Feature: Threadsafe RcParams

ultraplot/internals/rcsetup.py

@@ -4,6 +4,7 @@
 """
 import functools
 import re, matplotlib as mpl
+import threading
 from collections.abc import MutableMapping
 from numbers import Integral, Real
 
@@ -562,16 +563,42 @@ def _yaml_table(rcdict, comment=True, description=False):
 
 class _RcParams(MutableMapping, dict):
     """
-    A simple dictionary with locked inputs and validated assignments.
+    A thread-safe dictionary with validated assignments and thread-local storage used to store the configuration of UltraPlot.
+
+    It uses reentrant locks (RLock) to ensure that multiple threads can safely read and write to the configuration without causing data corruption.
+
+    Example
+    -------
+    >>> with rc_params:
+    ...     rc_params['key'] = 'value'  # Thread-local change
+    ...     # Changes are automatically cleaned up when exiting the context
     """
 
     # NOTE: By omitting __delitem__ in MutableMapping we effectively
     # disable mutability. Also disables deleting items with pop().
     def __init__(self, source, validate):
         self._validate = validate
+        self._lock = threading.RLock()
+        self._local = threading.local()
+        self._local.changes = {}  # Initialize thread-local storage
+        # Register all initial keys in the validation dictionary
+        for key in source:
+            if key not in validate:
+                validate[key] = lambda x: x  # Default validator
         for key, value in source.items():
             self.__setitem__(key, value)  # trigger validation
 
+    def __enter__(self):
+        """Context manager entry - initialize thread-local storage if needed."""
+        if not hasattr(self._local, "changes"):
+            self._local.changes = {}
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        """Context manager exit - clean up thread-local storage."""
+        if hasattr(self._local, "changes"):
+            del self._local.changes
+
     def __repr__(self):
         return RcParams.__repr__(self)
 
@@ -587,22 +614,33 @@ def __iter__(self):
         yield from sorted(dict.__iter__(self))
 
     def __getitem__(self, key):
-        key, _ = self._check_key(key)
-        return dict.__getitem__(self, key)
+        with self._lock:
+            key, _ = self._check_key(key)
+            # Check thread-local storage first
+            if key in self._local.changes:
+                return self._local.changes[key]
+            # Check global dictionary (will raise KeyError if not found)
+            return dict.__getitem__(self, key)
 
     def __setitem__(self, key, value):
-        key, value = self._check_key(key, value)
-        if key not in self._validate:
-            raise KeyError(f"Invalid rc key {key!r}.")
-        try:
-            value = self._validate[key](value)
-        except (ValueError, TypeError) as error:
-            raise ValueError(f"Key {key}: {error}") from None
-        if key is not None:
-            dict.__setitem__(self, key, value)
-
-    @staticmethod
-    def _check_key(key, value=None):
+        with self._lock:
+            key, value = self._check_key(key, value)
+            # Validate the value
+            try:
+                value = self._validate[key](value)
+            except KeyError:
+                # If key doesn't exist in validation, add it with default validator
+                self._validate[key] = lambda x: x
+                # Re-validate with new validator
+                value = self._validate[key](value)
+            except (ValueError, TypeError) as error:
+                raise ValueError(f"Key {key}: {error}") from None
+            if key is not None:
+                # Store in both thread-local storage and main dictionary
+                self._local.changes[key] = value
+                dict.__setitem__(self, key, value)
+
+    def _check_key(self, key, value=None):
         # NOTE: If we assigned from the Configurator then the deprecated key will
         # still propagate to the same 'children' as the new key.
         # NOTE: This also translates values for special cases of renamed keys.
@@ -624,10 +662,21 @@ def _check_key(key, value=None):
                 f"The rc setting {key!r} was removed in version {version}."
                 + (info and " " + info)
             )
+        # Register new keys in the validation dictionary
+        if key not in self._validate:
+            self._validate[key] = lambda x: x  # Default validator
         return key, value
 
     def copy(self):
-        source = {key: dict.__getitem__(self, key) for key in self}
+        with self._lock:
+            # Create a copy that includes both global and thread-local changes
+            source = {}
+            # Start with global values
+            for key in self:
+                if key not in self._local.changes:
+                    source[key] = dict.__getitem__(self, key)
+            # Add thread-local changes
+            source.update(self._local.changes)
         return _RcParams(source, self._validate)
 
