#990 lb reader- remove theConfig dep and avoid ParallelTestHarness

- The spec API has changed slightly to increase encapsulation.

  The 'openSpec(filename)' call now replaces disparate calls
  to read/check the specification and avoid any internal assumptions
  about which file is read.

src/vt/vrt/collection/balance/baselb/baselb.cc

@@ -121,7 +121,7 @@ void BaseLB::importProcessorData(
 void BaseLB::getArgs(PhaseType phase) {
   using namespace balance;
 
-  bool has_spec = ReadLBSpec::hasSpec();
+  bool has_spec = ReadLBSpec::openSpec(theConfig()->vt_lb_file_name);
   if (has_spec) {
     auto spec = ReadLBSpec::entry(phase);
     if (spec) {

src/vt/vrt/collection/balance/lb_invoke/lb_manager.cc

@@ -106,8 +106,9 @@ LBType LBManager::decideLBToRun(PhaseType phase, bool try_file) {
     return LBType::NoLB;
   }
 
-  if (theConfig()->vt_lb_file_name != "" and try_file) {
-    bool const has_spec = ReadLBSpec::hasSpec();
+  auto& spec_file = theConfig()->vt_lb_file_name;
+  if (spec_file != "" and try_file) {
+    bool const has_spec = ReadLBSpec::openSpec(spec_file);
     if (has_spec) {
       the_lb = ReadLBSpec::getLB(phase);
     }

src/vt/vrt/collection/balance/read_lb.cc

@@ -57,41 +57,44 @@
 
 namespace vt { namespace vrt { namespace collection { namespace balance {
 
-/*static*/ std::string ReadLBSpec::filename = {};
+/*static*/ std::string ReadLBSpec::open_filename_ = {};
 /*static*/ typename ReadLBSpec::SpecMapType ReadLBSpec::spec_mod_ = {};
 /*static*/ typename ReadLBSpec::SpecMapType ReadLBSpec::spec_exact_ = {};
 /*static*/ std::vector<SpecIndex> ReadLBSpec::spec_prec_ = {};
 /*static*/ bool ReadLBSpec::read_complete_ = false;
 
-/*static*/ bool ReadLBSpec::hasSpec() {
-  if (read_complete_) {
+/*static*/ bool ReadLBSpec::openSpec(std::string const& filename) {
+  // Ignore attempt to open same spec.
+  if (not open_filename_.empty() and open_filename_ == filename) {
     return true;
   }
 
-  auto const file_name = theConfig()->vt_lb_file_name;
-  if (file_name == "") {
+  // No-op if no file specified. Can't be used to clear.
+  if (filename.empty()) {
     return false;
   }
 
-  bool good = openFile(file_name);
-  if (not good) {
-    auto str =
-      fmt::format("--vt_lb_file_name={} is not a valid file", file_name);
+  vtAssert(
+    open_filename_.empty(),
+    "Spec already opened. Use clear first to load again."
+  );
+
+  // Ensure file can be opened.
+  std::ifstream file(filename);
+  if (not file.good()) {
+    auto str = fmt::format("Unable to open spec file: {}", filename);
     vtAbort(str);
   }
-  return good;
-}
 
-/*static*/ bool ReadLBSpec::openFile(std::string const name) {
-  std::ifstream file(name);
-  filename = name;
-  return file.good();
+  // Remember loaded file - multiple calls to same file are idempotent.
+  open_filename_ = filename;
+
+  readFile(filename);
+
+  return true;
 }
 
 /*static*/ LBType ReadLBSpec::getLB(SpecIndex const& idx) {
-  if (not read_complete_) {
-    readFile();
-  }
   auto const lb = entry(idx);
   if (lb) {
     return lb->getLB();
@@ -133,11 +136,7 @@ int eatWhitespace(std::ifstream& file) {
   return file.eof() ? 0 : file.peek();
 }
 
-/*static*/ void ReadLBSpec::readFile() {
-  if (read_complete_) {
-    return;
-  }
-
+/*static*/ void ReadLBSpec::readFile(std::string const& filename) {
   std::ifstream file(filename);
   vtAssert(file.good(), "must be valid");
 
@@ -245,7 +244,7 @@ int eatWhitespace(std::ifstream& file) {
 
 /*static*/ void ReadLBSpec::clear() {
   read_complete_ = false;
-  filename = "";
+  open_filename_ = "";
   spec_mod_.clear();
   spec_exact_.clear();
   spec_prec_.clear();
@@ -332,8 +331,9 @@ auto excluded_str = [](SpecIndex idx) -> std::string {
 /*static*/ std::string ReadLBSpec::toString() {
   std::stringstream ss;
 
-  ReadLBSpec::openFile(theConfig()->vt_lb_file_name);
-  ReadLBSpec::readFile();
+  if (open_filename_.empty()) {
+    return "";
+  }
 
   if (not ReadLBSpec::getExactEntries().empty()) {
     ss << fmt::format("{}\tExact specification lines:\n", vt::debug::vtPre());

src/vt/vrt/collection/balance/read_lb.h

@@ -181,23 +181,29 @@ struct ReadLBSpec {
   using SpecMapType  = std::map<SpecIndex,SpecEntry>;
   using ParamMapType = std::map<std::string, std::string>;
 
-  static bool openFile(std::string const name = "");
-  static void readFile();
+  /**
+   * \brief Prepare the spec for reading, if it exists.
+   *
+   * This will also ensure the spec is loaded.
+   * This method MUST be called before the other methods.
+   */
+  static bool openSpec(std::string const& filename);
 
-  static bool hasSpec();
   static SpecIndex numEntries() { return spec_mod_.size() + spec_exact_.size(); }
   static SpecEntry* entry(SpecIndex const& idx);
   static LBType getLB(SpecIndex const& idx);
   static SpecMapType getModEntries() { return spec_mod_; };
   static SpecMapType getExactEntries() {return spec_exact_; };
   static ParamMapType parseParams(std::vector<std::string> params);
   static SpecEntry makeSpecFromParams(std::string params);
-  static void clear();
   static std::string toString();
+  static void clear();
 
 private:
+  static void readFile(std::string const& filename);
+
   static bool read_complete_;
-  static std::string filename;
+  static std::string open_filename_;
   static SpecMapType spec_mod_;
   static SpecMapType spec_exact_;
   static std::vector<SpecIndex> spec_prec_;

tests/unit/lb/test_lb_reader.nompi.cc

@@ -45,11 +45,11 @@
 #include <vt/transport.h>
 #include <vt/vrt/collection/balance/read_lb.h>
 
-#include "test_parallel_harness.h"
+#include "test_harness.h"
 
 namespace vt { namespace tests { namespace unit {
 
-using TestLBReader = TestParallelHarness;
+using TestLBReader = TestHarness;
 
 TEST_F(TestLBReader, test_lb_read_1) {
 
@@ -64,9 +64,9 @@ TEST_F(TestLBReader, test_lb_read_1) {
   using Spec       = vt::vrt::collection::balance::ReadLBSpec;
   using SpecIdx    = vt::vrt::collection::balance::SpecIndex;
   using SpecLBType = vt::vrt::collection::balance::LBType;
+
   Spec::clear();
-  EXPECT_EQ(Spec::openFile(file_name), true);
-  Spec::readFile();
+  Spec::openSpec(file_name);
 
   EXPECT_EQ(Spec::numEntries(), 3);
   EXPECT_EQ(Spec::getExactEntries().size(), 2);
@@ -121,8 +121,7 @@ TEST_F(TestLBReader, test_lb_read_2) {
   using SpecIdx    = vt::vrt::collection::balance::SpecIndex;
   using SpecLBType = vt::vrt::collection::balance::LBType;
   Spec::clear();
-  Spec::openFile(file_name);
-  Spec::readFile();
+  Spec::openSpec(file_name);
 
   EXPECT_EQ(Spec::numEntries(), 5);
   for (SpecIdx i = 0; i < 121; i++) {