melting-pot: add flag to prune unaffected deps

ctrueden · ctrueden · commit c46b1000691f · 2015-07-30T18:14:35.000-04:00
The default behavior of the melting pot is to create a multi-module
build of all project components which match the inclusion criteria
(i.e., the includes and excludes), minus any changed components
specified by the '--changes' flag.

However, when the set of changes is small, and the main interest is in
testing breakages relating to those changes, then it is nice to limit
the build to only those components which depend on the changed
components (either directly or transitively).

Hence, the new '--prune' flag does exactly that!

Be warned that even if a component does not explicitly depend on a
changed component, it might still be affected by changes in that
component. One example is components which use dependency injection at
runtime, using resources discovered on the classpath (e.g., plugins).
diff --git a/melting-pot.sh b/melting-pot.sh
@@ -126,6 +126,9 @@ parseArguments() {
 				outputDir="$2"
 				shift
 				;;
+			-p|--prune)
+				prune=1
+				;;
 			-v|--verbose)
 				verbose=1
 				;;
@@ -154,7 +157,7 @@ parseArguments() {
 	if [ "$usage" ]
 	then
 		echo "Usage: $(basename "$0") <project> [-c <GAVs>] \\
-       [-i <GAs>] [-e <GAs>] [-r <URLs>] [-l <dir>] [-o <dir>] [-vfsh]
+       [-i <GAs>] [-e <GAs>] [-r <URLs>] [-l <dir>] [-o <dir>] [-pvfsh]
 
 <project>
     The project to build, including dependencies, with consistent versions.
@@ -174,6 +177,10 @@ parseArguments() {
     Overrides the directory of the Maven local repository cache.
 -o, --outputDir
     Overrides the output directory. The default is \"melting-pot\".
+-p, --prune
+    Build only the components which themselves depend on a changed
+    artifact. This will make the build much faster, at the expense of
+    not fully testing runtime compatibility across all components.
 -v, --verbose
     Enable verbose/debugging output.
 -f, --force
@@ -337,6 +344,32 @@ isIncluded() {
 	done
 }
 
+# Deletes components which do not depend on a changed GAV.
+pruneReactor() {
+	local dir
+	for dir in */*
+	do
+		debug "Checking relevance of component $dir"
+		local deps="$(deps "$dir")"
+
+		# Determine whether the component depends on a changed GAV.
+		local keep
+		unset keep
+		local dep
+		for dep in $deps
+		do
+			test "$(isChanged "$dep")" && keep=1 && break
+		done
+
+		# If the component is irrelevant, prune it.
+		if [ -z "$keep" ]
+		then
+			debug "Pruning irrelevant component: $dir"
+			rm -rf "$dir"
+		fi
+	done
+}
+
 # Generates an aggregator POM for all modules in the current directory.
 generatePOM() {
 	echo '<?xml version="1.0" encoding="UTF-8"?>' > pom.xml
@@ -411,6 +444,9 @@ meltDown() {
 	done
 	unset TLS
 
+	# Prune the build, if applicable.
+	test "$prune" && pruneReactor
+
 	# Generate the aggregator POM.
 	debug "Generating aggregator POM"
 	generatePOM
diff --git a/tests/melting-pot-prune.t b/tests/melting-pot-prune.t
@@ -0,0 +1,25 @@
+Test that the '--prune' flag works as intended:
+
+  $ sh "$TESTDIR/../melting-pot.sh" net.imagej:imagej-common:0.15.1 -r http://maven.imagej.net/content/groups/public -c org.scijava:scijava-common:2.44.2 -i 'org.scijava:*,net.imagej:*,net.imglib2:*' -p -v -f -s
+  [DEBUG] net.imagej:imagej-common:0.15.1: fetching project source
+  [DEBUG] net.imagej:imagej-common:0.15.1: determining project dependencies
+  [DEBUG] net.imagej:imagej-common:0.15.1: processing project dependencies
+  [DEBUG] net.imagej:imagej-common:0.15.1: imglib2-roi: fetching component source
+  [DEBUG] net.imagej:imagej-common:0.15.1: imglib2: fetching component source
+  [DEBUG] net.imagej:imagej-common:0.15.1: processing changed components
+  [DEBUG] Checking relevance of component net.imagej/imagej-common
+  [DEBUG] Checking relevance of component net.imglib2/imglib2
+  [DEBUG] Pruning irrelevant component: net.imglib2/imglib2
+  [DEBUG] Checking relevance of component net.imglib2/imglib2-roi
+  [DEBUG] Pruning irrelevant component: net.imglib2/imglib2-roi
+  [DEBUG] Generating aggregator POM
+  [DEBUG] Skipping the build; the command would have been:
+  [DEBUG] mvn -Denforcer.skip -Dimglib2-roi.version=0.3.0 -Djunit.version=4.11 -Dhamcrest-core.version=1.3 -Dimglib2.version=2.2.1 -Dtrove4j.version=3.0.3 -Dgentyref.version=1.1.0 -Dudunits.version=4.3.18 -Deventbus.version=1.4 -Dscijava-common.version=2.44.2 test
+  [DEBUG] net.imagej:imagej-common:0.15.1: complete
+
+  $ find melting-pot -maxdepth 2
+  melting-pot
+  melting-pot/net.imagej
+  melting-pot/net.imagej/imagej-common
+  melting-pot/net.imglib2
+  melting-pot/pom.xml
