safe tables access (#95)

* safer table access

* use withValue

dagger/blockexchange/network.nim

@@ -120,14 +120,16 @@ proc broadcastWantList*(
 
   trace "Sending want list to peer", peer = id, `type` = $wantType, len = cids.len
 
-  let wantList = makeWantList(
-    cids,
-    priority,
-    cancel,
-    wantType,
-    full,
-    sendDontHave)
-  b.peers[id].broadcast(Message(wantlist: wantList))
+  let
+    wantList = makeWantList(
+      cids,
+      priority,
+      cancel,
+      wantType,
+      full,
+      sendDontHave)
+  b.peers.withValue(id, peer):
+    peer[].broadcast(Message(wantlist: wantList))
 
 proc handleBlocks(
   b: BlockExcNetwork,
@@ -153,9 +155,7 @@ proc handleBlocks(
 
   b.handlers.onBlocks(peer.id, blks)
 
-template makeBlocks*(
-  blocks: seq[bt.Block]):
-  seq[pb.Block] =
+template makeBlocks*(blocks: seq[bt.Block]): seq[pb.Block] =
   var blks: seq[pb.Block]
   for blk in blocks:
     blks.add(pb.Block(
@@ -176,7 +176,8 @@ proc broadcastBlocks*(
     return
 
   trace "Sending blocks to peer", peer = id, len = blocks.len
-  b.peers[id].broadcast(pb.Message(payload: makeBlocks(blocks)))
+  b.peers.withValue(id, peer):
+    peer[].broadcast(pb.Message(payload: makeBlocks(blocks)))
 
 proc handleBlockPresence(
   b: BlockExcNetwork,
@@ -202,7 +203,8 @@ proc broadcastBlockPresence*(
     return
 
   trace "Sending presence to peer", peer = id
-  b.peers[id].broadcast(Message(blockPresences: presence))
+  b.peers.withValue(id, peer):
+    peer[].broadcast(Message(blockPresences: @presence))
 
 proc handleAccount(network: BlockExcNetwork,
                    peer: NetworkPeer,
@@ -218,7 +220,8 @@ proc broadcastAccount*(network: BlockExcNetwork,
     return
 
   let message = Message(account: AccountMessage.init(account))
-  network.peers[id].broadcast(message)
+  network.peers.withValue(id, peer):
+    peer[].broadcast(message)
 
 proc broadcastPayment*(network: BlockExcNetwork,
                        id: PeerId,
@@ -227,7 +230,8 @@ proc broadcastPayment*(network: BlockExcNetwork,
     return
 
   let message = Message(payment: StateChannelUpdate.init(payment))
-  network.peers[id].broadcast(message)
+  network.peers.withValue(id, peer):
+    peer[].broadcast(message)
 
 proc handlePayment(network: BlockExcNetwork,
                    peer: NetworkPeer,
@@ -261,13 +265,13 @@ proc getOrCreatePeer(b: BlockExcNetwork, peer: PeerID): NetworkPeer =
   ##
 
   if peer in b.peers:
-    return b.peers[peer]
+    return b.peers.getOrDefault(peer, nil)
 
   var getConn = proc(): Future[Connection] {.async.} =
     try:
       return await b.switch.dial(peer, Codec)
     except CatchableError as exc:
-      trace "unable to connect to blockexc peer", exc = exc.msg
+      trace "Unable to connect to blockexc peer", exc = exc.msg
 
   if not isNil(b.getConn):
     getConn = b.getConn
@@ -277,7 +281,7 @@ proc getOrCreatePeer(b: BlockExcNetwork, peer: PeerID): NetworkPeer =
 
   # create new pubsub peer
   let blockExcPeer = NetworkPeer.new(peer, getConn, rpcHandler)
-  debug "created new blockexc peer", peer
+  debug "Created new blockexc peer", peer
 
   b.peers[peer] = blockExcPeer
 
@@ -363,8 +367,7 @@ proc new*(
     sendBlocks: sendBlocks,
     sendPresence: sendPresence,
     sendAccount: sendAccount,
-    sendPayment: sendPayment
-  )
+    sendPayment: sendPayment)
 
   b.init()
   return b

dagger/blockexchange/peercontext.nim

@@ -13,12 +13,12 @@ export payments, nitro
 type
   BlockExcPeerCtx* = ref object of RootObj
     id*: PeerID
-    peerPrices*: Table[Cid, UInt256] # remote peer have list including price
-    peerWants*: seq[Entry]      # remote peers want lists
-    exchanged*: int             # times peer has exchanged with us
-    lastExchange*: Moment       # last time peer has exchanged with us
-    account*: ?Account          # ethereum account of this peer
-    paymentChannel*: ?ChannelId # payment channel id
+    peerPrices*: Table[Cid, UInt256]  # remote peer have list including price
+    peerWants*: seq[Entry]            # remote peers want lists
+    exchanged*: int                   # times peer has exchanged with us
+    lastExchange*: Moment             # last time peer has exchanged with us
+    account*: ?Account                # ethereum account of this peer
+    paymentChannel*: ?ChannelId       # payment channel id
 
 proc peerHave*(context: BlockExcPeerCtx): seq[Cid] =
   toSeq(context.peerPrices.keys)

dagger/blockexchange/pendingblocks.nim

@@ -10,6 +10,10 @@
 import std/tables
 import std/sequtils
 
+import pkg/upraises
+
+push: {.upraises: [].}
+
 import pkg/questionable
 import pkg/chronicles
 import pkg/chronos
@@ -63,11 +67,11 @@ proc resolve*(
   for blk in blocks:
     # resolve any pending blocks
     if blk.cid in p.blocks:
-      let pending = p.blocks[blk.cid]
-      if not pending.finished:
-        trace "Resolving block", cid = $blk.cid
-        pending.complete(blk)
-        p.blocks.del(blk.cid)
+      p.blocks.withValue(blk.cid, pending):
+        if not pending[].finished:
+          trace "Resolving block", cid = $blk.cid
+          pending[].complete(blk)
+          p.blocks.del(blk.cid)
 
 proc pending*(
   p: PendingBlocksManager,