[DRAFT] circuit breaker changes using pybreaker

pyproject.toml

@@ -26,6 +26,7 @@ pyarrow = [
     { version = ">=18.0.0", python = ">=3.13", optional=true }
 ]
 pyjwt = "^2.0.0"
+pybreaker = "^1.0.0"
 requests-kerberos = {version = "^0.15.0", optional = true}
 
 

src/databricks/sql/auth/common.py

@@ -50,6 +50,7 @@ def __init__(
         pool_connections: Optional[int] = None,
         pool_maxsize: Optional[int] = None,
         user_agent: Optional[str] = None,
+        telemetry_circuit_breaker_enabled: Optional[bool] = None,
     ):
         self.hostname = hostname
         self.access_token = access_token
@@ -81,6 +82,11 @@ def __init__(
         self.pool_connections = pool_connections or 10
         self.pool_maxsize = pool_maxsize or 20
         self.user_agent = user_agent
+        self.telemetry_circuit_breaker_enabled = (
+            telemetry_circuit_breaker_enabled
+            if telemetry_circuit_breaker_enabled is not None
+            else False
+        )
 
 
 def get_effective_azure_login_app_id(hostname) -> str:

src/databricks/sql/telemetry/circuit_breaker_manager.py

@@ -0,0 +1,138 @@
+"""
+Circuit breaker implementation for telemetry requests.
+
+This module provides circuit breaker functionality to prevent telemetry failures
+from impacting the main SQL operations. It uses pybreaker library to implement
+the circuit breaker pattern with configurable thresholds and timeouts.
+"""
+
+import logging
+import threading
+from typing import Dict, Optional, Any
+from dataclasses import dataclass
+
+import pybreaker
+from pybreaker import CircuitBreaker, CircuitBreakerError, CircuitBreakerListener
+
+logger = logging.getLogger(__name__)
+
+# Circuit Breaker Configuration Constants
+MINIMUM_CALLS = 20
+RESET_TIMEOUT = 30
+CIRCUIT_BREAKER_NAME = "telemetry-circuit-breaker"
+
+# Circuit Breaker State Constants
+CIRCUIT_BREAKER_STATE_OPEN = "open"
+CIRCUIT_BREAKER_STATE_CLOSED = "closed"
+CIRCUIT_BREAKER_STATE_HALF_OPEN = "half-open"
+CIRCUIT_BREAKER_STATE_DISABLED = "disabled"
+
+# Logging Message Constants
+LOG_CIRCUIT_BREAKER_STATE_CHANGED = "Circuit breaker state changed from %s to %s for %s"
+LOG_CIRCUIT_BREAKER_OPENED = (
+    "Circuit breaker opened for %s - telemetry requests will be blocked"
+)
+LOG_CIRCUIT_BREAKER_CLOSED = (
+    "Circuit breaker closed for %s - telemetry requests will be allowed"
+)
+LOG_CIRCUIT_BREAKER_HALF_OPEN = (
+    "Circuit breaker half-open for %s - testing telemetry requests"
+)
+
+
+class CircuitBreakerStateListener(CircuitBreakerListener):
+    """Listener for circuit breaker state changes."""
+
+    def before_call(self, cb: CircuitBreaker, func, *args, **kwargs) -> None:
+        """Called before the circuit breaker calls a function."""
+        pass
+
+    def failure(self, cb: CircuitBreaker, exc: BaseException) -> None:
+        """Called when a function called by the circuit breaker fails."""
+        pass
+
+    def success(self, cb: CircuitBreaker) -> None:
+        """Called when a function called by the circuit breaker succeeds."""
+        pass
+
+    def state_change(self, cb: CircuitBreaker, old_state, new_state) -> None:
+        """Called when the circuit breaker state changes."""
+        old_state_name = old_state.name if old_state else "None"
+        new_state_name = new_state.name if new_state else "None"
+
+        logger.info(
+            LOG_CIRCUIT_BREAKER_STATE_CHANGED, old_state_name, new_state_name, cb.name
+        )
+
+        if new_state_name == CIRCUIT_BREAKER_STATE_OPEN:
+            logger.warning(LOG_CIRCUIT_BREAKER_OPENED, cb.name)
+        elif new_state_name == CIRCUIT_BREAKER_STATE_CLOSED:
+            logger.info(LOG_CIRCUIT_BREAKER_CLOSED, cb.name)
+        elif new_state_name == CIRCUIT_BREAKER_STATE_HALF_OPEN:
+            logger.info(LOG_CIRCUIT_BREAKER_HALF_OPEN, cb.name)
+
+
+class CircuitBreakerManager:
+    """
+    Manages circuit breaker instances for telemetry requests.
+
+    This class provides a singleton pattern to manage circuit breaker instances
+    per host, ensuring that telemetry failures don't impact main SQL operations.
+
+    Circuit breaker configuration is fixed and cannot be overridden.
+    """
+
+    _instances: Dict[str, CircuitBreaker] = {}
+    _lock = threading.RLock()
+
+    @classmethod
+    def get_circuit_breaker(cls, host: str) -> CircuitBreaker:
+        """
+        Get or create a circuit breaker instance for the specified host.
+
+        Args:
+            host: The hostname for which to get the circuit breaker
+
+        Returns:
+            CircuitBreaker instance for the host
+        """
+        with cls._lock:
+            if host not in cls._instances:
+                cls._instances[host] = cls._create_circuit_breaker(host)
+                logger.debug("Created circuit breaker for host: %s", host)
+
+            return cls._instances[host]
+
+    @classmethod
+    def _create_circuit_breaker(cls, host: str) -> CircuitBreaker:
+        """
+        Create a new circuit breaker instance for the specified host.
+
+        Args:
+            host: The hostname for the circuit breaker
+
+        Returns:
+            New CircuitBreaker instance
+        """
+        # Create circuit breaker with fixed configuration
+        breaker = CircuitBreaker(
+            fail_max=MINIMUM_CALLS,
+            reset_timeout=RESET_TIMEOUT,
+            name=f"{CIRCUIT_BREAKER_NAME}-{host}",
+        )
+        breaker.add_listener(CircuitBreakerStateListener())
+
+        return breaker
+
+
+def is_circuit_breaker_error(exception: Exception) -> bool:
+    """
+    Check if an exception is a circuit breaker error.
+
+    Args:
+        exception: The exception to check
+
+    Returns:
+        True if the exception is a circuit breaker error
+    """
+    return isinstance(exception, CircuitBreakerError)

