Merge branch 'more_concurrency' into devel

Conflicts:
	doc/tut1.txt
	lib/core/locks.nim
	lib/pure/collections/tables.nim
	lib/pure/selectors.nim

compiler/lowerings.nim

@@ -187,7 +187,7 @@ proc genDeref*(n: PNode): PNode =
   result.add n
 
 proc callCodegenProc*(name: string, arg1: PNode;
-                      arg2, arg3: PNode = nil): PNode =
+                      arg2, arg3, optionalArgs: PNode = nil): PNode =
   result = newNodeI(nkCall, arg1.info)
   let sym = magicsys.getCompilerProc(name)
   if sym == nil:
@@ -197,6 +197,9 @@ proc callCodegenProc*(name: string, arg1: PNode;
     result.add arg1
     if arg2 != nil: result.add arg2
     if arg3 != nil: result.add arg3
+    if optionalArgs != nil:
+      for i in 1..optionalArgs.len-3:
+        result.add optionalArgs[i]
     result.typ = sym.typ.sons[0]
 
 proc callProc(a: PNode): PNode =
@@ -503,7 +506,7 @@ proc wrapProcForSpawn*(owner: PSym; spawnExpr: PNode; retType: PType;
                        barrier, dest: PNode = nil): PNode =
   # if 'barrier' != nil, then it is in a 'parallel' section and we
   # generate quite different code
-  let n = spawnExpr[1]
+  let n = spawnExpr[^2]
   let spawnKind = spawnResult(retType, barrier!=nil)
   case spawnKind
   of srVoid:
@@ -589,7 +592,7 @@ proc wrapProcForSpawn*(owner: PSym; spawnExpr: PNode; retType: PType;
     fvField = newDotExpr(scratchObj, field)
     fvAsExpr = indirectAccess(castExpr, field, n.info)
     # create flowVar:
-    result.add newFastAsgnStmt(fvField, callProc(spawnExpr[2]))
+    result.add newFastAsgnStmt(fvField, callProc(spawnExpr[^1]))
     if barrier == nil:
       result.add callCodegenProc("nimFlowVarCreateSemaphore", fvField)
 
@@ -604,7 +607,7 @@ proc wrapProcForSpawn*(owner: PSym; spawnExpr: PNode; retType: PType;
   let wrapper = createWrapperProc(fn, threadParam, argsParam,
                                   varSection, varInit, call,
                                   barrierAsExpr, fvAsExpr, spawnKind)
-  result.add callCodegenProc("nimSpawn", wrapper.newSymNode,
+  result.add callCodegenProc("nimSpawn" & $spawnExpr.len, wrapper.newSymNode,
-                             genAddrOf(scratchObj.newSymNode))
+                             genAddrOf(scratchObj.newSymNode), nil, spawnExpr)
 
   if spawnKind == srFlowVar: result.add fvField

compiler/semexprs.nim

@@ -1727,13 +1727,17 @@ proc semMagic(c: PContext, n: PNode, s: PSym, flags: TExprFlags): PNode =
     dec c.inParallelStmt
   of mSpawn:
     result = setMs(n, s)
-    result.sons[1] = semExpr(c, n.sons[1])
+    for i in 1 .. <n.len:
-    if not result[1].typ.isEmptyType:
+      result.sons[i] = semExpr(c, n.sons[i])
-      if spawnResult(result[1].typ, c.inParallelStmt > 0) == srFlowVar:
+    let typ = result[^1].typ
-        result.typ = createFlowVar(c, result[1].typ, n.info)
+    if not typ.isEmptyType:
+      if spawnResult(typ, c.inParallelStmt > 0) == srFlowVar:
+        result.typ = createFlowVar(c, typ, n.info)
       else:
-        result.typ = result[1].typ
+        result.typ = typ
-      result.add instantiateCreateFlowVarCall(c, result[1].typ, n.info).newSymNode
+      result.add instantiateCreateFlowVarCall(c, typ, n.info).newSymNode
+    else:
+      result.add emptyNode
   of mProcCall:
     result = setMs(n, s)
     result.sons[1] = semExpr(c, n.sons[1])

compiler/sempass2.nim

@@ -241,9 +241,10 @@ proc useVar(a: PEffects, n: PNode) =
         message(n.info, warnUninit, s.name.s)
       # prevent superfluous warnings about the same variable:
       a.init.add s.id
-  if {sfGlobal, sfThread} * s.flags == {sfGlobal} and s.kind in {skVar, skLet}:
+  if {sfGlobal, sfThread} * s.flags != {} and s.kind in {skVar, skLet}:
     if s.guard != nil: guardGlobal(a, n, s.guard)
-    if (tfHasGCedMem in s.typ.flags or s.typ.isGCedMem):
+    if {sfGlobal, sfThread} * s.flags == {sfGlobal} and
+        (tfHasGCedMem in s.typ.flags or s.typ.isGCedMem):
       #if warnGcUnsafe in gNotes: warnAboutGcUnsafe(n)
       markGcUnsafe(a, s)
 

doc/manual/types.txt

@@ -592,7 +592,7 @@ the ``of`` operator can be used to determine the object's type.
 
 .. code-block:: nim
   type
-    Person {.inheritable.} = object
+    Person = object of RootObj
       name*: string   # the * means that `name` is accessible from other modules
       age: int        # no * means that the field is hidden
 

doc/tut1.txt

@@ -1334,11 +1334,11 @@ define operators which accept Slice objects to define ranges.
     b = "Slices are useless."
 
   echo a[7..12] # --> 'a prog'
-  b[11.. ^2] = "useful"
+  b[11..^2] = "useful"
   echo b # --> 'Slices are useful.'
 
