Modules/_lsprof.c

#include "Python.h"
#include "rotatingtree.h"

/************************************************************/
/* Written by Brett Rosen and Ted Czotter */

struct _ProfilerEntry;

/* represents a function called from another function */
typedef struct _ProfilerSubEntry {
    rotating_node_t header;
    _PyTime_t tt;
    _PyTime_t it;
    long callcount;
    long recursivecallcount;
    long recursionLevel;
} ProfilerSubEntry;

/* represents a function or user defined block */
typedef struct _ProfilerEntry {
    rotating_node_t header;
    PyObject *userObj; /* PyCodeObject, or a descriptive str for builtins */
    _PyTime_t tt; /* total time in this entry */
    _PyTime_t it; /* inline time in this entry (not in subcalls) */
    long callcount; /* how many times this was called */
    long recursivecallcount; /* how many times called recursively */
    long recursionLevel;
    rotating_node_t *calls;
} ProfilerEntry;

typedef struct _ProfilerContext {
    _PyTime_t t0;
    _PyTime_t subt;
    struct _ProfilerContext *previous;
    ProfilerEntry *ctxEntry;
} ProfilerContext;

typedef struct {
    PyObject_HEAD
    rotating_node_t *profilerEntries;
    ProfilerContext *currentProfilerContext;
    ProfilerContext *freelistProfilerContext;
    int flags;
    PyObject *externalTimer;
    double externalTimerUnit;
} ProfilerObject;

#define POF_ENABLED     0x001
#define POF_SUBCALLS    0x002
#define POF_BUILTINS    0x004
#define POF_NOMEMORY    0x100

static PyTypeObject PyProfiler_Type;

#define PyProfiler_Check(op) PyObject_TypeCheck(op, &PyProfiler_Type)
#define PyProfiler_CheckExact(op) Py_IS_TYPE(op, &PyProfiler_Type)

/*** External Timers ***/

static _PyTime_t CallExternalTimer(ProfilerObject *pObj)
{
    PyObject *o = _PyObject_CallNoArg(pObj->externalTimer);
    if (o == NULL) {
        PyErr_WriteUnraisable(pObj->externalTimer);
        return 0;
    }

    _PyTime_t result;
    int err;
    if (pObj->externalTimerUnit > 0.0) {
        /* interpret the result as an integer that will be scaled
           in profiler_getstats() */
        err = _PyTime_FromNanosecondsObject(&result, o);
    }
    else {
        /* interpret the result as a double measured in seconds.
           As the profiler works with _PyTime_t internally
           we convert it to a large integer */
        err = _PyTime_FromSecondsObject(&result, o, _PyTime_ROUND_FLOOR);
    }
    Py_DECREF(o);
    if (err < 0) {
        PyErr_WriteUnraisable(pObj->externalTimer);
        return 0;
    }
    return result;
}

static inline _PyTime_t
call_timer(ProfilerObject *pObj)
{
    if (pObj->externalTimer != NULL) {
        return CallExternalTimer(pObj);
    }
    else {
        return _PyTime_GetPerfCounter();
    }
}


/*** ProfilerObject ***/

static PyObject *
normalizeUserObj(PyObject *obj)
{
    PyCFunctionObject *fn;
    if (!PyCFunction_Check(obj)) {
        Py_INCREF(obj);
        return obj;
    }
    /* Replace built-in function objects with a descriptive string
       because of built-in methods -- keeping a reference to
       __self__ is probably not a good idea. */
    fn = (PyCFunctionObject *)obj;

