50 lines
1.9 KiB
C
50 lines
1.9 KiB
C
/*
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* Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
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*
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* This program is free software: you can use, redistribute, and/or modify
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* it under the terms of the GNU Affero General Public License, version 3
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* or later ("AGPL"), as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file taos_metric.h
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* @brief Functions for retrieving metric samples from metrics given an ordered set of labels
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*/
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#ifndef TAOS_METRIC_H
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#define TAOS_METRIC_H
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#include "taos_metric_sample.h"
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struct taos_metric;
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/**
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* @brief A prometheus metric.
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*
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* Reference: https://prometheus.io/docs/concepts/data_model
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*/
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typedef struct taos_metric taos_metric_t;
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/**
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* @brief Returns a taos_metric_sample_t*. The order of label_values is significant.
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*
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* You may use this function to cache metric samples to avoid sample lookup. Metric samples are stored in a hash map
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* with O(1) lookups in average case; nonethless, caching metric samples and updating them directly might be
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* preferrable in performance-sensitive situations.
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*
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* @param self The target taos_metric_t*
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* @param label_values The label values associated with the metric sample being updated. The number of labels must
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* match the value passed to label_key_count in the counter's constructor. If no label values are
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* necessary, pass NULL. Otherwise, It may be convenient to pass this value as a literal.
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* @return A taos_metric_sample_t*
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*/
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taos_metric_sample_t *taos_metric_sample_from_labels(taos_metric_t *self, const char **label_values);
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#endif // TAOS_METRIC_H
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