[QA] store messages in file instead of in the environment

Bash can run out of environment memory if environment variables store
too much data. When the memory is exceeded, bash can't run system
commands anymore and, from then on, cryptically fails every command with
"Argument list too long".

This closes #670.

tools/qa-check.sh

@@ -68,7 +68,14 @@ cd flink
 
 # Initialize variables
 export TESTS_PASSED=true
-export MESSAGES="Flink QA-Check results:"$'\n'
+# Store output of results in a file in the qa dir
+QA_OUTPUT="$VAR_DIR/qa_results.txt"
+rm "$QA_OUTPUT"
+
+append_output() {
+	echo "$1"
+	echo "$1" >> "$QA_OUTPUT"
+}
 
 goToTestDirectory() {
 	cd $flink_home
@@ -88,10 +95,10 @@ checkJavadocsErrors() {
 	OLD_JAVADOC_ERR_CNT=`cat $VAR_DIR/_JAVADOCS_NUM_WARNINGS` 
 	NEW_JAVADOC_ERR_CNT=`eval $JAVADOC_MVN_COMMAND`
 	if [ "$NEW_JAVADOC_ERR_CNT" -gt "$OLD_JAVADOC_ERR_CNT" ]; then
-		MESSAGES+=":-1: The change increases the number of javadoc errors from $OLD_JAVADOC_ERR_CNT to $NEW_JAVADOC_ERR_CNT"$'\n'
+		append_output ":-1: The change increases the number of javadoc errors from $OLD_JAVADOC_ERR_CNT to $NEW_JAVADOC_ERR_CNT"
 		TESTS_PASSED=false
 	else
-		MESSAGES+=":+1: The number of javadoc errors was $OLD_JAVADOC_ERR_CNT and is now $NEW_JAVADOC_ERR_CNT"$'\n'
+		append_output ":+1: The number of javadoc errors was $OLD_JAVADOC_ERR_CNT and is now $NEW_JAVADOC_ERR_CNT"
 	fi
 }
 
@@ -106,13 +113,13 @@ checkCompilerWarnings() {
 	OLD_COMPILER_ERR_CNT=`cat $VAR_DIR/_COMPILER_NUM_WARNINGS` 
 	NEW_COMPILER_ERR_CNT=`eval $COMPILER_WARN_MVN_COMMAND | tee $VAR_DIR/_COMPILER_NEW_WARNINGS | wc -l`
 	if [ "$NEW_COMPILER_ERR_CNT" -gt "$OLD_COMPILER_ERR_CNT" ]; then
-		MESSAGES+=":-1: The change increases the number of compiler warnings from $OLD_COMPILER_ERR_CNT to $NEW_COMPILER_ERR_CNT"$'\n'
-		MESSAGES+='```diff'$'\n'
-		MESSAGES+=`diff $VAR_DIR/_COMPILER_REFERENCE_WARNINGS $VAR_DIR/_COMPILER_NEW_WARNINGS`$'\n'
-		MESSAGES+='```'$'\n'
+		append_output ":-1: The change increases the number of compiler warnings from $OLD_COMPILER_ERR_CNT to $NEW_COMPILER_ERR_CNT"
+		append_output '```diff'
+		append_output `diff $VAR_DIR/_COMPILER_REFERENCE_WARNINGS $VAR_DIR/_COMPILER_NEW_WARNINGS`
+		append_output '```'
 		TESTS_PASSED=false
 	else
-		MESSAGES+=":+1: The number of compiler warnings was $OLD_COMPILER_ERR_CNT and is now $NEW_COMPILER_ERR_CNT"$'\n'
+		append_output ":+1: The number of compiler warnings was $OLD_COMPILER_ERR_CNT and is now $NEW_COMPILER_ERR_CNT"
 	fi
 }
 
@@ -129,10 +136,10 @@ checkLibFiles() {
 	eval $BUILD_MVN_COMMAND > /dev/null
 	NEW_LIB_FILES_CNT=`eval $COUNT_LIB_FILES`
 	if [ "$NEW_LIB_FILES_CNT" -gt "$OLD_LIB_FILES_CNT" ]; then
-		MESSAGES+=":-1: The change increases the number of dependencies in the lib/ folder from $OLD_LIB_FILES_CNT to $NEW_LIB_FILES_CNT"$'\n'
+		append_output ":-1: The change increases the number of dependencies in the lib/ folder from $OLD_LIB_FILES_CNT to $NEW_LIB_FILES_CNT"
 		TESTS_PASSED=false
 	else
-		MESSAGES+=":+1: The number of files in the lib/ folder was $OLD_LIB_FILES_CNT before the change and is now $NEW_LIB_FILES_CNT"$'\n'
+		append_output ":+1: The number of files in the lib/ folder was $OLD_LIB_FILES_CNT before the change and is now $NEW_LIB_FILES_CNT"
 	fi
 }
 
@@ -141,7 +148,7 @@ checkLibFiles() {
 checkAuthorTag() {
 	# we are grep-ing for "java" but we've messed up the string a bit so that it doesn't find exactly this line.
 	if [ `grep -r "@author" . | grep "ja""va" | wc -l` -gt "0" ]; then
-		MESSAGES+=":-1: The change contains @author tags"$'\n'
+		append_output ":-1: The change contains @author tags"
 		TESTS_PASSED=false
 	fi
 }
@@ -149,6 +156,8 @@ checkAuthorTag() {
 
 ################################### QA checks ###################################
 
+append_output "Computing Flink QA-Check results (please be patient)."
+
 ##### Methods to be executed on the current 'master'
 referenceJavadocsErrors
 referenceCompilerWarnings
@@ -163,13 +172,9 @@ checkLibFiles
 checkAuthorTag
 
 
-MESSAGES+=$'\n'"Test finished."$'\n'
+append_output "QA-Check finished."
 if [ "$TESTS_PASSED" == "true" ]; then
-	MESSAGES+="Overall result: :+1:. All tests passed"$'\n'
+	append_output "Overall result: :+1:. All tests passed"
 else 
-	MESSAGES+="Overall result: :-1:. Some tests failed. Please check messages above"$'\n'
+	append_output "Overall result: :-1:. Some tests failed. Please check messages above"
 fi
-
-echo "$MESSAGES"
-
-