    if (fn->m_self == NULL) {
        /* built-in function: look up the module name */
        PyObject *mod = fn->m_module;
        PyObject *modname = NULL;
        if (mod != NULL) {
            if (PyUnicode_Check(mod)) {
                modname = mod;
                Py_INCREF(modname);
            }
            else if (PyModule_Check(mod)) {
                modname = PyModule_GetNameObject(mod);
                if (modname == NULL)
                    PyErr_Clear();
            }
        }
        if (modname != NULL) {
            if (!_PyUnicode_EqualToASCIIString(modname, "builtins")) {
                PyObject *result;
                result = PyUnicode_FromFormat("<%U.%s>", modname,
                                              fn->m_ml->ml_name);
                Py_DECREF(modname);
                return result;
            }
            Py_DECREF(modname);
        }
        return PyUnicode_FromFormat("<%s>", fn->m_ml->ml_name);
    }
    else {
        /* built-in method: try to return
            repr(getattr(type(__self__), __name__))
        */
        PyObject *self = fn->m_self;
        PyObject *name = PyUnicode_FromString(fn->m_ml->ml_name);
        PyObject *modname = fn->m_module;

        if (name != NULL) {
            PyObject *mo = _PyType_Lookup(Py_TYPE(self), name);
            Py_XINCREF(mo);
            Py_DECREF(name);
            if (mo != NULL) {
                PyObject *res = PyObject_Repr(mo);
                Py_DECREF(mo);
                if (res != NULL)
                    return res;
            }
        }
        /* Otherwise, use __module__ */
        PyErr_Clear();
        if (modname != NULL && PyUnicode_Check(modname))
            return PyUnicode_FromFormat("<built-in method %S.%s>",
                                        modname,  fn->m_ml->ml_name);
        else
            return PyUnicode_FromFormat("<built-in method %s>",
                                        fn->m_ml->ml_name);
    }
}

static ProfilerEntry*
newProfilerEntry(ProfilerObject *pObj, void *key, PyObject *userObj)
{
    ProfilerEntry *self;
    self = (ProfilerEntry*) PyMem_Malloc(sizeof(ProfilerEntry));
    if (self == NULL) {
        pObj->flags |= POF_NOMEMORY;
        return NULL;
    }
    userObj = normalizeUserObj(userObj);
    if (userObj == NULL) {
        PyErr_Clear();
        PyMem_Free(self);
        pObj->flags |= POF_NOMEMORY;
        return NULL;
    }
    self->header.key = key;
    self->userObj = userObj;
    self->tt = 0;
    self->it = 0;
    self->callcount = 0;
    self->recursivecallcount = 0;
    self->recursionLevel = 0;
    self->calls = EMPTY_ROTATING_TREE;
    RotatingTree_Add(&pObj->profilerEntries, &self->header);
    return self;
}

static ProfilerEntry*
getEntry(ProfilerObject *pObj, void *key)
{
    return (ProfilerEntry*) RotatingTree_Get(&pObj->profilerEntries, key);
}

static ProfilerSubEntry *
getSubEntry(ProfilerObject *pObj, ProfilerEntry *caller, ProfilerEntry* entry)
{
    return (ProfilerSubEntry*) RotatingTree_Get(&caller->calls,
                                                (void *)entry);
}

static ProfilerSubEntry *
newSubEntry(ProfilerObject *pObj,  ProfilerEntry *caller, ProfilerEntry* entry)
{
    ProfilerSubEntry *self;
    self = (ProfilerSubEntry*) PyMem_Malloc(sizeof(ProfilerSubEntry));
    if (self == NULL) {
        pObj->flags |= POF_NOMEMORY;
        return NULL;
    }
    self->header.key = (void *)entry;
    self->tt = 0;
    self->it = 0;
    self->callcount = 0;
    self->recursivecallcount = 0;
    self->recursionLevel = 0;
    RotatingTree_Add(&caller->calls, &self->header);
    return self;
}

static int freeSubEntry(rotating_node_t *header, void *arg)
{
    ProfilerSubEntry *subentry = (ProfilerSubEntry*) header;
    PyMem_Free(subentry);
    return 0;
}

static int freeEntry(rotating_node_t *header, void *arg)
{
    ProfilerEntry *entry = (ProfilerEntry*) header;
    RotatingTree_Enum(entry->calls, freeSubEntry, NULL);
    Py_DECREF(entry->userObj);
    PyMem_Free(entry);
    return 0;
}

