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/*
* Copyright (c) 2017 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef __included_maplog_h__
#define __included_maplog_h__
/** @file
@brief mmap-based thread-safe fixed-size record double-buffered logging.
This scheme should be about as fast as practicable. By fiat, log
records are rounded to a multiple of CLIB_CACHE_LINE_BYTES.
Consumer code calls clib_maplog_get_entry(...) to obtain a pointer
to a log entry.
We use an atomic ticket-counter to dole out log entries. Whichever
client thread crosses the double-buffer boundary is in charge of
replacing the log segment which just filled.
*/
#include <vppinfra/clib.h>
#include <vppinfra/cache.h>
#include <vppinfra/format.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
/** Maplog log file header segment. In a separate file */
typedef struct
{
u8 maplog_major_version; /**< library major version number */
u8 maplog_minor_version; /**< library minor version number */
u8 maplog_patch_version; /**< library patch version number */
u8 maplog_flag_wrapped; /**< log has wrapped */
u32 application_id; /**< application identifier */
u8 application_major_version; /**< application major version number */
u8 application_minor_version; /**< application minor version number */
u8 application_patch_version; /**< application patch version number */
u8 maplog_flag_circular; /**< log is circular */
u32 record_size_in_cachelines; /**< record size in cache lines */
u32 cacheline_size; /**< cache line size */
u64 file_size_in_records; /**< file size in records */
u64 number_of_records; /**< number of records in entire log */
u64 number_of_files; /**< number of files in entire log */
u8 file_basename[256]; /**< file basename */
} clib_maplog_header_t;
#define MAPLOG_MAJOR_VERSION 1
#define MAPLOG_MINOR_VERSION 1
#define MAPLOG_PATCH_VERSION 0
/** Process-private main data structure */
typedef struct
{
CLIB_CACHE_LINE_ALIGN_MARK (cacheline1);
/** rw cache line: atomic ticket-counter, file index */
volatile u64 next_record_index;
/** file size in records, rounded to a power of two */
u64 file_size_in_records;
u32 log2_file_size_in_records; /**< lg file size in records */
volatile u32 current_file_index; /**< current file index */
volatile u32 flags; /**< flags, currently just "init" or not */
/* read-mostly cache line: size parameters, file names, etc. */
CLIB_CACHE_LINE_ALIGN_MARK (cacheline2);
u32 record_size_in_cachelines; /**< record size in cache lines */
/* double-buffered mmap'ed logfiles */
volatile u8 *file_baseva[2]; /**< active segment base addresses */
u8 *filenames[2]; /**< active segment file names */
/* vector not c-string */
u8 *file_basename; /**< basename, e.g. "/tmp/mylog" */
u8 *header_filename; /**< log header file name */
} clib_maplog_main_t;
/* flag bits */
#define CLIB_MAPLOG_FLAG_INIT (1<<0)
#define CLIB_MAPLOG_FLAG_CIRCULAR (1<<1)
#define CLIB_MAPLOG_FLAG_WRAPPED (1<<2)
/** log initialization structure */
typedef struct
{
clib_maplog_main_t *mm; /**< pointer to the main structure */
char *file_basename; /**< file base name */
u64 file_size_in_bytes; /**< file size in bytes */
u32 record_size_in_bytes; /**< record size in bytes */
u32 application_id; /**< application identifier */
u8 application_major_version; /**< application major version number */
u8 application_minor_version; /**< application minor version number */
u8 application_patch_version; /**< application patch version number */
u8 maplog_is_circular; /**< single, circular log */
} clib_maplog_init_args_t;
/* function prototypes */
int clib_maplog_init (clib_maplog_init_args_t * ap);
void clib_maplog_update_header (clib_maplog_main_t * mm);
void clib_maplog_close (clib_maplog_main_t * mm);
int clib_maplog_process (char *file_basename, void *fp_arg);
format_function_t format_maplog_header;
u8 *_clib_maplog_get_entry_slowpath (clib_maplog_main_t * mm,
u64 my_record_index);
/**
* @brief Obtain a log entry pointer
*
* Increments the atomic ticket counter, and returns a pointer to
* the newly-allocated log entry. The slowpath function replaces
* a full log segment with a new/fresh/empty log segment
*
* @param[in] mm maplog object pointer
* @return pointer to the allocated log entry
*/
static inline void *
clib_maplog_get_entry (clib_maplog_main_t * mm)
{
u64 my_record_index;
u8 *rv;
ASSERT (mm->flags & CLIB_MAPLOG_FLAG_INIT);
my_record_index = clib_atomic_fetch_add (&mm->next_record_index, 1);
/* Time to unmap and create a new logfile? */
if (PREDICT_FALSE ((my_record_index & (mm->file_size_in_records - 1)) == 0))
{
/* Regular log? Switch file... */
if (!(mm->flags & CLIB_MAPLOG_FLAG_CIRCULAR))
{
/* Yes, but not the very first time... (;-)... */
if (my_record_index)
return _clib_maplog_get_entry_slowpath (mm, my_record_index);
}
else /* Circular log: set the wrap bit and move along */
mm->flags |= CLIB_MAPLOG_FLAG_WRAPPED;
/* FALLTHROUGH */
}
rv = (u8 *)
mm->file_baseva[(my_record_index >> mm->log2_file_size_in_records) & 1] +
(my_record_index & (mm->file_size_in_records - 1))
* mm->record_size_in_cachelines * CLIB_CACHE_LINE_BYTES;
return rv;
}
#endif /* __included_maplog_h__ */
/*
* fd.io coding-style-patch-verification: ON
*
* Local Variables:
* eval: (c-set-style "gnu")
* End:
*/
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