feat: add PublisherStalledCheck (#68)

* add PublisherStalledCheck

* update sample.config.yaml with per symbol config sample

* update comment

pyproject.toml

@@ -4,7 +4,7 @@ ignore_missing_imports = true
 
 [tool.poetry]
 name = "pyth-observer"
-version = "0.2.4"
+version = "0.2.5"
 description = "Alerts and stuff"
 authors = []
 readme = "README.md"

pyth_observer/check/publisher.py

@@ -1,3 +1,4 @@
+import time
 from dataclasses import dataclass
 from typing import Dict, Protocol, runtime_checkable
 
@@ -6,6 +7,8 @@
 
 PUBLISHER_EXCLUSION_DISTANCE = 25
 
+PUBLISHER_CACHE = {}
+
 
 @dataclass
 class PublisherState:
@@ -216,9 +219,48 @@ def ci_adjusted_price_diff(self) -> float:
         return max(price_only_diff - self.__state.confidence_interval, 0)
 
 
+class PublisherStalledCheck(PublisherCheck):
+    def __init__(self, state: PublisherState, config: PublisherCheckConfig):
+        self.__state = state
+        self.__stall_time_limit: int = int(
+            config["stall_time_limit"]
+        )  # Time in seconds
+
+    def state(self) -> PublisherState:
+        return self.__state
+
+    def run(self) -> bool:
+        publisher_key = (self.__state.publisher_name, self.__state.symbol)
+        current_time = time.time()
+        previous_price, last_change_time = PUBLISHER_CACHE.get(
+            publisher_key, (None, None)
+        )
+
+        if previous_price is None or self.__state.price != previous_price:
+            PUBLISHER_CACHE[publisher_key] = (self.__state.price, current_time)
+            return True
+
+        if (current_time - last_change_time) > self.__stall_time_limit:
+            return False
+
+        return True
+
+    def error_message(self) -> dict:
+        return {
+            "msg": f"{self.__state.publisher_name} has been publishing the same price for too long.",
+            "type": "PublisherStalledCheck",
+            "publisher": self.__state.publisher_name,
+            "symbol": self.__state.symbol,
+            "price": self.__state.price,
+            "stall_duration": time.time()
+            - PUBLISHER_CACHE[(self.__state.publisher_name, self.__state.symbol)][1],
+        }
+
+
 PUBLISHER_CHECKS = [
     PublisherWithinAggregateConfidenceCheck,
     PublisherConfidenceIntervalCheck,
     PublisherOfflineCheck,
     PublisherPriceCheck,
+    PublisherStalledCheck,
 ]

sample.config.yaml

@@ -44,10 +44,16 @@ checks:
       enable: true
       max_slot_distance: 25
       max_aggregate_distance: 6
+    PublisherStalledCheck:
+      enable: true
+      stall_time_limit: 60
   # Per-symbol config
   Crypto.MNGO/USD:
     PriceFeedOfflineCheck:
       max_slot_distance: 10000
   FX.USD/HKD:
     PriceFeedOfflineCheck:
       max_slot_distance: 10000
+  Crypto.BTC/USD:
+    PublisherStalledCheck:
+      stall_time_limit: 10 # This will override the global stall_time_limit for Crypto.BTC/USD

tests/test_checks_publisher.py

@@ -1,7 +1,15 @@
+import time
+from unittest.mock import patch
+
 from pythclient.pythaccounts import PythPriceStatus
 from pythclient.solana import SolanaPublicKey
 
-from pyth_observer.check.publisher import PublisherPriceCheck, PublisherState
+from pyth_observer.check.publisher import (
+    PUBLISHER_CACHE,
+    PublisherPriceCheck,
+    PublisherStalledCheck,
+    PublisherState,
+)
 
 
 def make_state(
@@ -44,3 +52,46 @@ def check_is_ok(
     state1 = make_state(1, 100.0, 2.0, 1, 110.0, 1.0)
     assert check_is_ok(state1, 10, 25)
     assert not check_is_ok(state1, 6, 25)
+
+
+def test_publisher_stalled_check():
+    current_time = time.time()
+
+    def simulate_time_pass(seconds):
+        nonlocal current_time
+        current_time += seconds
+        return current_time
+
+    def setup_check(state, stall_time_limit):
+        check = PublisherStalledCheck(state, {"stall_time_limit": stall_time_limit})
+        PUBLISHER_CACHE[(state.publisher_name, state.symbol)] = (
+            state.price,
+            current_time,
+        )
+        return check
+
+    def run_check(check, seconds, expected):
+        with patch("time.time", new=lambda: simulate_time_pass(seconds)):
+            assert check.run() == expected
+
+    PUBLISHER_CACHE.clear()
+    state_a = make_state(1, 100.0, 2.0, 1, 100.0, 1.0)
+    check_a = setup_check(state_a, 5)
+    run_check(check_a, 5, True)  # Should pass as it hits the limit exactly
+
+    PUBLISHER_CACHE.clear()
+    state_b = make_state(1, 100.0, 2.0, 1, 100.0, 1.0)
+    check_b = setup_check(state_b, 5)
+    run_check(check_b, 6, False)  # Should fail as it exceeds the limit
+
+    PUBLISHER_CACHE.clear()
+    state_c = make_state(1, 100.0, 2.0, 1, 100.0, 1.0)
+    check_c = setup_check(state_c, 5)
+    run_check(check_c, 2, True)  # Initial check should pass
+    state_c.price = 105.0  # Change the price
+    run_check(check_c, 3, True)  # Should pass as price changes
+    state_c.price = 100.0  # Change back to original price
+    run_check(check_c, 4, True)  # Should pass as price changes
+    run_check(
+        check_c, 8, False
+    )  # Should fail as price stalls for too long after last change