Contract store (#161)

* split out manifest and block retrieval

* adding test for `fetchManifest`

* raise exceptions in onStore

codex/node.nim

@@ -60,10 +60,11 @@ proc connect*(
   addrs: seq[MultiAddress]): Future[void] =
   node.switch.connect(peerId, addrs)
 
-# TODO: move code that retrieves blocks in manifest into blockstore
-proc retrieve*(
+proc fetchManifest*(
   node: CodexNodeRef,
-  cid: Cid): Future[?!LPStream] {.async.} =
+  cid: Cid): Future[?!Manifest] {.async.} =
+  ## Fetch and decode a manifest block
+  ##
 
   trace "Received retrieval request", cid
   without blkOrNone =? await node.blockStore.getBlock(cid), error:
@@ -73,8 +74,19 @@ proc retrieve*(
     trace "Block not found", cid
     return failure("Block not found")
 
-  if manifest =? Manifest.decode(blk.data, blk.cid):
+  without manifest =? Manifest.decode(blk.data, blk.cid):
+    return failure(
+      newException(CodexError, "Unable to decode as manifest"))
 
+  return manifest.success
+
+proc retrieve*(
+  node: CodexNodeRef,
+  cid: Cid): Future[?!LPStream] {.async.} =
+  ## Retrieve a block or manifest
+  ##
+
+  if manifest =? (await node.fetchManifest(cid)):
     if manifest.protected:
       proc erasureJob(): Future[void] {.async.} =
         try:
@@ -84,13 +96,10 @@ proc retrieve*(
           trace "Exception decoding manifest", cid
 
       asyncSpawn erasureJob()
-
-    proc prefetchBlocks() {.async.} =
-      ## Initiates requests to all blocks in the manifest
-      ##
+    else:
+      proc fetchBlocksJob() {.async.} =
         try:
-        let
-          batch = max(1, manifest.blocks.len div FetchBatch)
+          let batch = max(1, manifest.blocks.len div FetchBatch)
           trace "Prefetching in batches of", FetchBatch
           for blks in manifest.blocks.distribute(batch, true):
             discard await allFinished(
@@ -98,12 +107,14 @@ proc retrieve*(
         except CatchableError as exc:
           trace "Exception prefetching blocks", exc = exc.msg
 
-    asyncSpawn prefetchBlocks()
+      asyncSpawn fetchBlocksJob()
+
     return LPStream(StoreStream.new(node.blockStore, manifest)).success
 
   let
     stream = BufferStream.new()
 
+  if blkOrNone =? (await node.blockStore.getBlock(cid)) and blk =? blkOrNone:
     proc streamOneBlock(): Future[void] {.async.} =
       try:
         await stream.pushData(blk.data)
@@ -116,6 +127,8 @@ proc retrieve*(
     asyncSpawn streamOneBlock()
     return LPStream(stream).success()
 
+  return failure("Unable to retrieve Cid!")
+
 proc store*(
   node: CodexNodeRef,
   stream: LPStream): Future[?!Cid] {.async.} =
@@ -172,43 +185,6 @@ proc store*(
 
   return manifest.cid.success
 
-proc store(node: CodexNodeRef, cid: Cid): Future[?!void] {.async.}
-
-proc store(node: CodexNodeRef, cids: seq[Cid]): Future[?!void] {.async.} =
-  ## Retrieves multiple datasets from the network, and stores them locally
-
-  let batches = max(1, cids.len div FetchBatch)
-  for batch in cids.distribute(batches, true):
-    let results = await allFinished(cids.mapIt(node.store(it)))
-    for future in results:
-      let res = await future
-      if res.isFailure:
-        return failure res.error
-
-  return success()
-
-proc store(node: CodexNodeRef, cid: Cid): Future[?!void] {.async.} =
-  ## Retrieves dataset from the network, and stores it locally
-
-  without present =? await node.blockstore.hasBlock(cid):
-    return failure newException(CodexError, "Unable to find block " & $cid)
-  if present:
-    return success()
-
-  without blkOrNone =? await node.blockstore.getBlock(cid):
-    return failure newException(CodexError, "Unable to retrieve block " & $cid)
-  without blk =? blkOrNone:
-    return failure newException(CodexError, "Unable to retrieve block " & $cid)
-
-  if isErr (await node.blockstore.putBlock(blk)):
-    return failure newException(CodexError, "Unable to store block " & $cid)
-
-  if manifest =? Manifest.decode(blk.data, blk.cid):
-
-    let res = await node.store(manifest.blocks)
-    if res.isFailure:
-      return failure res.error
-
 proc requestStorage*(self: CodexNodeRef,
                      cid: Cid,
                      duration: UInt256,
@@ -326,14 +302,34 @@ proc start*(node: CodexNodeRef) {.async.} =
   if contracts =? node.contracts:
     # TODO: remove Sales callbacks, pass BlockStore and StorageProofs instead
     contracts.sales.onStore = proc(cid: string, _: Availability) {.async.} =
-      # store data in local storage
-      (await node.store(Cid.init(cid).tryGet())).tryGet()
+      ## store data in local storage
+      ##
+
+      without cid =? Cid.init(cid):
+        trace "Unable to parse Cid", cid
+        raise newException(CodexError, "Unable to parse Cid")
+
+      without manifest =? await node.fetchManifest(cid), error:
+        trace "Unable to fetch manifest for cid", cid
+        raise error
+
+      trace "Fetching block for cid", cid
+      let batch = max(1, manifest.blocks.len div FetchBatch)
+      trace "Prefetching in batches of", FetchBatch
+      for blks in manifest.blocks.distribute(batch, true):
+        await allFuturesThrowing(
+          allFinished(blks.mapIt(
+            node.blockStore.getBlock( it )
+          )))
+
     contracts.sales.onClear = proc(availability: Availability, request: StorageRequest) =
       # TODO: remove data from local storage
       discard
+
     contracts.sales.onProve = proc(cid: string): Future[seq[byte]] {.async.} =
       # TODO: generate proof
       return @[42'u8]
+
     await contracts.start()
 
   node.networkId = node.switch.peerInfo.peerId

tests/codex/testnode.nim

@@ -63,6 +63,33 @@ suite "Test Node":
     close(file)
     await node.stop()
 
+  test "Fetch Manifest":
+    var
+      manifest = Manifest.new().tryGet()
+
+    while (
+      let chunk = await chunker.getBytes();
+      chunk.len > 0):
+
+      let blk = bt.Block.new(chunk).tryGet()
+      (await localStore.putBlock(blk)).tryGet()
+      manifest.add(blk.cid)
+
+    let
+      manifestBlock = bt.Block.new(
+          manifest.encode().tryGet(),
+          codec = DagPBCodec
+        ).tryGet()
+
+    (await localStore.putBlock(manifestBlock)).tryGet()
+
+    let
+      fetched = (await node.fetchManifest(manifestBlock.cid)).tryGet()
+
+    check:
+      fetched.cid == manifest.cid
+      fetched.blocks == manifest.blocks
+
   test "Store Data Stream":
     let
       stream = BufferStream.new()