Add statistics gathering to help find a problem in the C tracer.

1 files changed, 83 insertions, 5 deletions

diff --git a/coverage/tracer.c b/coverage/tracer.c
index f05988d3..8c115708 100644
--- a/coverage/tracer.c
+++ b/coverage/tracer.c
@@ -6,8 +6,16 @@
 #include "structmember.h"

 #include "frameobject.h"

 

-#undef WHAT_LOG     /* Define to log the WHAT params in the trace function. */

-#undef TRACE_LOG    /* Define to log our bookkeeping. */

+/* Compile-time debugging helpers */

+#undef WHAT_LOG         /* Define to log the WHAT params in the trace function. */

+#undef TRACE_LOG        /* Define to log our bookkeeping. */

+#undef COLLECT_STATS    /* Collect counters: stats are printed when tracer is stopped. */

+

+#if COLLECT_STATS

+#define STATS(x)        x

+#else

+#define STATS(x)

+#endif

 

 /* Py 2.x and 3.x compatibility */

 

@@ -85,7 +93,20 @@ typedef struct {
 

     /* The parent frame for the last exception event, to fix missing returns. */

     PyFrameObject * last_exc_back;

-    

+

+#if COLLECT_STATS

+    struct {

+        unsigned int calls;

+        unsigned int lines;

+        unsigned int returns;

+        unsigned int exceptions;

+        unsigned int others;

+        unsigned int new_files;

+        unsigned int missed_returns;

+        unsigned int stack_reallocs;

+        unsigned int errors;

+    } stats;

+#endif /* COLLECT_STATS */

 } Tracer;

 

 #define STACK_DELTA    100

@@ -93,6 +114,18 @@ typedef struct {
 static int

 Tracer_init(Tracer *self, PyObject *args, PyObject *kwds)

 {

+#if COLLECT_STATS

+    self->stats.calls = 0;

+    self->stats.lines = 0;

+    self->stats.returns = 0;

+    self->stats.exceptions = 0;

+    self->stats.others = 0;

+    self->stats.new_files = 0;

+    self->stats.missed_returns = 0;

+    self->stats.stack_reallocs = 0;

+    self->stats.errors = 0;

+#endif /* COLLECT_STATS */

+

     self->should_trace = NULL;

     self->data = NULL;

     self->should_trace_cache = NULL;

@@ -104,6 +137,7 @@ Tracer_init(Tracer *self, PyObject *args, PyObject *kwds)
     self->depth = -1;

     self->data_stack = PyMem_Malloc(STACK_DELTA*sizeof(DataStackEntry));

     if (self->data_stack == NULL) {

+        STATS( self->stats.errors++; )

         return -1;

     }

     self->data_stack_alloc = STACK_DELTA;

@@ -191,11 +225,13 @@ Tracer_record_pair(Tracer *self, int l1, int l2)
         PyTuple_SET_ITEM(t, 0, MyInt_FromLong(l1));

         PyTuple_SET_ITEM(t, 1, MyInt_FromLong(l2));

         if (PyDict_SetItem(self->cur_file_data, t, Py_None) < 0) {

+            STATS( self->stats.errors++; )

             ret = -1;

         }

         Py_DECREF(t);

     }

     else {

+        STATS( self->stats.errors++; )

         ret = -1;

     }

     return ret;

@@ -235,6 +271,7 @@ Tracer_trace(Tracer *self, PyFrameObject *frame, int what, PyObject *arg)
                If someday we need to examine the frame when doing RETURN, then

                we'll need to keep more of the missed frame's state.

             */

+            STATS( self->stats.missed_returns++; )

             if (self->depth >= 0) {

                 if (self->tracing_arcs && self->cur_file_data) {

                     if (Tracer_record_pair(self, self->last_line, -1) < 0) {

@@ -253,13 +290,16 @@ Tracer_trace(Tracer *self, PyFrameObject *frame, int what, PyObject *arg)
 

     switch (what) {

     case PyTrace_CALL:      /* 0 */

+        STATS( self->stats.calls++; )

         /* Grow the stack. */

         self->depth++;

         if (self->depth >= self->data_stack_alloc) {

+            STATS( self->stats.stack_reallocs++; )

             /* We've outgrown our data_stack array: make it bigger. */

             int bigger = self->data_stack_alloc + STACK_DELTA;

             DataStackEntry * bigger_data_stack = PyMem_Realloc(self->data_stack, bigger * sizeof(DataStackEntry));

             if (bigger_data_stack == NULL) {

+                STATS( self->stats.errors++; )

                 self->depth--;

                 return -1;