 

ultraplot/tests/test_config.py

@@ -1,37 +1,35 @@
 import ultraplot as uplt, pytest
 import importlib
+import threading
+import time
 
 
 def test_wrong_keyword_reset():
     """
     The context should reset after a failed attempt.
     """
-    # Init context
-    uplt.rc.context()
-    config = uplt.rc
-    # Set a wrong key
-    with pytest.raises(KeyError):
-        config._get_item_dicts("non_existing_key", "non_existing_value")
-    # Set a known good value
-    config._get_item_dicts("coastcolor", "black")
-    # Confirm we can still plot
-    fig, ax = uplt.subplots(proj="cyl")
-    ax.format(coastcolor="black")
-    fig.canvas.draw()
+    # Use context manager for temporary rc changes
+    # Use context manager with direct value setting
+    with uplt.rc.context(coastcolor="black"):
+        # Set a wrong key
+        with pytest.raises(KeyError):
+            uplt.rc._get_item_dicts("non_existing_key", "non_existing_value")
+        # Confirm we can still plot
+        fig, ax = uplt.subplots(proj="cyl")
+        ax.format(coastcolor="black")
+        fig.canvas.draw()
 
 
 def test_cycle_in_rc_file(tmp_path):
     """
     Test that loading an rc file correctly overwrites the cycle setting.
     """
+    rc = uplt.config.Configurator()
     rc_content = "cycle: colorblind"
     rc_file = tmp_path / "test.rc"
     rc_file.write_text(rc_content)
-
-    # Load the file directly. This should overwrite any existing settings.
-    uplt.rc.load(str(rc_file))
-
-    assert uplt.rc["cycle"] == "colorblind"
+    rc.load(str(rc_file))
+    assert rc["cycle"] == "colorblind"
 
 
 import io
@@ -96,6 +94,95 @@ def test_dev_version_skipped(mock_urlopen, mock_version, mock_print):
     mock_print.assert_not_called()
 