-In the previous example slices are used to modify a part of a string, and even
+In the previous example slices are used to modify a part of a string. The
-a negative index is used. The slice's bounds can hold any value supported by
+slice's bounds can hold any value supported by
 their type, but it is the proc using the slice object which defines what values
 are accepted.
 

lib/core/locks.nim

@@ -14,7 +14,6 @@ include "system/syslocks"
 type
   Lock* = SysLock ## Nim lock; whether this is re-entrant
                   ## or not is unspecified!
-
   Cond* = SysCond ## Nim condition variable
 
 {.deprecated: [TLock: Lock, TCond: Cond].}

lib/pure/asyncdispatch.nim

@@ -122,7 +122,6 @@ export Port, SocketFlag
 ## Limitations/Bugs
 ## ----------------
 ##
-## * ``except`` statement (without `try`) does not work inside async procedures.
 ## * The effect system (``raises: []``) does not work with async procedures.
 ## * Can't await in a ``except`` body
 

lib/pure/collections/sharedstrings.nim

@@ -0,0 +1,154 @@
+#
+#
+#            Nim's Runtime Library
+#        (c) Copyright 2015 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## Shared string support for Nim.
+
+const ArrayDummySize = when defined(cpu16): 10_000 else: 100_000_000
+
+type
+  UncheckedCharArray {.unchecked.} = array[0..ArrayDummySize, char]
+
+type
+  Buffer = ptr object
+    refcount: int
+    capacity, realLen: int
+    data: UncheckedCharArray
+
+  SharedString* = object ## A string that can be shared. Slicing is O(1).
+    buffer: Buffer
+    first, len: int
+
+proc decRef(b: Buffer) {.inline.} =
+  if atomicDec(b.refcount) <= 0:
+    deallocShared(b)
+
+proc incRef(b: Buffer) {.inline.} =
+  atomicInc(b.refcount)
+
+{.experimental.}
+
+proc `=destroy`*(s: SharedString) =
+  #echo "destroyed"
+  if not s.buffer.isNil:
+    decRef(s.buffer)
+
+when false:
+  proc `=`*(dest: var SharedString; src: SharedString) =
+    incRef(src.buffer)
+    if not dest.buffer.isNil:
+      decRef(dest.buffer)
+    dest.buffer = src.buffer
+    dest.first = src.first
+    dest.len = src.len
+
+proc len*(s: SharedString): int = s.len
+
+proc `[]`*(s: SharedString; i: Natural): char =
+  if i < s.len: result = s.buffer.data[i+s.first]
+  else: raise newException(IndexError, "index out of bounds")
+
+proc `[]=`*(s: var SharedString; i: Natural; value: char) =
+  if i < s.len: s.buffer.data[i+s.first] = value
+  else: raise newException(IndexError, "index out of bounds")
+
+proc `[]`*(s: SharedString; ab: Slice[int]): SharedString =
+  #incRef(src.buffer)
+  if ab.a < s.len:
+    result.buffer = s.buffer
+    result.first = ab.a
+    result.len = min(s.len, ab.b - ab.a + 1)
+  # else: produce empty string ;-)
+
+proc newBuffer(cap, len: int): Buffer =
+  assert cap >= len
+  result = cast[Buffer](allocShared0(sizeof(int)*3 + cap))
+  result.refcount = 0
+  result.capacity = cap
+  result.realLen = len
+
+proc newSharedString*(len: Natural): SharedString =
+  if len != 0:
+    # optimization: Don't have an underlying buffer when 'len == 0'
+    result.buffer = newBuffer(len, len)
+  result.first = 0
+  result.len = len
+
+proc newSharedString*(s: string): SharedString =
+  let len = s.len
+  if len != 0:
+    # optimization: Don't have an underlying buffer when 'len == 0'
+    result.buffer = newBuffer(len, len)
+    copyMem(addr result.buffer.data[0], cstring(s), s.len)
+  result.first = 0
+  result.len = len
+
+when declared(atomicLoadN):
+  template load(x): expr = atomicLoadN(addr x, ATOMIC_SEQ_CST)
+else:
+  # XXX Fixme
+  template load(x): expr = x
+
+proc add*(s: var SharedString; t: cstring; len: Natural) =
+  if len == 0: return
+  let newLen = s.len + len
+  if s.buffer.isNil:
+    s.buffer = newBuffer(len, len)
+    copyMem(addr s.buffer.data[0], t, len)
+    s.len = len
+  elif newLen >= s.buffer.capacity or s.first != 0 or
+      s.len != s.buffer.realLen or load(s.buffer.refcount) > 1:
+    let oldBuf = s.buffer
+    s.buffer = newBuffer(max(s.buffer.capacity * 3 div 2, newLen), newLen)
+    copyMem(addr s.buffer.data[0], addr oldBuf.data[s.first], s.len)
+    copyMem(addr s.buffer.data[s.len], t, len)
+    decRef(oldBuf)
+  else:
+    copyMem(addr s.buffer.data[s.len], t, len)
+    s.buffer.realLen += len
+    s.len += len
+
+proc add*(s: var SharedString; t: string) =
+  s.add(t.cstring, t.len)
+
+proc rawData*(s: var SharedString): pointer =
+  if s.buffer.isNil: result = nil
+  else: result = addr s.buffer.data[s.first]
+
+proc add*(s: var SharedString; t: SharedString) =
+  if t.buffer.isNil: return
+  s.add(cast[cstring](addr s.buffer.data[s.first]), t.len)
+
+proc `$`*(s: SharedString): string =
+  result = newString(s.len)
+  if s.len > 0:
+    copyMem(addr result[0], addr s.buffer.data[s.first], s.len)
+
+proc `==`*(s: SharedString; t: string): bool =
+  if s.buffer.isNil: result = t.len == 0
+  else: result = t.len == s.len and equalMem(addr s.buffer.data[s.first],
+                                             cstring(t), t.len)
+
+proc `==`*(s, t: SharedString): bool =
+  if s.buffer.isNil: result = t.len == 0
+  else: result = t.len == s.len and equalMem(addr s.buffer.data[s.first],
+                                             addr t.buffer.data[t.first], t.len)
+
+iterator items*(s: SharedString): char =
+  let buf = s.buffer.data
+  let x = s.first
+  if buf != nil:
+    for i in 0..<s.len:
+      yield buf[i+x]
+
+import hashes
+
+proc hash*(s: SharedString): THash =
+  var h: THash = 0
+  for x in s: h = h !& x.hash
+  result = !$h

