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