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pythongh-108216: Add pycore_dict_struct.h internal header file
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Add a new internal pycore_dict_struct.h header file. It can be used
by debuggers and profilers to inspect a Python dictionary without
having to call Python functions. It should be usable in C++.

pycore_dict.h includes pycore_dict_struct.h (no API change).
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vstinner committed Aug 21, 2023
1 parent d63972e commit ead4453
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Showing 7 changed files with 136 additions and 105 deletions.
104 changes: 5 additions & 99 deletions Include/internal/pycore_dict.h
Original file line number Diff line number Diff line change
@@ -1,4 +1,3 @@

#ifndef Py_INTERNAL_DICT_H
#define Py_INTERNAL_DICT_H
#ifdef __cplusplus
Expand All @@ -9,8 +8,12 @@ extern "C" {
# error "this header requires Py_BUILD_CORE define"
#endif

#include "pycore_dict_state.h" // DICT_MAX_WATCHERS
#include "pycore_dict_struct.h" // export PyDictKeysObject and DKIX_EMPTY
#include "pycore_interp.h" // PyInterpreter.dict_state
#include "pycore_object.h" // PyDictOrValues


// Unsafe flavor of PyDict_GetItemWithError(): no error checking
extern PyObject* _PyDict_GetItemWithError(PyObject *dp, PyObject *key);

Expand Down Expand Up @@ -39,18 +42,6 @@ extern void _PyDict_Fini(PyInterpreterState *interp);

/* other API */

typedef struct {
/* Cached hash code of me_key. */
Py_hash_t me_hash;
PyObject *me_key;
PyObject *me_value; /* This field is only meaningful for combined tables */
} PyDictKeyEntry;

typedef struct {
PyObject *me_key; /* The key must be Unicode and have hash. */
PyObject *me_value; /* This field is only meaningful for combined tables */
} PyDictUnicodeEntry;

extern PyDictKeysObject *_PyDict_NewKeysForClass(void);
extern PyObject *_PyDict_FromKeys(PyObject *, PyObject *, PyObject *);

Expand Down Expand Up @@ -78,95 +69,10 @@ extern int _PyObjectDict_SetItem(PyTypeObject *tp, PyObject **dictptr, PyObject

extern PyObject *_PyDict_Pop_KnownHash(PyObject *, PyObject *, Py_hash_t, PyObject *);

#define DKIX_EMPTY (-1)
#define DKIX_DUMMY (-2) /* Used internally */
#define DKIX_ERROR (-3)
#define DKIX_KEY_CHANGED (-4) /* Used internally */

typedef enum {
DICT_KEYS_GENERAL = 0,
DICT_KEYS_UNICODE = 1,
DICT_KEYS_SPLIT = 2
} DictKeysKind;

/* See dictobject.c for actual layout of DictKeysObject */
struct _dictkeysobject {
Py_ssize_t dk_refcnt;

/* Size of the hash table (dk_indices). It must be a power of 2. */
uint8_t dk_log2_size;

/* Size of the hash table (dk_indices) by bytes. */
uint8_t dk_log2_index_bytes;

/* Kind of keys */
uint8_t dk_kind;

/* Version number -- Reset to 0 by any modification to keys */
uint32_t dk_version;

/* Number of usable entries in dk_entries. */
Py_ssize_t dk_usable;

/* Number of used entries in dk_entries. */
Py_ssize_t dk_nentries;

/* Actual hash table of dk_size entries. It holds indices in dk_entries,
or DKIX_EMPTY(-1) or DKIX_DUMMY(-2).
Indices must be: 0 <= indice < USABLE_FRACTION(dk_size).
The size in bytes of an indice depends on dk_size:
- 1 byte if dk_size <= 0xff (char*)
- 2 bytes if dk_size <= 0xffff (int16_t*)
- 4 bytes if dk_size <= 0xffffffff (int32_t*)
- 8 bytes otherwise (int64_t*)
Dynamically sized, SIZEOF_VOID_P is minimum. */
char dk_indices[]; /* char is required to avoid strict aliasing. */