lib/pure/collections/sharedtables.nim

@@ -0,0 +1,105 @@
+#
+#
+#            Nim's Runtime Library
+#        (c) Copyright 2015 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## Shared table support for Nim. Use plain old non GC'ed keys and values or
+## you'll be in trouble. Uses a single lock to protect the table, lockfree
+## implementations welcome but if lock contention is so high that you need a
+## lockfree hash table, you're doing it wrong.
+
+import
+  hashes, math, locks
+
+type
+  KeyValuePair[A, B] = tuple[hcode: THash, key: A, val: B]
+  KeyValuePairSeq[A, B] = ptr array[10_000_000, KeyValuePair[A, B]]
+  SharedTable* [A, B] = object ## generic hash SharedTable
+    data: KeyValuePairSeq[A, B]
+    counter, dataLen: int
+    lock: TLock
+
+template maxHash(t): expr = t.dataLen-1
+
+include tableimpl
+
+proc enlarge[A, B](t: var SharedTable[A, B]) =
+  let oldSize = t.dataLen
+  let size = oldSize * growthFactor
+  var n = cast[KeyValuePairSeq[A, B]](allocShared0(
+                                      sizeof(KeyValuePair[A, B]) * size))
+  t.dataLen = size
+  swap(t.data, n)
+  for i in 0..<oldSize:
+    if isFilled(n[i].hcode):
+      var j = -1 - rawGetKnownHC(t, n[i].key, n[i].hcode)
+      rawInsert(t, t.data, n[i].key, n[i].val, n[i].hcode, j)
+  deallocShared(n)
+
+template withLock(t, x: untyped) =
+  acquire(t.lock)
+  x
+  release(t.lock)
+
+proc mget*[A, B](t: var SharedTable[A, B], key: A): var B =
+  ## retrieves the value at ``t[key]``. The value can be modified.
+  ## If `key` is not in `t`, the ``KeyError`` exception is raised.
+  withLock t:
+    var hc: THash
+    var index = rawGet(t, key, hc)
+    let hasKey = index >= 0
+    if hasKey: result = t.data[index].val
+  if not hasKey:
+    when compiles($key):
+      raise newException(KeyError, "key not found: " & $key)
+    else:
+      raise newException(KeyError, "key not found")
+
+proc mgetOrPut*[A, B](t: var SharedTable[A, B], key: A, val: B): var B =
+  ## retrieves value at ``t[key]`` or puts ``val`` if not present, either way
+  ## returning a value which can be modified. **Note**: This is inherently
+  ## unsafe in the context of multi-threading since it returns a pointer
+  ## to ``B``.
+  withLock t:
+    mgetOrPutImpl(enlarge)
+
+proc hasKeyOrPut*[A, B](t: var SharedTable[A, B], key: A, val: B): bool =
+  ## returns true iff `key` is in the table, otherwise inserts `value`.
+  withLock t:
+    hasKeyOrPutImpl(enlarge)
+
+proc `[]=`*[A, B](t: var SharedTable[A, B], key: A, val: B) =
+  ## puts a (key, value)-pair into `t`.
+  withLock t:
+    putImpl(enlarge)
+
+proc add*[A, B](t: var SharedTable[A, B], key: A, val: B) =
+  ## puts a new (key, value)-pair into `t` even if ``t[key]`` already exists.
+  withLock t:
+    addImpl(enlarge)
+
+proc del*[A, B](t: var SharedTable[A, B], key: A) =
+  ## deletes `key` from hash table `t`.
+  withLock t:
+    delImpl()
+
+proc initSharedTable*[A, B](initialSize=64): SharedTable[A, B] =
+  ## creates a new hash table that is empty.
+  ##
+  ## `initialSize` needs to be a power of two. If you need to accept runtime
+  ## values for this you could use the ``nextPowerOfTwo`` proc from the
+  ## `math <math.html>`_ module or the ``rightSize`` proc from this module.
+  assert isPowerOfTwo(initialSize)
+  result.counter = 0
+  result.dataLen = initialSize
+  result.data = cast[KeyValuePairSeq[A, B]](allocShared0(
+                                      sizeof(KeyValuePair[A, B]) * initialSize))
+  initLock result.lock
+
+proc deinitSharedTable*[A, B](t: var SharedTable[A, B]) =
+  deallocShared(t.data)
+  deinitLock t.lock

lib/pure/collections/tableimpl.nim

@@ -0,0 +1,132 @@
+#
+#
+#            Nim's Runtime Library
+#        (c) Copyright 2015 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## An ``include`` file for the different table implementations.
+
+# hcode for real keys cannot be zero.  hcode==0 signifies an empty slot.  These
+# two procs retain clarity of that encoding without the space cost of an enum.
+proc isEmpty(hcode: Hash): bool {.inline.} =
+  result = hcode == 0
+
+proc isFilled(hcode: Hash): bool {.inline.} =
+  result = hcode != 0
+
+const
+  growthFactor = 2
+
+proc mustRehash(length, counter: int): bool {.inline.} =
+  assert(length > counter)
+  result = (length * 2 < counter * 3) or (length - counter < 4)
+
+proc nextTry(h, maxHash: Hash): Hash {.inline.} =
+  result = (h + 1) and maxHash
+
+template rawGetKnownHCImpl() {.dirty.} =
+  var h: Hash = hc and maxHash(t)   # start with real hash value
+  while isFilled(t.data[h].hcode):
+    # Compare hc THEN key with boolean short circuit. This makes the common case
+    # zero ==key's for missing (e.g.inserts) and exactly one ==key for present.
+    # It does slow down succeeding lookups by one extra Hash cmp&and..usually
+    # just a few clock cycles, generally worth it for any non-integer-like A.
+    if t.data[h].hcode == hc and t.data[h].key == key:
+      return h
+    h = nextTry(h, maxHash(t))
+  result = -1 - h                   # < 0 => MISSING; insert idx = -1 - result
+
+template rawGetImpl() {.dirty.} =
+  hc = hash(key)
+  if hc == 0:       # This almost never taken branch should be very predictable.
+    hc = 314159265  # Value doesn't matter; Any non-zero favorite is fine.
+  rawGetKnownHCImpl()
+
+template rawGetDeepImpl() {.dirty.} =   # Search algo for unconditional add
+  hc = hash(key)
+  if hc == 0:
+    hc = 314159265
+  var h: Hash = hc and maxHash(t)
+  while isFilled(t.data[h].hcode):
+    h = nextTry(h, maxHash(t))
+  result = h
+
+template rawInsertImpl() {.dirty.} =
+  data[h].key = key
+  data[h].val = val
+  data[h].hcode = hc
+
+proc rawGetKnownHC[X, A](t: X, key: A, hc: Hash): int {.inline.} =
+  rawGetKnownHCImpl()
+
+proc rawGetDeep[X, A](t: X, key: A, hc: var Hash): int {.inline.} =
+  rawGetDeepImpl()
+
+proc rawGet[X, A](t: X, key: A, hc: var Hash): int {.inline.} =
+  rawGetImpl()
+
+proc rawInsert[X, A, B](t: var X, data: var KeyValuePairSeq[A, B],
+                     key: A, val: B, hc: Hash, h: Hash) =
+  rawInsertImpl()
+
+template addImpl(enlarge) {.dirty, immediate.} =
+  if mustRehash(t.dataLen, t.counter): enlarge(t)
+  var hc: Hash
+  var j = rawGetDeep(t, key, hc)
+  rawInsert(t, t.data, key, val, hc, j)
+  inc(t.counter)
+
+template maybeRehashPutImpl(enlarge) {.dirty, immediate.} =
+  if mustRehash(t.dataLen, t.counter):
+    enlarge(t)
+    index = rawGetKnownHC(t, key, hc)
+  index = -1 - index                  # important to transform for mgetOrPutImpl
+  rawInsert(t, t.data, key, val, hc, index)
+  inc(t.counter)
+
+template putImpl(enlarge) {.dirty, immediate.} =
+  var hc: Hash
+  var index = rawGet(t, key, hc)
+  if index >= 0: t.data[index].val = val
+  else: maybeRehashPutImpl(enlarge)
+
+template mgetOrPutImpl(enlarge) {.dirty, immediate.} =
+  var hc: Hash
+  var index = rawGet(t, key, hc)
+  if index < 0:
+    # not present: insert (flipping index)
+    maybeRehashPutImpl(enlarge)
+  # either way return modifiable val
+  result = t.data[index].val
+
+template hasKeyOrPutImpl(enlarge) {.dirty, immediate.} =
+  var hc: Hash
+  var index = rawGet(t, key, hc)
+  if index < 0:
+    result = false
+    maybeRehashPutImpl(enlarge)
+  else: result = true
+
+template delImpl() {.dirty, immediate.} =
+  var hc: Hash
+  var i = rawGet(t, key, hc)
+  let msk = maxHash(t)
+  if i >= 0:
+    t.data[i].hcode = 0
+    dec(t.counter)
+    block outer:
+      while true:         # KnuthV3 Algo6.4R adapted for i=i+1 instead of i=i-1
+        var j = i         # The correctness of this depends on (h+1) in nextTry,
+        var r = j         # though may be adaptable to other simple sequences.
+        t.data[i].hcode = 0              # mark current EMPTY
+        while true:
+          i = (i + 1) and msk            # increment mod table size
+          if isEmpty(t.data[i].hcode):   # end of collision cluster; So all done
+            break outer
+          r = t.data[i].hcode and msk    # "home" location of key@i
+          if not ((i >= r and r > j) or (r > j and j > i) or (j > i and i >= r)):
+            break
+        shallowCopy(t.data[j], t.data[i]) # data[j] will be marked EMPTY next loop

