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## Adding metrics for a new feature?
Please do **not** add your metrics in `autofill_metrics.*`! Instead, help
support code clarity and organization by adding a pair of files **per feature**.
### The old way
Originally, when making metrics for a new feature, everything was thrown into
the `autofill_metrics.*` files:
*autofill_metrics.h*:
```c++ {.bad}
class AutofillMetrics {
enum class CoolFeatureInteractionMetric {
// User accepted the cool feature.
kAccepted = 0,
// User explicitly denied the feature.
kCancelled = 1,
// User left the page without interacting with the feature.
kIgnored = 2,
kMaxValue = kIgnored,
};
// ...Roughly 1500 lines of other enums and functions...
static void LogCoolFeatureInteraction(CoolFeatureInteractionMetric metric);
}
```
*autofill_metrics.cc*:
```c++ {.bad}
// ...In the middle of 3000 lines of similar code...
// static
void AutofillMetrics::LogCoolFeatureInteraction(
CoolFeatureInteractionMetric metric) {
base::UmaHistogramEnumeration("Autofill.CoolFeatureInteraction", metric);
}
```
The calling code of this function would be
`AutofillMetrics::LogCoolFeatureInteraction(~)`.
The biggest downside to this approach was not just how large the two files
became, but also how far apart enums/metrics related to the same feature were
located, as well as how hard it was to find **all** metrics for a given feature.
### The new way
**Don't** use a class, but **do** use the `autofill::autofill_metrics` namespace. Then,
combine all metrics that are part of a single feature together, so they're not
intertwined with the rest of Autofill's metrics.
*cool_feature_metrics.h*:
(Put this header file under components/autofill/core/browser/metrics/[optional_sub_directory])
```c++ {.good}
// [Copyright notice and include guards]
namespace autofill::autofill_metrics {
enum class CoolFeatureInteractionMetric {
// User accepted the cool feature.
kAccepted = 0,
// User explicitly denied the feature.
kCancelled = 1,
// User left the page without interacting with the feature.
kIgnored = 2,
kMaxValue = kIgnored,
};
void LogCoolFeatureInteraction(CoolFeatureInteractionMetric metric);
} // namespace autofill::autofill_metrics
```
*cool_feature_metrics.cc*:
```c++ {.good}
// [Copyright notice]
#include "components/autofill/core/browser/metrics/[optional_sub_directory]/cool_feature_metrics.h"
namespace autofill::autofill_metrics {
void LogCoolFeatureInteraction(CoolFeatureInteractionMetric metric) {
base::UmaHistogramEnumeration("Autofill.CoolFeatureInteraction", metric);
}
// If there are other metrics related to this feature, they'd go here, and it
// would be very obvious they're related!
} // namespace autofill::autofill_metrics
```
The calling code of this function would be
`autofill::autofill_metrics::LogCoolFeatureInteraction(~)`.
|
