C++ client: process the envp argument to main instead of calling gete…

…nv() (#5393)

* C++ client: process the envp argument to main instead of calling getenv()

* Respond to review feedback

cpp-client/deephaven/tests/include/private/deephaven/tests/test_util.h

@@ -24,6 +24,35 @@
 #include "deephaven/dhcore/utility/utility.h"
 
 namespace deephaven::client::tests {
+/**
+ * Stores a static global map of environment variable key/value pairs.
+ * Initialized from the 'envp' variable passed in to main.
+ */
+class GlobalEnvironmentForTests {
+public:
+  /**
+   * Initialize the environment_ map from the envp array passed into main().
+   * @param envp The envp parameter that was passed by the OS into 'main'.
+   */
+  static void Init(char **envp);
+
+  /**
+   * Look up 'key' in the environment_ map. Returns the associated value if found;
+   * otherwise returns the value contained in 'defaultValue'.
+   *
+   * @param key The key
+   * @param default_value The value to return if the key is not found.
+   * @return The associated value if found, otherwise the value contained in 'defaultValue'.
+   */
+  static std::string_view GetEnv(std::string_view key, std::string_view default_value);
+
+  // This is a pointer, so we don't have to worry about global construction/destruction.
+  // At global teardown time we will just leak memory.
+  // Also, std::less<> gets us the transparent comparator, so we can do lookups
+  // directly with string_view.
+  static std::map<std::string, std::string, std::less<>> *environment_;
+};
+
 class ColumnNamesForTests {
 public:
   ColumnNamesForTests();

cpp-client/deephaven/tests/src/main.cc

@@ -1,5 +1,14 @@
 /*
  * Copyright (c) 2016-2024 Deephaven Data Labs and Patent Pending
  */
-#define CATCH_CONFIG_MAIN
+#define CATCH_CONFIG_RUNNER
 #include "deephaven/third_party/catch.hpp"
+#include "deephaven/tests/test_util.h"
+
+using deephaven::client::tests::GlobalEnvironmentForTests;
+
+int main(int argc, char *argv[], char **envp) {
+  // Process envp so we don't have to call getenv(), which Windows complains about.
+  GlobalEnvironmentForTests::Init(envp);
+  return Catch::Session().run(argc, argv);
+}

cpp-client/deephaven/tests/src/test_util.cc

@@ -15,6 +15,40 @@ using deephaven::client::utility::TableMaker;
 using deephaven::client::utility::ValueOrThrow;
 
 namespace deephaven::client::tests {
+std::map<std::string, std::string, std::less<>> *GlobalEnvironmentForTests::environment_ = nullptr;
+
+void GlobalEnvironmentForTests::Init(char **envp) {
+  if (environment_ != nullptr) {
+    throw std::runtime_error(DEEPHAVEN_LOCATION_STR("It's an error to call Init() twice"));
+  }
+  environment_ = new std::map<std::string, std::string, std::less<>>();
+
+  for (char **current = envp; *current != nullptr; ++current) {
+    std::string_view sv(*current);
+
+    // Find the equal sign and split the strings into keys and values.
+    auto pos = sv.find('=');
+    if (pos == std::string_view::npos) {
+      continue;
+    }
+    auto key = sv.substr(0, pos);
+    auto value = sv.substr(pos + 1);
+    environment_->try_emplace(std::string(key), value);
+  }
+}
+
+std::string_view GlobalEnvironmentForTests::GetEnv(std::string_view key,
+    std::string_view default_value) {
+  if (environment_ == nullptr) {
+    return default_value;
+  }
+  auto ip = environment_->find(key);
+  if (ip == environment_->end()) {
+    return default_value;
+  }
+  return ip->second;
+}
+
 ColumnNamesForTests::ColumnNamesForTests() : importDate_("ImportDate"), ticker_("Ticker"),
   open_("Open"), close_("Close"), volume_("Volume") {}
 ColumnNamesForTests::ColumnNamesForTests(ColumnNamesForTests &&other) noexcept = default;
@@ -116,11 +150,9 @@ TableMakerForTests TableMakerForTests::Create() {
 }
 
 Client TableMakerForTests::CreateClient(const ClientOptions &options) {
-  const char *hostptr = std::getenv("DH_HOST");
-  const char *portptr = std::getenv("DH_PORT");
-  std::string host = (hostptr == nullptr) ? "localhost" : hostptr;
-  std::string port = (portptr == nullptr) ? "10000" : portptr;
-  std::string connection_string(host + ":" + port);
+  auto host = GlobalEnvironmentForTests::GetEnv("DH_HOST", "localhost");
+  auto port = GlobalEnvironmentForTests::GetEnv("DH_PORT", "10000");
+  auto connection_string = fmt::format("{}:{}", host, port);
   fmt::print(std::cerr, "Connecting to {}\n", connection_string);
   auto client = Client::Connect(connection_string, options);
   return client;