lib/pure/collections/tables.nim

@@ -68,65 +68,20 @@
 import
   hashes, math
 
-{.pragma: myShallow.}
-
 type
   KeyValuePair[A, B] = tuple[hcode: Hash, key: A, val: B]
   KeyValuePairSeq[A, B] = seq[KeyValuePair[A, B]]
-  Table* {.myShallow.}[A, B] = object ## generic hash table
+  Table*[A, B] = object ## generic hash table
     data: KeyValuePairSeq[A, B]
     counter: int
   TableRef*[A,B] = ref Table[A, B]
 
 {.deprecated: [TTable: Table, PTable: TableRef].}
 
-when not defined(nimhygiene):
+template maxHash(t): expr {.immediate.} = high(t.data)
-  {.pragma: dirty.}
+template dataLen(t): expr = len(t.data)
 
-# hcode for real keys cannot be zero.  hcode==0 signifies an empty slot.  These
+include tableimpl
-# two procs retain clarity of that encoding without the space cost of an enum.
-proc isEmpty(hcode: Hash): bool {.inline.} =
-  result = hcode == 0
-
-proc isFilled(hcode: Hash): bool {.inline.} =
-  result = hcode != 0
-
-proc len*[A, B](t: Table[A, B]): int =
-  ## returns the number of keys in `t`.
-  result = t.counter
-
-iterator pairs*[A, B](t: Table[A, B]): (A, B) =
-  ## iterates over any (key, value) pair in the table `t`.
-  for h in 0..high(t.data):
-    if isFilled(t.data[h].hcode): yield (t.data[h].key, t.data[h].val)
-
-iterator mpairs*[A, B](t: var Table[A, B]): (A, var B) =
-  ## iterates over any (key, value) pair in the table `t`. The values
-  ## can be modified.
-  for h in 0..high(t.data):
-    if isFilled(t.data[h].hcode): yield (t.data[h].key, t.data[h].val)
-
-iterator keys*[A, B](t: Table[A, B]): A =
-  ## iterates over any key in the table `t`.
-  for h in 0..high(t.data):
-    if isFilled(t.data[h].hcode): yield t.data[h].key
-
-iterator values*[A, B](t: Table[A, B]): B =
-  ## iterates over any value in the table `t`.
-  for h in 0..high(t.data):
-    if isFilled(t.data[h].hcode): yield t.data[h].val
-
-iterator mvalues*[A, B](t: var Table[A, B]): var B =
-  ## iterates over any value in the table `t`. The values can be modified.
-  for h in 0..high(t.data):
-    if isFilled(t.data[h].hcode): yield t.data[h].val
-
-const
-  growthFactor = 2
-
-proc mustRehash(length, counter: int): bool {.inline.} =
-  assert(length > counter)
-  result = (length * 2 < counter * 3) or (length - counter < 4)
 
 proc rightSize*(count: Natural): int {.inline.} =
   ## Return the value of `initialSize` to support `count` items.
@@ -137,49 +92,9 @@ proc rightSize*(count: Natural): int {.inline.} =
   ## Internally, we want mustRehash(rightSize(x), x) == false.
   result = nextPowerOfTwo(count * 3 div 2  +  4)
 
-proc nextTry(h, maxHash: Hash): Hash {.inline.} =
+proc len*[A, B](t: Table[A, B]): int =
-  result = (h + 1) and maxHash
+  ## returns the number of keys in `t`.
-
+  result = t.counter
-template rawGetKnownHCImpl() {.dirty.} =
-  var h: Hash = hc and high(t.data)   # start with real hash value
-  while isFilled(t.data[h].hcode):
-    # Compare hc THEN key with boolean short circuit. This makes the common case
-    # zero ==key's for missing (e.g.inserts) and exactly one ==key for present.
-    # It does slow down succeeding lookups by one extra Hash cmp&and..usually
-    # just a few clock cycles, generally worth it for any non-integer-like A.
-    if t.data[h].hcode == hc and t.data[h].key == key:
-      return h
-    h = nextTry(h, high(t.data))
-  result = -1 - h                   # < 0 => MISSING; insert idx = -1 - result
-
-template rawGetImpl() {.dirty.} =
-  hc = hash(key)
-  if hc == 0:       # This almost never taken branch should be very predictable.
-    hc = 314159265  # Value doesn't matter; Any non-zero favorite is fine.
-  rawGetKnownHCImpl()
-
-template rawGetDeepImpl() {.dirty.} =   # Search algo for unconditional add
-  hc = hash(key)
-  if hc == 0:
-    hc = 314159265
-  var h: Hash = hc and high(t.data)
-  while isFilled(t.data[h].hcode):
-    h = nextTry(h, high(t.data))
-  result = h
-
-template rawInsertImpl() {.dirty.} =
-  data[h].key = key
-  data[h].val = val
-  data[h].hcode = hc
-
-proc rawGetKnownHC[A, B](t: Table[A, B], key: A, hc: Hash): int {.inline.} =
-  rawGetKnownHCImpl()
-
-proc rawGetDeep[A, B](t: Table[A, B], key: A, hc: var Hash): int {.inline.} =
-  rawGetDeepImpl()
-
-proc rawGet[A, B](t: Table[A, B], key: A, hc: var Hash): int {.inline.} =
-  rawGetImpl()
 