src/databricks/sql/telemetry/telemetry_client.py

@@ -41,6 +41,14 @@
 from databricks.sql.common.feature_flag import FeatureFlagsContextFactory
 from databricks.sql.common.unified_http_client import UnifiedHttpClient
 from databricks.sql.common.http import HttpMethod
+from databricks.sql.telemetry.telemetry_push_client import (
+    ITelemetryPushClient,
+    TelemetryPushClient,
+    CircuitBreakerTelemetryPushClient,
+)
+from databricks.sql.telemetry.circuit_breaker_manager import (
+    is_circuit_breaker_error,
+)
 
 if TYPE_CHECKING:
     from databricks.sql.client import Connection
@@ -189,6 +197,21 @@ def __init__(
         # Create own HTTP client from client context
         self._http_client = UnifiedHttpClient(client_context)
 
+        # Create telemetry push client based on circuit breaker enabled flag
+        if client_context.telemetry_circuit_breaker_enabled:
+            # Create circuit breaker telemetry push client with fixed configuration
+            self._telemetry_push_client: ITelemetryPushClient = (
+                CircuitBreakerTelemetryPushClient(
+                    TelemetryPushClient(self._http_client),
+                    host_url,
+                )
+            )
+        else:
+            # Circuit breaker disabled - use direct telemetry push client
+            self._telemetry_push_client: ITelemetryPushClient = TelemetryPushClient(
+                self._http_client
+            )
+
     def _export_event(self, event):
         """Add an event to the batch queue and flush if batch is full"""
         logger.debug("Exporting event for connection %s", self._session_id_hex)
@@ -252,14 +275,21 @@ def _send_telemetry(self, events):
             logger.debug("Failed to submit telemetry request: %s", e)
 
     def _send_with_unified_client(self, url, data, headers, timeout=900):
-        """Helper method to send telemetry using the unified HTTP client."""
+        """Helper method to send telemetry using the telemetry push client."""
         try:
-            response = self._http_client.request(
+            response = self._telemetry_push_client.request(
                 HttpMethod.POST, url, body=data, headers=headers, timeout=timeout
             )
             return response
         except Exception as e:
-            logger.error("Failed to send telemetry with unified client: %s", e)
+            if is_circuit_breaker_error(e):
+                logger.warning(
+                    "Telemetry request blocked by circuit breaker for connection %s: %s",
+                    self._session_id_hex,
+                    e,
+                )
+            else:
+                logger.error("Failed to send telemetry: %s", e)
             raise
 
     def _telemetry_request_callback(self, future, sent_count: int):