perf: cache timezone objects at module level for better performance

Cache frequently instantiated timezone objects (UTC and available timezones)
at module level to avoid repeated overhead:

- Cache available_timezones() set in trigger_models.py to prevent repeated
  filesystem queries during timezone validation
- Cache ZoneInfo("UTC") constant in trigger_cron.py and verify_graph.py
  to avoid repeated ZoneInfo instantiation in hot paths

These optimizations reduce unnecessary overhead in functions that are called
frequently, particularly in cron trigger scheduling operations.

Signed-off-by: Sparsh <sparsh.raj30@gmail.com>

Author: spa-raj

state-manager/app/models/trigger_models.py

@@ -4,6 +4,9 @@
 from typing import Self, Optional
 from zoneinfo import available_timezones
 
+# Cache available timezones at module level to avoid repeated filesystem queries
+_AVAILABLE_TIMEZONES = available_timezones()
+
 class TriggerTypeEnum(str, Enum):
     CRON = "CRON"
 
@@ -30,7 +33,7 @@ def validate_expression(cls, v: str) -> str:
     def validate_timezone(cls, v: Optional[str]) -> str:
         if v is None:
             return "UTC"
-        if v not in available_timezones():
+        if v not in _AVAILABLE_TIMEZONES:
             raise ValueError(f"Invalid timezone: {v}. Must be a valid IANA timezone (e.g., 'America/New_York', 'Europe/London', 'UTC')")
         return v
 

state-manager/app/tasks/trigger_cron.py

@@ -12,6 +12,9 @@
 import croniter
 import asyncio
 
+# Cache UTC timezone at module level to avoid repeated instantiation
+UTC = ZoneInfo("UTC")
+
 logger = LogsManager().get_logger()
 
 async def get_due_triggers(cron_time: datetime) -> DatabaseTriggers | None:
@@ -48,15 +51,15 @@ async def create_next_triggers(trigger: DatabaseTriggers, cron_time: datetime):
     tz = ZoneInfo(trigger.timezone or "UTC")
 
     # Convert trigger_time to the specified timezone for croniter
-    trigger_time_tz = trigger.trigger_time.replace(tzinfo=ZoneInfo("UTC")).astimezone(tz)
+    trigger_time_tz = trigger.trigger_time.replace(tzinfo=UTC).astimezone(tz)
     iter = croniter.croniter(trigger.expression, trigger_time_tz)
 
     while True:
         # Get next trigger time in the specified timezone
         next_trigger_time_tz = iter.get_next(datetime)
 
         # Convert back to UTC for storage
-        next_trigger_time = next_trigger_time_tz.astimezone(ZoneInfo("UTC")).replace(tzinfo=None)
+        next_trigger_time = next_trigger_time_tz.astimezone(UTC).replace(tzinfo=None)
 
         try:
             await DatabaseTriggers(

state-manager/app/tasks/verify_graph.py

@@ -12,6 +12,9 @@
 from app.models.trigger_models import TriggerStatusEnum, TriggerTypeEnum
 from app.models.db.trigger import DatabaseTriggers
 
+# Cache UTC timezone at module level to avoid repeated instantiation
+UTC = ZoneInfo("UTC")
+
 logger = LogsManager().get_logger()
 
 async def verify_node_exists(graph_template: GraphTemplate, registered_nodes: list[RegisteredNode]) -> list[str]:
@@ -111,22 +114,22 @@ async def create_crons(graph_template: GraphTemplate):
             cron_trigger = CronTrigger.model_validate(trigger.value)
             triggers_to_create[(cron_trigger.expression, cron_trigger.timezone)] = cron_trigger
 
-    current_time = datetime.now(ZoneInfo("UTC")).replace(tzinfo=None)
+    current_time = datetime.now(UTC).replace(tzinfo=None)
 
     new_db_triggers = []
     for (expression, timezone), cron_trigger in triggers_to_create.items():
         # Use the validated timezone (guaranteed to be valid IANA timezone, never None)
         tz = ZoneInfo(timezone)
 
         # Get current time in the specified timezone
-        current_time_tz = current_time.replace(tzinfo=ZoneInfo("UTC")).astimezone(tz)
+        current_time_tz = current_time.replace(tzinfo=UTC).astimezone(tz)
         iter = croniter.croniter(expression, current_time_tz)
 
         # Get next trigger time in the specified timezone
         next_trigger_time_tz = iter.get_next(datetime)
 
         # Convert back to UTC for storage (remove timezone info for storage)
-        next_trigger_time = next_trigger_time_tz.astimezone(ZoneInfo("UTC")).replace(tzinfo=None)
+        next_trigger_time = next_trigger_time_tz.astimezone(UTC).replace(tzinfo=None)
 
         new_db_triggers.append(
             DatabaseTriggers(