Spec: Timeout contributions from Shared Storage when context ID is set (

#102)

Prevents a Shared Storage operation from sending contributions after a
timeout, if a context ID was used. This will allow for reducing the
reporting delay for this case as it prevents the reporting time from
leaking any information about how long execution took (see issue #80 and
the corresponding explainer change #100).

spec.bs

@@ -251,8 +251,8 @@ available.
 For any [=batching scope=] returned by the [=scoping details/get batching scope
 steps=], the [=process contributions for a batching scope=] steps should later
 be performed given that same batching scope, the global scope's [=relevant
-settings object=]'s [=environment settings object/origin=] and some [=context
-type=].
+settings object=]'s [=environment settings object/origin=], some [=context
+type=] and a timeout (or null).
 
 Note: This last requirement means that global scopes with different origins
     cannot share the same batching scope, see [Same-origin
@@ -382,7 +382,7 @@ The user agent may expose controls that allow the user to delete data from the
 many contributions can be present in a single report.
 
 <dfn>Minimum report delay</dfn> is a non-negative [=duration=] that controls the
-minimum delay to deliver an [=aggregatable report=]
+minimum delay to deliver an [=aggregatable report=].
 
 <dfn>Randomized report delay</dfn> is a positive [=duration=] that controls the
 random delay to deliver an [=aggregatable report=]. This delay is additional to
@@ -459,8 +459,8 @@ scope=] |debugScope|:
         |debugDetails|.
 
 To <dfn algorithm export>process contributions for a batching scope</dfn> given
-a [=batching scope=] |batchingScope|, an [=origin=] |reportingOrigin| and a
-[=context type=] |contextType|:
+a [=batching scope=] |batchingScope|, an [=origin=] |reportingOrigin|, a
+[=context type=] |contextType| and a [=moment=] or null |timeout|:
 1. Let |batchEntries| be a new [=list=].
 1. [=list/iterate|For each=] |entry| of the [=contribution cache=]:
     1. If |entry|'s [=contribution cache entry/batching scope=] is
@@ -478,6 +478,9 @@ a [=batching scope=] |batchingScope|, an [=origin=] |reportingOrigin| and a
 1. If |contextIdMap|[|batchingScope|] [=map/exists=]:
     1. Set |contextId| to |contextIdMap|[|batchingScope|].
     1. [=map/Remove=] |contextIdMap|[|batchingScope|].
+1. Otherwise, [=assert=]: |timeout| is null.
+
+    Note: Timeouts can only be used for deterministic reports.
 1. If |batchEntries| [=list/is empty=] and |contextId| is null, return.
 
     Note: If a context ID was specified, a report is sent, even if there are no
@@ -506,8 +509,8 @@ a [=batching scope=] |batchingScope|, an [=origin=] |reportingOrigin| and a
 1. [=map/iterate|For each=] |debugDetails| → |contributions| of
     |batchedContributions|:
     1. Perform the [=report creation and scheduling steps=] with
-        |reportingOrigin|, |contextType|, |contributions|, |debugDetails| and
-        |contextId|.
+        |reportingOrigin|, |contextType|, |contributions|, |debugDetails|,
+        |contextId| and |timeout|.
 
 Note: These steps break up the contributions based on their [=debug details=] as
     each report can only have one set of metadata.
@@ -524,8 +527,9 @@ Scheduling reports {#scheduling-reports}
 
 To perform the <dfn algorithm>report creation and scheduling steps</dfn> with an
 [=origin=] |reportingOrigin|, a [=context type=] |api|, a [=list=] of
-{{PAHistogramContribution}}s |contributions|, a [=debug details=] |debugDetails|
-and a [=string=] or null |contextId|:
+{{PAHistogramContribution}}s |contributions|, a [=debug details=]
+|debugDetails|, a [=string=] or null |contextId| and a [=moment=] or null
+|timeout|:
 1. [=Assert=]: |reportingOrigin| is a [=potentially trustworthy origin=].
 1. Optionally, return.
 
