More strict use of errbacks when using deferreds.
[quix0rs-apt-p2p.git] / apt_p2p_Khashmir / DHT.py
index edb626d7b338116bad8493bb9a267d6ec44eb7b1..f773482695428b03e044153e3b2e2b3e8a6be8e1 100644 (file)
@@ -45,6 +45,8 @@ class DHT:
     @ivar joined: whether the DHT network has been successfully joined
     @type outstandingJoins: C{int}
     @ivar outstandingJoins: the number of bootstrap nodes that have yet to respond
+    @type next_rejoin: C{int}
+    @ivar next_rejoin: the number of seconds before retrying the next join
     @type foundAddrs: C{list} of (C{string}, C{int})
     @ivar foundAddrs: the IP address an port that were returned by bootstrap nodes
     @type storing: C{dictionary}
@@ -79,8 +81,10 @@ class DHT:
         self.bootstrap = []
         self.bootstrap_node = False
         self.joining = None
+        self.khashmir = None
         self.joined = False
         self.outstandingJoins = 0
+        self.next_rejoin = 20
         self.foundAddrs = []
         self.storing = {}
         self.retrieving = {}
@@ -115,34 +119,62 @@ class DHT:
             else:
                 self.config[k] = self.config_parser.get(section, k)
     
-    def join(self):
-        """See L{apt_p2p.interfaces.IDHT}."""
-        if self.config is None:
-            raise DHTError, "configuration not loaded"
+    def join(self, deferred = None):
+        """See L{apt_p2p.interfaces.IDHT}.
+        
+        @param deferred: the deferred to callback when the join is complete
+            (optional, defaults to creating a new deferred and returning it)
+        """
+        # Check for multiple simultaneous joins 
         if self.joining:
-            raise DHTError, "a join is already in progress"
+            if deferred:
+                deferred.errback(DHTError("a join is already in progress"))
+                return
+            else:
+                raise DHTError, "a join is already in progress"
+
+        if deferred:
+            self.joining = deferred
+        else:
+            self.joining = defer.Deferred()
+
+        if self.config is None:
+            self.joining.errback(DHTError("configuration not loaded"))
+            return self.joining
 
         # Create the new khashmir instance
-        self.khashmir = Khashmir(self.config, self.cache_dir)
-        
-        self.joining = defer.Deferred()
+        if not self.khashmir:
+            self.khashmir = Khashmir(self.config, self.cache_dir)
+
+        self.outstandingJoins = 0
         for node in self.bootstrap:
             host, port = node.rsplit(':', 1)
             port = int(port)
+            self.outstandingJoins += 1
             
             # Translate host names into IP addresses
             if isIPAddress(host):
                 self._join_gotIP(host, port)
             else:
-                reactor.resolve(host).addCallback(self._join_gotIP, port)
+                reactor.resolve(host).addCallbacks(self._join_gotIP,
+                                                   self._join_resolveFailed,
+                                                   callbackArgs = (port, ),
+                                                   errbackArgs = (host, port))
         
         return self.joining
 
     def _join_gotIP(self, ip, port):
         """Join the DHT using a single bootstrap nodes IP address."""
-        self.outstandingJoins += 1
         self.khashmir.addContact(ip, port, self._join_single, self._join_error)
     
+    def _join_resolveFailed(self, err, host, port):
+        """Failed to lookup the IP address of the bootstrap node."""
+        log.msg('Failed to find an IP address for host: (%r, %r)' % (host, port))
+        log.err(err)
+        self.outstandingJoins -= 1
+        if self.outstandingJoins <= 0:
+            self.khashmir.findCloseNodes(self._join_complete)
+    
     def _join_single(self, addr):
         """Process the response from the bootstrap node.
         
