library: normalize/standardize an i/f, <DISKSTATS> api

This patch will bring this interface up to our 3rd gen
standards. The following summarizes the major changes.

* New delta provisions have been added to most fields.

There are, of course, some fields for which a delta is
inappropriate. They include the identifying items such
as name, type, major and minor. Plus the io_inprogress
field which already acts, in effect, as a delta value.

* To provide delta support, dev_node historical values
have become persistent. By the same token, the library
must provide for future removal of disks/partitions. A
timestamp is used to detect 'stale' data which will be
deleted so as not to satisfy some get, select or reap.

* Such persistent support is provided by a linked list
which, by default, grows from the bottom down so as to
maintain compatibility with the /proc/diskstats order.

Initially, I was tempted to use the GNU tsearch (tree)
provisions until I discovered the overhead of building
that tree plus costs of a subsequent 'twalk'. Besides,
walking such a tree means retrieval order would differ
from an order required/expected by the vmstat program.

* The '/sys/block' directory is no longer scanned with
every refresh cycle. Rather, it's only accessed when a
node is first encountered. Then, that node's 'type' is
persistent for its lifetime like several other fields.

* A sort provision was included, at virtually no cost,
even though such a provision was not currently needed.

Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is contained in:
Jim Warner 2016-07-20 00:00:00 -05:00 committed by Craig Small
parent 8e5d5e44e9
commit ecd64f4445
3 changed files with 962 additions and 281 deletions

