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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.
use crate::error_recording::{record_error, ErrorType};
use crate::metrics::Metric;
use crate::metrics::MetricType;
use crate::storage::StorageManager;
use crate::CommonMetricData;
use crate::Glean;
/// A counter metric.
///
/// Used to count things.
/// The value can only be incremented, not decremented.
#[derive(Clone, Debug)]
pub struct CounterMetric {
meta: CommonMetricData,
}
impl MetricType for CounterMetric {
fn meta(&self) -> &CommonMetricData {
&self.meta
}
fn meta_mut(&mut self) -> &mut CommonMetricData {
&mut self.meta
}
}
impl CounterMetric {
/// Create a new counter metric.
pub fn new(meta: CommonMetricData) -> Self {
Self { meta }
}
/// Increase the counter by `amount`.
///
/// ## Arguments
///
/// * `glean` - The Glean instance this metric belongs to.
/// * `amount` - The amount to increase by. Should be positive.
///
/// ## Notes
///
/// Logs an error if the `amount` is 0 or negative.
pub fn add(&self, glean: &Glean, amount: i32) {
if !self.should_record(glean) {
return;
}
if amount <= 0 {
record_error(
glean,
&self.meta,
ErrorType::InvalidValue,
format!("Added negative or zero value {}", amount),
None,
);
return;
}
glean
.storage()
.record_with(glean, &self.meta, |old_value| match old_value {
Some(Metric::Counter(old_value)) => {
Metric::Counter(old_value.saturating_add(amount))
}
_ => Metric::Counter(amount),
})
}
/// **Test-only API (exported for FFI purposes).**
///
/// Get the currently stored value as an integer.
///
/// This doesn't clear the stored value.
pub fn test_get_value(&self, glean: &Glean, storage_name: &str) -> Option<i32> {
match StorageManager.snapshot_metric(
glean.storage(),
storage_name,
&self.meta.identifier(glean),
) {
Some(Metric::Counter(i)) => Some(i),
_ => None,
}
}
}