xpay: make the xpay layer persistent.

As the first user of a persistent layer, this tripped tests which
assumed the datastore would be empty!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

plugins/xpay/xpay.c

@@ -1582,6 +1582,7 @@ static const char *init(struct command *init_cmd,
 				    plugin_broken_cb,
 				    "askrene-create-layer");
 	json_add_string(req->js, "layer", "xpay");
+	json_add_bool(req->js, "persistent", true);
 	send_outreq(req);
 
 	start_aging_timer(plugin);

tests/test_askrene.py

@@ -294,7 +294,8 @@ def test_layers(node_factory):
 
 def test_layer_persistence(node_factory):
     """Test persistence of layers across restart"""
-    l1, l2 = node_factory.line_graph(2, wait_for_announce=True)
+    l1, l2 = node_factory.line_graph(2, wait_for_announce=True,
+                                     opts={'disable-plugin': 'cln-xpay'})
 
     assert l1.rpc.askrene_listlayers() == {'layers': []}
     with pytest.raises(RpcError, match="Unknown layer"):

tests/test_misc.py

@@ -3509,7 +3509,8 @@ def test_datastore_escapeing(node_factory):
 
 
 def test_datastore(node_factory):
-    l1 = node_factory.get_node()
+    # Suppress xpay, which makes a layer
+    l1 = node_factory.get_node(options={"disable-plugin": "cln-xpay"})
 
     # Starts empty
     assert l1.rpc.listdatastore() == {'datastore': []}
@@ -3623,7 +3624,8 @@ def test_datastore(node_factory):
 
 
 def test_datastore_keylist(node_factory):
-    l1 = node_factory.get_node()
+    # Suppress xpay, which makes a layer
+    l1 = node_factory.get_node(options={"disable-plugin": "cln-xpay"})
 
     # Starts empty
     assert l1.rpc.listdatastore() == {'datastore': []}
@@ -3685,7 +3687,7 @@ def test_datastore_keylist(node_factory):
 
 
 def test_datastoreusage(node_factory):
-    l1: LightningNode = node_factory.get_node()
+    l1: LightningNode = node_factory.get_node(options={"disable-plugin": "cln-xpay"})
     assert l1.rpc.datastoreusage() == {'datastoreusage': {'key': '[]', 'total_bytes': 0}}
 
     data = 'somedatatostoreinthedatastore'  # len 29

tests/test_opening.py

@@ -576,6 +576,10 @@ def test_v2_rbf_liquidity_ad(node_factory, bitcoind, chainparams):
 
     l1, l2 = node_factory.get_nodes(2, opts=opts)
 
+    # Other plugins use datastore, but we want to make sure our own
+    # data is cleared!
+    empty_datastore = l1.rpc.listdatastore()
+
     # what happens when we RBF?
     feerate = 2000
     amount = 500000
@@ -632,7 +636,7 @@ def test_v2_rbf_liquidity_ad(node_factory, bitcoind, chainparams):
     l1.rpc.openchannel_signed(chan_id, signed_psbt)
 
     # There's data in the datastore now (l2 only)
-    assert l1.rpc.listdatastore() == {'datastore': []}
+    assert l1.rpc.listdatastore() == empty_datastore
     only_one(l2.rpc.listdatastore("funder/{}".format(chan_id))['datastore'])
 
     # what happens when the channel opens?
@@ -640,8 +644,8 @@ def test_v2_rbf_liquidity_ad(node_factory, bitcoind, chainparams):
     l1.daemon.wait_for_log('to CHANNELD_NORMAL')
 
     # Datastore should be cleaned up!
-    assert l1.rpc.listdatastore() == {'datastore': []}
-    wait_for(lambda: l2.rpc.listdatastore() == {'datastore': []})
+    assert l1.rpc.listdatastore() == empty_datastore
+    wait_for(lambda: l2.rpc.listdatastore() == empty_datastore)
 
     # This should be the accepter's amount
     fundings = only_one(l1.rpc.listpeerchannels()['channels'])['funding']

tests/test_xpay.py

@@ -229,6 +229,7 @@ def test_xpay_fake_channeld(node_factory, bitcoind, chainparams):
     shaseed = subprocess.check_output(["tools/hsmtool", "dumpcommitments", l1.info['id'], "1", "0", hsmfile]).decode('utf-8').strip().partition(": ")[2]
     l1.rpc.dev_peer_shachain(l2.info['id'], shaseed)
 
+    failed_parts = []
     for n in range(0, 100):
         if n in (62, 76, 80, 97):
             continue
@@ -246,7 +247,47 @@ def test_xpay_fake_channeld(node_factory, bitcoind, chainparams):
                                        f"d=Paying node {n}",
                                        f"amount={AMOUNT}msat"]).decode('utf-8').strip()
         assert l1.rpc.decode(inv)['payee'] == nodeids[n]
-        l1.rpc.xpay(inv)
+        failed_parts.append(l1.rpc.xpay(inv)['failed_parts'])
+
+    # Should be no reservations left (clean up happens after return though)
+    wait_for(lambda: l1.rpc.askrene_listreservations() == {'reservations': []})
+
+    # It should remember the information it learned across restarts!
+    # FIXME: channeld_fakenet doesn't restart properly, so just redo xpay.
+    layers = l1.rpc.askrene_listlayers()
+    # Temporary layers should be gone.
+    assert len(layers['layers']) == 1
+
+    l1.rpc.plugin_stop("cln-askrene")
+    l1.rpc.plugin_start(os.path.join(os.getcwd(), 'plugins/cln-askrene'))
+    layers_after = l1.rpc.askrene_listlayers()
+    assert layers == layers_after
+
+    failed_parts_retry = []
+    for n in range(0, 100):
+        if n in (62, 76, 80, 97):
+            continue
+
+        print(f"PAYING Node #{n}")
+
+        preimage_hex = bytes([n + 100]).hex() + '00' * 31
+        hash_hex = sha256(bytes.fromhex(preimage_hex)).hexdigest()
+        inv = subprocess.check_output(["devtools/bolt11-cli",
+                                       "encode",
+                                       n.to_bytes(length=8, byteorder=sys.byteorder).hex() + '01' * 24,
+                                       f"p={hash_hex}",
+                                       f"s={'00' * 32}",
+                                       f"d=Paying node {n}",
+                                       f"amount={AMOUNT}msat"]).decode('utf-8').strip()
+        assert l1.rpc.decode(inv)['payee'] == nodeids[n]
+        failed_parts_retry.append(l1.rpc.xpay(inv)['failed_parts'])
+
+    # At least some will have improved!
+    assert failed_parts_retry != failed_parts
+
+    # Now, we should be as good *or better* than the first time, since we remembered!
+    for p in zip(failed_parts_retry, failed_parts):
+        assert p[0] <= p[1]
 
 
 def test_xpay_timeout(node_factory, executor):