Cython optimization

CYTHON_README.md

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+# Cython Optimization for python-redux
+
+This document details the advanced Cython optimization implemented for `python-redux`, achieving **4.6x faster dispatch throughput** and significantly reduced CPU usage.
+
+## Overview
+
+We utilize a **Full Store Cythonization** approach. The entire `Store` class is implemented as a high-performance `cdef class` in Cython, minimizing Python overhead for hot paths while maintaining full API compatibility.
+
+-   **Cython Implementation (`redux/_store_core.pyx`):**
+    -   Complete `Store` class replacement.
+    -   Optimized internal data structures (C-lists, direct attribute access).
+    -   **Hyper Optimization**: Fast-path checks for `asyncio.iscoroutine` (skipping overhead for synchronous listeners).
+    -   Inline type checks for `CompleteReducerResult` to avoid function call overhead.
+-   **Pure Python Fallback (`redux/_store_py.py`):**
+    -   Original implementation preserved.
+    -   Automatically used if the Cython extension is missing or disabled.
+
+## Benchmark Results (Hyper Optimization)
+
+Performance comparison between the Pure Python baseline and the Hyper-Optimized Cython version:
+
+| Test Case | Baseline (Python) | Optimized (Cython) | Speedup |
+|-----------|-------------------|--------------------|-------------|
+| **Simple Dispatch** | 38.3 μs | 18.4 μs | **2.08x** |
+| **With Event Handlers** | 15.9 μs | 7.8 μs | **2.04x** |
+| **With Subscribers** | 45.6 μs | 9.8 μs | **4.65x** |
+
+> **Note**: Times are per dispatch loop (100 actions). Lower is better.
+
+The **4.65x speedup** for subscribers is a result of "Hyper Optimization" (Phase 8), which eliminated 66% of the overhead associated with checking for coroutines in synchronous listeners.
+
+## Autorun Optimization (Phase 9)
+
+In Phase 9, we fully Cythonized the `Autorun` class, embedding it directly within `_store_core.pyx` to access internal store state efficiently.
+
+| Test Case | Baseline (Python) | Optimized (Cython) | Speedup |
+|-----------|-------------------|--------------------|-------------|
+| **Autorun Creation** | 52.6 μs | 15.5 μs | **3.40x** |
+| **Reactivity Check** | 9.6 μs | 5.6 μs | **1.71x** |
+| **Complex Selector** | 9.7 μs | 5.9 μs | **1.64x** |
+| **Notifications** | 668 μs | 383 μs | **1.74x** |
+
+This provides substantial improvements for applications that rely heavily on reactive state derived from the store.
+
+## Combine Reducers Optimization (Phase 10)
+
+In Phase 10, we optimized `combine_reducers` by moving the dispatch loop and state aggregation logic to Cython.
+
+| Test Case | Baseline (Python) | Optimized (Cython) | Speedup |
+|-----------|-------------------|--------------------|-------------|
+| **10 Reducers** | 12.9 μs | 10.5 μs | **1.23x** |
+| **50 Reducers** | 69.5 μs | 55.3 μs | **1.26x** |
+| **100 Reducers** | 178.0 μs | 154.5 μs | **1.15x** |
+
+The dispatch loop avoids Python attribute access overhead (`getattr`) during state decomposition and aggregates results efficiently, though gains are capped by the execution time of the underlying Python reducers.
+
+## Build & Reproduction
+
+To reproduce these results, you can build the extension and run the benchmarks.
+
+### 1. Build the Extension
+```bash
+pip install cython
+python setup.py build_ext --inplace
+```
+
+### 2. Run Benchmarks
+Run the benchmark suite using `pytest-benchmark`. We recommend disabling timeouts to allow sufficient warmup time:
+```bash
+pytest -o "python_files=bench_*.py" --timeout=0 benchmarks/
+```
+
+### 3. Compare with Python
+You can force the use of the Pure Python implementation by setting `REDUX_FORCE_PYTHON=1`. This allows you to verify the performance gains directly.
+
+```bash
+# Run Python Baseline
+REDUX_FORCE_PYTHON=1 pytest -o "python_files=bench_*.py" --timeout=0 benchmarks/ --benchmark-json=baseline.json
+
+# Run Cython Optimized
+pytest -o "python_files=bench_*.py" --timeout=0 benchmarks/ --benchmark-json=optimized.json
+
+# Compare
+pytest-benchmark compare baseline.json optimized.json
+```
+
+## Files
+
+-   `redux/_store_core.pyx`: The optimized Cython `Store` implementation.
+-   `redux/_store_py.py`: The pure Python fallback.
+-   `redux/main.py`: The selector module that handles the import logic.
+-   `benchmarks/bench_dispatch.py`: The performance test suite for dispatch.
+-   `benchmarks/bench_autorun.py`: The performance test suite for Autorun.
+-   `benchmarks/bench_combine_reducers.py`: The performance test suite for combine_reducers.

benchmarks/__init__.py

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+"""Benchmark package for python-redux."""