static void clearEntries(ProfilerObject *pObj)
{
    RotatingTree_Enum(pObj->profilerEntries, freeEntry, NULL);
    pObj->profilerEntries = EMPTY_ROTATING_TREE;
    /* release the memory hold by the ProfilerContexts */
    if (pObj->currentProfilerContext) {
        PyMem_Free(pObj->currentProfilerContext);
        pObj->currentProfilerContext = NULL;
    }
    while (pObj->freelistProfilerContext) {
        ProfilerContext *c = pObj->freelistProfilerContext;
        pObj->freelistProfilerContext = c->previous;
        PyMem_Free(c);
    }
    pObj->freelistProfilerContext = NULL;
}

static void
initContext(ProfilerObject *pObj, ProfilerContext *self, ProfilerEntry *entry)
{
    self->ctxEntry = entry;
    self->subt = 0;
    self->previous = pObj->currentProfilerContext;
    pObj->currentProfilerContext = self;
    ++entry->recursionLevel;
    if ((pObj->flags & POF_SUBCALLS) && self->previous) {
        /* find or create an entry for me in my caller's entry */
        ProfilerEntry *caller = self->previous->ctxEntry;
        ProfilerSubEntry *subentry = getSubEntry(pObj, caller, entry);
        if (subentry == NULL)
            subentry = newSubEntry(pObj, caller, entry);
        if (subentry)
            ++subentry->recursionLevel;
    }
    self->t0 = call_timer(pObj);
}

static void
Stop(ProfilerObject *pObj, ProfilerContext *self, ProfilerEntry *entry)
{
    _PyTime_t tt = call_timer(pObj) - self->t0;
    _PyTime_t it = tt - self->subt;
    if (self->previous)
        self->previous->subt += tt;
    pObj->currentProfilerContext = self->previous;
    if (--entry->recursionLevel == 0)
        entry->tt += tt;
    else
        ++entry->recursivecallcount;
    entry->it += it;
    entry->callcount++;
    if ((pObj->flags & POF_SUBCALLS) && self->previous) {
        /* find or create an entry for me in my caller's entry */
        ProfilerEntry *caller = self->previous->ctxEntry;
        ProfilerSubEntry *subentry = getSubEntry(pObj, caller, entry);
        if (subentry) {
            if (--subentry->recursionLevel == 0)
                subentry->tt += tt;
            else
                ++subentry->recursivecallcount;
            subentry->it += it;
            ++subentry->callcount;
        }
    }
}

static void
ptrace_enter_call(PyObject *self, void *key, PyObject *userObj)
{
    /* entering a call to the function identified by 'key'
       (which can be a PyCodeObject or a PyMethodDef pointer) */
    ProfilerObject *pObj = (ProfilerObject*)self;
    ProfilerEntry *profEntry;
    ProfilerContext *pContext;

    /* In the case of entering a generator expression frame via a
     * throw (gen_send_ex(.., 1)), we may already have an
     * Exception set here. We must not mess around with this
     * exception, and some of the code under here assumes that
     * PyErr_* is its own to mess around with, so we have to
     * save and restore any current exception. */
    PyObject *last_type, *last_value, *last_tb;
    PyErr_Fetch(&last_type, &last_value, &last_tb);

    profEntry = getEntry(pObj, key);
    if (profEntry == NULL) {
        profEntry = newProfilerEntry(pObj, key, userObj);
        if (profEntry == NULL)
            goto restorePyerr;
    }
    /* grab a ProfilerContext out of the free list */
    pContext = pObj->freelistProfilerContext;
    if (pContext) {
        pObj->freelistProfilerContext = pContext->previous;
    }
    else {
        /* free list exhausted, allocate a new one */
        pContext = (ProfilerContext*)
            PyMem_Malloc(sizeof(ProfilerContext));
        if (pContext == NULL) {
            pObj->flags |= POF_NOMEMORY;
            goto restorePyerr;
        }
    }
    initContext(pObj, pContext, profEntry);