/* "PyDictKeyEntry or PyDictUnicodeEntry dk_entries[USABLE_FRACTION(DK_SIZE(dk))];" array follows:
see the DK_ENTRIES() macro */
};

/* This must be no more than 250, for the prefix size to fit in one byte. */
#define SHARED_KEYS_MAX_SIZE 30
#define NEXT_LOG2_SHARED_KEYS_MAX_SIZE 6

/* Layout of dict values:
*
* The PyObject *values are preceded by an array of bytes holding
* the insertion order and size.
* [-1] = prefix size. [-2] = used size. size[-2-n...] = insertion order.
*/
struct _dictvalues {
PyObject *values[1];
};

#define DK_LOG_SIZE(dk) _Py_RVALUE((dk)->dk_log2_size)
#if SIZEOF_VOID_P > 4
#define DK_SIZE(dk) (((int64_t)1)<<DK_LOG_SIZE(dk))
#else
#define DK_SIZE(dk) (1<<DK_LOG_SIZE(dk))
#endif

static inline void* _DK_ENTRIES(PyDictKeysObject *dk) {
int8_t *indices = (int8_t*)(dk->dk_indices);
size_t index = (size_t)1 << dk->dk_log2_index_bytes;
return (&indices[index]);
}
static inline PyDictKeyEntry* DK_ENTRIES(PyDictKeysObject *dk) {
assert(dk->dk_kind == DICT_KEYS_GENERAL);
return (PyDictKeyEntry*)_DK_ENTRIES(dk);
}
static inline PyDictUnicodeEntry* DK_UNICODE_ENTRIES(PyDictKeysObject *dk) {
assert(dk->dk_kind != DICT_KEYS_GENERAL);
return (PyDictUnicodeEntry*)_DK_ENTRIES(dk);
}

#define DK_IS_UNICODE(dk) ((dk)->dk_kind != DICT_KEYS_GENERAL)

#define DICT_VERSION_INCREMENT (1 << DICT_MAX_WATCHERS)
#define DICT_VERSION_MASK (DICT_VERSION_INCREMENT - 1)

Expand Down Expand Up @@ -218,4 +124,4 @@ _PyDictValues_AddToInsertionOrder(PyDictValues *values, Py_ssize_t ix)
#ifdef __cplusplus
}
#endif
#endif /* !Py_INTERNAL_DICT_H */
#endif // !Py_INTERNAL_DICT_H
117 changes: 117 additions & 0 deletions Include/internal/pycore_dict_struct.h
Original file line number Diff line number Diff line change
@@ -0,0 +1,117 @@
// Internal header which can be used by debuggers and profilers
// to inspect a Python dictionary by reading memory, without executing
// Python functions. Only define static inline functions to inspect a
// dictionary. Sub-set of pycore_dict.h which should be usable in C++
// (gh-108216).

#ifndef Py_INTERNAL_DICT_STRUCT_H
#define Py_INTERNAL_DICT_STRUCT_H
#ifdef __cplusplus
extern "C" {
#endif

#ifndef Py_BUILD_CORE
# error "this header requires Py_BUILD_CORE define"
#endif

typedef struct {
/* Cached hash code of me_key. */
Py_hash_t me_hash;
PyObject *me_key;
PyObject *me_value; /* This field is only meaningful for combined tables */
} PyDictKeyEntry;

typedef struct {
PyObject *me_key; /* The key must be Unicode and have hash. */
PyObject *me_value; /* This field is only meaningful for combined tables */
} PyDictUnicodeEntry;

#define DKIX_EMPTY (-1)
#define DKIX_DUMMY (-2) /* Used internally */
#define DKIX_ERROR (-3)
#define DKIX_KEY_CHANGED (-4) /* Used internally */

typedef enum {
DICT_KEYS_GENERAL = 0,
DICT_KEYS_UNICODE = 1,
DICT_KEYS_SPLIT = 2
} DictKeysKind;

/* See dictobject.c for actual layout of DictKeysObject */
struct _dictkeysobject {
Py_ssize_t dk_refcnt;

