Add ttl for peer data expiration (#655)

* Add ttl and last_identified to peerdata

* Add test for ttl

Signed-off-by: sukhman <sukhmansinghsaluja@gmail.com>

* Fix lint and add newsfragments

Signed-off-by: sukhman <sukhmansinghsaluja@gmail.com>

* Fix failing ci

Signed-off-by: sukhman <sukhmansinghsaluja@gmail.com>

* fix ttl time from 600 to 120

Signed-off-by: sukhman <sukhmansinghsaluja@gmail.com>

* fix test ttl timeout and lint errors

Signed-off-by: sukhman <sukhmansinghsaluja@gmail.com>

* Fix docstrings

Signed-off-by: sukhman <sukhmansinghsaluja@gmail.com>

* rebase main

* remove print statement

---------

Signed-off-by: sukhman <sukhmansinghsaluja@gmail.com>
Co-authored-by: pacrob <5199899+pacrob@users.noreply.github.com>

libp2p/peer/peerdata.py

@@ -1,7 +1,10 @@
 from collections.abc import (
     Sequence,
 )
-from typing import Any
+import time
+from typing import (
+    Any,
+)
 
 from multiaddr import (
     Multiaddr,
@@ -22,6 +25,8 @@ class PeerData(IPeerData):
     metadata: dict[Any, Any]
     protocols: list[str]
     addrs: list[Multiaddr]
+    last_identified: int
+    ttl: int  # Keep ttl=0 by default for always valid
 
     def __init__(self) -> None:
         self.pubkey = None
@@ -29,6 +34,8 @@ class PeerData(IPeerData):
         self.metadata = {}
         self.protocols = []
         self.addrs = []
+        self.last_identified = int(time.time())
+        self.ttl = 0
 
     def get_protocols(self) -> list[str]:
         """
@@ -113,6 +120,36 @@ class PeerData(IPeerData):
             raise PeerDataError("private key not found")
         return self.privkey
 
+    def update_last_identified(self) -> None:
+        self.last_identified = int(time.time())
+
+    def get_last_identified(self) -> int:
+        """
+        :return: last identified timestamp
+        """
+        return self.last_identified
+
+    def get_ttl(self) -> int:
+        """
+        :return: ttl for current peer
+        """
+        return self.ttl
+
+    def set_ttl(self, ttl: int) -> None:
+        """
+        :param ttl: ttl to set
+        """
+        self.ttl = ttl
+
+    def is_expired(self) -> bool:
+        """
+        :return: true, if last_identified+ttl > current_time
+        """
+        # for ttl = 0; peer_data is always valid
+        if self.ttl > 0 and self.last_identified + self.ttl < int(time.time()):
+            return True
+        return False
+
 
 class PeerDataError(KeyError):
     """Raised when a key is not found in peer metadata."""