restorePyerr:
    PyErr_Restore(last_type, last_value, last_tb);
}

static void
ptrace_leave_call(PyObject *self, void *key)
{
    /* leaving a call to the function identified by 'key' */
    ProfilerObject *pObj = (ProfilerObject*)self;
    ProfilerEntry *profEntry;
    ProfilerContext *pContext;

    pContext = pObj->currentProfilerContext;
    if (pContext == NULL)
        return;
    profEntry = getEntry(pObj, key);
    if (profEntry) {
        Stop(pObj, pContext, profEntry);
    }
    else {
        pObj->currentProfilerContext = pContext->previous;
    }
    /* put pContext into the free list */
    pContext->previous = pObj->freelistProfilerContext;
    pObj->freelistProfilerContext = pContext;
}

static int
profiler_callback(PyObject *self, PyFrameObject *frame, int what,
                  PyObject *arg)
{
    switch (what) {

    /* the 'frame' of a called function is about to start its execution */
    case PyTrace_CALL:
    {
        PyCodeObject *code = PyFrame_GetCode(frame);
        ptrace_enter_call(self, (void *)code, (PyObject *)code);
        Py_DECREF(code);
        break;
    }

    /* the 'frame' of a called function is about to finish
       (either normally or with an exception) */
    case PyTrace_RETURN:
    {
        PyCodeObject *code = PyFrame_GetCode(frame);
        ptrace_leave_call(self, (void *)code);
        Py_DECREF(code);
        break;
    }

    /* case PyTrace_EXCEPTION:
        If the exception results in the function exiting, a
        PyTrace_RETURN event will be generated, so we don't need to
        handle it. */

    /* the Python function 'frame' is issuing a call to the built-in
       function 'arg' */
    case PyTrace_C_CALL:
        if ((((ProfilerObject *)self)->flags & POF_BUILTINS)
            && PyCFunction_Check(arg)) {
            ptrace_enter_call(self,
                              ((PyCFunctionObject *)arg)->m_ml,
                              arg);
        }
        break;

    /* the call to the built-in function 'arg' is returning into its
       caller 'frame' */
    case PyTrace_C_RETURN:              /* ...normally */
    case PyTrace_C_EXCEPTION:           /* ...with an exception set */
        if ((((ProfilerObject *)self)->flags & POF_BUILTINS)
            && PyCFunction_Check(arg)) {
            ptrace_leave_call(self,
                              ((PyCFunctionObject *)arg)->m_ml);
        }
        break;

    default:
        break;
    }
    return 0;
}

static int
pending_exception(ProfilerObject *pObj)
{
    if (pObj->flags & POF_NOMEMORY) {
        pObj->flags -= POF_NOMEMORY;
        PyErr_SetString(PyExc_MemoryError,
                        "memory was exhausted while profiling");
        return -1;
    }
    return 0;
}

/************************************************************/

static PyStructSequence_Field profiler_entry_fields[] = {
    {"code",         "code object or built-in function name"},
    {"callcount",    "how many times this was called"},
    {"reccallcount", "how many times called recursively"},
    {"totaltime",    "total time in this entry"},
    {"inlinetime",   "inline time in this entry (not in subcalls)"},
    {"calls",        "details of the calls"},
    {0}
};

static PyStructSequence_Field profiler_subentry_fields[] = {
    {"code",         "called code object or built-in function name"},
    {"callcount",    "how many times this is called"},
    {"reccallcount", "how many times this is called recursively"},
    {"totaltime",    "total time spent in this call"},
    {"inlinetime",   "inline time (not in further subcalls)"},
    {0}
};

static PyStructSequence_Desc profiler_entry_desc = {
    "_lsprof.profiler_entry", /* name */
    NULL, /* doc */
    profiler_entry_fields,
    6
};

static PyStructSequence_Desc profiler_subentry_desc = {
    "_lsprof.profiler_subentry", /* name */
    NULL, /* doc */
    profiler_subentry_fields,
    5
};

static int initialized;
static PyTypeObject StatsEntryType;
static PyTypeObject StatsSubEntryType;


