HADOOP-15019. Honor HADOOP_USER_CLASSPATH_FIRST for deduped entries.

hadoop-common-project/hadoop-common/src/main/bin/hadoop-functions.sh

@@ -1177,6 +1177,10 @@ function hadoop_add_profile
 ## @return       1 = failure (doesn't exist or some other reason)
 function hadoop_add_classpath
 {
+  declare -a classpath_entries
+  declare idx
+  declare rebuilt_classpath=""
+
   # However, with classpath (& JLP), we can do dedupe
   # along with some sanity checking (e.g., missing directories)
   # since we have a better idea of what is legal
@@ -1209,7 +1213,26 @@ function hadoop_add_classpath
       hadoop_debug "Append CLASSPATH: $1"
     fi
   else
-    hadoop_debug "Dupe CLASSPATH: $1"
+    if [[ "$2" = "before" ]] && [[ "${CLASSPATH%%:*}" != "$1" ]]; then
+      IFS=':' read -r -a classpath_entries <<< "${CLASSPATH}"
+      for idx in "${classpath_entries[@]}"; do
+        if [[ "${idx}" != "$1" ]]; then
+          if [[ -z "${rebuilt_classpath}" ]]; then
+            rebuilt_classpath="${idx}"
+          else
+            rebuilt_classpath="${rebuilt_classpath}:${idx}"
+          fi
+        fi
+      done
+      if [[ -n "${rebuilt_classpath}" ]]; then
+        CLASSPATH="$1:${rebuilt_classpath}"
+      else
+        CLASSPATH="$1"
+      fi
+      hadoop_debug "Moved CLASSPATH to front: $1"
+    else
+      hadoop_debug "Dupe CLASSPATH: $1"
+    fi
   fi
   return 0
 }

hadoop-common-project/hadoop-common/src/test/scripts/hadoop_add_classpath.bats

@@ -80,6 +80,15 @@ load hadoop-functions_test_helper
   [ "${CLASSPATH}" = "/tmp:${TMP}/*" ]
 }
 
+@test "hadoop_add_classpath (duplicate before moves to front)" {
+  mkdir "${TMP}/first" "${TMP}/second"
+  hadoop_add_classpath "${TMP}/first"
+  hadoop_add_classpath "${TMP}/second"
+  hadoop_add_classpath "${TMP}/second" before
+  echo ">${CLASSPATH}<"
+  [ "${CLASSPATH}" = "${TMP}/second:${TMP}/first" ]
+}
+
 @test "hadoop_add_classpath (complex ordering)" {
   local j
   local style="after"
@@ -97,4 +106,4 @@ load hadoop-functions_test_helper
   done
   echo ">${CLASSPATH}<"
   [ "${CLASSPATH}" = "${TMP}/4:${TMP}/2:${TMP}/1:${TMP}/3:${TMP}/5" ]
-}
+}

hadoop-common-project/hadoop-common/src/test/scripts/hadoop_finalize_classpath.bats

@@ -61,4 +61,18 @@ load hadoop-functions_test_helper
   hadoop_add_to_classpath_userpath () { true; }
 
   hadoop_finalize_classpath
-}
+}
+
+@test "hadoop_finalize_classpath (user classpath duplicate stays first)" {
+  mkdir -p "${TMP}/new" "${TMP}/old"
+  CLASSPATH=""
+  HADOOP_CONF_DIR="${TMP}"
+  HADOOP_CLASSPATH="${TMP}:${TMP}/new:${TMP}/old"
+  HADOOP_USER_CLASSPATH_FIRST="true"
+
+  hadoop_translate_cygwin_path () { true; }
+
+  hadoop_finalize_classpath
+
+  [ "${CLASSPATH}" = "${TMP}:${TMP}/new:${TMP}/old" ]
+}