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