some changes

compiler/ast.nim

@@ -560,7 +560,7 @@ type
     mFloat, mFloat32, mFloat64, mFloat128,
     mBool, mChar, mString, mCstring,
     mPointer, mEmptySet, mIntSetBaseType, mNil, mExpr, mStmt, mTypeDesc,
-    mVoidType, mPNimrodNode, mShared, mGuarded, mLock, mSpawn,
+    mVoidType, mPNimrodNode, mShared, mGuarded, mLock, mSpawn, mDeepCopy,
     mIsMainModule, mCompileDate, mCompileTime, mNimrodVersion, mNimrodMajor,
     mNimrodMinor, mNimrodPatch, mCpuEndian, mHostOS, mHostCPU, mAppType,
     mNaN, mInf, mNegInf,

compiler/semtypes.nim

@@ -1087,7 +1087,7 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
     elif n[0].kind notin nkIdentKinds:
       result = semTypeExpr(c, n)
     else:
-      let op = considerAcc(n.sons[0])
+      let op = considerQuotedIdent(n.sons[0])
       if op.id in {ord(wAnd), ord(wOr)} or op.s == "|":
         checkSonsLen(n, 3)
         var

doc/spawn.txt

@@ -6,6 +6,8 @@ Nimrod has two flavors of parallelism:
 1) `Structured`:idx parallelism via the ``parallel`` statement.
 2) `Unstructured`:idx: parallelism via the standalone ``spawn`` statement.
 
+Both need the `threadpool <threadpool.html>`_ module to work.
+
 Somewhat confusingly, ``spawn`` is also used in the ``parallel`` statement
 with slightly different semantics. ``spawn`` always takes a call expression of
 the form ``f(a, ...)``. Let ``T`` be ``f``'s return type. If ``T`` is ``void``
@@ -20,6 +22,25 @@ the overhead of an indirection via ``FlowVar[T]`` to ensure correctness.
 Parallel statement
 ==================
 
+Example:
+
+.. code-block:: nimrod
+  # Compute PI in an inefficient way
+  import strutils, math, threadpool
+
+  proc term(k: float): float = 4 * math.pow(-1, k) / (2*k + 1)
+
+  proc pi(n: int): float =
+    var ch = newSeq[float](n+1)
+    parallel:
+      for k in 0..ch.high:
+        ch[k] = spawn term(float(k))
+    for k in 0..ch.high:
+      result += ch[k]
+
+  echo formatFloat(pi(5000))
+
+
 The parallel statement is the preferred mechanism to introduce parallelism
 in a Nimrod program. A subset of the Nimrod language is valid within a
 ``parallel`` section. This subset is checked to be free of data races at
@@ -30,17 +51,21 @@ The subset is in fact the full language with the following
 restrictions / changes:
 
 * ``spawn`` within a ``parallel`` section has special semantics.
-* Every location of the form ``a[i]`` and ``a[i..j]`` and ``dest`` where 
+* Every location of the form ``a[i]`` and ``a[i..j]`` and ``dest`` where
   ``dest`` is part of the pattern ``dest = spawn f(...)`` has to be
   provable disjoint. This is called the *disjoint check*.
-* Every other complex location ``loc`` that is used in a spawned 
-  proc (``spawn f(loc)``) has to immutable for the duration of
-  the ``parallel``. This is called the *immutability check*. Currently it
-  is not specified what exactly "complex location" means. We need to make that
-  an optimization!
-* Every array access has to be provable within bounds.
+* Every other complex location ``loc`` that is used in a spawned
+  proc (``spawn f(loc)``) has to be immutable for the duration of
+  the ``parallel`` section. This is called the *immutability check*. Currently
+  it is not specified what exactly "complex location" means. We need to make
+  this an optimization!
+* Every array access has to be provable within bounds. This is called 
+  the *bounds check*.
 * Slices are optimized so that no copy is performed. This optimization is not
-  yet performed for ordinary slices outside of a ``parallel`` section.
+  yet performed for ordinary slices outside of a ``parallel`` section. Slices
+  are also special in that they currently do not support negative indexes!
+
+
 
 
 Spawn statement
@@ -49,9 +74,25 @@ Spawn statement
 A standalone ``spawn`` statement is a simple construct. It executes
 the passed expression on the thread pool and returns a `data flow variable`:idx:
 ``FlowVar[T]`` that can be read from. The reading with the ``^`` operator is
-**blocking**. However, one can use ``awaitAny`` to wait on multiple flow variables
-at the same time.
+**blocking**. However, one can use ``awaitAny`` to wait on multiple flow
+variables at the same time:
+
+.. code-block:: nimrod
+  import threadpool, ...
+  
+  # wait until 2 out of 3 servers received the update:
+  proc main =
+    var responses = newSeq[RawFlowVar](3)
+    for i in 0..2:
+      responses[i] = spawn tellServer(Update, "key", "value")
+    var index = awaitAny(responses)
+    assert index >= 0
+    responses.del(index)
+    discard awaitAny(responses)
 
 Like the ``parallel`` statement data flow variables ensure that no data races
-are possible.
+are possible. Due to technical limitations not every type ``T`` is possible in
+a data flow variable: ``T`` has to be of the type ``ref``, ``string``, ``seq``
+or of a type that doesn't contain a type that is garbage collected. This
+restriction will be removed in the future.
 

lib/pure/concurrency/threadpool.nim

@@ -47,7 +47,7 @@ type
     entered: int
     cv: CondVar # condvar takes 3 words at least
     when sizeof(int) < 8:
-      cacheAlign: array[CacheLineSize-4*sizeof(int), byte] 
+      cacheAlign: array[CacheLineSize-4*sizeof(int), byte]
     left: int
     cacheAlign2: array[CacheLineSize-sizeof(int), byte]
     interest: bool ## wether the master is interested in the "all done" event
@@ -90,8 +90,8 @@ type
     cv: CondVar
     idx: int
 
-  RawFlowVar* = ref RawFlowVarObj ## untyped base class for 'FlowVar[T]'
-  RawFlowVarObj = object of TObject
+  FlowVarBase* = ref FlowVarBaseObj ## untyped base class for 'FlowVar[T]'
+  FlowVarBaseObj = object of TObject
     ready, usesCondVar: bool
     cv: CondVar #\
     # for 'awaitAny' support
@@ -100,7 +100,7 @@ type
     data: pointer  # we incRef and unref it to keep it alive
     owner: pointer # ptr Worker
 
-  FlowVarObj[T] = object of RawFlowVarObj
+  FlowVarObj[T] = object of FlowVarBaseObj
     blob: T
 
   FlowVar*{.compilerProc.}[T] = ref FlowVarObj[T] ## a data flow variable
@@ -123,7 +123,7 @@ type
     shutdown: bool # the pool requests to shut down this worker thread
     q: ToFreeQueue
 
-proc await*(fv: RawFlowVar) =
+proc await*(fv: FlowVarBase) =
   ## waits until the value for the flowVar arrives. Usually it is not necessary
   ## to call this explicitly.
   if fv.usesCondVar:
@@ -131,7 +131,7 @@ proc await*(fv: RawFlowVar) =
     await(fv.cv)
     destroyCondVar(fv.cv)
 
-proc finished(fv: RawFlowVar) =
+proc finished(fv: FlowVarBase) =
   doAssert fv.ai.isNil, "flowVar is still attached to an 'awaitAny'"
   # we have to protect against the rare cases where the owner of the flowVar
   # simply disregards the flowVar and yet the "flowVarr" has not yet written
@@ -171,11 +171,11 @@ proc fvFinalizer[T](fv: FlowVar[T]) = finished(fv)
 proc nimCreateFlowVar[T](): FlowVar[T] {.compilerProc.} =
   new(result, fvFinalizer)
 
-proc nimFlowVarCreateCondVar(fv: RawFlowVar) {.compilerProc.} =
+proc nimFlowVarCreateCondVar(fv: FlowVarBase) {.compilerProc.} =
   fv.cv = createCondVar()
   fv.usesCondVar = true
 
-proc nimFlowVarSignal(fv: RawFlowVar) {.compilerProc.} =
+proc nimFlowVarSignal(fv: FlowVarBase) {.compilerProc.} =
   if fv.ai != nil:
     acquire(fv.ai.cv.L)
     fv.ai.idx = fv.idx
@@ -211,7 +211,7 @@ proc `^`*[T](fv: FlowVar[T]): T =
   else:
     result = fv.blob
 
-proc awaitAny*(flowVars: openArray[RawFlowVar]): int =
+proc awaitAny*(flowVars: openArray[FlowVarBase]): int =
   ## awaits any of the given flowVars. Returns the index of one flowVar for
   ## which a value arrived. A flowVar only supports one call to 'awaitAny' at
   ## the same time. That means if you await([a,b]) and await([b,c]) the second

lib/system.nim

@@ -2942,6 +2942,10 @@ proc locals*(): TObject {.magic: "Locals", noSideEffect.} =
   ##   # -> B is 1
   discard
 
+proc deepCopy*[T](x: T): T {.magic: "DeepCopy", noSideEffect.}
+  ## performs a deep copy of `x`. This is also used by the code generator
+  ## for the implementation of ``spawn``.
+
 when not defined(booting):
   type
     semistatic*[T] = static[T] | T

tests/parallel/tpi.nim

@@ -8,7 +8,7 @@ import strutils, math, threadpool
 proc term(k: float): float = 4 * math.pow(-1, k) / (2*k + 1)
 
 proc piU(n: int): float =
-  var ch = newSeq[Promise[float]](n+1)
+  var ch = newSeq[FlowVar[float]](n+1)
   for k in 0..n:
     ch[k] = spawn term(float(k))
   for k in 0..n:

todo.txt

@@ -4,15 +4,15 @@ version 0.9.6
 Concurrency
 -----------
 
-- document the new 'spawn' and 'parallel' statements
+- the disjoint checker needs to deal with 'a = spawn f(); g = spawn f()'
 - implement 'deepCopy' builtin
 - implement 'foo[1..4] = spawn(f[4..7])'
-- the disjoint checker needs to deal with 'a = spawn f(); g = spawn f()'
 - support for exception propagation
 - Minor: The copying of the 'ref Promise' into the thead local storage only
   happens to work due to the write barrier's implementation
 - 'gcsafe' inferrence needs to be fixed
 - implement lock levels --> first without the more complex race avoidance
+- document the new 'spawn' and 'parallel' statements
 
 
 Misc