mirror of https://gerrit.osmocom.org/libosmocore
360 lines
11 KiB
C
360 lines
11 KiB
C
/*! \file stat_item.c
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* utility routines for keeping statistical values */
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/*
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* (C) 2009-2010 by Harald Welte <laforge@gnumonks.org>
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* (C) 2015 by sysmocom - s.f.m.c. GmbH
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*
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* All Rights Reserved
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*
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* SPDX-License-Identifier: GPL-2.0+
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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/*! \addtogroup osmo_stat_item
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* @{
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*
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* This osmo_stat_item module adds instrumentation capabilities to
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* gather measurement and statistical values in a similar fashion to
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* what we have as \ref osmo_counter_group.
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*
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* As opposed to counters, osmo_stat_item do not increment but consist
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* of a configurable-sized FIFO, which can store not only the current
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* (most recent) value, but also historic values.
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*
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* The only supported value type is an int32_t.
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*
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* Getting values from the osmo_stat_item does not modify its state to
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* allow for multiple independent back-ends retrieving values (e.g. VTY
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* and statd).
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*
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* Each value stored in the FIFO of an osmo_stat_item has an associated
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* value_id. The value_id is derived from an application-wide globally
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* incrementing counter, so (until the counter wraps) more recent
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* values will have higher values.
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*
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* When a new value is set, the oldest value in the FIFO gets silently
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* overwritten. Lost values are skipped when getting values from the
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* item.
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*
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*/
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#include <stdint.h>
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#include <string.h>
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#include <osmocom/core/utils.h>
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#include <osmocom/core/linuxlist.h>
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#include <osmocom/core/talloc.h>
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#include <osmocom/core/timer.h>
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#include <osmocom/core/stat_item.h>
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/*! global list of stat_item groups */
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static LLIST_HEAD(osmo_stat_item_groups);
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/*! counter for assigning globally unique value identifiers */
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static int32_t global_value_id = 0;
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/*! talloc context from which we allocate */
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static void *tall_stat_item_ctx;
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/*! Allocate a new group of counters according to description.
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* Allocate a group of stat items described in \a desc from talloc context \a ctx,
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* giving the new group the index \a idx.
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* \param[in] ctx \ref talloc context
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* \param[in] desc Statistics item group description
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* \param[in] idx Index of new stat item group
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*/
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struct osmo_stat_item_group *osmo_stat_item_group_alloc(void *ctx,
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const struct osmo_stat_item_group_desc *desc,
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unsigned int idx)
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{
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unsigned int group_size;
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unsigned long items_size = 0;
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unsigned int item_idx;
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void *items;
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struct osmo_stat_item_group *group;
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group_size = sizeof(struct osmo_stat_item_group) +
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desc->num_items * sizeof(struct osmo_stat_item *);
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if (!ctx)
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ctx = tall_stat_item_ctx;
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group = talloc_zero_size(ctx, group_size);
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if (!group)
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return NULL;
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group->desc = desc;
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group->idx = idx;
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/* Get combined size of all items */
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for (item_idx = 0; item_idx < desc->num_items; item_idx++) {
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unsigned int size;
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size = sizeof(struct osmo_stat_item) +
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sizeof(struct osmo_stat_item_value) *
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desc->item_desc[item_idx].num_values;
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/* Align to pointer size */
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size = (size + sizeof(void *) - 1) & ~(sizeof(void *) - 1);
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/* Store offsets into the item array */
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group->items[item_idx] = (void *)items_size;
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items_size += size;
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}
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items = talloc_zero_size(group, items_size);
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if (!items) {
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talloc_free(group);
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return NULL;
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}
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/* Update item pointers */
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for (item_idx = 0; item_idx < desc->num_items; item_idx++) {
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struct osmo_stat_item *item = (struct osmo_stat_item *)
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((uint8_t *)items + (unsigned long)group->items[item_idx]);
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unsigned int i;
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group->items[item_idx] = item;
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item->last_offs = desc->item_desc[item_idx].num_values - 1;
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item->last_value_index = -1;
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item->desc = &desc->item_desc[item_idx];
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for (i = 0; i <= item->last_offs; i++) {
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item->values[i].value = desc->item_desc[item_idx].default_value;
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item->values[i].id = OSMO_STAT_ITEM_NOVALUE_ID;
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}
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}
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llist_add(&group->list, &osmo_stat_item_groups);
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return group;
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}
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/*! Free the memory for the specified group of stat items */
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void osmo_stat_item_group_free(struct osmo_stat_item_group *grp)
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{
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llist_del(&grp->list);
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talloc_free(grp);
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}
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/*! Increase the stat_item to the given value.
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* This function adds a new value for the given stat_item at the end of
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* the FIFO.
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* \param[in] item The stat_item whose \a value we want to set
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* \param[in] value The numeric value we want to store at end of FIFO
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*/
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void osmo_stat_item_inc(struct osmo_stat_item *item, int32_t value)
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{
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int32_t oldvalue = item->values[item->last_offs].value;
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osmo_stat_item_set(item, oldvalue + value);
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}
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/*! Descrease the stat_item to the given value.
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* This function adds a new value for the given stat_item at the end of
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* the FIFO.
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* \param[in] item The stat_item whose \a value we want to set
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* \param[in] value The numeric value we want to store at end of FIFO
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*/
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void osmo_stat_item_dec(struct osmo_stat_item *item, int32_t value)
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{
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int32_t oldvalue = item->values[item->last_offs].value;
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osmo_stat_item_set(item, oldvalue - value);
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}
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/*! Set the a given stat_item to the given value.
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* This function adds a new value for the given stat_item at the end of
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* the FIFO.
