[Build] Remove old builds from composite p2-repo when adding new ones

Previously the I/Y-builds only added the just built p2-repository to
their corresponding composite repository and a separate job, running
twice a day, has trimmed down that repositorie's content afterwards to
retain only two children.
This made the setup's and job configurations more cumbersome and the
repository content less predictable.
Furthermore the the pruning only removed children that where located
directly within the composite's directory and not absolute references to
other repositories.

This simplifies this task by removing the oldest children while adding
the new, just built one, making sure the composite contains at most
three children.

Permanently fixes
- #3123

Author: HannesWell

JenkinsJobs/Cleanup/pruneDailyRepos.groovy

@@ -22,6 +22,7 @@ fi
 source $CJE_ROOT/scripts/common-functions.shsource
 source $1
 
+compositeTargetSize=3
 epUpdateDir=/home/data/httpd/download.eclipse.org/eclipse/updates
 dropsPath=${epUpdateDir}/${STREAMMajor}.${STREAMMinor}-${BUILD_TYPE}-builds
 latestRelDir=/home/data/httpd/download.eclipse.org/eclipse/downloads/drops4
@@ -48,7 +49,35 @@ epRelDir=$(ssh [email protected] ls -d --format=single-c
 ssh [email protected] tar -C ${workspace} -xzf ${epRelDir}/eclipse-platform-*-linux-gtk-x86_64.tar.gz
 
 #get requisite tools
-ssh [email protected] wget -O ${workspace}/addToComposite.xml https://download.eclipse.org/eclipse/relengScripts/cje-production/scripts/addToComposite.xml
+# Enhance the addToComposite ANT script to remove the oldest/earliest children to ensure the target-size is not exceeded
+scp [email protected]:${dropsPath}/compositeArtifacts.jar compositeArtifacts.jar
+#Unzip compositeArtifacts.xml and read the current children from it
+currentChildren=$(unzip -p compositeArtifacts.jar compositeArtifacts.xml |\
+	xmllint - --xpath '/repository/children/child/@location' |\
+	sed --expression 's|location="||g' --expression 's|"||g')
+rm compositeArtifacts.jar
+childrenArray=(${currentChildren})
+echo "Current children of composite repository: ${childrenArray[@]}"
+
+addToComposite_xml=$(curl https://download.eclipse.org/eclipse/relengScripts/cje-production/scripts/addToComposite.xml)
+extraTasksMarker='<!--EXTRA_TASKS-->'
+
+# One more child is about to be added to the composite.
+# Remove those children from the beginning of the list if the target-size would be exceeded.
+removalCount=$(( ${#childrenArray[@]} + 1 - compositeTargetSize ))
+if [ "${removalCount}" -gt 0 ]; then
+	childrenToRemove="${childrenArray[@]:0:${removalCount}}"
+	echo "Remove from composite repsitory: ${childrenToRemove}"
+	extraAntTask=''
+	for child in ${childrenToRemove}; do
+		extraAntTask+="<remove><repository location=\\\"${child}\\\"/></remove>\\n            "
+	done
+	addToComposite_xml=$(cat <<<"${addToComposite_xml}" | sed --expression "s|${extraTasksMarker}|${extraAntTask}|g")
+else
+	echo "Composite p2-repository contains only ${#childrenArray[@]} children and adding one will not exceed its target size of ${compositeTargetSize}: ${dropsPath}"
+fi
+
+ssh [email protected] "cat<<<'${addToComposite_xml}' > ${workspace}/addToComposite.xml"
 
 #triggering ant runner
 baseBuilderDir=${workspace}/eclipse

cje-production/cleaners/cleanupNightlyRepo.sh

@@ -1,5 +1,4 @@
 <?xml version="1.0" encoding="UTF-8"?>
-
 <project
     default="addToComposite"
     basedir=".">
@@ -16,7 +15,7 @@
             <add>
                 <repository location="${complocation}" />
             </add>
+            <!--EXTRA_TASKS-->
         </p2.composite.repository>
     </target>
 </project>
-