Restore functionality of zero-sized bounded reader/writer streams. (#184)

* Restore functionality of zero-sized bounded reader/writer streams.
Adding tests for it.

* run build_nim.sh unconditionally

Co-authored-by: Ștefan Talpalaru <stefantalpalaru@yahoo.com>

.github/workflows/ci.yml

@@ -129,7 +129,6 @@ jobs:
           key: 'nim-${{ matrix.target.os }}-${{ matrix.target.cpu }}-${{ steps.versions.outputs.nimbus_build_system }}-2'
 
       - name: Build Nim and associated tools
-        if: steps.nim-cache.outputs.cache-hit != 'true'
         shell: bash
         run: |
           curl -O -L -s -S https://raw.githubusercontent.com/status-im/nimbus-build-system/master/scripts/build_nim.sh

chronos/streams/boundstream.nim

@@ -42,7 +42,6 @@ type
 
 const
   BoundedBufferSize* = 4096
-  BoundSizeDefectMessage = "Bound size must be bigger than zero"
   BoundarySizeDefectMessage = "Boundary must not be empty array"
 
 template newBoundedStreamIncompleteError(): ref BoundedStreamError =
@@ -108,6 +107,11 @@ proc boundedReadLoop(stream: AsyncStreamReader) {.async.} =
       else:
         int(min(rstream.boundSize.get() - rstream.offset, uint64(len(buffer))))
     try:
+      if toRead == 0:
+        # When ``rstream.boundSize`` is set and we already readed
+        # ``rstream.boundSize`` bytes.
+        rstream.state = AsyncStreamState.Finished
+      else:
         let res = await readUntilBoundary(rstream.rsource, addr buffer[0],
                                           toRead, rstream.boundary)
         if res > 0:
@@ -134,11 +138,6 @@ proc boundedReadLoop(stream: AsyncStreamReader) {.async.} =
                   rstream.error = newBoundedStreamIncompleteError()
                 of BoundCmp.LessOrEqual:
                   rstream.state = AsyncStreamState.Finished
-
-            if rstream.state == AsyncStreamState.Running and
-               rstream.boundSize.isSome() and
-               (rstream.offset == rstream.boundSize.get()):
-              rstream.state = AsyncStreamState.Finished
           else:
             rstream.offset = rstream.offset + uint64(res)
             # There should be one step between transferring last bytes to the
@@ -153,11 +152,6 @@ proc boundedReadLoop(stream: AsyncStreamReader) {.async.} =
                 rstream.error = newBoundedStreamIncompleteError()
               of BoundCmp.LessOrEqual:
                 rstream.state = AsyncStreamState.Finished
-
-          if rstream.state == AsyncStreamState.Running and
-             rstream.boundSize.isSome() and
-             (rstream.offset == rstream.boundSize.get()):
-            rstream.state = AsyncStreamState.Finished
         else:
           case rstream.cmpop
           of BoundCmp.Equal:
@@ -258,7 +252,6 @@ proc bytesLeft*(stream: BoundedStreamRW): uint64 =
 proc init*[T](child: BoundedStreamReader, rsource: AsyncStreamReader,
               boundSize: uint64, comparison = BoundCmp.Equal,
               bufferSize = BoundedBufferSize, udata: ref T) =
-  doAssert(boundSize > 0'u64, BoundSizeDefectMessage)
   child.boundSize = some(boundSize)
   child.cmpop = comparison
   init(AsyncStreamReader(child), rsource, boundedReadLoop, bufferSize,
@@ -277,7 +270,6 @@ proc init*[T](child: BoundedStreamReader, rsource: AsyncStreamReader,
               boundSize: uint64, boundary: openarray[byte],
               comparison = BoundCmp.Equal,
               bufferSize = BoundedBufferSize, udata: ref T) =
-  doAssert(boundSize > 0'u64, BoundSizeDefectMessage)
   doAssert(len(boundary) > 0, BoundarySizeDefectMessage)
   child.boundSize = some(boundSize)
   child.boundary = @boundary
@@ -288,7 +280,6 @@ proc init*[T](child: BoundedStreamReader, rsource: AsyncStreamReader,
 proc init*(child: BoundedStreamReader, rsource: AsyncStreamReader,
            boundSize: uint64, comparison = BoundCmp.Equal,
            bufferSize = BoundedBufferSize) =
-  doAssert(boundSize > 0'u64, BoundSizeDefectMessage)
   child.boundSize = some(boundSize)
   child.cmpop = comparison
   init(AsyncStreamReader(child), rsource, boundedReadLoop, bufferSize)
@@ -304,7 +295,6 @@ proc init*(child: BoundedStreamReader, rsource: AsyncStreamReader,
 proc init*(child: BoundedStreamReader, rsource: AsyncStreamReader,
            boundSize: uint64, boundary: openarray[byte],
            comparison = BoundCmp.Equal, bufferSize = BoundedBufferSize) =
-  doAssert(boundSize > 0'u64, BoundSizeDefectMessage)
   doAssert(len(boundary) > 0, BoundarySizeDefectMessage)
   child.boundSize = some(boundSize)
   child.boundary = @boundary
@@ -430,7 +420,6 @@ proc newBoundedStreamReader*(rsource: AsyncStreamReader,
 proc init*[T](child: BoundedStreamWriter, wsource: AsyncStreamWriter,
               boundSize: uint64, comparison = BoundCmp.Equal,
               queueSize = AsyncStreamDefaultQueueSize, udata: ref T) =
-  doAssert(boundSize > 0'u64, BoundSizeDefectMessage)
   child.boundSize = boundSize
   child.cmpop = comparison
   init(AsyncStreamWriter(child), wsource, boundedWriteLoop, queueSize,
@@ -439,7 +428,6 @@ proc init*[T](child: BoundedStreamWriter, wsource: AsyncStreamWriter,
 proc init*(child: BoundedStreamWriter, wsource: AsyncStreamWriter,
            boundSize: uint64, comparison = BoundCmp.Equal,
            queueSize = AsyncStreamDefaultQueueSize) =
-  doAssert(boundSize > 0'u64, BoundSizeDefectMessage)
   child.boundSize = boundSize
   child.cmpop = comparison
   init(AsyncStreamWriter(child), wsource, boundedWriteLoop, queueSize)