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* \param[in] item The stat_item whose \a value we want to set
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* \param[in] value The numeric value we want to store at end of FIFO
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*/
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void osmo_stat_item_set(struct osmo_stat_item *item, int32_t value)
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{
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item->last_offs += 1;
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if (item->last_offs >= item->desc->num_values)
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item->last_offs = 0;
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global_value_id += 1;
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if (global_value_id == OSMO_STAT_ITEM_NOVALUE_ID)
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global_value_id += 1;
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item->values[item->last_offs].value = value;
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item->values[item->last_offs].id = global_value_id;
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}
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/*! Retrieve the next value from the osmo_stat_item object.
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* If a new value has been set, it is returned. The idx is used to decide
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* which value to return.
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* On success, *idx is updated to refer to the next unread value. If
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* values have been missed due to FIFO overflow, *idx is incremented by
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* (1 + num_lost).
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* This way, the osmo_stat_item object can be kept stateless from the reader's
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* perspective and therefore be used by several backends simultaneously.
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*
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* \param val the osmo_stat_item object
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* \param idx identifies the next value to be read
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* \param value a pointer to store the value
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* \returns the increment of the index (0: no value has been read,
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* 1: one value has been taken,
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* (1+n): n values have been skipped, one has been taken)
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*/
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int osmo_stat_item_get_next(const struct osmo_stat_item *item, int32_t *next_idx,
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int32_t *value)
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{
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const struct osmo_stat_item_value *next_value;
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const struct osmo_stat_item_value *item_value = NULL;
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int idx_delta;
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int next_offs;
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next_offs = item->last_offs;
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next_value = &item->values[next_offs];
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while (next_value->id - *next_idx >= 0 &&
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next_value->id != OSMO_STAT_ITEM_NOVALUE_ID)
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{
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item_value = next_value;
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next_offs -= 1;
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if (next_offs < 0)
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next_offs = item->desc->num_values - 1;
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if (next_offs == item->last_offs)
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break;
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next_value = &item->values[next_offs];
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}
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if (!item_value)
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/* All items have been read */
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return 0;
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*value = item_value->value;
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idx_delta = item_value->id + 1 - *next_idx;
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*next_idx = item_value->id + 1;
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return idx_delta;
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}
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/*! Skip/discard all values of this item and update \a idx accordingly */
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int osmo_stat_item_discard(const struct osmo_stat_item *item, int32_t *idx)
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{
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int discarded = item->values[item->last_offs].id + 1 - *idx;
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*idx = item->values[item->last_offs].id + 1;
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return discarded;
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}
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/*! Skip all values of all items and update \a idx accordingly */
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int osmo_stat_item_discard_all(int32_t *idx)
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{
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int discarded = global_value_id + 1 - *idx;
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*idx = global_value_id + 1;
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return discarded;
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}
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/*! Initialize the stat item module. Call this once from your program.
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* \param[in] tall_ctx Talloc context from which this module allocates */
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int osmo_stat_item_init(void *tall_ctx)
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{
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tall_stat_item_ctx = tall_ctx;
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return 0;
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}
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/*! Search for item group based on group name and index
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* \param[in] name Name of stats_item_group we want to find
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* \param[in] idx Index of the group we want to find
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* \returns pointer to group, if found; NULL otherwise */
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struct osmo_stat_item_group *osmo_stat_item_get_group_by_name_idx(
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const char *name, const unsigned int idx)
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{
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struct osmo_stat_item_group *statg;
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llist_for_each_entry(statg, &osmo_stat_item_groups, list) {
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if (!statg->desc)
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continue;
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if (!strcmp(statg->desc->group_name_prefix, name) &&
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statg->idx == idx)
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return statg;
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}
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return NULL;
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}
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/*! Search for item based on group + item name
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* \param[in] statg group in which to search for the item
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* \param[in] name name of item to search within \a statg
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* \returns pointer to item, if found; NULL otherwise */
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const struct osmo_stat_item *osmo_stat_item_get_by_name(
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const struct osmo_stat_item_group *statg, const char *name)
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{
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int i;
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const struct osmo_stat_item_desc *item_desc;
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if (!statg->desc)
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return NULL;
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for (i = 0; i < statg->desc->num_items; i++) {
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item_desc = &statg->desc->item_desc[i];
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if (!strcmp(item_desc->name, name)) {
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return statg->items[i];
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}
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}
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return NULL;
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}
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/*! Iterate over all items in group, call user-supplied function on each
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* \param[in] statg stat_item group over whose items to iterate
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* \param[in] handle_item Call-back function, aborts if rc < 0
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* \param[in] data Private data handed through to \a handle_item
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*/
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int osmo_stat_item_for_each_item(struct osmo_stat_item_group *statg,
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osmo_stat_item_handler_t handle_item, void *data)
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{
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int rc = 0;
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int i;
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for (i = 0; i < statg->desc->num_items; i++) {
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struct osmo_stat_item *item = statg->items[i];
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rc = handle_item(statg, item, data);
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if (rc < 0)
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return rc;
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}
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return rc;
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}
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/*! Iterate over all stat_item groups in system, call user-supplied function on each
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* \param[in] handle_group Call-back function, aborts if rc < 0
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* \param[in] data Private data handed through to \a handle_group
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*/
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int osmo_stat_item_for_each_group(osmo_stat_item_group_handler_t handle_group, void *data)
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{
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struct osmo_stat_item_group *statg;
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int rc = 0;
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llist_for_each_entry(statg, &osmo_stat_item_groups, list) {
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rc = handle_group(statg, data);
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if (rc < 0)
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return rc;
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}
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return rc;
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}
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/*! @} */
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