Dynamic noising calculations based on event reporting windows

Details:
Implemented the formula from
https://github.com/WICG/attribution-reporting-api/blob/main/EVENT.md#differential-privacy.

Bug: 282881409

Test: atest AdServicesServiceCoreUnitTests
Change-Id: Ie5e91ba9676479519fbeaf70a884b2f73413fcfc

1 files changed, 9 insertions, 1 deletions

diff --git a/adservices/service-core/java/com/android/adservices/service/measurement/reporting/EventReportWindowCalcDelegate.java b/adservices/service-core/java/com/android/adservices/service/measurement/reporting/EventReportWindowCalcDelegate.java
index f1ccb28c82..b14d447960 100644
--- a/adservices/service-core/java/com/android/adservices/service/measurement/reporting/EventReportWindowCalcDelegate.java
+++ b/adservices/service-core/java/com/android/adservices/service/measurement/reporting/EventReportWindowCalcDelegate.java
@@ -111,7 +111,8 @@ public class EventReportWindowCalcDelegate {
     }
 
     /**
-     * Returns event reporting windows count for noising cases.
+     * Returns effective, i.e. the ones that occur before {@link Source#getEventReportWindow()},
+     * event reporting windows count for noising cases.
      *
      * @param source source for which the count is requested
      * @param isInstallCase true of cooldown window was specified
@@ -137,6 +138,13 @@ public class EventReportWindowCalcDelegate {
         return destinationType == EventSurfaceType.APP && source.isInstallAttributed();
     }
 
+    /**
+     * If the flag is enabled and the specified report windows are valid, picks from flag controlled
+     * configurable early reporting windows. Otherwise, falls back to the statical {@link
+     * com.android.adservices.service.measurement.PrivacyParams} values. It curtails the windows
+     * that occur after {@link Source#getEventReportWindow()} because they would effectively be
+     * unusable.
+     */
     private List<Long> getEarlyReportingWindows(Source source, boolean installState) {
         List<Long> earlyWindows;
         List<Long> defaultEarlyWindows = getDefaultEarlyReportingWindows(source, installState);