/* Size of the hash table (dk_indices). It must be a power of 2. */
uint8_t dk_log2_size;

/* Size of the hash table (dk_indices) by bytes. */
uint8_t dk_log2_index_bytes;

/* Kind of keys */
uint8_t dk_kind;

/* Version number -- Reset to 0 by any modification to keys */
uint32_t dk_version;

/* Number of usable entries in dk_entries. */
Py_ssize_t dk_usable;

/* Number of used entries in dk_entries. */
Py_ssize_t dk_nentries;

/* Actual hash table of dk_size entries. It holds indices in dk_entries,
or DKIX_EMPTY(-1) or DKIX_DUMMY(-2).
Indices must be: 0 <= indice < USABLE_FRACTION(dk_size).
The size in bytes of an indice depends on dk_size:
- 1 byte if dk_size <= 0xff (char*)
- 2 bytes if dk_size <= 0xffff (int16_t*)
- 4 bytes if dk_size <= 0xffffffff (int32_t*)
- 8 bytes otherwise (int64_t*)
Dynamically sized, SIZEOF_VOID_P is minimum. */
char dk_indices[]; /* char is required to avoid strict aliasing. */

/* "PyDictKeyEntry or PyDictUnicodeEntry dk_entries[USABLE_FRACTION(DK_SIZE(dk))];" array follows:
see the DK_ENTRIES() macro */
};

/* Layout of dict values:
*
* The PyObject *values are preceded by an array of bytes holding
* the insertion order and size.
* [-1] = prefix size. [-2] = used size. size[-2-n...] = insertion order.
*/
struct _dictvalues {
PyObject *values[1];
};

#define DK_LOG_SIZE(dk) _Py_RVALUE((dk)->dk_log2_size)
#if SIZEOF_VOID_P > 4
#define DK_SIZE(dk) (((int64_t)1)<<DK_LOG_SIZE(dk))
#else
#define DK_SIZE(dk) (1<<DK_LOG_SIZE(dk))
#endif

static inline void* _DK_ENTRIES(PyDictKeysObject *dk) {
int8_t *indices = (int8_t*)(dk->dk_indices);
size_t index = (size_t)1 << dk->dk_log2_index_bytes;
return (&indices[index]);
}
static inline PyDictKeyEntry* DK_ENTRIES(PyDictKeysObject *dk) {
assert(dk->dk_kind == DICT_KEYS_GENERAL);
return (PyDictKeyEntry*)_DK_ENTRIES(dk);
}
static inline PyDictUnicodeEntry* DK_UNICODE_ENTRIES(PyDictKeysObject *dk) {
assert(dk->dk_kind != DICT_KEYS_GENERAL);
return (PyDictUnicodeEntry*)_DK_ENTRIES(dk);
}

#define DK_IS_UNICODE(dk) ((dk)->dk_kind != DICT_KEYS_GENERAL)

#ifdef __cplusplus
}
#endif
#endif // !Py_INTERNAL_DICT_STRUCT_H
3 changes: 2 additions & 1 deletion Makefile.pre.in
Original file line number Diff line number Diff line change
Expand Up @@ -1759,9 +1759,10 @@ PYTHON_HEADERS= \
$(srcdir)/Include/internal/pycore_complexobject.h \
$(srcdir)/Include/internal/pycore_condvar.h \
$(srcdir)/Include/internal/pycore_context.h \
$(srcdir)/Include/internal/pycore_descrobject.h \
$(srcdir)/Include/internal/pycore_dict.h \
$(srcdir)/Include/internal/pycore_dict_state.h \
$(srcdir)/Include/internal/pycore_descrobject.h \
$(srcdir)/Include/internal/pycore_dict_struct.h \
$(srcdir)/Include/internal/pycore_dtoa.h \
$(srcdir)/Include/internal/pycore_exceptions.h \
$(srcdir)/Include/internal/pycore_faulthandler.h \
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Add a new internal pycore_dict_struct.h header file. It can be used by
debuggers and profilers to inspect a Python dictionary without having to
call Python functions. It should be usable in C++. Patch by Victor Stinner.
2 changes: 1 addition & 1 deletion Objects/odictobject.c
Original file line number Diff line number Diff line change
Expand Up @@ -466,8 +466,8 @@ Potential Optimizations

