Load view and document metadata in parallel (#444)

* Load view and document metadata in parallel

The object labels (/sparql), the ontology object labels (/ns) and the
property labels (/ns) are all built from the results alone, so the view,
ontology-view and document-load chains now fire them together through
ldh:fire-load-set-parallel instead of one after another.

Driven on the local LTLOD stack with Playwright, serving a baseline and a
patched site SEF through page.route: the three requests start together,
the rendered content is unchanged, and the calendar pages finish their
block loading ~100-125 ms (4-5%) sooner; the homepage shows no difference.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* A block load superseded by navigation reports nothing

A content block's load chain outlives its pane: going back or on while
the blocks are still loading replaces the pane, and the chain runs on
against a detached block. There it fails - key() has no containing
document (XTDE1270) - and ldh:promise-failure, handed the detached
content body, fell through to the alert() kept for dialogs closed while
their request was in flight.

ldh:block-load-failure passes the content body on only while it is still
in the page, checked when the failure arrives. Without a host
ldh:promise-failure only resets the cursor and the busy regions.

Loading the metadata in parallel made the race reliable: the results
table spec, which leaves for the root document and comes straight back,
failed on every attempt (UI-tests run 39172274618).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: namedgraph

src/main/webapp/static/com/atomgraph/linkeddatahub/xsl/client.xsl

@@ -771,7 +771,7 @@ WHERE
             <xsl:otherwise>
                 <xsl:for-each select="$factories">
                     <xsl:variable name="factory" select="."/>
-                    <ixsl:promise select="$factory(())" on-failure="ldh:promise-failure($content-body, 'failed-to-load-block-data', ?)"/>
+                    <ixsl:promise select="$factory(())" on-failure="ldh:block-load-failure($content-body, ?)"/>
                 </xsl:for-each>
             </xsl:otherwise>
         </xsl:choose>
@@ -841,15 +841,26 @@ WHERE
         </xsl:if>
     </xsl:function>
 
-    <!-- failure twin of ldh:block-hydrated: reports the error like ldh:promise-failure would, then counts the block down all the same so the deferred scroll is not stuck pending -->
+    <!-- reports a content block's failed load in its pane. A pane that has left the page was replaced by a later
+         navigation, which superseded the load: the chain ran on against a detached block and failed there, and that is
+         nothing to report - no host, so ldh:promise-failure only resets the cursor and the busy regions. Checked when the
+         failure arrives, not when the load starts -->
+    <xsl:function name="ldh:block-load-failure" ixsl:updating="yes">
+        <xsl:param name="host" as="element()?"/> <!-- the pane's content body -->
+        <xsl:param name="error" as="map(*)"/>
+
+        <xsl:sequence select="ldh:promise-failure($host[ancestor::body], 'failed-to-load-block-data', $error)"/>
+    </xsl:function>
+
+    <!-- failure twin of ldh:block-hydrated: reports the error like ldh:block-load-failure, then counts the block down all the same so the deferred scroll is not stuck pending -->
     <xsl:function name="ldh:block-hydration-failure" ixsl:updating="yes">
         <xsl:param name="host" as="element()?"/> <!-- the pane's content body -->
         <xsl:param name="scroll-id" as="xs:string"/>
         <xsl:param name="doc-uri" as="xs:anyURI"/>
         <xsl:param name="fragment" as="xs:string"/>
         <xsl:param name="error" as="map(*)"/>
 
-        <xsl:sequence select="ldh:promise-failure($host, 'failed-to-load-block-data', $error)"/>
+        <xsl:sequence select="ldh:block-load-failure($host, $error)"/>
         <xsl:sequence select="ldh:block-hydrated($scroll-id, $doc-uri, $fragment, ())"/>
     </xsl:function>
 
@@ -1045,18 +1056,12 @@ WHERE
             ixsl:then(ldh:rethread-response($context, ?)) =>
             ixsl:then(ldh:handle-response#1) =>
             ixsl:then(ldh:load-diff-version#1) =>
-            ixsl:then(ldh:load-object-metadata#1) =>
-            ixsl:then(ldh:http-request-threaded(?, 'metadata-request', 'metadata-response')) =>
-            ixsl:then(ldh:handle-response(?, 'metadata-response')) =>
-            ixsl:then(ldh:set-object-metadata#1) =>
-            ixsl:then(ldh:http-request-threaded(?, 'ns-metadata-request', 'ns-metadata-response')) =>
-            ixsl:then(ldh:handle-response(?, 'ns-metadata-response')) =>
-            ixsl:then(ldh:set-object-metadata-ns#1) =>
+            ixsl:then(ldh:fire-load-set-parallel(?, [
+              [ ldh:load-object-metadata#1,   'metadata-request',          'metadata-response',          ldh:set-object-metadata#1 ],
+              [ ldh:load-object-metadata#1,   'ns-metadata-request',       'ns-metadata-response',       ldh:set-object-metadata-ns#1 ],
+              [ ldh:load-property-metadata#1, 'property-metadata-request', 'property-metadata-response', ldh:set-property-metadata#1 ]
+            ])) =>
             ixsl:then(ldh:merge-object-metadata#1) =>
-            ixsl:then(ldh:load-property-metadata#1) =>
-            ixsl:then(ldh:http-request-threaded(?, 'property-metadata-request', 'property-metadata-response')) =>
-            ixsl:then(ldh:handle-response(?, 'property-metadata-response')) =>
-            ixsl:then(ldh:set-property-metadata#1) =>
             ixsl:then(ldh:rdf-document-response#1)"
             on-failure="ldh:promise-failure(id('tab-content', ixsl:page()), 'document-not-loaded', ?)"/>
     </xsl:template>