             }

@@ -275,6 +315,7 @@ Tracer_trace(Tracer *self, PyFrameObject *frame, int what, PyObject *arg)
         filename = frame->f_code->co_filename;

         tracename = PyDict_GetItem(self->should_trace_cache, filename);

         if (tracename == NULL) {

+            STATS( self->stats.new_files++; )

             /* We've never considered this file before. */

             /* Ask should_trace about it. */

             PyObject * args = Py_BuildValue("(OO)", filename, frame);

@@ -282,6 +323,7 @@ Tracer_trace(Tracer *self, PyFrameObject *frame, int what, PyObject *arg)
             Py_DECREF(args);

             if (tracename == NULL) {

                 /* An error occurred inside should_trace. */

+                STATS( self->stats.errors++; )

                 return -1;

             }

             PyDict_SetItem(self->should_trace_cache, filename, tracename);

@@ -295,6 +337,10 @@ Tracer_trace(Tracer *self, PyFrameObject *frame, int what, PyObject *arg)
             PyObject * file_data = PyDict_GetItem(self->data, tracename);

             if (file_data == NULL) {

                 file_data = PyDict_New();

+                if (file_data == NULL) {

+                    STATS( self->stats.errors++; )

+                    return -1;

+                }

                 PyDict_SetItem(self->data, tracename, file_data);

                 Py_DECREF(file_data);

             }

@@ -312,6 +358,7 @@ Tracer_trace(Tracer *self, PyFrameObject *frame, int what, PyObject *arg)
         break;

     

     case PyTrace_RETURN:    /* 3 */

+        STATS( self->stats.returns++; )

         /* A near-copy of this code is above in the missing-return handler. */

         if (self->depth >= 0) {

             if (self->tracing_arcs && self->cur_file_data) {

@@ -328,6 +375,7 @@ Tracer_trace(Tracer *self, PyFrameObject *frame, int what, PyObject *arg)
         break;

     

     case PyTrace_LINE:      /* 2 */

+        STATS( self->stats.lines++; )

         if (self->depth >= 0) {

             SHOWLOG(self->depth, frame->f_lineno, frame->f_code->co_filename, "line");

             if (self->cur_file_data) {

@@ -362,8 +410,13 @@ Tracer_trace(Tracer *self, PyFrameObject *frame, int what, PyObject *arg)
            

            More about this fix: http://nedbatchelder.com/blog/200907/a_nasty_little_bug.html

         */

+        STATS( self->stats.exceptions++; )

         self->last_exc_back = frame->f_back;

         break;

+    

+    default:

+        STATS( self->stats.others++; )

+        break;    

     }

 

     return 0;

@@ -391,6 +444,28 @@ Tracer_stop(Tracer *self, PyObject *args)
     return Py_BuildValue("");

 }

 

+static PyObject *

+Tracer_get_stats(Tracer *self)

+{

+#if COLLECT_STATS

+    return Py_BuildValue(

+        "{sI,sI,sI,sI,sI,sI,sI,sI,si,sI}",

+        "calls", self->stats.calls,

+        "lines", self->stats.lines,

+        "returns", self->stats.returns,

+        "exceptions", self->stats.exceptions,

+        "others", self->stats.others,

+        "new_files", self->stats.new_files,

+        "missed_returns", self->stats.missed_returns,

+        "stack_reallocs", self->stats.stack_reallocs,

+        "stack_alloc", self->data_stack_alloc,

+        "errors", self->stats.errors

+        );

+#else

+    return Py_BuildValue("");

+#endif /* COLLECT_STATS */

+}

+

 static PyMemberDef

 Tracer_members[] = {

     { "should_trace",       T_OBJECT, offsetof(Tracer, should_trace), 0,

@@ -410,12 +485,15 @@ Tracer_members[] = {
 

 static PyMethodDef

 Tracer_methods[] = {

-    { "start",  (PyCFunction) Tracer_start, METH_VARARGS,

+    { "start",      (PyCFunction) Tracer_start,         METH_VARARGS,

             PyDoc_STR("Start the tracer") },

 

-    { "stop",   (PyCFunction) Tracer_stop,  METH_VARARGS,

+    { "stop",       (PyCFunction) Tracer_stop,          METH_VARARGS,

             PyDoc_STR("Stop the tracer") },

 

+    { "get_stats",  (PyCFunction) Tracer_get_stats,     METH_VARARGS,

+            PyDoc_STR("Get statistics about the tracing") },

+

     { NULL }

 };