@@ -152,7 +184,7 @@ class DHT:
         if addr:
             self.foundAddrs.append(addr)
         if addr or self.outstandingJoins <= 0:
-            self.khashmir.findCloseNodes(self._join_complete, self._join_complete)
+            self.khashmir.findCloseNodes(self._join_complete)
         log.msg('Got back from bootstrap node: %r' % (addr,))
     
     def _join_error(self, failure = None):
@@ -164,11 +196,11 @@ class DHT:
         self.outstandingJoins -= 1
         log.msg("bootstrap node could not be reached")
         if self.outstandingJoins <= 0:
-            self.khashmir.findCloseNodes(self._join_complete, self._join_complete)
+            self.khashmir.findCloseNodes(self._join_complete)
 
     def _join_complete(self, result):
         """End the joining process and return the addresses found for this node."""
-        if not self.joined and len(result) > 0:
+        if not self.joined and isinstance(result, list) and len(result) > 1:
             self.joined = True
         if self.joining and self.outstandingJoins <= 0:
             df = self.joining
@@ -177,7 +209,10 @@ class DHT:
                 self.joined = True
                 df.callback(self.foundAddrs)
             else:
-                df.errback(DHTError('could not find any nodes to bootstrap to'))
+                # Try to join later using exponential backoff delays
+                log.msg('Join failed, retrying in %d seconds' % self.next_rejoin)
+                reactor.callLater(self.next_rejoin, self.join, df)
+                self.next_rejoin *= 2
         
     def getAddrs(self):
         """Get the list of addresses returned by bootstrap nodes for this node."""
@@ -214,14 +249,17 @@ class DHT:
 
     def getValue(self, key):
         """See L{apt_p2p.interfaces.IDHT}."""
+        d = defer.Deferred()
+
         if self.config is None:
-            raise DHTError, "configuration not loaded"
+            d.errback(DHTError("configuration not loaded"))
+            return d
         if not self.joined:
-            raise DHTError, "have not joined a network yet"
+            d.errback(DHTError("have not joined a network yet"))
+            return d
         
         key = self._normKey(key)
 
-        d = defer.Deferred()
         if key not in self.retrieving:
             self.khashmir.valueForKey(key, self._getValue)
         self.retrieving.setdefault(key, []).append(d)
@@ -245,10 +283,14 @@ class DHT:
 
     def storeValue(self, key, value):
         """See L{apt_p2p.interfaces.IDHT}."""
+        d = defer.Deferred()
+
         if self.config is None:
-            raise DHTError, "configuration not loaded"
+            d.errback(DHTError("configuration not loaded"))
+            return d
         if not self.joined:
-            raise DHTError, "have not joined a network yet"
+            d.errback(DHTError("have not joined a network yet"))
+            return d
 
         key = self._normKey(key)
         bvalue = bencode(value)
@@ -256,7 +298,6 @@ class DHT:
         if key in self.storing and bvalue in self.storing[key]:
             raise DHTError, "already storing that key with the same value"
 
-        d = defer.Deferred()
         self.khashmir.storeValueForKey(key, bvalue, self._storeValue)
         self.storing.setdefault(key, {})[bvalue] = d
         return d
@@ -301,7 +342,7 @@ class DHT:
 class TestSimpleDHT(unittest.TestCase):
     """Simple 2-node unit tests for the DHT."""
     
-    timeout = 2
+    timeout = 50
     DHT_DEFAULTS = {'PORT': 9977, 'K': 8, 'HASH_LENGTH': 160,
                     'CHECKPOINT_INTERVAL': 300, 'CONCURRENT_REQS': 4,
                     'STORE_REDUNDANCY': 3, 'RETRIEVE_VALUES': -10000,
@@ -325,6 +366,16 @@ class TestSimpleDHT(unittest.TestCase):
     def test_bootstrap_join(self):
         d = self.a.join()
         return d
+
+    def test_failed_join(self):
+        from krpc import KrpcError
+        d = self.b.join()
+        reactor.callLater(30, self.a.join)
+        def no_errors(result, self = self):
+            self.flushLoggedErrors(KrpcError)
+            return result
+        d.addCallback(no_errors)
+        return d
         
     def node_join(self, result):
         d = self.b.join()
@@ -406,7 +457,7 @@ class TestSimpleDHT(unittest.TestCase):
 class TestMultiDHT(unittest.TestCase):
     """More complicated 20-node tests for the DHT."""
     
-    timeout = 60
+    timeout = 80
     num = 20
     DHT_DEFAULTS = {'PORT': 9977, 'K': 8, 'HASH_LENGTH': 160,
                     'CHECKPOINT_INTERVAL': 300, 'CONCURRENT_REQS': 4,