java_stub_template to use argument file instead of classpath jar (#1410)

* java_stub_template to use argument file instead of classpath jar (shaves 1s-1.5s, works java>8)

Author: ittaiz

java_stub_template/file/file.txt

@@ -289,6 +289,14 @@ ARGS=(
   "${ARGS[@]}")
 
 
+function run_test_with_large_classpath() {
+  if [ "%test_runner_classpath_mode%" == "argsfile" ]; then
+    run_test_with_argument_file "$1"
+  else
+    create_and_run_classpath_jar "$2"
+  fi
+}
+
 function create_and_run_classpath_jar() {
   # Build class path as one single string separated by spaces
   MANIFEST_CLASSPATH=""
@@ -311,7 +319,7 @@ function create_and_run_classpath_jar() {
 
   (
     echo "Manifest-Version: 1.0"
-    
+
     CLASSPATH_LINE="Class-Path:$MANIFEST_CLASSPATH"
     # No line in the MANIFEST.MF file may be longer than 72 bytes.
     # A space prefix indicates the line is still the content of the last attribute.
@@ -338,6 +346,15 @@ function create_and_run_classpath_jar() {
   exit $exit_code
 }
 
+function run_test_with_argument_file() {
+  ARGS_FILE="$(mktemp -t XXXXXXXX.args)"
+  echo "-cp "$CLASSPATH >> $ARGS_FILE
+  $JAVABIN @$ARGS_FILE "${ARGS[@]}"
+  exit_code=$?
+  rm -f "$ARGS_FILE"
+  exit $exit_code
+}
+
 # If the user didn't specify a --classpath_limit, use the default value.
 if [ -z "$CLASSPATH_LIMIT" ]; then
   # Windows per-arg limit MAX_ARG_STRLEN == 8k
@@ -357,9 +374,9 @@ fi
 #Difference ends
 
 if is_windows && (("${#CLASSPATH}" > ${CLASSPATH_LIMIT} )); then
-  create_and_run_classpath_jar "${JARBIN}.exe"
+  run_test_with_large_classpath "${JARBIN}.exe"
 elif (("${#CLASSPATH}" > ${CLASSPATH_LIMIT})); then
-  create_and_run_classpath_jar "$JARBIN"
+  run_test_with_large_classpath "$JARBIN"
 else
   exec $JAVABIN -classpath $CLASSPATH "${ARGS[@]}"
 fi

scala/BUILD

@@ -11,6 +11,7 @@ toolchain_type(
 scala_toolchain(
     name = "default_toolchain_impl",
     scalacopts = [],
+    use_argument_file_in_runner = True,
     visibility = ["//visibility:public"],
 )
 

scala/private/phases/phase_write_executable.bzl

@@ -108,8 +108,12 @@ def _write_executable_non_windows(ctx, executable, rjars, main_class, jvm_flags,
         wrapper.short_path,
     )
 
+    scala_toolchain = ctx.toolchains["//scala:toolchain_type"]
+
+    test_runner_classpath_mode = "argsfile" if scala_toolchain.use_argument_file_in_runner else "manifest"
+
     if use_jacoco and ctx.configuration.coverage_enabled:
-        jacocorunner = ctx.toolchains["@io_bazel_rules_scala//scala:toolchain_type"].jacocorunner
+        jacocorunner = scala_toolchain.jacocorunner
         classpath = ctx.configuration.host_path_separator.join(
             ["${RUNPATH}%s" % (j.short_path) for j in rjars.to_list() + jacocorunner.files.to_list()],
         )
@@ -137,6 +141,7 @@ def _write_executable_non_windows(ctx, executable, rjars, main_class, jvm_flags,
                 "%set_jacoco_main_class%": """export JACOCO_MAIN_CLASS={}""".format(main_class),
                 "%set_jacoco_java_runfiles_root%": """export JACOCO_JAVA_RUNFILES_ROOT=$JAVA_RUNFILES/{}/""".format(ctx.workspace_name),
                 "%set_java_coverage_new_implementation%": """export JAVA_COVERAGE_NEW_IMPLEMENTATION=YES""",
+                "%test_runner_classpath_mode%": test_runner_classpath_mode,
             },
             is_executable = True,
         )
@@ -163,6 +168,7 @@ def _write_executable_non_windows(ctx, executable, rjars, main_class, jvm_flags,
                 "%set_jacoco_java_runfiles_root%": "",
                 "%workspace_prefix%": ctx.workspace_name + "/",
                 "%set_java_coverage_new_implementation%": """export JAVA_COVERAGE_NEW_IMPLEMENTATION=NO""",
+                "%test_runner_classpath_mode%": test_runner_classpath_mode,
             },
             is_executable = True,
         )

