Synchronize basilisp.main.init to allow repeat invocations

Author: chrisrink10

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  * Removed implicit support for single-use iterables in sequences, and introduced `iterator-seq` to expliciltly handle them (#1192)
  * `basilisp.core/str` now delegates to the builtin Python `str` in all cases except for customizing the string output for builtin Python types (#1237)
  * Optimised mainstream seq-consuming functions by coercing their inputs into `seq` upfront (#1234)
+ * `basilisp.main.init` will only initialize the runtime environment on the first invocation (#1242)
 
 ### Fixed
  * Fix a bug where protocols with methods with leading hyphens in the could not be defined (#1230)

src/basilisp/main.py

@@ -1,6 +1,7 @@
 import importlib
 import os
 import sysconfig
+import threading
 from pathlib import Path
 from typing import Optional
 
@@ -11,8 +12,11 @@
 from basilisp.lang.typing import CompilerOpts
 from basilisp.lang.util import munge
 
+_INIT_LOCK = threading.Lock()
+_runtime_is_initialized = False
 
-def init(opts: Optional[CompilerOpts] = None) -> None:
+
+def init(opts: Optional[CompilerOpts] = None, force_reload: bool = False) -> None:
     """
     Initialize the runtime environment for Basilisp code evaluation.
 
@@ -22,12 +26,22 @@ def init(opts: Optional[CompilerOpts] = None) -> None:
 
     If you want to execute a Basilisp file which is stored in a well-formed package
     or module structure, you probably want to use :py:func:`bootstrap`.
+
+    ``init()`` may be called more than once. Only the first invocation will initialize
+    the runtime unless ``force_reload=True``.
     """
-    logconfig.configure_root_logger()
-    runtime.init_ns_var()
-    runtime.bootstrap_core(opts if opts is not None else compiler_opts())
-    importer.hook_imports()
-    importlib.import_module("basilisp.core")
+    global _runtime_is_initialized
+
+    with _INIT_LOCK:
+        if _runtime_is_initialized and not force_reload:
+            return
+
+        logconfig.configure_root_logger()
+        runtime.init_ns_var()
+        runtime.bootstrap_core(opts if opts is not None else compiler_opts())
+        importer.hook_imports()
+        importlib.import_module("basilisp.core")
+        _runtime_is_initialized = True
 
 
 def bootstrap(

tests/basilisp/cli_test.py

@@ -81,20 +81,25 @@ class CapturedIO:
 
 
 @pytest.fixture
-def run_cli(monkeypatch, capsys, cap_lisp_io):
+def run_cli(monkeypatch):
     def _run_cli(args: Sequence[str], input: Optional[str] = None):
         if input is not None:
             monkeypatch.setattr(
                 "sys.stdin", io.TextIOWrapper(io.BytesIO(input.encode("utf-8")))
             )
-        invoke_cli([*args])
-        python_io = capsys.readouterr()
-        lisp_out, lisp_err = cap_lisp_io
+        process = subprocess.run(
+            ["basilisp", *args],
+            stdin=io.StringIO(input) if input is not None else None,
+            encoding="utf-8",
+            capture_output=True,
+            check=True,
+        )
+
         return CapturedIO(
-            out=python_io.out,
-            err=python_io.err,
-            lisp_out=lisp_out.getvalue(),
-            lisp_err=lisp_err.getvalue(),
+            out=process.stdout,
+            err=process.stderr,
+            lisp_out=process.stdout,
+            lisp_err=process.stderr,
         )
 
     return _run_cli
@@ -204,7 +209,7 @@ def test_valid_flag(self, run_cli, val):
 
     @pytest.mark.parametrize("val", ["maybe", "not-no", "4"])
     def test_invalid_flag(self, run_cli, val):
-        with pytest.raises(SystemExit):
+        with pytest.raises(subprocess.CalledProcessError):
             run_cli(["run", "--warn-on-var-indirection", val, "-c", "(+ 1 2)"])
 
 
@@ -355,7 +360,7 @@ def test_repl_include_extra_path(
 
 class TestRun:
     def test_run_ns_and_code_mutually_exclusive(self, run_cli):
-        with pytest.raises(SystemExit):
+        with pytest.raises(subprocess.CalledProcessError):
             run_cli(["run", "-c", "-n"])
 
     class TestRunCode:
@@ -550,7 +555,7 @@ def test_cannot_run_namespace_with_in_ns_arg(
             self, run_cli, namespace_name: str, namespace_file: pathlib.Path
         ):
             namespace_file.write_text("(println (+ 1 2))")
-            with pytest.raises(SystemExit):
+            with pytest.raises(subprocess.CalledProcessError):
                 run_cli(["run", "--in-ns", "otherpackage.core", "-n", namespace_name])
 
         def test_run_namespace(