typedef struct {
    PyObject *list;
    PyObject *sublist;
    double factor;
} statscollector_t;

static int statsForSubEntry(rotating_node_t *node, void *arg)
{
    ProfilerSubEntry *sentry = (ProfilerSubEntry*) node;
    statscollector_t *collect = (statscollector_t*) arg;
    ProfilerEntry *entry = (ProfilerEntry*) sentry->header.key;
    int err;
    PyObject *sinfo;
    sinfo = PyObject_CallFunction((PyObject*) &StatsSubEntryType,
                                  "((Olldd))",
                                  entry->userObj,
                                  sentry->callcount,
                                  sentry->recursivecallcount,
                                  collect->factor * sentry->tt,
                                  collect->factor * sentry->it);
    if (sinfo == NULL)
        return -1;
    err = PyList_Append(collect->sublist, sinfo);
    Py_DECREF(sinfo);
    return err;
}

static int statsForEntry(rotating_node_t *node, void *arg)
{
    ProfilerEntry *entry = (ProfilerEntry*) node;
    statscollector_t *collect = (statscollector_t*) arg;
    PyObject *info;
    int err;
    if (entry->callcount == 0)
        return 0;   /* skip */

    if (entry->calls != EMPTY_ROTATING_TREE) {
        collect->sublist = PyList_New(0);
        if (collect->sublist == NULL)
            return -1;
        if (RotatingTree_Enum(entry->calls,
                              statsForSubEntry, collect) != 0) {
            Py_DECREF(collect->sublist);
            return -1;
        }
    }
    else {
        Py_INCREF(Py_None);
        collect->sublist = Py_None;
    }

    info = PyObject_CallFunction((PyObject*) &StatsEntryType,
                                 "((OllddO))",
                                 entry->userObj,
                                 entry->callcount,
                                 entry->recursivecallcount,
                                 collect->factor * entry->tt,
                                 collect->factor * entry->it,
                                 collect->sublist);
    Py_DECREF(collect->sublist);
    if (info == NULL)
        return -1;
    err = PyList_Append(collect->list, info);
    Py_DECREF(info);
    return err;
}

PyDoc_STRVAR(getstats_doc, "\
getstats() -> list of profiler_entry objects\n\
\n\
Return all information collected by the profiler.\n\
Each profiler_entry is a tuple-like object with the\n\
following attributes:\n\
\n\
    code          code object\n\
    callcount     how many times this was called\n\
    reccallcount  how many times called recursively\n\
    totaltime     total time in this entry\n\
    inlinetime    inline time in this entry (not in subcalls)\n\
    calls         details of the calls\n\
\n\
The calls attribute is either None or a list of\n\
profiler_subentry objects:\n\
\n\
    code          called code object\n\
    callcount     how many times this is called\n\
    reccallcount  how many times this is called recursively\n\
    totaltime     total time spent in this call\n\
    inlinetime    inline time (not in further subcalls)\n\
");

static PyObject*
profiler_getstats(ProfilerObject *pObj, PyObject* noarg)
{
    statscollector_t collect;
    if (pending_exception(pObj)) {
        return NULL;
    }
    if (!pObj->externalTimer || pObj->externalTimerUnit == 0.0) {
        _PyTime_t onesec = _PyTime_FromSeconds(1);
        collect.factor = (double)1 / onesec;
    }
    else {
        collect.factor = pObj->externalTimerUnit;
    }

    collect.list = PyList_New(0);
    if (collect.list == NULL)
        return NULL;
    if (RotatingTree_Enum(pObj->profilerEntries, statsForEntry, &collect)
        != 0) {
        Py_DECREF(collect.list);
        return NULL;
    }
    return collect.list;
}

static int
setSubcalls(ProfilerObject *pObj, int nvalue)
{
    if (nvalue == 0)
        pObj->flags &= ~POF_SUBCALLS;
    else if (nvalue > 0)
        pObj->flags |=  POF_SUBCALLS;
    return 0;
}

static int
setBuiltins(ProfilerObject *pObj, int nvalue)
{
    if (nvalue == 0)
        pObj->flags &= ~POF_BUILTINS;
    else if (nvalue > 0) {
        pObj->flags |=  POF_BUILTINS;
    }
    return 0;
}