scala/scala_toolchain.bzl

@@ -84,6 +84,7 @@ def _scala_toolchain_impl(ctx):
         enable_diagnostics_report = enable_diagnostics_report,
         jacocorunner = ctx.attr.jacocorunner,
         enable_stats_file = enable_stats_file,
+        use_argument_file_in_runner = ctx.attr.use_argument_file_in_runner,
     )
     return [toolchain]
 
@@ -137,6 +138,10 @@ scala_toolchain = rule(
             default = True,
             doc = "Enable writing of statsfile",
         ),
+        "use_argument_file_in_runner": attr.bool(
+            default = False,
+            doc = "Changes java binaries scripts (including tests) to use argument files and not classpath jars to improve performance, requires java > 8",
+        ),
     },
     fragments = ["java"],
 )

test/shell/test_scala_binary.sh

@@ -18,5 +18,26 @@ test_scala_binary_expect_failure_on_missing_direct_deps_located_in_dependency_wh
   test_scala_library_expect_failure_on_missing_direct_deps ${dependency_target} ${test_target}
 }
 
+test_scala_binary_allows_opt_in_to_use_of_argument_file_in_runner_for_improved_performance() {
+
+  bazel run --extra_toolchains="//test/toolchains:use_argument_file_in_runner" //test/src/main/scala/scalarules/test/large_classpath:largeClasspath
+  grep "\"argsfile\" == \"argsfile\"" bazel-bin/test/src/main/scala/scalarules/test/large_classpath/largeClasspath
+  RESPONSE_CODE=$?
+  if [ $RESPONSE_CODE -ne 0 ]; then
+    echo -e "${RED} Binary script does not use the argument file. $NC"
+    exit -1
+  fi
+
+  bazel run //test/src/main/scala/scalarules/test/large_classpath:largeClasspath
+  grep "\"manifest\" == \"argsfile\"" bazel-bin/test/src/main/scala/scalarules/test/large_classpath/largeClasspath
+  RESPONSE_CODE=$?
+  if [ $RESPONSE_CODE -ne 0 ]; then
+    echo -e "${RED} Binary script does not use the classpath jar. $NC"
+    exit -1
+  fi
+
+}
+
 $runner test_scala_binary_expect_failure_on_missing_direct_deps
 $runner test_scala_binary_expect_failure_on_missing_direct_deps_located_in_dependency_which_is_scala_binary
+$runner test_scala_binary_allows_opt_in_to_use_of_argument_file_in_runner_for_improved_performance

test/toolchains/BUILD.bazel

@@ -117,3 +117,16 @@ toolchain(
     toolchain_type = "@io_bazel_rules_scala//scala:toolchain_type",
     visibility = ["//visibility:public"],
 )
+
+scala_toolchain(
+    name = "use_argument_file_in_runner_impl",
+    use_argument_file_in_runner = True,
+    visibility = ["//visibility:public"],
+)
+
+toolchain(
+    name = "use_argument_file_in_runner",
+    toolchain = "use_argument_file_in_runner_impl",
+    toolchain_type = "@io_bazel_rules_scala//scala:toolchain_type",
+    visibility = ["//visibility:public"],
+)