oai-statsig-rust 0.27.0

Statsig Rust SDK for usage in multi-user server environments.
Documentation 
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use std::{collections::HashMap, sync::Arc};

use async_trait::async_trait;

use crate::{observability::ops_stats::OpsStatsEventObserver, statsig_metadata::StatsigMetadata};

use super::ops_stats::OpsStatsEvent;

static HIGH_CARDINALITY_TAGS: &[&str] = &["lcut", "prev_lcut"];
static SDK_EXCEPTION_COUNT_EXTRA_TAGS: &[&str] = &["request_path", "status_code"];

#[derive(Clone)]
pub enum MetricType {
    Increment,
    Gauge,
    Dist,
}

#[derive(Clone)]
pub struct ObservabilityEvent {
    pub metric_type: MetricType,
    pub metric_name: String,
    pub value: f64,
    pub tags: Option<HashMap<String, String>>,
}

impl ObservabilityEvent {
    pub fn new_event(
        metric_type: MetricType,
        metric_name: String,
        value: f64,
        tags: Option<HashMap<String, String>>,
    ) -> OpsStatsEvent {
        OpsStatsEvent::Observability(ObservabilityEvent {
            metric_type,
            metric_name,
            value,
            tags,
        })
    }
}

fn add_default_metric_tags(mut tags: HashMap<String, String>) -> HashMap<String, String> {
    let metadata = StatsigMetadata::get_metadata();
    tags.insert("sdk_type".to_string(), metadata.sdk_type);
    tags.insert("sdk_version".to_string(), metadata.sdk_version);
    tags
}

pub trait ObservabilityClient: Send + Sync + 'static + OpsStatsEventObserver {
    fn init(&self);
    fn increment(&self, metric_name: String, value: f64, tags: Option<HashMap<String, String>>);
    fn gauge(&self, metric_name: String, value: f64, tags: Option<HashMap<String, String>>);
    fn dist(&self, metric_name: String, value: f64, tags: Option<HashMap<String, String>>);
    fn error(&self, tag: String, error: String);
    fn should_enable_high_cardinality_for_this_tag(&self, tag: String) -> Option<bool>;
    // This is needed since upper casting is not officially supported yet
    // (WIP to support https://github.com/rust-lang/rust/issues/65991)
    // For implementation, just return Self; should be sufficient
    fn to_ops_stats_event_observer(self: Arc<Self>) -> Arc<dyn OpsStatsEventObserver>;
}

#[async_trait]
impl<T: ObservabilityClient> OpsStatsEventObserver for T {
    async fn handle_event(&self, event: OpsStatsEvent) {
        match event {
            OpsStatsEvent::Observability(data) => {
                let tags = data
                    .tags
                    .unwrap_or_default()
                    .into_iter()
                    .filter(|(key, _)| {
                        if HIGH_CARDINALITY_TAGS.contains(&key.as_str()) {
                            self.should_enable_high_cardinality_for_this_tag(key.to_string())
                                .unwrap_or_default()
                        } else {
                            true
                        }
                    })
                    .collect();
                let tags = Some(add_default_metric_tags(tags));
                let metric_name = format!("statsig.sdk.{}", data.metric_name.clone());
                match data.metric_type {
                    MetricType::Increment => self.increment(metric_name, data.value, tags),
                    MetricType::Gauge => self.gauge(metric_name, data.value, tags),
                    MetricType::Dist => self.dist(metric_name, data.value, tags),
                };
            }
            OpsStatsEvent::SDKError(error) => {
                self.error(error.tag.clone(), error.info.to_string());
                let mut tags = HashMap::from([
                    ("tag".to_string(), error.tag),
                    ("exception".to_string(), error.exception),
                ]);

                if let Some(extra) = error.extra {
                    for (key, value) in extra {
                        if SDK_EXCEPTION_COUNT_EXTRA_TAGS.contains(&key.as_str()) {
                            tags.insert(key, value);
                        }
                    }
                }

                self.increment(
                    "statsig.sdk.sdk_exceptions_count".to_string(),
                    1.0,
                    Some(add_default_metric_tags(tags)),
                );
            }
            _ => {}
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn add_default_metric_tags_attaches_sdk_metadata() {
        let metadata = StatsigMetadata::get_metadata();

        let tags = add_default_metric_tags(HashMap::new());

        assert_eq!(tags.get("sdk_type"), Some(&metadata.sdk_type));
        assert_eq!(tags.get("sdk_version"), Some(&metadata.sdk_version));
    }

    #[test]
    fn add_default_metric_tags_overwrites_call_site_sdk_metadata() {
        let metadata = StatsigMetadata::get_metadata();
        let tags = add_default_metric_tags(HashMap::from([
            ("sdk_type".to_string(), "wrong".to_string()),
            ("sdk_version".to_string(), "wrong".to_string()),
        ]));

        assert_eq!(tags.get("sdk_type"), Some(&metadata.sdk_type));
        assert_eq!(tags.get("sdk_version"), Some(&metadata.sdk_version));
    }
}