re-adding databuf

datastore/threads/databuffer.nim

@@ -0,0 +1,87 @@
+import threading/smartptrs
+import std/hashes
+
+export hashes
+
+type
+  DataBufferHolder* = object
+    buf: ptr UncheckedArray[byte]
+    size: int
+
+  DataBuffer* = SharedPtr[DataBufferHolder] ##\
+    ## A fixed length data buffer using a SharedPtr.
+    ## It is thread safe even with `refc` since
+    ## it doesn't use string or seq types internally.
+    ##
+
+proc `=destroy`*(x: var DataBufferHolder) =
+  ## copy pointer implementation
+  ##
+
+  if x.buf != nil:
+    # when isMainModule or true:
+    #   echo "buffer: FREE: ", repr x.buf.pointer
+    deallocShared(x.buf)
+
+proc len*(a: DataBuffer): int = a[].size
+
+proc isNil*(a: DataBuffer): bool = smartptrs.isNil(a)
+
+proc hash*(a: DataBuffer): Hash =
+  a[].buf.toOpenArray(0, a[].size-1).hash()
+
+proc `==`*(a, b: DataBuffer): bool =
+  if a.isNil and b.isNil: return true
+  elif a.isNil or b.isNil: return false
+  elif a[].size != b[].size: return false
+  elif a[].buf == b[].buf: return true
+  else: a.hash() == b.hash()
+
+proc new*(tp: type DataBuffer, size: int = 0): DataBuffer =
+  ## allocate new buffer with given size
+  ##
+
+  newSharedPtr(DataBufferHolder(
+    buf: cast[typeof(result[].buf)](allocShared0(size)),
+    size: size,
+  ))
+
+proc new*[T: byte | char](tp: type DataBuffer, data: openArray[T]): DataBuffer =
+  ## allocate new buffer and copies indata from openArray
+  ##
+  result = DataBuffer.new(data.len)
+  if data.len() > 0:
+    copyMem(result[].buf, unsafeAddr data[0], data.len)
+
+proc toSequence(T: typedesc[byte | char], a: DataBuffer): seq[T] =
+  ## convert buffer to a seq type using copy and either a byte or char
+  result = newSeq[T](a.len)
+  copyMem(addr result[0], unsafeAddr a[].buf[0], a.len)
+
+converter toSeq*(a: DataBuffer): seq[byte] =
+  ## convert buffer to a seq type using copy and either a byte or char
+  ##
+
+  byte.toSequence(a)
+
+proc `@`*(self: DataBuffer): seq[byte] =
+  ## Convert a buffer to a seq type using copy and
+  ## either a byte or char
+  ##
+
+  self.toSeq()
+
+converter toString*(data: DataBuffer): string =
+  ## convert buffer to string type using copy
+  ##
+
+  if data.isNil: return ""
+  result = newString(data.len())
+  if data.len() > 0:
+    copyMem(addr result[0], unsafeAddr data[].buf[0], data.len)
+
+converter toBuffer*(err: ref CatchableError): DataBuffer =
+  ## convert exception to an object with StringBuffer
+  ##
+
+  return DataBuffer.new(err.msg)