Seekable stream (#58)

* cleanup manifest

* adding a "seekable" base stream

dagger/streams.nim

@@ -0,0 +1,4 @@
+import ./streams/seekablestream
+import ./streams/storestream
+
+export seekablestream, storestream

dagger/streams/seekablestream.nim

@@ -0,0 +1,27 @@
+## Nim-Dagger
+## Copyright (c) 2022 Status Research & Development GmbH
+## Licensed under either of
+##  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
+##  * MIT license ([LICENSE-MIT](LICENSE-MIT))
+## at your option.
+## This file may not be copied, modified, or distributed except according to
+## those terms.
+
+import pkg/libp2p
+import pkg/chronos
+import pkg/chronicles
+
+export libp2p, chronos, chronicles
+
+logScope:
+  topics = "dagger seekablestream"
+
+type
+  SeekableStream* = ref object of LPStream
+    offset*: int
+
+method size*(self: SeekableStream): int {.base.} =
+  raiseAssert("method unimplemented")
+
+proc setPos*(self: SeekableStream, pos: int) =
+  self.offset = pos

dagger/streams/storestream.nim

@@ -7,18 +7,22 @@
 ## This file may not be copied, modified, or distributed except according to
 ## those terms.
 
-{.push raises: [Defect].}
+import pkg/upraises
+
+push: {.upraises: [].}
 
 import pkg/libp2p
 import pkg/chronos
 import pkg/chronicles
 import pkg/stew/ptrops
 
-import ./stores
+import ../stores
-import ./manifest
+import ../manifest
-import ./blocktype
+import ../blocktype
 
-export stores
+import ./seekablestream
+
+export stores, blocktype, manifest, chronos
 
 logScope:
   topics = "dagger storestream"
@@ -28,11 +32,10 @@ type
     Sequential,
     Grid
 
-  StoreStream* = ref object of LPStream
+  StoreStream* = ref object of SeekableStream
     store*: BlockStore
     manifest*: Manifest
     pattern*: ReadPattern
-    offset*: int
 
 proc init*(
   T: type StoreStream,
@@ -47,6 +50,9 @@ proc init*(
 
   result.initStream()
 
+method size*(self: StoreStream): int =
+  self.manifest.len * self.manifest.blockSize
+
 method readOnce*(
   self: StoreStream,
   pbytes: pointer,
@@ -61,8 +67,6 @@ method readOnce*(
   while read < nbytes and self.atEof.not:
     let
       pos = self.offset div self.manifest.blockSize
-
-    let
       blk = (await self.store.getBlock(self.manifest[pos])).tryGet()
       blockOffset = if self.offset >= self.manifest.blockSize:
           self.offset mod self.manifest.blockSize

tests/dagger/teststorestream.nim

@@ -5,10 +5,9 @@ import pkg/questionable/results
 
 import ./helpers
 
-import pkg/dagger/storestream
+import pkg/dagger/streams
 import pkg/dagger/stores
 import pkg/dagger/manifest
-import pkg/dagger/chunker
 import pkg/dagger/rng
 
 suite "StoreStream":
@@ -85,7 +84,6 @@ suite "StoreStream":
       buf = newSeq[byte](5)
 
     await stream.readExactly(addr buf[0], 5)
-
     check buf == [byte 0, 1, 2, 3, 4]
 
   test "Read exact bytes outside of block boundary":
@@ -93,5 +91,4 @@ suite "StoreStream":
       buf = newSeq[byte](15)
 
     await stream.readExactly(addr buf[0], 15)
-
     check buf == [byte 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]