 proc `[]`*[A, B](t: Table[A, B], key: A): B =
   ## retrieves the value at ``t[key]``. If `key` is not in `t`,
@@ -219,9 +134,35 @@ proc contains*[A, B](t: Table[A, B], key: A): bool =
   ## alias of `hasKey` for use with the `in` operator.
   return hasKey[A, B](t, key)
 
-proc rawInsert[A, B](t: var Table[A, B], data: var KeyValuePairSeq[A, B],
+iterator pairs*[A, B](t: Table[A, B]): (A, B) =
-                     key: A, val: B, hc: Hash, h: Hash) =
+  ## iterates over any (key, value) pair in the table `t`.
-  rawInsertImpl()
+  for h in 0..high(t.data):
+    if isFilled(t.data[h].hcode): yield (t.data[h].key, t.data[h].val)
+
+iterator mpairs*[A, B](t: var Table[A, B]): (A, var B) =
+  ## iterates over any (key, value) pair in the table `t`. The values
+  ## can be modified.
+  for h in 0..high(t.data):
+    if isFilled(t.data[h].hcode): yield (t.data[h].key, t.data[h].val)
+
+iterator keys*[A, B](t: Table[A, B]): A =
+  ## iterates over any key in the table `t`.
+  for h in 0..high(t.data):
+    if isFilled(t.data[h].hcode): yield t.data[h].key
+
+iterator values*[A, B](t: Table[A, B]): B =
+  ## iterates over any value in the table `t`.
+  for h in 0..high(t.data):
+    if isFilled(t.data[h].hcode): yield t.data[h].val
+
+iterator mvalues*[A, B](t: var Table[A, B]): var B =
+  ## iterates over any value in the table `t`. The values can be modified.
+  for h in 0..high(t.data):
+    if isFilled(t.data[h].hcode): yield t.data[h].val
+
+proc del*[A, B](t: var Table[A, B], key: A) =
+  ## deletes `key` from hash table `t`.
+  delImpl()
 
 proc enlarge[A, B](t: var Table[A, B]) =
   var n: KeyValuePairSeq[A, B]
@@ -232,81 +173,26 @@ proc enlarge[A, B](t: var Table[A, B]) =
       var j = -1 - rawGetKnownHC(t, n[i].key, n[i].hcode)
       rawInsert(t, t.data, n[i].key, n[i].val, n[i].hcode, j)
 
-template addImpl() {.dirty.} =
-  if mustRehash(len(t.data), t.counter): enlarge(t)
-  var hc: Hash
-  var j = rawGetDeep(t, key, hc)
-  rawInsert(t, t.data, key, val, hc, j)
-  inc(t.counter)
-
-template maybeRehashPutImpl() {.dirty.} =
-  if mustRehash(len(t.data), t.counter):
-    enlarge(t)
-    index = rawGetKnownHC(t, key, hc)
-  index = -1 - index                  # important to transform for mgetOrPutImpl
-  rawInsert(t, t.data, key, val, hc, index)
-  inc(t.counter)
-
-template putImpl() {.dirty.} =
-  var hc: Hash
-  var index = rawGet(t, key, hc)
-  if index >= 0: t.data[index].val = val
-  else: maybeRehashPutImpl()
-
-template mgetOrPutImpl() {.dirty.} =
-  var hc: Hash
-  var index = rawGet(t, key, hc)
-  if index < 0: maybeRehashPutImpl()    # not present: insert (flipping index)
-  result = t.data[index].val            # either way return modifiable val
-
-template hasKeyOrPutImpl() {.dirty.} =
-  var hc: Hash
-  var index = rawGet(t, key, hc)
-  if index < 0:
-    result = false
-    maybeRehashPutImpl()
-  else: result = true
-
 proc mgetOrPut*[A, B](t: var Table[A, B], key: A, val: B): var B =
   ## retrieves value at ``t[key]`` or puts ``val`` if not present, either way
   ## returning a value which can be modified.
-  mgetOrPutImpl()
+  mgetOrPutImpl(enlarge)
 
 proc hasKeyOrPut*[A, B](t: var Table[A, B], key: A, val: B): bool =
   ## returns true iff `key` is in the table, otherwise inserts `value`.
-  hasKeyOrPutImpl()
+  hasKeyOrPutImpl(enlarge)
 
 proc `[]=`*[A, B](t: var Table[A, B], key: A, val: B) =
   ## puts a (key, value)-pair into `t`.
-  putImpl()
+  putImpl(enlarge)
 
 proc add*[A, B](t: var Table[A, B], key: A, val: B) =
   ## puts a new (key, value)-pair into `t` even if ``t[key]`` already exists.
-  addImpl()
+  addImpl(enlarge)
 
-template doWhile(a: expr, b: stmt): stmt =
+proc len*[A, B](t: TableRef[A, B]): int =
-  while true:
+  ## returns the number of keys in `t`.
-    b
+  result = t.counter
-    if not a: break
-
-proc del*[A, B](t: var Table[A, B], key: A) =
-  ## deletes `key` from hash table `t`.
-  var hc: Hash
-  var i = rawGet(t, key, hc)
-  let msk = high(t.data)
-  if i >= 0:
-    t.data[i].hcode = 0
-    dec(t.counter)
-    while true:         # KnuthV3 Algo6.4R adapted for i=i+1 instead of i=i-1
-      var j = i         # The correctness of this depends on (h+1) in nextTry,
-      var r = j         # though may be adaptable to other simple sequences.
-      t.data[i].hcode = 0              # mark current EMPTY
-      doWhile ((i >= r and r > j) or (r > j and j > i) or (j > i and i >= r)):
-        i = (i + 1) and msk            # increment mod table size
-        if isEmpty(t.data[i].hcode):   # end of collision cluster; So all done
-          return
-        r = t.data[i].hcode and msk    # "home" location of key@i
-      shallowCopy(t.data[j], t.data[i]) # data[j] will be marked EMPTY next loop
 
 proc initTable*[A, B](initialSize=64): Table[A, B] =
   ## creates a new hash table that is empty.
@@ -360,10 +246,6 @@ proc indexBy*[A, B, C](collection: A, index: proc(x: B): C): Table[C, B] =
   for item in collection:
     result[index(item)] = item
 