#include "Python.h"
#include "pycore_call.h" // _PyObject_CallNoArgs()
#include "pycore_object.h" // _PyObject_GC_UNTRACK()
#include "pycore_dict.h" // _Py_dict_lookup()
#include "pycore_object.h" // _PyObject_GC_UNTRACK()
#include <stddef.h> // offsetof()

#include "clinic/odictobject.c.h"
Expand Down
5 changes: 3 additions & 2 deletions PCbuild/pythoncore.vcxproj
Original file line number Diff line number Diff line change
Expand Up @@ -218,6 +218,7 @@
<ClInclude Include="..\Include\internal\pycore_descrobject.h" />
<ClInclude Include="..\Include\internal\pycore_dict.h" />
<ClInclude Include="..\Include\internal\pycore_dict_state.h" />
<ClInclude Include="..\Include\internal\pycore_dict_struct.h" />
<ClInclude Include="..\Include\internal\pycore_dtoa.h" />
<ClInclude Include="..\Include\internal\pycore_exceptions.h" />
<ClInclude Include="..\Include\internal\pycore_faulthandler.h" />
Expand Down Expand Up @@ -248,7 +249,7 @@
<ClInclude Include="..\Include\internal\pycore_object_state.h" />
<ClInclude Include="..\Include\internal\pycore_obmalloc.h" />
<ClInclude Include="..\Include\internal\pycore_obmalloc_init.h" />
<ClInclude Include="..\Include\internal\pycore_optimizer.h" />
<ClInclude Include="..\Include\internal\pycore_optimizer.h" />
<ClInclude Include="..\Include\internal\pycore_pathconfig.h" />
<ClInclude Include="..\Include\internal\pycore_pyarena.h" />
<ClInclude Include="..\Include\internal\pycore_pyerrors.h" />
Expand Down Expand Up @@ -280,7 +281,7 @@
<ClInclude Include="..\Include\internal\pycore_unionobject.h" />
<ClInclude Include="..\Include\internal\pycore_unicodeobject.h" />
<ClInclude Include="..\Include\internal\pycore_unicodeobject_generated.h" />
<ClInclude Include="..\Include\internal\pycore_uops.h" />
<ClInclude Include="..\Include\internal\pycore_uops.h" />
<ClInclude Include="..\Include\internal\pycore_warnings.h" />
<ClInclude Include="..\Include\internal\pycore_weakref.h" />
<ClInclude Include="..\Include\interpreteridobject.h" />
Expand Down
7 changes: 5 additions & 2 deletions PCbuild/pythoncore.vcxproj.filters
Original file line number Diff line number Diff line change
Expand Up @@ -561,6 +561,9 @@
<ClInclude Include="..\Include\internal\pycore_dict_state.h">
<Filter>Include\internal</Filter>
</ClInclude>
<ClInclude Include="..\Include\internal\pycore_dict_struct.h">
<Filter>Include\internal</Filter>
</ClInclude>
<ClInclude Include="..\Include\internal\pycore_dtoa.h">
<Filter>Include\internal</Filter>
</ClInclude>
Expand Down Expand Up @@ -650,7 +653,7 @@
</ClInclude>
<ClInclude Include="..\Include\internal\pycore_optimizer.h">
<Filter>Include\internal</Filter>
</ClInclude>
</ClInclude>
<ClInclude Include="..\Include\internal\pycore_pathconfig.h">
<Filter>Include\internal</Filter>
</ClInclude>
Expand Down Expand Up @@ -737,7 +740,7 @@
</ClInclude>
<ClInclude Include="..\Include\internal\pycore_uops.h">
<Filter>Include\internal</Filter>
</ClInclude>
</ClInclude>
<ClInclude Include="$(zlibDir)\crc32.h">
<Filter>Modules\zlib</Filter>
</ClInclude>
Expand Down

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