chore: add get_percentage_remaining_ttl helper to DNSRecord (#1343)

bdraco · web-flow · commit 7a24b88ee2a7 · 2023-12-15T09:26:12.000-10:00
diff --git a/src/zeroconf/_dns.pxd b/src/zeroconf/_dns.pxd
@@ -54,6 +54,8 @@ cdef class DNSRecord(DNSEntry):
 
     cpdef get_remaining_ttl(self, double now)
 
+    cpdef unsigned int get_percentage_remaining_ttl(self, double now)
+
     cpdef double get_expiration_time(self, cython.uint percent)
 
     cpdef bint is_expired(self, double now)
diff --git a/src/zeroconf/_dns.py b/src/zeroconf/_dns.py
@@ -193,6 +193,11 @@ def get_expiration_time(self, percent: _int) -> float:
         by a certain percentage."""
         return self.created + (percent * self.ttl * 10)
 
+    def get_percentage_remaining_ttl(self, now: _float) -> _int:
+        """Returns the percentage remaining of the ttl between 0-100."""
+        remain = (self.created + (_EXPIRE_FULL_TIME_MS * self.ttl) - now) / self.ttl / 10
+        return 0 if remain <= 0 else round(remain)
+
     # TODO: Switch to just int here
     def get_remaining_ttl(self, now: _float) -> Union[int, float]:
         """Returns the remaining TTL in seconds."""
diff --git a/tests/test_dns.py b/tests/test_dns.py
@@ -6,7 +6,6 @@
 import logging
 import os
 import socket
-import time
 import unittest
 import unittest.mock
 
@@ -86,19 +85,32 @@ def test_dns_record_abc(self):
             record.write(None)  # type: ignore[arg-type]
 
     def test_dns_record_reset_ttl(self):
-        record = r.DNSRecord('irrelevant', const._TYPE_SRV, const._CLASS_IN, const._DNS_HOST_TTL)
-        time.sleep(1)
-        record2 = r.DNSRecord('irrelevant', const._TYPE_SRV, const._CLASS_IN, const._DNS_HOST_TTL)
+        start = r.current_time_millis()
+        record = r.DNSRecord(
+            'irrelevant', const._TYPE_SRV, const._CLASS_IN, const._DNS_HOST_TTL, created=start
+        )
+        later = start + 1000
+        record2 = r.DNSRecord(
+            'irrelevant', const._TYPE_SRV, const._CLASS_IN, const._DNS_HOST_TTL, created=later
+        )
         now = r.current_time_millis()
 
         assert record.created != record2.created
         assert record.get_remaining_ttl(now) != record2.get_remaining_ttl(now)
+        assert record.get_percentage_remaining_ttl(now) != record2.get_percentage_remaining_ttl(now)
+        assert record2.get_percentage_remaining_ttl(later) == 100
+        assert record2.get_percentage_remaining_ttl(later + (const._DNS_HOST_TTL * 1000 / 2)) == 50
 
         record.reset_ttl(record2)
 
         assert record.ttl == record2.ttl
         assert record.created == record2.created
         assert record.get_remaining_ttl(now) == record2.get_remaining_ttl(now)
+        assert record.get_percentage_remaining_ttl(now) == record2.get_percentage_remaining_ttl(now)
+        assert record.get_percentage_remaining_ttl(later) == 100
+        assert record2.get_percentage_remaining_ttl(later) == 100
+        assert record.get_percentage_remaining_ttl(later + (const._DNS_HOST_TTL * 1000 / 2)) == 50
+        assert record2.get_percentage_remaining_ttl(later + (const._DNS_HOST_TTL * 1000 / 2)) == 50
 
     def test_service_info_dunder(self):
         type_ = "_test-srvc-type._tcp.local."
