
 176         Py_INCREF(callback);
 177         Py_XINCREF(data);
 178         c = malloc(sizeof(*c));
 179         c->name = strdup(name);
 180         c->callback = callback;
 181         c->data = data;
 182         c->next = *list_head;
 183         *list_head = c;
 184         Py_RETURN_NONE;
 185 }
 186
 187 static PyObject *cpy_register_config(PyObject *self, PyObject *args, PyObject *kwds) {
 188         return cpy_register_generic(&cpy_config_callbacks, args, kwds);
 189 }
 190
 191 static PyObject *cpy_register_init(PyObject *self, PyObject *args, PyObject *kwds) {
 192         return cpy_register_generic(&cpy_init_callbacks, args, kwds);
 193 }
 194
 195 static PyObject *cpy_register_shutdown(PyObject *self, PyObject *args, PyObject *kwds) {
 196         return cpy_register_generic(&cpy_shutdown_callbacks, args, kwds);
 197 }
 198
 199 static PyMethodDef cpy_methods[] = {
 200         {"register_init", (PyCFunction) cpy_register_init, METH_VARARGS | METH_KEYWORDS, "This is an unhelpful text."},
 201         {"register_config", (PyCFunction) cpy_register_config, METH_VARARGS | METH_KEYWORDS, "This is an unhelpful text."},
 202         {"register_shutdown", (PyCFunction) cpy_register_shutdown, METH_VARARGS | METH_KEYWORDS, "This is an unhelpful text."},
 203         {0, 0, 0, 0}
 204 };
 205
 206 static int cpy_shutdown(void) {
 207         cpy_callback_t *c;
 208         PyObject *ret;
 209
 210         /* This can happen if the module was loaded but not configured. */
 211         if (state != NULL)
 212                 PyEval_RestoreThread(state);
 213
 214         for (c = cpy_shutdown_callbacks; c; c = c->next) {
 215                 if (c->data == NULL)
 216                         ret = PyObject_CallObject(c->callback, NULL); /* New reference. */
 217                 else
 218                         ret = PyObject_CallFunctionObjArgs(c->callback, c->data, (void *) 0); /* New reference. */
 219                 if (ret == NULL)
 220                         PyErr_Print(); /* FIXME */
 221                 else
 222                         Py_DECREF(ret);
 223         }
 224         Py_Finalize();
 225         return 0;
 226 }
 227
 228 static int cpy_init(void) {
 229         cpy_callback_t *c;
 230         PyObject *ret;
 231
 232         PyEval_InitThreads();
 233         /* Now it's finally OK to use python threads. */
 234         for (c = cpy_init_callbacks; c; c = c->next) {
 235                 if (c->data == NULL)
 236                         ret = PyObject_CallObject(c->callback, NULL); /* New reference. */
 237                 else
 238                         ret = PyObject_CallFunctionObjArgs(c->callback, c->data, (void *) 0); /* New reference. */
 239                 if (ret == NULL)
 240                         PyErr_Print(); /* FIXME */
 241                 else
 242                         Py_DECREF(ret);
 243         }
 244         state = PyEval_SaveThread();
 245         return 0;
 246 }
 247
 248 static PyObject *cpy_oconfig_to_pyconfig(oconfig_item_t *ci, PyObject *parent) {
 249         int i;
 250         PyObject *item, *values, *children, *tmp;
 251
 252         if (parent == NULL)
 253                 parent = Py_None;
 254
 255         values = PyTuple_New(ci->values_num); /* New reference. */
 256         for (i = 0; i < ci->values_num; ++i) {
 257                 if (ci->values[i].type == OCONFIG_TYPE_STRING) {
 258                         PyTuple_SET_ITEM(values, i, PyString_FromString(ci->values[i].value.string));
 259                 } else if (ci->values[i].type == OCONFIG_TYPE_NUMBER) {
 260                         PyTuple_SET_ITEM(values, i, PyFloat_FromDouble(ci->values[i].value.number));
 261                 } else if (ci->values[i].type == OCONFIG_TYPE_BOOLEAN) {
 262                         PyTuple_SET_ITEM(values, i, PyBool_FromLong(ci->values[i].value.boolean));
 263                 }
 264         }
 265
 266         item = PyObject_CallFunction((PyObject *) &ConfigType, "sONO", ci->key, parent, values, Py_None);
 267         if (item == NULL)
 268                 return NULL;
 269         children = PyTuple_New(ci->children_num); /* New reference. */
 270         for (i = 0; i < ci->children_num; ++i) {
 271                         PyTuple_SET_ITEM(children, i, cpy_oconfig_to_pyconfig(ci->children + i, item));
 272         }
 273         tmp = ((Config *) item)->children;
 274         ((Config *) item)->children = children;
 275         Py_XDECREF(tmp);
 276         return item;
 277 }
 278
 279 static int cpy_config(oconfig_item_t *ci) {
 280         int i;
 281         PyObject *sys;
 282         PyObject *sys_path;
 283         PyObject *module;
 284
 285         /* Ok in theory we shouldn't do initialization at this point
 286          * but we have to. In order to give python scripts a chance
 287          * to register a config callback we need to be able to execute
 288          * python code during the config callback so we have to start
 289          * the interpreter here. */
 290         /* Do *not* use the python "thread" module at this point! */
 291         Py_Initialize();
 292