tests/testasyncstream.nim

@@ -1202,6 +1202,50 @@ suite "BoundedStream test suite":
     check waitFor(testSmallChunk(address, 262400, 4096, 61)) == true
     check waitFor(testSmallChunk(address, 767309, 4457, 173)) == true
 
+  test "BoundedStream zero-sized streams test":
+    proc checkEmptyStreams(address: TransportAddress): Future[bool] {.async.} =
+      var writer1Res = false
+      proc serveClient(server: StreamServer,
+                       transp: StreamTransport) {.async.} =
+        var wstream = newAsyncStreamWriter(transp)
+        var wstream2 = newBoundedStreamWriter(wstream, 0'u64)
+        await wstream2.finish()
+        let res = wstream2.atEof()
+        await wstream2.closeWait()
+        await wstream.closeWait()
+        await transp.closeWait()
+        server.stop()
+        server.close()
+        writer1Res = res
+
+      var server = createStreamServer(address, serveClient, {ReuseAddr})
+      server.start()
+      var transp = await connect(address)
+      var rstream = newAsyncStreamReader(transp)
+      var wstream3 = newAsyncStreamWriter(transp)
+      var rstream2 = newBoundedStreamReader(rstream, 0'u64)
+      var wstream4 = newBoundedStreamWriter(wstream3, 0'u64)
+
+      let readerRes = rstream2.atEof()
+      let writer2Res =
+        try:
+          await wstream4.write("data")
+          false
+        except BoundedStreamOverflowError:
+          true
+        except CatchableError:
+          false
+
+      await wstream4.closeWait()
+      await wstream3.closeWait()
+      await rstream2.closeWait()
+      await rstream.closeWait()
+      await transp.closeWait()
+      await server.join()
+      return (writer1Res and writer2Res and readerRes)
+
+    let address = initTAddress("127.0.0.1:46001")
+    check waitFor(checkEmptyStreams(address)) == true
 
   test "BoundedStream leaks test":
     check: