Fix: multichain does not use any init file besides the first

src/cmdstan/command.hpp

@@ -210,7 +210,7 @@ int command(int argc, const char *argv[]) {
   }
 
   std::vector<std::shared_ptr<stan::io::var_context>> init_contexts
-      = get_vec_var_context(init, num_chains);
+      = get_vec_var_context(init, num_chains, id);
   std::vector<std::string> model_compile_info = model.model_compile_info();
 
   for (int i = 0; i < num_chains; ++i) {
@@ -510,7 +510,7 @@ int command(int argc, const char *argv[]) {
           dynamic_cast<string_argument *>(algo->arg("hmc")->arg("metric_file"))
               ->value());
       context_vector metric_contexts
-          = get_vec_var_context(metric_filename, num_chains);
+          = get_vec_var_context(metric_filename, num_chains, id);
       categorical_argument *adapt
           = dynamic_cast<categorical_argument *>(sample_arg->arg("adapt"));
       categorical_argument *hmc

src/cmdstan/command_helper.hpp

@@ -192,6 +192,29 @@ inline shared_context_ptr get_var_context(const std::string &file) {
   return std::make_shared<stan::io::dump>(var_context);
 }
 
+std::vector<std::string> make_filenames(const std::string &filename,
+                                        const std::string &tag,
+                                        const std::string &type,
+                                        unsigned int num_chains,
+                                        unsigned int id) {
+  std::vector<std::string> names(num_chains);
+  auto base_sfx = get_basename_suffix(filename);
+  if (base_sfx.second.empty()) {
+    base_sfx.second = type;
+  }
+  auto name_iterator = [num_chains, id](auto i) {
+    if (num_chains == 1) {
+      return std::string("");
+    } else {
+      return std::string("_" + std::to_string(i + id));
+    }
+  };
+  for (int i = 0; i < num_chains; ++i) {
+    names[i] = base_sfx.first + tag + name_iterator(i) + base_sfx.second;
+  }
+  return names;
+}
+
 using context_vector = std::vector<shared_context_ptr>;
 /**
  * Make a vector of shared pointers to contexts.
@@ -201,7 +224,8 @@ using context_vector = std::vector<shared_context_ptr>;
  * @param num_chains The number of chains to run
  * @return a std vector of shared pointers to var contexts
  */
-context_vector get_vec_var_context(const std::string &file, size_t num_chains) {
+context_vector get_vec_var_context(const std::string &file, size_t num_chains,
+                                   unsigned int id) {
   using stan::io::var_context;
   if (num_chains == 1) {
     return context_vector(1, get_var_context(file));
@@ -249,8 +273,9 @@ context_vector get_vec_var_context(const std::string &file, size_t num_chains) {
              "\tConsider saving your data in JSON format instead."
           << std::endl;
     }
-    std::string file_1
-        = std::string(file_name + "_" + std::to_string(1) + file_ending);
+
+    auto filenames = make_filenames(file_name, "", file_ending, num_chains, id);
+    auto &file_1 = filenames[0];
     std::fstream stream_1(file_1.c_str(), std::fstream::in);
     // if file_1 exists we'll assume num_chains of these files exist
     if (stream_1.rdstate() & std::ifstream::failbit) {
@@ -274,9 +299,8 @@ context_vector get_vec_var_context(const std::string &file, size_t num_chains) {
       ret.reserve(num_chains);
       ret.push_back(make_context(file_1, stream_1, file_ending));
       for (size_t i = 1; i < num_chains; ++i) {
-        std::string file_i
-            = std::string(file_name + "_" + std::to_string(i) + file_ending);
-        std::fstream stream_i(file_1.c_str(), std::fstream::in);
+        auto &file_i = filenames[i];
+        std::fstream stream_i(file_i.c_str(), std::fstream::in);
         // If any stream fails here something went wrong with file names
         if (stream_i.rdstate() & std::ifstream::failbit) {
           std::string file_name_err = std::string(
@@ -737,29 +761,6 @@ void check_file_config(argument_parser &parser) {
   }
 }
 
