Add DTrace probes

Modules/gcmodule.c

 /*
 
   Reference Cycle Garbage Collection
   ==================================
 
   Neil Schemenauer <nas@arctrix.com>
 
   Based on a post on the python-dev list.  Ideas from Guido van Rossum,
   Eric Tiedemann, and various others.
 
   http://www.arctrix.com/nas/python/gc/
 
   The following mailing list threads provide a historical perspective on
   the design of this module.  Note that a fair amount of refinement has
   occurred since those discussions.
 
   http://mail.python.org/pipermail/python-dev/2000-March/002385.html
   http://mail.python.org/pipermail/python-dev/2000-March/002434.html
   http://mail.python.org/pipermail/python-dev/2000-March/002497.html
 
   For a highlevel view of the collection process, read the collect
   function.
 
 */
 
 #include "Python.h"
 #include "frameobject.h"        /* for PyFrame_ClearFreeList */
+
+#ifdef WITH_DTRACE
+#include "pydtrace.h"
+#endif
 
 /* Get an object's GC head */
 #define AS_GC(o) ((PyGC_Head *)(o)-1)
 
 /* Get the object given the GC head */
 #define FROM_GC(g) ((PyObject *)(((PyGC_Head *)g)+1))
 
 /*** Global GC state ***/
 
 struct gc_generation {
@@ skipping 796 matching lines @@
                 result = PyFloat_AsDouble(f);
             Py_DECREF(f);
         }
     }
     return result;
 }
 
 /* This is the main function.  Read this to understand how the
  * collection process works. */
 static Py_ssize_t
-collect(int generation, Py_ssize_t *n_collected, Py_ssize_t *n_uncollectable)
+#ifdef WITH_DTRACE
+collect2
+#else
+collect
+#endif
+(int generation, Py_ssize_t *n_collected, Py_ssize_t *n_uncollectable)
 {
     int i;
     Py_ssize_t m = 0; /* # objects collected */
     Py_ssize_t n = 0; /* # unreachable objects that couldn't be collected */
     PyGC_Head *young; /* the generation we are examining */
     PyGC_Head *old; /* next older generation */
     PyGC_Head unreachable; /* non-problematic unreachable trash */
     PyGC_Head finalizers;  /* objects with, & reachable from, __del__ */
     PyGC_Head *gc;
     double t1 = 0.0;
@@ skipping 137 matching lines @@
         PyErr_WriteUnraisable(gc_str);
         Py_FatalError("unexpected exception during garbage collection");
     }
 
     if (n_collected)
         *n_collected = m;
     if (n_uncollectable)
         *n_uncollectable = n;
     return n+m;
 }
+
+#ifdef WITH_DTRACE
+static void
+dtrace_gc_start(int collection)
+{
+    PYTHON_GC_START(collection);
+
+    /*
+     * Currently a USDT tail-call will not receive the correct arguments.
+     * Disable the tail call here.
+     */
+#if defined(__sparc)
+    asm("nop");
+#endif
+}
+
+static void
+dtrace_gc_done(Py_ssize_t value)
+{
+    PYTHON_GC_DONE((long) value);
+
+    /*
+     * Currently a USDT tail-call will not receive the correct arguments.
+     * Disable the tail call here.
+     */
+#if defined(__sparc)
+    asm("nop");
+#endif
+}
+
+static Py_ssize_t
+collect(int collection, Py_ssize_t *n_collected, Py_ssize_t *n_uncollectable)
+{
+    Py_ssize_t value;
+
+    if (PYTHON_GC_START_ENABLED())
+        dtrace_gc_start(collection);
+    value = collect2(collection, n_collected, n_uncollectable);
+    if (PYTHON_GC_DONE_ENABLED())
+        dtrace_gc_done(value);
+    return value;
+}
+#endif /* WITH_DTRACE */
 
 /* Invoke progress callbacks to notify clients that garbage collection
  * is starting or stopping
  */
 static void
 invoke_gc_callback(const char *phase, int generation,
                    Py_ssize_t collected, Py_ssize_t uncollectable)
 {
     Py_ssize_t i;
     PyObject *info = NULL;
@@ skipping 610 matching lines @@
 PyObject_GC_Del(void *op)
 {
     PyGC_Head *g = AS_GC(op);
     if (IS_TRACKED(op))
         gc_list_remove(g);
     if (generations[0].count > 0) {
         generations[0].count--;
     }
     PyObject_FREE(g);
 }