Rename rust folder to sgl-router (#2464)

Signed-off-by: Ata Fatahi <immrata@gmail.com>

sgl-router/py_src/sglang_router/router.py

@@ -0,0 +1,67 @@
+from typing import List, Optional
+
+from sglang_router_rs import PolicyType
+from sglang_router_rs import Router as _Router
+
+
+class Router:
+    """
+    A high-performance router for distributing requests across worker nodes.
+
+    Args:
+        worker_urls: List of URLs for worker nodes that will handle requests. Each URL should include
+            the protocol, host, and port (e.g., ['http://worker1:8000', 'http://worker2:8000'])
+        policy: Load balancing policy to use. Options:
+            - PolicyType.Random: Randomly select workers
+            - PolicyType.RoundRobin: Distribute requests in round-robin fashion
+            - PolicyType.CacheAware: Distribute requests based on cache state and load balance
+        host: Host address to bind the router server. Default: '127.0.0.1'
+        port: Port number to bind the router server. Default: 3001
+        cache_threshold: Cache threshold (0.0-1.0) for cache-aware routing. Routes to cached worker
+            if the match rate exceeds threshold, otherwise routes to the worker with the smallest
+            tree. Default: 0.5
+        balance_abs_threshold: Load balancing is triggered when (max_load - min_load) > abs_threshold
+            AND max_load > min_load * rel_threshold. Otherwise, use cache aware. Default: 32
+        balance_rel_threshold: Load balancing is triggered when (max_load - min_load) > abs_threshold
+            AND max_load > min_load * rel_threshold. Otherwise, use cache aware. Default: 1.0001
+        eviction_interval_secs: Interval in seconds between cache eviction operations in cache-aware
+            routing. Default: 60
+        max_payload_size: Maximum payload size in bytes. Default: 4MB
+        max_tree_size: Maximum size of the approximation tree for cache-aware routing. Default: 2^24
+        verbose: Enable verbose logging. Default: False
+    """
+
+    def __init__(
+        self,
+        worker_urls: List[str],
+        policy: PolicyType = PolicyType.RoundRobin,
+        host: str = "127.0.0.1",
+        port: int = 3001,
+        cache_threshold: float = 0.50,
+        balance_abs_threshold: int = 32,
+        balance_rel_threshold: float = 1.0001,
+        eviction_interval_secs: int = 60,
+        max_tree_size: int = 2**24,
+        max_payload_size: int = 4 * 1024 * 1024,  # 4MB
+        verbose: bool = False,
+    ):
+        self._router = _Router(
+            worker_urls=worker_urls,
+            policy=policy,
+            host=host,
+            port=port,
+            cache_threshold=cache_threshold,
+            balance_abs_threshold=balance_abs_threshold,
+            balance_rel_threshold=balance_rel_threshold,
+            eviction_interval_secs=eviction_interval_secs,
+            max_tree_size=max_tree_size,
+            max_payload_size=max_payload_size,
+            verbose=verbose,
+        )
+
+    def start(self) -> None:
+        """Start the router server.
+
+        This method blocks until the server is shut down.
+        """
+        self._router.start()