-std::vector<std::string> make_filenames(const std::string &filename,
-                                        const std::string &tag,
-                                        const std::string &type,
-                                        unsigned int num_chains,
-                                        unsigned int id) {
-  std::vector<std::string> names(num_chains);
-  auto base_sfx = get_basename_suffix(filename);
-  if (base_sfx.second.empty()) {
-    base_sfx.second = type;
-  }
-  auto name_iterator = [num_chains, id](auto i) {
-    if (num_chains == 1) {
-      return std::string("");
-    } else {
-      return std::string("_" + std::to_string(i + id));
-    }
-  };
-  for (int i = 0; i < num_chains; ++i) {
-    names[i] = base_sfx.first + tag + name_iterator(i) + base_sfx.second;
-  }
-  return names;
-}
-
 void init_callbacks(
     argument_parser &parser,
     std::vector<stan::callbacks::unique_stream_writer<std::ofstream>>

src/test/interface/multi_chain_init_test.cpp

@@ -18,6 +18,7 @@ class CmdStan : public testing::Test {
     init_data = {"src", "test", "test-models", "bern_init.json"};
     init2_data = {"src", "test", "test-models", "bern_init2.json"};
     init3_data = {"src", "test", "test-models", "bern_init2.R"};
+    init_bad_data = {"src", "test", "test-models", "bern_init_bad.json"};
     dev_null_path = {"/dev", "null"};
   }
   std::vector<std::string> bern_model;
@@ -26,6 +27,7 @@ class CmdStan : public testing::Test {
   std::vector<std::string> init_data;
   std::vector<std::string> init2_data;
   std::vector<std::string> init3_data;
+  std::vector<std::string> init_bad_data;
 };
 
 TEST_F(CmdStan, multi_chain_single_init_file_good) {
@@ -52,6 +54,44 @@ TEST_F(CmdStan, multi_chain_multi_init_file_good) {
   ASSERT_FALSE(out.hasError);
 }
 
+TEST_F(CmdStan, multi_chain_multi_init_file_id_good) {
+  std::stringstream ss;
+  ss << convert_model_path(bern_model)
+     << " data file=" << convert_model_path(bern_data)
+     << " output file=" << convert_model_path(dev_null_path)
+     << " init=" << convert_model_path(init2_data) << " id=2"
+     << " method=sample num_chains=2";
+  std::string cmd = ss.str();
+  run_command_output out = run_command(cmd);
+  ASSERT_FALSE(out.hasError) << out.output;
+}
+
+TEST_F(CmdStan, multi_chain_multi_init_file_id_bad) {
+  // this will start by requesting ..._4.json, which doesn't exist
+  std::stringstream ss;
+  ss << convert_model_path(bern_model)
+     << " data file=" << convert_model_path(bern_data)
+     << " output file=" << convert_model_path(dev_null_path)
+     << " init=" << convert_model_path(init2_data) << " id=4"
+     << " method=sample num_chains=3";
+  std::string cmd = ss.str();
+  run_command_output out = run_command(cmd);
+  ASSERT_TRUE(out.hasError);
+}
+
+TEST_F(CmdStan, multi_chain_multi_init_file_actually_used) {
+  // the second chain has a bad init value
+  std::stringstream ss;
+  ss << convert_model_path(bern_model)
+     << " data file=" << convert_model_path(bern_data)
+     << " output file=" << convert_model_path(dev_null_path)
+     << " init=" << convert_model_path(init_bad_data)
+     << " method=sample num_chains=2";
+  std::string cmd = ss.str();
+  run_command_output out = run_command(cmd);
+  ASSERT_TRUE(out.hasError) << out.output;
+}
+
 TEST_F(CmdStan, multi_chain_multi_init_file_R) {
   std::stringstream ss;
   ss << convert_model_path(bern_model)

src/test/test-models/bern_init_bad_1.json

@@ -0,0 +1,3 @@
+{
+    "theta" : 0.1
+}

src/test/test-models/bern_init_bad_2.json

@@ -0,0 +1,3 @@
+{
+    "theta" : 3.0
+}