-proc len*[A, B](t: TableRef[A, B]): int =
-  ## returns the number of keys in `t`.
-  result = t.counter
-
 iterator pairs*[A, B](t: TableRef[A, B]): (A, B) =
   ## iterates over any (key, value) pair in the table `t`.
   for h in 0..high(t.data):
@@ -462,8 +344,7 @@ type
   OrderedKeyValuePair[A, B] = tuple[
     hcode: Hash, next: int, key: A, val: B]
   OrderedKeyValuePairSeq[A, B] = seq[OrderedKeyValuePair[A, B]]
-  OrderedTable* {.
+  OrderedTable* [A, B] = object ## table that remembers insertion order
-      myShallow.}[A, B] = object ## table that remembers insertion order
     data: OrderedKeyValuePairSeq[A, B]
     counter, first, last: int
   OrderedTableRef*[A, B] = ref OrderedTable[A, B]
@@ -569,20 +450,20 @@ proc enlarge[A, B](t: var OrderedTable[A, B]) =
 
 proc `[]=`*[A, B](t: var OrderedTable[A, B], key: A, val: B) =
   ## puts a (key, value)-pair into `t`.
-  putImpl()
+  putImpl(enlarge)
 
 proc add*[A, B](t: var OrderedTable[A, B], key: A, val: B) =
   ## puts a new (key, value)-pair into `t` even if ``t[key]`` already exists.
-  addImpl()
+  addImpl(enlarge)
 
 proc mgetOrPut*[A, B](t: var OrderedTable[A, B], key: A, val: B): var B =
   ## retrieves value at ``t[key]`` or puts ``value`` if not present, either way
   ## returning a value which can be modified.
-  mgetOrPutImpl()
+  mgetOrPutImpl(enlarge)
 
 proc hasKeyOrPut*[A, B](t: var OrderedTable[A, B], key: A, val: B): bool =
   ## returns true iff `key` is in the table, otherwise inserts `value`.
-  hasKeyOrPutImpl()
+  hasKeyOrPutImpl(enlarge)
 
 proc initOrderedTable*[A, B](initialSize=64): OrderedTable[A, B] =
   ## creates a new ordered hash table that is empty.
@@ -757,7 +638,7 @@ proc sort*[A, B](t: OrderedTableRef[A, B],
 # ------------------------------ count tables -------------------------------
 
 type
-  CountTable* {.myShallow.}[
+  CountTable* [
       A] = object ## table that counts the number of each key
     data: seq[tuple[key: A, val: int]]
     counter: int

lib/pure/concurrency/threadpool.nim

@@ -128,6 +128,7 @@ type
     initialized: bool # whether it has even been initialized
     shutdown: bool # the pool requests to shut down this worker thread
     q: ToFreeQueue
+    readyForTask: Semaphore
 
 proc await*(fv: FlowVarBase) =
   ## waits until the value for the flowVar arrives. Usually it is not necessary
@@ -273,6 +274,10 @@ proc nimArgsPassingDone(p: pointer) {.compilerProc.} =
 const
   MaxThreadPoolSize* = 256 ## maximal size of the thread pool. 256 threads
                            ## should be good enough for anybody ;-)
+  MaxDistinguishedThread* = 32 ## maximal number of "distinguished" threads.
+
+type
+  ThreadId* = range[0..MaxDistinguishedThread-1]
 
 var
   currentPoolSize: int
@@ -298,10 +303,25 @@ proc slave(w: ptr Worker) {.thread.} =
       w.shutdown = false
       atomicDec currentPoolSize
 
+proc distinguishedSlave(w: ptr Worker) {.thread.} =
+  while true:
+    when declared(atomicStoreN):
+      atomicStoreN(addr(w.ready), true, ATOMIC_SEQ_CST)
+    else:
+      w.ready = true
+    signal(w.readyForTask)
+    await(w.taskArrived)
+    assert(not w.ready)
+    w.f(w, w.data)
+    if w.q.len != 0: w.cleanFlowVars
+
 var
   workers: array[MaxThreadPoolSize, TThread[ptr Worker]]
   workersData: array[MaxThreadPoolSize, Worker]
 
+  distinguished: array[MaxDistinguishedThread, TThread[ptr Worker]]
+  distinguishedData: array[MaxDistinguishedThread, Worker]
+
 proc setMinPoolSize*(size: range[1..MaxThreadPoolSize]) =
   ## sets the minimal thread pool size. The default value of this is 4.
   minPoolSize = size
@@ -315,7 +335,7 @@ proc setMaxPoolSize*(size: range[1..MaxThreadPoolSize]) =
       let w = addr(workersData[i])
       w.shutdown = true
 
-proc activateThread(i: int) {.noinline.} =
+proc activateWorkerThread(i: int) {.noinline.} =
   workersData[i].taskArrived = createSemaphore()
   workersData[i].taskStarted = createSemaphore()
   workersData[i].initialized = true
@@ -323,10 +343,19 @@ proc activateThread(i: int) {.noinline.} =
   initLock(workersData[i].q.lock)
   createThread(workers[i], slave, addr(workersData[i]))
 
+proc activateDistinguishedThread(i: int) {.noinline.} =
+  distinguishedData[i].taskArrived = createSemaphore()
+  distinguishedData[i].taskStarted = createSemaphore()
+  distinguishedData[i].initialized = true
+  distinguishedData[i].q.empty = createSemaphore()
+  initLock(distinguishedData[i].q.lock)
+  distinguishedData[i].readyForTask = createSemaphore()
+  createThread(distinguished[i], distinguishedSlave, addr(distinguishedData[i]))
+
 proc setup() =
   currentPoolSize = min(countProcessors(), MaxThreadPoolSize)
   readyWorker = addr(workersData[0])
-  for i in 0.. <currentPoolSize: activateThread(i)
+  for i in 0.. <currentPoolSize: activateWorkerThread(i)
 
 proc preferSpawn*(): bool =
   ## Use this proc to determine quickly if a 'spawn' or a direct call is
@@ -340,6 +369,13 @@ proc spawn*(call: expr): expr {.magic: "Spawn".}
   ## is gcsafe and has a return type that is either 'void' or compatible
   ## with ``FlowVar[T]``.
 
