Define type for stored impressions and use it in algorithms

CC #63
patcg · Jan 30, 2025 · 6402c09 · 6402c09
1 parent 0f49386
commit 6402c09
Showing 1 changed file with 37 additions and 42 deletions.
diff --git a/api.bs b/api.bs
@@ -676,18 +676,17 @@ for=PrivateAttribution>measureConversion()</a> method to find matching
 
 ### Contents ### {#impression-store-contents}
 
-The [=impression store=] must store the following information:
+The [=impression store=] must store the following information per [=impression=]:
 
-<div link-for=PrivateAttribution>
+<div dfn-for=impression link-for=PrivateAttribution>
 <pre class=simpledef>
-Filter Data: The {{PrivateAttributionConversionOptions/filterData}} value passed to <a>saveImpression()</a>.
-Impression Site: The site that called <a>saveImpression()</a>.
-Intermediary Site: The site corresponding to the script that called <a>saveImpression()</a>.
-Conversion Sites: The conversion site(s) that were passed to <a>saveImpression()</a>.
-Timestamp: The time at which <a>saveImpression()</a> was called.
-Lifetime: The number of days an [=/impression=] remains eligible for attribution,
-Lifetime: either from the call to <a>saveImpression()</a>, or a [=/user agent=]-defined limit.
-Histogram Index: The histogram index passed to <a>saveImpression()</a>.
+<dfn>Filter Data</dfn>: The {{PrivateAttributionConversionOptions/filterData}} value passed to <a>saveImpression()</a>.
+<dfn>Impression Site</dfn>: The site that called <a>saveImpression()</a>.
+<dfn>Intermediary Site</dfn>: The site corresponding to the script that called <a>saveImpression()</a>.
+<dfn>Conversion Sites</dfn>: The conversion site(s) that were passed to <a>saveImpression()</a>.
+<dfn>Timestamp</dfn>: The time at which <a>saveImpression()</a> was called.
+<dfn>Lifetime</dfn>: The number of days an [=/impression=] remains eligible for attribution, either from the call to <a>saveImpression()</a>, or a [=/user agent=]-defined limit.
+<dfn>Histogram Index</dfn>: The histogram index passed to <a>saveImpression()</a>.
 </pre>
 </div>
 
@@ -775,9 +774,9 @@ the process will set a value of zero for all histogram buckets.
 To <dfn>fill a histogram using last-touch attribution</dfn>,
 given <a dictionary lt=PrivateAttributionConversionOptions>|options|</a>:
 
-1.  Initialize |impression| to a null value.
+1.  Let |impression| be null.
 
-1.  Initialize |value| to |options|.{{PrivateAttributionConversionOptions/value}}.
+1.  Let |value| be |options|.{{PrivateAttributionConversionOptions/value}}.
 
 1.  Let |now| be the current time.<!-- TODO: cite HRTIME spec -->
 
@@ -787,35 +786,30 @@ given <a dictionary lt=PrivateAttributionConversionOptions>|options|</a>:
     1.  Let |impressions| be the result of invoking [=common matching logic=]
         with |options|, |epoch|, and |now|.
 
-    1.  If |impressions| is not empty:
+    1.  If |impressions| [=set/is empty|is not empty=]:
 
-        1.  Retain the value of |epoch|.
+        1.  Retain the value of |epoch|.<!-- TODO: Clarify "Retain" -->
 
         1.  Set |impression| to the value in |impressions|
-            with the most recent |impression|.timestamp.
-            <!-- TODO define a type for stored impressions -->
+            with the most recent [=impression/timestamp=].
 
-        1.  Exit the loop.
+        1.  [=iteration/Break=].
 
-1.  If |impression| is null, let |budgetOk| be false.
+1.  Let |histogram| be a [=list=] of [=list/size=]
+    |options|.{{PrivateAttributionConversionOptions/histogramSize}}, whose
+    [=list/items=] are all 0.
 
-1.  Otherwise, let |budgetOk| be the result of [=deduct privacy budget=]
-    with |epoch| and |options|.{{PrivateAttributionConversionOptions/epsilon}}.
+1.  If |impression| is not null:
 
-1.  If |budgetOk| is false, set |value| to 0.
+    1.  Let |budgetOk| be the result of [=deduct privacy budget=]
+        with |epoch| and |options|.{{PrivateAttributionConversionOptions/epsilon}}.
 
-1.  If |impression|.<var ignore=''>histogramIndex</var>
-    is |options|.{{PrivateAttributionConversionOptions/histogramSize}} or greater,
-    set |value| to 0.
+    1.  Let |index| be |impression|'s [=impression/histogram index=].
 
-1.  If |value| is not 0, set |index|
-    to |impression|.{{PrivateAttributionImpressionOptions/histogramIndex}}.
+    1.  If |budgetOk| is true and |index| is less than |histogram|'s
+        [=list/size=], set |histogram|[|index|] to |value|.
 
-1.  Otherwise, set |index| to 0.
-
-1.  Return a histogram containing |options|.{{PrivateAttributionConversionOptions/histogramSize}} values,
-    with a value of |value| at an index of |index|
-    and a value of zero at all other indices.
+1.  Return |histogram|.
 
 
 ### Common Impression Matching Logic ### {#logic-matching}
@@ -827,25 +821,26 @@ Discuss "infinite" lookbackDays. Clarify when it apples. When field is missing?
 To perform <dfn>common matching logic</dfn>,
 given |options|, |epoch|, and [=moment=] |now|:
 
-1.  If number of days since the end of |epoch| exceeds |lookbackDays|,
-    return an empty set.
+1.  Let |matching| be an [=set/is empty|empty=] [=set=].
 
-1.  Initialize |matching| to an empty set.
+1.  If number of days since the end of |epoch| exceeds |lookbackDays|,
+    return |matching|.<!-- TODO: Define a day -->
 
-1.  For each |impression| in the saved impressions for the |epoch|:
+1.  [=set/iterate|For each=] |impression| in the [=impression store=] for the |epoch|:
+<!-- TODO: Clarify "for the |epoch|" -->
 
-    1.  If |now| - |lookbackDays| is after |impression|.timestamp,
-        continue the loop.
+    1.  If |now| - |lookbackDays| is after |impression|'s [=impression/timestamp=],
+        [=iteration/continue=].
 
     1.  If |options|.{{PrivateAttributionConversionOptions/filterData}}
-        does not match |impression|.filterData,
-        continue the loop.
+        does not match |impression|'s [=impression/filter data=],
+        [=iteration/continue=].<!-- TODO: Clarify "does not match" -->
 
     1.  If |options|.{{PrivateAttributionConversionOptions/impressionSites}}
-        does not contain |impression|.impressionSite,
-        continue the loop.
+        does not [=list/contain=] |impression|'s [=impression/impression site=],
+        [=iteration/continue=].
 
-    1.  Add |impression| to |matching|.
+    1.  [=set/Append=] |impression| to |matching|.
 
 1.  Return |matching|.