#ifndef __included_maplog_h__
#define __included_maplog_h__
-/** \file
+/** @file
+ @brief mmap-based thread-safe fixed-size record double-buffered logging.
- mmap-based 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 <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
{
- /* rw: atomic ticket-counter, file index */
CLIB_CACHE_LINE_ALIGN_MARK (cacheline1);
+ /** rw cache line: atomic ticket-counter, file index */
volatile u64 next_record_index;
- u64 file_size_in_records; /**< power of two */
- u32 log2_file_size_in_records;
- volatile u32 current_file_index;
- volatile u32 flags;
+ /** 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 */
- /* ro: size parameters */
+ /* read-mostly cache line: size parameters, file names, etc. */
CLIB_CACHE_LINE_ALIGN_MARK (cacheline2);
- u32 record_size_in_cachelines;
+ u32 record_size_in_cachelines; /**< record size in cache lines */
/* double-buffered mmap'ed logfiles */
- volatile u8 *file_baseva[2];
- u8 *filenames[2];
+ volatile u8 *file_baseva[2]; /**< active segment base addresses */
+ u8 *filenames[2]; /**< active segment file names */
/* vector not c-string */
- u8 *file_basename;
+ u8 *file_basename; /**< basename, e.g. "/tmp/mylog" */
+ u8 *header_filename; /**< log header file name */
} clib_maplog_main_t;
-int clib_maplog_init (clib_maplog_main_t * mm, char *file_basename,
- u64 file_size, u32 record_size_in_bytes);
+/* 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);
-#define CLIB_MAPLOG_FLAG_INIT (1<<0)
+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)
{
ASSERT (mm->flags & CLIB_MAPLOG_FLAG_INIT);
- my_record_index = __sync_fetch_and_add (&mm->next_record_index, 1);
+ 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))
{
- /* Yes, but not the very first time... (;-)... */
- if (my_record_index)
- return _clib_maplog_get_entry_slowpath (mm, my_record_index);
+ /* 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 */
}
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