src/main/webapp/static/com/atomgraph/linkeddatahub/xsl/client/block.xsl

@@ -1013,18 +1013,12 @@ exclude-result-prefixes="#all"
                     ixsl:http-request($view-context('request')) =>
                         ixsl:then(ldh:rethread-response($view-context, ?)) =>
                         ixsl:then(ldh:handle-response#1) =>
-                        ixsl:then(ldh:load-object-metadata#1) =>
-                        ixsl:then(ldh:http-request-threaded(?, 'metadata-request', 'metadata-response')) =>
-                        ixsl:then(ldh:handle-response(?, 'metadata-response')) =>
-                        ixsl:then(ldh:set-object-metadata#1) =>
-                        ixsl:then(ldh:http-request-threaded(?, 'ns-metadata-request', 'ns-metadata-response')) =>
-                        ixsl:then(ldh:handle-response(?, 'ns-metadata-response')) =>
-                        ixsl:then(ldh:set-object-metadata-ns#1) =>
+                        ixsl:then(ldh:fire-load-set-parallel(?, [
+                          [ ldh:load-object-metadata#1,   'metadata-request',          'metadata-response',          ldh:set-object-metadata#1 ],
+                          [ ldh:load-object-metadata#1,   'ns-metadata-request',       'ns-metadata-response',       ldh:set-object-metadata-ns#1 ],
+                          [ ldh:load-property-metadata#1, 'property-metadata-request', 'property-metadata-response', ldh:set-property-metadata#1 ]
+                        ])) =>
                         ixsl:then(ldh:merge-object-metadata#1) =>
-                        ixsl:then(ldh:load-property-metadata#1) =>
-                        ixsl:then(ldh:http-request-threaded(?, 'property-metadata-request', 'property-metadata-response')) =>
-                        ixsl:then(ldh:handle-response(?, 'property-metadata-response')) =>
-                        ixsl:then(ldh:set-property-metadata#1) =>
                         ixsl:then(ldh:ontology-view-render-thunk#1)
             }) => ixsl:then(ldh:ontology-views-inserted($context, ?))
             "/>

src/main/webapp/static/com/atomgraph/linkeddatahub/xsl/client/block/view.xsl

@@ -168,18 +168,12 @@ exclude-result-prefixes="#all"
                 ixsl:then(ldh:rethread-response($context, ?, 'view-results-response')) =>
                 ixsl:then(ldh:handle-response(?, 'view-results-response')) =>
                 ixsl:then(ldh:view-results-error-handler#1) =>
-                ixsl:then(ldh:load-object-metadata(?, 'view-results-response')) =>
-                ixsl:then(ldh:http-request-threaded(?, 'metadata-request', 'metadata-response')) =>
-                ixsl:then(ldh:handle-response(?, 'metadata-response')) =>
-                ixsl:then(ldh:set-object-metadata#1) =>
-                ixsl:then(ldh:http-request-threaded(?, 'ns-metadata-request', 'ns-metadata-response')) =>
-                ixsl:then(ldh:handle-response(?, 'ns-metadata-response')) =>
-                ixsl:then(ldh:set-object-metadata-ns#1) =>
+                ixsl:then(ldh:fire-load-set-parallel(?, [
+                  [ ldh:load-object-metadata(?, 'view-results-response'),   'metadata-request',          'metadata-response',          ldh:set-object-metadata#1 ],
+                  [ ldh:load-object-metadata(?, 'view-results-response'),   'ns-metadata-request',       'ns-metadata-response',       ldh:set-object-metadata-ns#1 ],
+                  [ ldh:load-property-metadata(?, 'view-results-response'), 'property-metadata-request', 'property-metadata-response', ldh:set-property-metadata#1 ]
+                ])) =>
                 ixsl:then(ldh:merge-object-metadata#1) =>
-                ixsl:then(ldh:load-property-metadata(?, 'view-results-response')) =>
-                ixsl:then(ldh:http-request-threaded(?, 'property-metadata-request', 'property-metadata-response')) =>
-                ixsl:then(ldh:handle-response(?, 'property-metadata-response')) =>
-                ixsl:then(ldh:set-property-metadata#1) =>
                 ixsl:then(ldh:render-view#1)
         "/>
     </xsl:function>