 293         PyType_Ready(&ConfigType);
 294         sys = PyImport_ImportModule("sys"); /* New reference. */
 295         if (sys == NULL) {
 296                 ERROR("python module: Unable to import \"sys\" module.");
 297                 /* Just print the default python exception text to stderr. */
 298                 PyErr_Print();
 299                 return 1;
 300         }
 301         sys_path = PyObject_GetAttrString(sys, "path"); /* New reference. */
 302         Py_DECREF(sys);
 303         if (sys_path == NULL) {
 304                 ERROR("python module: Unable to read \"sys.path\".");
 305                 PyErr_Print();
 306                 return 1;
 307         }
 308         module = Py_InitModule("collectd", cpy_methods); /* Borrowed reference. */
 309         PyModule_AddObject(module, "Config", (PyObject *) &ConfigType); /* Steals a reference. */
 310         for (i = 0; i < ci->children_num; ++i) {
 311                 oconfig_item_t *item = ci->children + i;
 312
 313                 if (strcasecmp(item->key, "ModulePath") == 0) {
 314                         char *dir = NULL;
 315                         PyObject *dir_object;
 316
 317                         if (cf_util_get_string(item, &dir) != 0)
 318                                 continue;
 319                         dir_object = PyString_FromString(dir); /* New reference. */
 320                         if (dir_object == NULL) {
 321                                 ERROR("python plugin: Unable to convert \"%s\" to "
 322                                       "a python object.", dir);
 323                                 free(dir);
 324                                 PyErr_Print();
 325                                 continue;
 326                         }
 327                         if (PyList_Append(sys_path, dir_object) != 0) {
 328                                 ERROR("python plugin: Unable to append \"%s\" to "
 329                                       "python module path.", dir);
 330                                 PyErr_Print();
 331                         }
 332                         Py_DECREF(dir_object);
 333                         free(dir);
 334                 } else if (strcasecmp(item->key, "Import") == 0) {
 335                         char *module_name = NULL;
 336                         PyObject *module;
 337
 338                         if (cf_util_get_string(item, &module_name) != 0)
 339                                 continue;
 340                         module = PyImport_ImportModule(module_name); /* New reference. */
 341                         if (module == NULL) {
 342                                 ERROR("python plugin: Error importing module \"%s\".", module_name);
 343                                 PyErr_Print();
 344                         }
 345                         free(module_name);
 346                         Py_XDECREF(module);
 347                 } else if (strcasecmp(item->key, "Module") == 0) {
 348                         char *name = NULL;
 349                         cpy_callback_t *c;
 350                         PyObject *ret;
 351
 352                         if (cf_util_get_string(item, &name) != 0)
 353                                 continue;
 354                         for (c = cpy_config_callbacks; c; c = c->next) {
 355                                 if (strcasecmp(c->name, name) == 0)
 356                                         break;
 357                         }
 358                         if (c == NULL) {
 359                                 WARNING("python plugin: Found a configuration for the \"%s\" plugin, "
 360                                         "but the plugin isn't loaded or didn't register "
 361                                         "a configuration callback.", name);
 362                                 free(name);
 363                                 continue;
 364                         }
 365                         free(name);
 366                         if (c->data == NULL)
 367                                 ret = PyObject_CallFunction(c->callback, "N",
 368                                         cpy_oconfig_to_pyconfig(item, NULL)); /* New reference. */
 369                         else
 370                                 ret = PyObject_CallFunction(c->callback, "NO",
 371                                         cpy_oconfig_to_pyconfig(item, NULL), c->data); /* New reference. */
 372                         if (ret == NULL)
 373                                 PyErr_Print();
 374                         else
 375                                 Py_DECREF(ret);
 376                 } else {
 377                         WARNING("python plugin: Ignoring unknown config key \"%s\".", item->key);
 378                 }
 379         }
 380         Py_DECREF(sys_path);
 381         return 0;
 382 }
 383
 384 void module_register(void) {
 385         plugin_register_complex_config("python", cpy_config);
 386         plugin_register_init("python", cpy_init);
 387 //      plugin_register_read("python", cna_read);
 388         plugin_register_shutdown("python", cpy_shutdown);
 389 }