+proc pinnedSpawn*(id: ThreadId; call: expr): expr {.magic: "Spawn".}
+  ## always spawns a new task on the worker thread with ``id``, so that
+  ## the 'call' is **always** executed on
+  ## the this thread. 'call' has to be proc call 'p(...)' where 'p'
+  ## is gcsafe and has a return type that is either 'void' or compatible
+  ## with ``FlowVar[T]``.
+
 template spawnX*(call: expr): expr =
   ## spawns a new task if a CPU core is ready, otherwise executes the
   ## call in the calling thread. Usually it is advised to
@@ -360,7 +396,7 @@ var
 
 initLock stateLock
 
-proc nimSpawn(fn: WorkerProc; data: pointer) {.compilerProc.} =
+proc nimSpawn3(fn: WorkerProc; data: pointer) {.compilerProc.} =
   # implementation of 'spawn' that is used by the code generator.
   while true:
     if selectWorker(readyWorker, fn, data): return
@@ -377,7 +413,7 @@ proc nimSpawn(fn: WorkerProc; data: pointer) {.compilerProc.} =
         of doCreateThread:
           if currentPoolSize < maxPoolSize:
             if not workersData[currentPoolSize].initialized:
-              activateThread(currentPoolSize)
+              activateWorkerThread(currentPoolSize)
             let w = addr(workersData[currentPoolSize])
             atomicInc currentPoolSize
             if selectWorker(w, fn, data):
@@ -394,6 +430,21 @@ proc nimSpawn(fn: WorkerProc; data: pointer) {.compilerProc.} =
       # other thread succeeded, so we don't need to do anything here.
     await(gSomeReady)
 
+var
+  distinguishedLock: TLock
+
+initLock distinguishedLock
+
+proc nimSpawn4(fn: WorkerProc; data: pointer; id: ThreadId) {.compilerProc.} =
+  acquire(distinguishedLock)
+  if not distinguishedData[id].initialized:
+    activateDistinguishedThread(id)
+  release(distinguishedLock)
+  while true:
+    if selectWorker(addr(distinguishedData[id]), fn, data): break
+    await(distinguishedData[id].readyForTask)
+
+
 proc sync*() =
   ## a simple barrier to wait for all spawn'ed tasks. If you need more elaborate
   ## waiting, you have to use an explicit barrier.

lib/pure/selectors.nim

@@ -25,19 +25,20 @@ type
   Event* = enum
     EvRead, EvWrite, EvError
 
-  SelectorKey* = ref object
+  SelectorKey* = object
     fd*: SocketHandle
     events*: set[Event] ## The events which ``fd`` listens for.
-    data*: RootRef ## User object.
+    data*: pointer ## User object.
 
   ReadyInfo* = tuple[key: SelectorKey, events: set[Event]]
 
+
+
 when defined(nimdoc):
   type
     Selector* = ref object
       ## An object which holds file descriptors to be checked for read/write
       ## status.
-      fds: Table[SocketHandle, SelectorKey]
 
   proc register*(s: Selector, fd: SocketHandle, events: set[Event],
                  data: RootRef): SelectorKey {.discardable.} =
@@ -57,7 +58,7 @@ when defined(nimdoc):
   proc select*(s: Selector, timeout: int): seq[ReadyInfo] =
     ## The ``events`` field of the returned ``key`` contains the original events
     ## for which the ``fd`` was bound. This is contrary to the ``events`` field
-    ## of the ``TReadyInfo`` tuple which determines which events are ready
+    ## of the ``ReadyInfo`` tuple which determines which events are ready
     ## on the ``fd``.
 
   proc newSelector*(): Selector =
@@ -72,10 +73,10 @@ when defined(nimdoc):
 
 elif defined(linux):
   type
-    Selector* = ref object
+    Selector* = object
       epollFD: cint
       events: array[64, epoll_event]
-      fds: Table[SocketHandle, SelectorKey]
+      fds: SharedTable[SocketHandle, SelectorKey]
 
   proc createEventStruct(events: set[Event], fd: SocketHandle): epoll_event =
     if EvRead in events:
@@ -86,7 +87,7 @@ elif defined(linux):
     result.data.fd = fd.cint
 
   proc register*(s: Selector, fd: SocketHandle, events: set[Event],
-      data: RootRef): SelectorKey {.discardable.} =
+      data: pointer) =
     var event = createEventStruct(events, fd)
     if events != {}:
       if epoll_ctl(s.epollFD, EPOLL_CTL_ADD, fd, addr(event)) != 0:
@@ -95,10 +96,8 @@ elif defined(linux):
     var key = SelectorKey(fd: fd, events: events, data: data)
 
     s.fds[fd] = key
-    result = key
 
-  proc update*(s: Selector, fd: SocketHandle,
+  proc update*(s: var Selector, fd: SocketHandle, events: set[Event]) =
-      events: set[Event]): SelectorKey {.discardable.} =
     if s.fds[fd].events != events:
       if events == {}:
         # This fd is idle -- it should not be registered to epoll.
@@ -108,7 +107,7 @@ elif defined(linux):
         # are therefore constantly ready. (leading to 100% CPU usage).
         if epoll_ctl(s.epollFD, EPOLL_CTL_DEL, fd, nil) != 0:
           raiseOSError(osLastError())
-        s.fds[fd].events = events
+        s.fds.mget(fd).events = events
       else:
         var event = createEventStruct(events, fd)
         if s.fds[fd].events == {}:
@@ -119,21 +118,19 @@ elif defined(linux):
         else:
           if epoll_ctl(s.epollFD, EPOLL_CTL_MOD, fd, addr(event)) != 0:
             raiseOSError(osLastError())
-        s.fds[fd].events = events
+        s.fds.mget(fd).events = events
 
-      result = s.fds[fd]
+  proc unregister*(s: var Selector, fd: SocketHandle) =
-  
-  proc unregister*(s: Selector, fd: SocketHandle): SelectorKey {.discardable.} =
     if epoll_ctl(s.epollFD, EPOLL_CTL_DEL, fd, nil) != 0:
       let err = osLastError()
-      if err.cint notin {ENOENT, EBADF}: # TODO: Why do we sometimes get an EBADF? Is this normal?
+      if err.cint notin {ENOENT, EBADF}:
+        # TODO: Why do we sometimes get an EBADF? Is this normal?
         raiseOSError(err)
-    result = s.fds[fd]
     s.fds.del(fd)
 
