gh-108753: Enhance pystats (#108754)

Statistics gathering is now off by default. Use the "-X pystats"
command line option or set the new PYTHONSTATS environment variable
to 1 to turn statistics gathering on at Python startup.

Statistics are no longer dumped at exit if statistics gathering was
off or statistics have been cleared.

Changes:

* Add PYTHONSTATS environment variable.
* sys._stats_dump() now returns False if statistics are not dumped
  because they are all equal to zero.
* Add PyConfig._pystats member.
* Add tests on sys functions and on setting PyConfig._pystats to 1.
* Add Include/cpython/pystats.h and Include/internal/pycore_pystats.h
  header files.
* Rename '_py_stats' variable to '_Py_stats'.
* Exclude Include/cpython/pystats.h from the Py_LIMITED_API.
* Move pystats.h include from object.h to Python.h.
* Add _Py_StatsOn() and _Py_StatsOff() functions. Remove
  '_py_stats_struct' variable from the API: make it static in
  specialize.c.
* Document API in Include/pystats.h and Include/cpython/pystats.h.
* Complete pystats documentation in Doc/using/configure.rst.
* Don't write "all zeros" stats: if _stats_off() and _stats_clear()
  or _stats_dump() were called.
* _PyEval_Fini() now always call _Py_PrintSpecializationStats() which
  does nothing if stats are all zeros.

Co-authored-by: Michael Droettboom <mdboom@gmail.com>

1 files changed, 13 insertions, 111 deletions

diff --git a/Include/pystats.h b/Include/pystats.h
index b195759..acfa322 100644
--- a/Include/pystats.h
+++ b/Include/pystats.h
@@ -1,4 +1,9 @@
-
+// Statistics on Python performance (public API).
+//
+// Define _Py_INCREF_STAT_INC() and _Py_DECREF_STAT_INC() used by Py_INCREF()
+// and Py_DECREF().
+//
+// See Include/cpython/pystats.h for the full API.
 
 #ifndef Py_PYSTATS_H
 #define Py_PYSTATS_H
@@ -6,119 +11,16 @@
 extern "C" {
 #endif
 
-#ifdef Py_STATS
-
-#define SPECIALIZATION_FAILURE_KINDS 36
-
-/* Stats for determining who is calling PyEval_EvalFrame */
-#define EVAL_CALL_TOTAL 0
-#define EVAL_CALL_VECTOR 1
-#define EVAL_CALL_GENERATOR 2
-#define EVAL_CALL_LEGACY 3
-#define EVAL_CALL_FUNCTION_VECTORCALL 4
-#define EVAL_CALL_BUILD_CLASS 5
-#define EVAL_CALL_SLOT 6
-#define EVAL_CALL_FUNCTION_EX 7
-#define EVAL_CALL_API 8
-#define EVAL_CALL_METHOD 9
-
-#define EVAL_CALL_KINDS 10
-
-typedef struct _specialization_stats {
-    uint64_t success;
-    uint64_t failure;
-    uint64_t hit;
-    uint64_t deferred;
-    uint64_t miss;
-    uint64_t deopt;
-    uint64_t failure_kinds[SPECIALIZATION_FAILURE_KINDS];
-} SpecializationStats;
-
-typedef struct _opcode_stats {
-    SpecializationStats specialization;
-    uint64_t execution_count;
-    uint64_t pair_count[256];
-} OpcodeStats;
-
-typedef struct _call_stats {
-    uint64_t inlined_py_calls;
-    uint64_t pyeval_calls;
-    uint64_t frames_pushed;
-    uint64_t frame_objects_created;
-    uint64_t eval_calls[EVAL_CALL_KINDS];
-} CallStats;
-
-typedef struct _object_stats {
-    uint64_t increfs;
-    uint64_t decrefs;
-    uint64_t interpreter_increfs;
-    uint64_t interpreter_decrefs;
-    uint64_t allocations;
-    uint64_t allocations512;
-    uint64_t allocations4k;
-    uint64_t allocations_big;
-    uint64_t frees;
-    uint64_t to_freelist;
-    uint64_t from_freelist;
-    uint64_t new_values;
-    uint64_t dict_materialized_on_request;
-    uint64_t dict_materialized_new_key;
-    uint64_t dict_materialized_too_big;
-    uint64_t dict_materialized_str_subclass;
-    uint64_t dict_dematerialized;
-    uint64_t type_cache_hits;
-    uint64_t type_cache_misses;
-    uint64_t type_cache_dunder_hits;
-    uint64_t type_cache_dunder_misses;
-    uint64_t type_cache_collisions;
-    uint64_t optimization_attempts;
-    uint64_t optimization_traces_created;
-    uint64_t optimization_traces_executed;
-    uint64_t optimization_uops_executed;
-    /* Temporary value used during GC */
-    uint64_t object_visits;
-} ObjectStats;
-
-typedef struct _gc_stats {
-    uint64_t collections;
-    uint64_t object_visits;
-    uint64_t objects_collected;
-} GCStats;
-
-typedef struct _stats {
-    OpcodeStats opcode_stats[256];
-    CallStats call_stats;
-    ObjectStats object_stats;
-    GCStats *gc_stats;
-} PyStats;
-
-
-PyAPI_DATA(PyStats) _py_stats_struct;
-PyAPI_DATA(PyStats *) _py_stats;
-
-extern void _Py_StatsClear(void);
-extern void _Py_PrintSpecializationStats(int to_file);
-
-#ifdef _PY_INTERPRETER
-
-#define _Py_INCREF_STAT_INC() do { if (_py_stats) _py_stats->object_stats.interpreter_increfs++; } while (0)
-#define _Py_DECREF_STAT_INC() do { if (_py_stats) _py_stats->object_stats.interpreter_decrefs++; } while (0)
-
+#if defined(Py_STATS) && !defined(Py_LIMITED_API)
+#  define Py_CPYTHON_PYSTATS_H
+#  include "cpython/pystats.h"
+#  undef Py_CPYTHON_PYSTATS_H
 #else
-
-#define _Py_INCREF_STAT_INC() do { if (_py_stats) _py_stats->object_stats.increfs++; } while (0)
-#define _Py_DECREF_STAT_INC() do { if (_py_stats) _py_stats->object_stats.decrefs++; } while (0)
-
-#endif
-
-#else
-
-#define _Py_INCREF_STAT_INC() ((void)0)
-#define _Py_DECREF_STAT_INC() ((void)0)
-
+#  define _Py_INCREF_STAT_INC() ((void)0)
+#  define _Py_DECREF_STAT_INC() ((void)0)
 #endif  // !Py_STATS
 
 #ifdef __cplusplus
 }
 #endif
-#endif /* !Py_PYSTATs_H */
+#endif   // !Py_PYSTATS_H