1 files changed, 105 insertions, 1 deletions
diff --git a/synapse/storage/transactions.py b/synapse/storage/transactions.py
index 00d0f48082..423cc3f02a 100644
--- a/synapse/storage/transactions.py
+++ b/synapse/storage/transactions.py
@@ -17,6 +17,8 @@ from ._base import SQLBaseStore, Table
 
 from collections import namedtuple
 
+from twisted.internet import defer
+
 import logging
 
 logger = logging.getLogger(__name__)
@@ -26,6 +28,10 @@ class TransactionStore(SQLBaseStore):
     """A collection of queries for handling PDUs.
     """
 
+    # a write-through cache of DestinationsTable.EntryType indexed by
+    # destination string
+    destination_retry_cache = {}
+
     def get_received_txn_response(self, transaction_id, origin):
         """For an incoming transaction from a given origin, check if we have
         already responded to it. If so, return the response code and response
@@ -114,7 +120,7 @@ class TransactionStore(SQLBaseStore):
     def _prep_send_transaction(self, txn, transaction_id, destination,
                                origin_server_ts):
 
-        # First we find out what the prev_txs should be.
+        # First we find out what the prev_txns should be.
         # Since we know that we are only sending one transaction at a time,
         # we can simply take the last one.
         query = "%s ORDER BY id DESC LIMIT 1" % (
@@ -205,6 +211,92 @@ class TransactionStore(SQLBaseStore):
 
         return ReceivedTransactionsTable.decode_results(txn.fetchall())
 
+    def get_destination_retry_timings(self, destination):
+        """Gets the current retry timings (if any) for a given destination.
+
+        Args:
+            destination (str)
+
+        Returns:
+            None if not retrying
+            Otherwise a DestinationsTable.EntryType for the retry scheme
+        """
+        if destination in self.destination_retry_cache:
+            return defer.succeed(self.destination_retry_cache[destination])
+
+        return self.runInteraction(
+            "get_destination_retry_timings",
+            self._get_destination_retry_timings, destination)
+
+    def _get_destination_retry_timings(cls, txn, destination):
+        query = DestinationsTable.select_statement("destination = ?")
+        txn.execute(query, (destination,))
+        result = txn.fetchall()
+        if result:
+            result = DestinationsTable.decode_single_result(result)
+            if result.retry_last_ts > 0:
+                return result
+            else:
+                return None
+
+    def set_destination_retry_timings(self, destination,
+                                      retry_last_ts, retry_interval):
+        """Sets the current retry timings for a given destination.
+        Both timings should be zero if retrying is no longer occuring.
+
+        Args:
+            destination (str)
+            retry_last_ts (int) - time of last retry attempt in unix epoch ms
+            retry_interval (int) - how long until next retry in ms
+        """
+
+        self.destination_retry_cache[destination] = (
+            DestinationsTable.EntryType(
+                destination,
+                retry_last_ts,
+                retry_interval
+            )
+        )
+
+        # XXX: we could chose to not bother persisting this if our cache thinks
+        # this is a NOOP
+        return self.runInteraction(
+            "set_destination_retry_timings",
+            self._set_destination_retry_timings,
+            destination,
+            retry_last_ts,
+            retry_interval,
+        )
+
+    def _set_destination_retry_timings(cls, txn, destination,
+                                       retry_last_ts, retry_interval):
+
+        query = (
+            "INSERT OR REPLACE INTO %s "
+            "(destination, retry_last_ts, retry_interval) "
+            "VALUES (?, ?, ?) "
+        ) % DestinationsTable.table_name
+
+        txn.execute(query, (destination, retry_last_ts, retry_interval))
+
+    def get_destinations_needing_retry(self):
+        """Get all destinations which are due a retry for sending a transaction.
+
+        Returns:
+            list: A list of `DestinationsTable.EntryType`
+        """
+
+        return self.runInteraction(
+            "get_destinations_needing_retry",
+            self._get_destinations_needing_retry
+        )
+
+    def _get_destinations_needing_retry(cls, txn):
+        where = "retry_last_ts > 0 and retry_next_ts < now()"
+        query = DestinationsTable.select_statement(where)
+        txn.execute(query)
+        return DestinationsTable.decode_results(txn.fetchall())
+
 
 class ReceivedTransactionsTable(Table):
     table_name = "received_transactions"
@@ -247,3 +339,15 @@ class TransactionsToPduTable(Table):
     ]
 
     EntryType = namedtuple("TransactionsToPduEntry", fields)
+
+
+class DestinationsTable(Table):
+    table_name = "destinations"
+
+    fields = [
+        "destination",
+        "retry_last_ts",
+        "retry_interval",
+    ]
+
+    EntryType = namedtuple("DestinationsEntry", fields)