-  proc close*(s: Selector) =
+  proc close*(s: var Selector) =
+    deinitSharedTable(s.fds)
     if s.epollFD.close() != 0: raiseOSError(osLastError())
-    dealloc(addr s.events) # TODO: Test this
 
   proc epollHasFd(s: Selector, fd: SocketHandle): bool =
     result = true
@@ -142,9 +139,9 @@ elif defined(linux):
       let err = osLastError()
       if err.cint in {ENOENT, EBADF}:
         return false
-      raiseOSError(osLastError())
+      raiseOSError(err)
 
-  proc select*(s: Selector, timeout: int): seq[ReadyInfo] =
+  proc select*(s: var Selector, timeout: int): seq[ReadyInfo] =
     ##
     ## The ``events`` field of the returned ``key`` contains the original events
     ## for which the ``fd`` was bound. This is contrary to the ``events`` field
@@ -156,7 +153,7 @@ elif defined(linux):
       let err = osLastError()
       if err.cint == EINTR:
         return @[]
-      raiseOSError(osLastError())
+      raiseOSError(err)
     if evNum == 0: return @[]
     for i in 0 .. <evNum:
       let fd = s.events[i].data.fd.SocketHandle
@@ -172,12 +169,10 @@ elif defined(linux):
       #echo("Epoll: ", result[i].key.fd, " ", result[i].events, " ", result[i].key.events)
 
   proc newSelector*(): Selector =
-    new result
     result.epollFD = epoll_create(64)
-    #result.events = cast[array[64, epoll_event]](alloc0(sizeof(epoll_event)*64))
-    result.fds = initTable[SocketHandle, SelectorKey]()
     if result.epollFD < 0:
       raiseOSError(osLastError())
+    result.fds = initSharedTable[SocketHandle, SelectorKey]()
 
   proc contains*(s: Selector, fd: SocketHandle): bool =
     ## Determines whether selector contains a file descriptor.
@@ -196,31 +191,27 @@ elif defined(linux):
 
 elif not defined(nimdoc):
   # TODO: kqueue for bsd/mac os x.
+  import sharedtables
+
   type
-    Selector* = ref object
+    Selector* = object
-      fds: Table[SocketHandle, SelectorKey]
+      fds: SharedTable[SocketHandle, SelectorKey]
 
-  proc register*(s: Selector, fd: SocketHandle, events: set[Event],
+  proc register*(s: var Selector, fd: SocketHandle, events: set[Event],
-      data: RootRef): SelectorKey {.discardable.} =
+                 data: pointer) =
-    if s.fds.hasKey(fd):
+    let result = SelectorKey(fd: fd, events: events, data: data)
+    if s.fds.hasKeyOrPut(fd, result):
       raise newException(ValueError, "File descriptor already exists.")
-    var sk = SelectorKey(fd: fd, events: events, data: data)
-    s.fds[fd] = sk
-    result = sk
 
-  proc update*(s: Selector, fd: SocketHandle,
+  proc update*(s: var Selector, fd: SocketHandle, events: set[Event]) =
-      events: set[Event]): SelectorKey {.discardable.} =
+    #if not s.fds.hasKey(fd):
-    if not s.fds.hasKey(fd):
+    #  raise newException(ValueError, "File descriptor not found.")
-      raise newException(ValueError, "File descriptor not found.")
+    s.fds.mget(fd).events = events
 
-    s.fds[fd].events = events
+  proc unregister*(s: var Selector, fd: SocketHandle) =
-    result = s.fds[fd]
-
-  proc unregister*(s: Selector, fd: SocketHandle): SelectorKey {.discardable.} =
-    result = s.fds[fd]
     s.fds.del(fd)
 
-  proc close*(s: Selector) = discard
+  proc close*(s: var Selector) = deinitSharedTable(s.fds)
 
   proc timeValFromMilliseconds(timeout: int): TimeVal =
     if timeout != -1:
@@ -228,7 +219,7 @@ elif not defined(nimdoc):
       result.tv_sec = seconds.int32
       result.tv_usec = ((timeout - seconds * 1000) * 1000).int32
 
-  proc createFdSet(rd, wr: var TFdSet, fds: Table[SocketHandle, SelectorKey],
+  proc createFdSet(rd, wr: var TFdSet, fds: SharedTable[SocketHandle, SelectorKey],
       m: var int) =
     FD_ZERO(rd); FD_ZERO(wr)
     for k, v in pairs(fds):
@@ -239,8 +230,8 @@ elif not defined(nimdoc):
         m = max(m, int(k))
         FD_SET(k, wr)
 
-  proc getReadyFDs(rd, wr: var TFdSet, fds: Table[SocketHandle, SelectorKey]):
+  proc getReadyFDs(rd, wr: var TFdSet,
-      seq[ReadyInfo] =
+                   fds: SharedTable[SocketHandle, SelectorKey]): seq[ReadyInfo] =
     result = @[]
     for k, v in pairs(fds):
       var events: set[Event] = {}
@@ -250,8 +241,8 @@ elif not defined(nimdoc):
         events = events + {EvWrite}
       result.add((v, events))
 
-  proc select(fds: Table[SocketHandle, SelectorKey], timeout = 500):
+  proc select(fds: var SharedTable[SocketHandle, SelectorKey],
-    seq[ReadyInfo] =
+              timeout = 500): seq[ReadyInfo] =
     var tv {.noInit.}: TimeVal = timeValFromMilliseconds(timeout)
 
     var rd, wr: TFdSet
@@ -275,8 +266,7 @@ elif not defined(nimdoc):
     result = select(s.fds, timeout)
 
   proc newSelector*(): Selector =
-    new result
+    result.fds = initSharedTable[SocketHandle, SelectorKey]()
-    result.fds = initTable[SocketHandle, SelectorKey]()
 
   proc contains*(s: Selector, fd: SocketHandle): bool =
     return s.fds.hasKey(fd)
@@ -300,7 +290,7 @@ when not defined(testing) and isMainModule and not defined(nimdoc):
   # Select()
   import sockets
   type
-    SockWrapper = ref object of RootObj
+    SockWrapper = object
       sock: Socket
 
   var sock = socket()
@@ -310,7 +300,7 @@ when not defined(testing) and isMainModule and not defined(nimdoc):
 
   var selector = newSelector()
   var data = SockWrapper(sock: sock)
-  let key = selector.register(sock.getFD, {EvWrite}, data)
+  let key = selector.register(sock.getFD, {EvWrite}, addr data)
   var i = 0
   while true:
     let ready = selector.select(1000)