@@ -564,7 +568,7 @@ and a [=string=] or null |contextId|:
             reports](#protecting-against-leaks-via-the-number-of-reports).
 1. Let |report| be the result of [=obtaining an aggregatable report=] given
     |reportingOrigin|, |api|, |truncatedContributions|, |debugDetails|,
-    |contextId| and |currentWallTime|.
+    |contextId|, |timeout| and |currentWallTime|.
 1. [=set/Append=] |report| to the user agent's [=aggregatable report cache=].
 
 To <dfn algorithm>consume budget if permitted</dfn> given a {{long}} |value|, an
@@ -580,11 +584,12 @@ this algorithm should return true.
 To <dfn>obtain an aggregatable report</dfn> given an [=origin=]
 |reportingOrigin|, a [=context type=] |api|, a [=list=] of
 {{PAHistogramContribution}}s |contributions|, a [=debug details=]
-|debugDetails|, a [=string=] or null |contextId| and a [=moment=] |currentTime|,
+|debugDetails|, a [=string=] or null |contextId|, a [=moment] or null |timeout|
+and a [=moment=] |currentTime|,
 perform the following steps. They return an [=aggregatable report=].
 1. [=Assert=]: |reportingOrigin| is a [=potentially trustworthy origin=].
 1. Let |reportTime| be the result of running [=obtain a report delivery time=]
-    given |currentTime|.
+    given |currentTime| and |timeout|.
 1. Let |report| be a new [=aggregatable report=] with the items:
     : [=aggregatable report/reporting origin=]
     :: |reportingOrigin|
@@ -607,12 +612,19 @@ perform the following steps. They return an [=aggregatable report=].
 1. Return |report|.
 
 To <dfn algorithm>obtain a report delivery time</dfn> given a [=moment=]
-|currentTime|, perform the following steps. They return a [=moment=].
-1. If [=automation local testing mode enabled=] is true, return |currentTime|.
+|currentTime| and a [=moment=] or null |timeout|, perform the following steps.
+They return a [=moment=].
+
+1. Let |reportTriggeredTime| be |currentTime|.
+1. If |timeout| is not null, set |reportTriggeredTime| to |timeout|.
+    Issue(80): Reduce the delay when a |timeout| is provided, i.e. when a
+        context ID is set.
+1. If [=automation local testing mode enabled=] is true, return
+    |reportTriggeredTime|.
 1. Let |r| be a random double between 0 (inclusive) and 1 (exclusive) with
     uniform probability.
-1. Return |currentTime| + [=minimum report delay=] + |r| * [=randomized report
-    delay=].
+1. Return |reportTriggeredTime| + [=minimum report delay=] + |r| * [=randomized
+    report delay=].
 
 Sending reports {#sending-reports}
 ----------------------------------
@@ -949,7 +961,7 @@ steps. They return a [=string=], null, or a {{DOMException}}:
 1. Return |contextId|.
 
 The {{WindowSharedStorage}}'s {{WindowSharedStorage/run()}} method steps are
-modified in three ways. First, add the following steps just after step 2 ("If
+modified in four ways. First, add the following steps just after step 2 ("If
 {{Worklet/addModule()}} has not yet been called, ..."), renumbering later steps
 as appropriate:
 <div algorithm="shared-storage-run-monkey-patch-1">
@@ -964,18 +976,44 @@ be |operationMap|[|name|]." (renumbering later steps as appropriate):
 <div algorithm="shared-storage-run-monkey-patch-2">
 2. Let |batchingScope| be a new [=batching scope=].
 1. Let <var ignore>debugScope</var> be a new [=debug scope=].
-1. If |contextId| is not null, [=set the context ID for a batching scope=] given
-        |contextId| and |batchingScope|.
+1. Let |privateAggregationTimeout| be null.
+1. If |contextId| is not null:
+    1. Set |privateAggregationTimeout| to the [=current wall time=] plus a
+        non-negative [=implementation-defined=] [=duration=].
+    1. [=Set the context ID for a batching scope=] given |contextId| and
+        |batchingScope|.
 
