Enhance retry policy error handling and validation

- Added validation to ensure the retry count is greater than 0 in the compute_delay method of RetryPolicyModel, raising a ValueError for invalid inputs.
- Updated the compute_delay method to correctly calculate delays based on the retry count, adjusting the exponentiation logic.
- Refined error handling in the GraphTemplate model by replacing ValueError with HTTPException for better integration with FastAPI, ensuring a 404 response when a graph template is not found.

Author: NiveditJain

state-manager/app/models/db/graph_template_model.py

@@ -5,6 +5,8 @@
 from pymongo import IndexModel
 from pydantic import Field, field_validator, PrivateAttr, model_validator
 from typing import List, Self, Dict
+from fastapi.exceptions import HTTPException
+from fastapi import status
 
 from .base import BaseDatabaseModel
 from ..graph_template_validation_status import GraphTemplateValidationStatus
@@ -303,7 +305,7 @@ def get_path_by_identifier(self, identifier: str) -> set[str]:
     async def get(namespace: str, graph_name: str) -> "GraphTemplate":
         graph_template = await GraphTemplate.find_one(GraphTemplate.namespace == namespace, GraphTemplate.name == graph_name)
         if not graph_template:
-            raise ValueError(f"Graph template not found for namespace: {namespace} and graph name: {graph_name}")
+            raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Graph template not found")
         return graph_template
 
     @staticmethod

state-manager/app/models/retry_policy_model.py

@@ -22,15 +22,18 @@ class RetryPolicyModel(BaseModel):
     exponent: int = Field(default=2, description="The exponent for the exponential retry strategy", gt=0)
 
     def compute_delay(self, retry_count: int) -> int:
+        if retry_count < 1:
+            raise ValueError(f"Retry count must be greater than 1, got {retry_count}")
+        
         if self.strategy == RetryStrategy.EXPONENTIAL:
-            return (self.backoff_factor * (self.exponent ** retry_count))
+            return (self.backoff_factor * (self.exponent ** (retry_count - 1)))
 
         elif self.strategy == RetryStrategy.EXPONENTIAL_FULL_JITTER:
-            base = self.backoff_factor * (self.exponent ** retry_count)
+            base = self.backoff_factor * (self.exponent ** (retry_count - 1))
             return int(random.uniform(0, base))
 
         elif self.strategy == RetryStrategy.EXPONENTIAL_EQUAL_JITTER:
-            base = self.backoff_factor * (self.exponent ** retry_count)
+            base = self.backoff_factor * (self.exponent ** (retry_count - 1))
             return int(base/2 + random.uniform(0, base / 2))
 
         elif self.strategy == RetryStrategy.LINEAR:
@@ -56,4 +59,4 @@ def compute_delay(self, retry_count: int) -> int:
             return int(base/2 + random.uniform(0, base / 2))
 
         else:
-            raise Exception("Invalid retry strategy")
+            raise ValueError(f"Invalid retry strategy: {self.strategy}")