upstream/mercurial-mirror Files · mercurial/util.h

revlog: make compressed size comparisons consistent...

revlog: make compressed size comparisons consistent revlog.compress() compares the compressed size to the input size and throws away the compressed data if it is larger than the input. This is the correct thing to do, as storing compressed data that is larger than the input takes up more storage space and makes reading slower. However, the comparison was implemented inconsistently. For the streaming compression mode, we threw away the result if it was greater than or equal to the input size. But for the one-shot compression, we threw away the compression only if it was greater than the input size! This patch changes the comparison for the simple case so it is consistent with the streaming case. As a few tests demonstrate, this adds 1 byte to some revlog entries. This is because of an added 'u' header on the chunk. It seems somewhat wrong to increase the revlog size here. However, IMO the cost of 1 byte in storage is insignificant compared to the performance gains of avoiding decompression. This patch should invite questions around the heuristic for throwing away compressed data. For example, I'd argue we should be more liberal about rejecting compressed data, additionally doing so where the number of bytes saved fails to reach a threshold. But we can have this discussion another time.

Gregory Szorc - - Load All Authors

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      /*

       util.h - utility functions for interfacing with the various python APIs.

       This software may be used and distributed according to the terms of

       the GNU General Public License, incorporated herein by reference.

      */

      #ifndef _HG_UTIL_H_

      #define _HG_UTIL_H_

      #include "compat.h"

      #if PY_MAJOR_VERSION >= 3

      #define IS_PY3K

      #endif

      typedef struct {

      	PyObject_HEAD

      	char state;

      	int mode;

      	int size;

      	int mtime;

      } dirstateTupleObject;

      extern PyTypeObject dirstateTupleType;

      #define dirstate_tuple_check(op) (Py_TYPE(op) == &dirstateTupleType)

      /* This should be kept in sync with normcasespecs in encoding.py. */

      enum normcase_spec {

      	NORMCASE_LOWER = -1,

      	NORMCASE_UPPER = 1,

      	NORMCASE_OTHER = 0

      };

      #define MIN(a, b) (((a)<(b))?(a):(b))

      /* VC9 doesn't include bool and lacks stdbool.h based on my searching */

      #if defined(_MSC_VER) || __STDC_VERSION__ < 199901L

      #define true 1

      #define false 0

      typedef unsigned char bool;

      #else

      #include <stdbool.h>

      #endif

      #endif /* _HG_UTIL_H_ */

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				/*
				util.h - utility functions for interfacing with the various python APIs.

				This software may be used and distributed according to the terms of
				the GNU General Public License, incorporated herein by reference.
				*/

				#ifndef _HG_UTIL_H_
				#define _HG_UTIL_H_

				#include "compat.h"

				#if PY_MAJOR_VERSION >= 3
				#define IS_PY3K
				#endif

				typedef struct {
				PyObject_HEAD
				char state;
				int mode;
				int size;
				int mtime;
				} dirstateTupleObject;

				extern PyTypeObject dirstateTupleType;
				#define dirstate_tuple_check(op) (Py_TYPE(op) == &dirstateTupleType)

				/* This should be kept in sync with normcasespecs in encoding.py. */
				enum normcase_spec {
				NORMCASE_LOWER = -1,
				NORMCASE_UPPER = 1,
				NORMCASE_OTHER = 0
				};

				#define MIN(a, b) (((a)<(b))?(a):(b))
				/* VC9 doesn't include bool and lacks stdbool.h based on my searching */
				#if defined(_MSC_VER) \|\| __STDC_VERSION__ < 199901L
				#define true 1
				#define false 0
				typedef unsigned char bool;
				#else
				#include <stdbool.h>
				#endif

				#endif /* _HG_UTIL_H_ */