PyDoc_STRVAR(enable_doc, "\
enable(subcalls=True, builtins=True)\n\
\n\
Start collecting profiling information.\n\
If 'subcalls' is True, also records for each function\n\
statistics separated according to its current caller.\n\
If 'builtins' is True, records the time spent in\n\
built-in functions separately from their caller.\n\
");

static PyObject*
profiler_enable(ProfilerObject *self, PyObject *args, PyObject *kwds)
{
    int subcalls = -1;
    int builtins = -1;
    static char *kwlist[] = {"subcalls", "builtins", 0};
    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|ii:enable",
                                     kwlist, &subcalls, &builtins))
        return NULL;
    if (setSubcalls(self, subcalls) < 0 || setBuiltins(self, builtins) < 0) {
        return NULL;
    }

    PyThreadState *tstate = PyThreadState_GET();
    if (_PyEval_SetProfile(tstate, profiler_callback, (PyObject*)self) < 0) {
        return NULL;
    }

    self->flags |= POF_ENABLED;
    Py_RETURN_NONE;
}

static void
flush_unmatched(ProfilerObject *pObj)
{
    while (pObj->currentProfilerContext) {
        ProfilerContext *pContext = pObj->currentProfilerContext;
        ProfilerEntry *profEntry= pContext->ctxEntry;
        if (profEntry)
            Stop(pObj, pContext, profEntry);
        else
            pObj->currentProfilerContext = pContext->previous;
        if (pContext)
            PyMem_Free(pContext);
    }

}

PyDoc_STRVAR(disable_doc, "\
disable()\n\
\n\
Stop collecting profiling information.\n\
");

static PyObject*
profiler_disable(ProfilerObject *self, PyObject* noarg)
{
    PyThreadState *tstate = PyThreadState_GET();
    if (_PyEval_SetProfile(tstate, NULL, NULL) < 0) {
        return NULL;
    }
    self->flags &= ~POF_ENABLED;

    flush_unmatched(self);
    if (pending_exception(self)) {
        return NULL;
    }
    Py_RETURN_NONE;
}

PyDoc_STRVAR(clear_doc, "\
clear()\n\
\n\
Clear all profiling information collected so far.\n\
");

static PyObject*
profiler_clear(ProfilerObject *pObj, PyObject* noarg)
{
    clearEntries(pObj);
    Py_RETURN_NONE;
}

static void
profiler_dealloc(ProfilerObject *op)
{
    if (op->flags & POF_ENABLED) {
        PyThreadState *tstate = PyThreadState_GET();
        if (_PyEval_SetProfile(tstate, NULL, NULL) < 0) {
            PyErr_WriteUnraisable((PyObject *)op);
        }
    }

    flush_unmatched(op);
    clearEntries(op);
    Py_XDECREF(op->externalTimer);
    Py_TYPE(op)->tp_free(op);
}

static int
profiler_init(ProfilerObject *pObj, PyObject *args, PyObject *kw)
{
    PyObject *timer = NULL;
    double timeunit = 0.0;
    int subcalls = 1;
    int builtins = 1;
    static char *kwlist[] = {"timer", "timeunit",
                                   "subcalls", "builtins", 0};

    if (!PyArg_ParseTupleAndKeywords(args, kw, "|Odii:Profiler", kwlist,
                                     &timer, &timeunit,
                                     &subcalls, &builtins))
        return -1;

    if (setSubcalls(pObj, subcalls) < 0 || setBuiltins(pObj, builtins) < 0)
        return -1;
    pObj->externalTimerUnit = timeunit;
    Py_XINCREF(timer);
    Py_XSETREF(pObj->externalTimer, timer);
    return 0;
}

static PyMethodDef profiler_methods[] = {
    {"getstats",    (PyCFunction)profiler_getstats,
                    METH_NOARGS,                        getstats_doc},
    {"enable",          (PyCFunction)(void(*)(void))profiler_enable,
                    METH_VARARGS | METH_KEYWORDS,       enable_doc},
    {"disable",         (PyCFunction)profiler_disable,
                    METH_NOARGS,                        disable_doc},
    {"clear",           (PyCFunction)profiler_clear,
                    METH_NOARGS,                        clear_doc},
    {NULL, NULL}
};