File diff suppressed because it is too large Load Diff

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@ -1,9 +1,10 @@
/*
* diskstat - Disk statistics - part of procps
* diskstats - Disk statistics - part of procps
*
* Copyright (c) 2003 Fabian Frederick
* Copyright (C) 2003 Albert Cahalan
* Copyright (C) 2015 Craig Small <csmall@enc.com.au>
* Copyright (C) 2016 Jim Warner <james.warner@comcast.net>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
@ -19,52 +20,110 @@
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef PROC_DISKSTAT_H
#define PROC_DISKSTAT_H
#ifndef PROC_DISKSTATS_H
#define PROC_DISKSTATS_H
#include <sys/cdefs.h>
__BEGIN_DECLS
enum procps_diskstat_devitem {
PROCPS_DISKSTAT_READS,
PROCPS_DISKSTAT_READS_MERGED,
PROCPS_DISKSTAT_READ_SECTORS,
PROCPS_DISKSTAT_READ_TIME,
PROCPS_DISKSTAT_WRITES,
PROCPS_DISKSTAT_WRITES_MERGED,
PROCPS_DISKSTAT_WRITE_SECTORS,
PROCPS_DISKSTAT_WRITE_TIME,
PROCPS_DISKSTAT_IO_INPROGRESS,
PROCPS_DISKSTAT_IO_TIME,
PROCPS_DISKSTAT_IO_WTIME
enum diskstats_item {
PROCPS_DISKSTATS_noop, // ( never altered )
PROCPS_DISKSTATS_extra, // ( reset to zero )
PROCPS_DISKSTATS_NAME, // str
PROCPS_DISKSTATS_TYPE, // s_int
PROCPS_DISKSTATS_MAJOR, // s_int
PROCPS_DISKSTATS_MINOR, // s_int
PROCPS_DISKSTATS_READS, // ul_int
PROCPS_DISKSTATS_READS_MERGED, // ul_int
PROCPS_DISKSTATS_READ_SECTORS, // ul_int
PROCPS_DISKSTATS_READ_TIME, // ul_int
PROCPS_DISKSTATS_WRITES, // ul_int
PROCPS_DISKSTATS_WRITES_MERGED, // ul_int
PROCPS_DISKSTATS_WRITE_SECTORS, // ul_int
PROCPS_DISKSTATS_WRITE_TIME, // ul_int
PROCPS_DISKSTATS_IO_TIME, // ul_int
PROCPS_DISKSTATS_IO_WTIME, // ul_int
PROCPS_DISKSTATS_IO_INPROGRESS, // s_int
PROCPS_DISKSTATS_DELTA_READS, // s_int
PROCPS_DISKSTATS_DELTA_READS_MERGED, // s_int
PROCPS_DISKSTATS_DELTA_READ_SECTORS, // s_int
PROCPS_DISKSTATS_DELTA_READ_TIME, // s_int
PROCPS_DISKSTATS_DELTA_WRITES, // s_int
PROCPS_DISKSTATS_DELTA_WRITES_MERGED, // s_int
PROCPS_DISKSTATS_DELTA_WRITE_SECTORS, // s_int
PROCPS_DISKSTATS_DELTA_WRITE_TIME, // s_int
PROCPS_DISKSTATS_DELTA_IO_TIME, // s_int
PROCPS_DISKSTATS_DELTA_IO_WTIME // s_int
};
struct procps_diskstat;
struct procps_diskstat_dev;
enum diskstats_sort_order {
PROCPS_DISKSTATS_SORT_ASCEND = +1,
PROCPS_DISKSTATS_SORT_DESCEND = -1
};
int procps_diskstat_new (struct procps_diskstat **info);
int procps_diskstat_read (struct procps_diskstat *info);
int procps_diskstat_ref (struct procps_diskstat *info);
int procps_diskstat_unref (struct procps_diskstat **info);
struct diskstats_result {
enum diskstats_item item;
union {
signed int s_int;
unsigned long ul_int;
char *str;
} result;
};
int procps_diskstat_dev_count (const struct procps_diskstat *info);
int procps_diskstat_dev_getbyname(
const struct procps_diskstat *info,
const char *name);
struct diskstats_stack {
struct diskstats_result *head;
};
unsigned long procps_diskstat_dev_get(
const struct procps_diskstat *info,
const enum procps_diskstat_devitem item,
const unsigned int devid);
struct diskstats_reap {
int total;
struct diskstats_stack **stacks;
};
char* procps_diskstat_dev_getname(
const struct procps_diskstat *info,
const unsigned int devid);
int procps_diskstat_dev_isdisk(
const struct procps_diskstat *info,
const unsigned int devid);
#define PROCPS_DISKSTATS_TYPE_DISK -11111
#define PROCPS_DISKSTATS_TYPE_PARTITION -22222
#define PROCPS_DISKSTATS_GET( diskstats, actual_enum, type ) \
procps_diskstats_get( diskstats, actual_enum ) -> result . type
#define PROCPS_DISKSTATS_VAL( relative_enum, type, stack) \
stack -> head [ relative_enum ] . result . type
struct procps_diskstats;
int procps_diskstats_new (struct procps_diskstats **info);
int procps_diskstats_ref (struct procps_diskstats *info);
int procps_diskstats_unref (struct procps_diskstats **info);
struct diskstats_result *procps_diskstats_get (
struct procps_diskstats *info,
const char *name,
enum diskstats_item item);
struct diskstats_reap *procps_diskstats_reap (
struct procps_diskstats *info,
enum diskstats_item *items,
int numitems);
struct diskstats_stack *procps_diskstats_select (
struct procps_diskstats *info,
const char *name,
enum diskstats_item *items,
int numitems);
struct diskstats_stack **procps_diskstats_sort (
struct procps_diskstats *info,
struct diskstats_stack *stacks[],
int numstacked,
enum diskstats_item sortitem,
enum diskstats_sort_order order);
__END_DECLS
#endif

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@ -3,15 +3,13 @@ global:
escape_str;
fatal_proc_unmounted;
procps_cpu_count;
procps_diskstat_dev_count;
procps_diskstat_dev_get;
procps_diskstat_dev_getbyname;
procps_diskstat_dev_getname;
procps_diskstat_dev_isdisk;
procps_diskstat_new;
procps_diskstat_read;
procps_diskstat_ref;
procps_diskstat_unref;
procps_diskstats_new;
procps_diskstats_ref;
procps_diskstats_unref;
procps_diskstats_get;
procps_diskstats_reap;
procps_diskstats_select;
procps_diskstats_sort;
procps_hertz_get;
procps_linux_version;
procps_loadavg;