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bundle2: implement consume() API on unbundlepart...
bundle2: implement consume() API on unbundlepart We want bundle parts to not be seekable by default. That means eliminating the generic seek() method. A common pattern in bundle2.py is to seek to the end of the part data. This is mainly used by the part iteration code to ensure the underlying stream is advanced to the next bundle part. In this commit, we establish a dedicated API for consuming a bundle2 part data. We switch users of seek() to it. The old implementation of seek(0, os.SEEK_END) would effectively call self.read(). The new implementation calls self.read(32768) in a loop. The old implementation would therefore assemble a buffer to hold all remaining data being seeked over. For seeking over large bundle parts, this would involve a large allocation and a lot of overhead to collect intermediate data! This overhead can be seen in the results for `hg perfbundleread`: ! bundle2 iterparts() ! wall 10.891305 comb 10.820000 user 7.990000 sys 2.830000 (best of 3) ! wall 8.070791 comb 8.060000 user 7.180000 sys 0.880000 (best of 3) ! bundle2 part seek() ! wall 12.991478 comb 10.390000 user 7.720000 sys 2.670000 (best of 3) ! wall 10.370142 comb 10.350000 user 7.430000 sys 2.920000 (best of 3) Of course, skipping over large payload data isn't likely very common. So I doubt the performance wins will be observed in the wild. Differential Revision: https://phab.mercurial-scm.org/D1388

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error_private.h
76 lines | 2.2 KiB | text/x-c | CLexer
/**
* Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
/* Note : this module is expected to remain private, do not expose it */
#ifndef ERROR_H_MODULE
#define ERROR_H_MODULE
#if defined (__cplusplus)
extern "C" {
#endif
/* ****************************************
* Dependencies
******************************************/
#include <stddef.h> /* size_t */
#include "zstd_errors.h" /* enum list */
/* ****************************************
* Compiler-specific
******************************************/
#if defined(__GNUC__)
# define ERR_STATIC static __attribute__((unused))
#elif defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
# define ERR_STATIC static inline
#elif defined(_MSC_VER)
# define ERR_STATIC static __inline
#else
# define ERR_STATIC static /* this version may generate warnings for unused static functions; disable the relevant warning */
#endif
/*-****************************************
* Customization (error_public.h)
******************************************/
typedef ZSTD_ErrorCode ERR_enum;
#define PREFIX(name) ZSTD_error_##name
/*-****************************************
* Error codes handling
******************************************/
#ifdef ERROR
# undef ERROR /* reported already defined on VS 2015 (Rich Geldreich) */
#endif
#define ERROR(name) ((size_t)-PREFIX(name))
ERR_STATIC unsigned ERR_isError(size_t code) { return (code > ERROR(maxCode)); }
ERR_STATIC ERR_enum ERR_getErrorCode(size_t code) { if (!ERR_isError(code)) return (ERR_enum)0; return (ERR_enum) (0-code); }
/*-****************************************
* Error Strings
******************************************/
const char* ERR_getErrorString(ERR_enum code); /* error_private.c */
ERR_STATIC const char* ERR_getErrorName(size_t code)
{
return ERR_getErrorString(ERR_getErrorCode(code));
}
#if defined (__cplusplus)
}
#endif
#endif /* ERROR_H_MODULE */