 
+def test_rcparams_thread_safety():
+    """
+    Test that _RcParams is thread-safe when accessed concurrently.
+    Each thread works with its own unique key to verify proper isolation.
+    Thread-local changes are properly managed with context manager.
+    """
+    # Create a new _RcParams instance for testing
+    from ultraplot.internals.rcsetup import _RcParams
+
+    # Initialize with base keys
+    base_keys = {f"base_key_{i}": f"base_value_{i}" for i in range(3)}
+    rc_params = _RcParams(base_keys, {k: lambda x: x for k in base_keys})
+
+    # Number of threads and operations per thread
+    num_threads = 5
+    operations_per_thread = 20
+
+    # Each thread will work with its own unique key
+    thread_keys = {}
+
+    def worker(thread_id):
+        """Thread function that works with its own unique key using context manager."""
+        # Each thread gets its own unique key
+        thread_key = f"thread_{thread_id}_key"
+        thread_keys[thread_id] = thread_key
+
+        # Use context manager to ensure proper thread-local cleanup
+        with rc_params:
+            # Initialize the key with a base value
+            rc_params[thread_key] = f"initial_{thread_id}"
+
+            # Perform operations
+            for i in range(operations_per_thread):
+                try:
+                    # Read the current value
+                    current = rc_params[thread_key]
+
+                    # Update with new value
+                    new_value = f"thread_{thread_id}_value_{i}"
+                    rc_params[thread_key] = new_value
+
+                    # Verify the update worked
+                    assert rc_params[thread_key] == new_value
+
+                    # Also read some base keys to test mixed access
+                    if i % 5 == 0:
+                        base_key = f"base_key_{i % 3}"
+                        base_value = rc_params[base_key]
+                        assert isinstance(base_value, str)
+
+                except Exception as e:
+                    raise AssertionError(f"Thread {thread_id} failed: {str(e)}")
+
+    # Create and start threads
+    threads = []
+    for i in range(num_threads):
+        t = threading.Thread(target=worker, args=(i,))
+        threads.append(t)
+        t.start()
+
+    # Wait for all threads to complete
+    for t in threads:
+        t.join()
+
+    # Verify each thread's key exists and has the expected final value
+    for thread_id in range(num_threads):
+        thread_key = thread_keys[thread_id]
+        assert thread_key in rc_params, f"Thread {thread_id}'s key was lost"
+        final_value = rc_params[thread_key]
+        assert final_value == f"thread_{thread_id}_value_{operations_per_thread - 1}"
+
+    # Verify base keys are still intact
+    for key, expected_value in base_keys.items():
+        assert key in rc_params, f"Base key {key} was lost"
+        assert rc_params[key] == expected_value, f"Base key {key} value was corrupted"
+
+    # Verify that thread-local changes are properly merged
+    # Create a copy to verify the copy includes thread-local changes
+    rc_copy = rc_params.copy()
+    assert len(rc_copy) == len(base_keys) + num_threads, "Copy doesn't include all keys"
+
+    # Verify all keys are in the copy
+    for key in base_keys:
+        assert key in rc_copy, f"Base key {key} missing from copy"
+    for thread_id in range(num_threads):
+        thread_key = thread_keys[thread_id]
+        assert thread_key in rc_copy, f"Thread {thread_id}'s key missing from copy"
+
+
 @pytest.mark.parametrize(
     "cycle, raises_error",
     [
@@ -117,6 +204,78 @@ def test_cycle_rc_setting(cycle, raises_error):
     """
     if raises_error:
         with pytest.raises(ValueError):
-            uplt.rc["cycle"] = cycle
+            with uplt.rc.context(cycle=cycle):
+                pass
     else:
-        uplt.rc["cycle"] = cycle
+        with uplt.rc.context(cycle=cycle):
+            pass
+
+
+def test_rc_check_key():
+    """
+    Test the _check_key method in _RcParams
+    """
+    from ultraplot.internals.rcsetup import _RcParams
+
+    # Create a test instance
+    rc_params = _RcParams({"test_key": "test_value"}, {"test_key": lambda x: x})
+
+    # Test valid key
+    key, value = rc_params._check_key("test_key", "new_value")
+    assert key == "test_key"
+    assert value == "new_value"
+
+    # Test new key (should be registered with default validator)
+    key, value = rc_params._check_key("new_key", "new_value")
+    assert key == "new_key"
+    assert value == "new_value"
+    assert "new_key" in rc_params._validate
+
+
+def test_rc_repr():
+    """
+    Test the __repr__ method in _RcParams
+    """
+    from ultraplot.internals.rcsetup import _RcParams
+
+    # Create a test instance
+    rc_params = _RcParams({"test_key": "test_value"}, {"test_key": lambda x: x})
+
+    # Test __repr__
+    repr_str = repr(rc_params)
+    assert "RcParams" in repr_str
+    assert "test_key" in repr_str
+
+
+def test_rc_validators():
+    """
+    Test validators in _RcParams
+    """
+    from ultraplot.internals.rcsetup import _RcParams
+
+    # Create a test instance with various validators
+    validators = {
+        "int_val": lambda x: int(x),
+        "float_val": lambda x: float(x),
+        "str_val": lambda x: str(x),
+    }
+    rc_params = _RcParams(
+        {"int_val": 1, "float_val": 1.0, "str_val": "test"}, validators
+    )
+
+    # Test valid values
+    rc_params["int_val"] = 2
+    assert rc_params["int_val"] == 2
+
+    rc_params["float_val"] = 2.5
+    assert rc_params["float_val"] == 2.5
+
+    rc_params["str_val"] = "new_value"
+    assert rc_params["str_val"] == "new_value"
+
+    # Test invalid values
+    with pytest.raises(ValueError):
+        rc_params["int_val"] = "not_an_int"
+
+    with pytest.raises(ValueError):
+        rc_params["float_val"] = "not_a_float"