 </div>
-Finally, at the end of the same nested scope, add the following step:
+
+Third, add the following steps in the same nested scope just before the current
+last step ("Otherwise, [=call=] operation without any arguments list",
+renumbering the last step as appropriate):
 <div algorithm="shared-storage-run-monkey-patch-3">
-6. When the above [=call=] returns, perform the following steps:
+1. Let |hasRunPrivateAggregationCompletionTask| be false.
+1. Let |privateAggregationCompletionTask| be an algorithm to perform the
+    following steps:
+    1. If |hasRunPrivateAggregationCompletionTask|, return.
+    1. Set |hasRunPrivateAggregationCompletionTask| to true.
     1. [=Mark a debug scope complete=] given <var ignore>debugScope</var>.
     1. [=Process contributions for a batching scope=] given
-        <var ignore>batchingScope</var>, <var ignore>outsideSettings</var>'
-        [=environment settings object/origin=] and
-        "<code>shared-storage</code>".
+        |batchingScope|, <var ignore>outsideSettings</var>' [=environment
+        settings object/origin=], "<code>shared-storage</code>" and
+        |privateAggregationTimeout|.
+1. If |contextId| is not null:
+    1. Set |privateAggregationTimeout| to the [=current wall time=] plus a
+        non-negative [=implementation-defined=] [=duration=].
+    1. [=Set the context ID for a batching scope=] given |contextId| and
+        |batchingScope|.
+    1. Run the following steps [=in parallel=]:
+        1. Wait until |privateAggregationTimeout|.
+        1. Run |privateAggregationCompletionTask|.
+
+</div>
+
+Finally, at the end of the same nested scope, add the following step:
+<div algorithm="shared-storage-run-monkey-patch-4">
+9. When the above [=call=] returns, perform the following steps:
+    1. Run <var ignore>privateAggregationCompletionTask</var>.
 
 </div>
 
@@ -994,17 +1032,31 @@ Second, add the following steps in the nested scope just after "Let |operation|
 be |operationMap|[|name|]." (renumbering later steps as appropriate):
 <div algorithm="shared-storage-selecturl-monkey-patch-2">
 2. Let |batchingScope| be a new [=batching scope=].
-1. Let <var ignore>debugScope</var> be a new [=debug scope=].
-1. If |contextId| is not null, [=set the context ID for a batching scope=] given
-        |contextId| and |batchingScope|.
+1. Let |debugScope| be a new [=debug scope=].
+1. Let |privateAggregationTimeout| be null.
+1. Let |hasRunPrivateAggregationCompletionTask| be false.
+1. Let |privateAggregationCompletionTask| be an algorithm to perform the
+    following steps:
+    1. If |hasRunPrivateAggregationCompletionTask|, return.
+    1. Set |hasRunPrivateAggregationCompletionTask| to true.
+    1. [=Mark a debug scope complete=] given |debugScope|.
+    1. [=Process contributions for a batching scope=] given
+        |batchingScope|, <var ignore>outsideSettings</var>'
+        [=environment settings object/origin=], "<code>shared-storage</code>"
+        and |privateAggregationTimeout|.
+1. If |contextId| is not null:
+    1. Set |privateAggregationTimeout| to the [=current wall time=] plus a
+        non-negative [=implementation-defined=] [=duration=].
+    1. [=Set the context ID for a batching scope=] given |contextId| and
+        |batchingScope|.
+    1. Run the following steps [=in parallel=]:
+        1. Wait until |privateAggregationTimeout|.
+        1. Run |privateAggregationCompletionTask|.
 
 </div>
 Finally, at the end of the same nested scope, add the following steps:
 <div algorithm="shared-storage-selecturl-monkey-patch-3">
-9. [=Mark a debug scope complete=] given <var ignore>debugScope</var>.
-1. [=Process contributions for a batching scope=] given
-    <var ignore>batchingScope</var>, <var ignore>outsideSettings</var>'
-    [=environment settings object/origin=] and "<code>shared-storage</code>".
+13. Run <var ignore>privateAggregationCompletionTask</var>.
 
 </div>
 
@@ -1510,7 +1562,7 @@ an <a spec="turtledove">auction config</a> |auctionConfig| and a
 1. [=list/iterate|For each=] |origin| → |batchingScope| of
     |auctionConfig|'s [=auction config/batching scope map=]:
     1. [=Process contributions for a batching scope=] given |batchingScope|,
-        |origin| and "<code>protected-audience</code>".
+        |origin|, "<code>protected-audience</code>" and null.
 
 Issue: Verify interaction with component auctions.