PyDoc_STRVAR(profiler_doc, "\
Profiler(timer=None, timeunit=None, subcalls=True, builtins=True)\n\
\n\
    Builds a profiler object using the specified timer function.\n\
    The default timer is a fast built-in one based on real time.\n\
    For custom timer functions returning integers, timeunit can\n\
    be a float specifying a scale (i.e. how long each integer unit\n\
    is, in seconds).\n\
");

static PyTypeObject PyProfiler_Type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "_lsprof.Profiler",                     /* tp_name */
    sizeof(ProfilerObject),                 /* tp_basicsize */
    0,                                      /* tp_itemsize */
    (destructor)profiler_dealloc,           /* tp_dealloc */
    0,                                      /* tp_vectorcall_offset */
    0,                                      /* tp_getattr */
    0,                                      /* tp_setattr */
    0,                                      /* tp_as_async */
    0,                                      /* tp_repr */
    0,                                      /* tp_as_number */
    0,                                      /* tp_as_sequence */
    0,                                      /* tp_as_mapping */
    0,                                      /* tp_hash */
    0,                                      /* tp_call */
    0,                                      /* tp_str */
    0,                                      /* tp_getattro */
    0,                                      /* tp_setattro */
    0,                                      /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
    profiler_doc,                           /* tp_doc */
    0,                                      /* tp_traverse */
    0,                                      /* tp_clear */
    0,                                      /* tp_richcompare */
    0,                                      /* tp_weaklistoffset */
    0,                                      /* tp_iter */
    0,                                      /* tp_iternext */
    profiler_methods,                       /* tp_methods */
    0,                                      /* tp_members */
    0,                                      /* tp_getset */
    0,                                      /* tp_base */
    0,                                      /* tp_dict */
    0,                                      /* tp_descr_get */
    0,                                      /* tp_descr_set */
    0,                                      /* tp_dictoffset */
    (initproc)profiler_init,                /* tp_init */
    PyType_GenericAlloc,                    /* tp_alloc */
    PyType_GenericNew,                      /* tp_new */
    PyObject_Del,                           /* tp_free */
};

static PyMethodDef moduleMethods[] = {
    {NULL, NULL}
};


static struct PyModuleDef _lsprofmodule = {
    PyModuleDef_HEAD_INIT,
    "_lsprof",
    "Fast profiler",
    -1,
    moduleMethods,
    NULL,
    NULL,
    NULL,
    NULL
};

PyMODINIT_FUNC
PyInit__lsprof(void)
{
    PyObject *module, *d;
    module = PyModule_Create(&_lsprofmodule);
    if (module == NULL)
        return NULL;
    d = PyModule_GetDict(module);
    if (PyType_Ready(&PyProfiler_Type) < 0)
        return NULL;
    PyDict_SetItemString(d, "Profiler", (PyObject *)&PyProfiler_Type);

    if (!initialized) {
        if (PyStructSequence_InitType2(&StatsEntryType,
                                       &profiler_entry_desc) < 0)
            return NULL;
        if (PyStructSequence_InitType2(&StatsSubEntryType,
                                       &profiler_subentry_desc) < 0)
            return NULL;
    }
    Py_INCREF((PyObject*) &StatsEntryType);
    Py_INCREF((PyObject*) &StatsSubEntryType);
    PyModule_AddObject(module, "profiler_entry",
                       (PyObject*) &StatsEntryType);
    PyModule_AddObject(module, "profiler_subentry",
                       (PyObject*) &StatsSubEntryType);
    initialized = 1;
    return module;
}