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|
#
#
# The Nim Compiler
# (c) Copyright 2015 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module implements threadpool's ``spawn``.
import ast, types, idents, magicsys, msgs, options, modulegraphs,
lowerings, liftdestructors, renderer
from trees import getMagic, getRoot
proc callProc(a: PNode): PNode =
result = newNodeI(nkCall, a.info)
result.add a
result.typ = a.typ.returnType
# we have 4 cases to consider:
# - a void proc --> nothing to do
# - a proc returning GC'ed memory --> requires a flowVar
# - a proc returning non GC'ed memory --> pass as hidden 'var' parameter
# - not in a parallel environment --> requires a flowVar for memory safety
type
TSpawnResult* = enum
srVoid, srFlowVar, srByVar
TFlowVarKind = enum
fvInvalid # invalid type T for 'FlowVar[T]'
fvGC # FlowVar of a GC'ed type
fvBlob # FlowVar of a blob type
proc spawnResult*(t: PType; inParallel: bool): TSpawnResult =
if t.isEmptyType: srVoid
elif inParallel and not containsGarbageCollectedRef(t): srByVar
else: srFlowVar
proc flowVarKind(c: ConfigRef, t: PType): TFlowVarKind =
if c.selectedGC in {gcArc, gcOrc, gcAtomicArc}: fvBlob
elif t.skipTypes(abstractInst).kind in {tyRef, tyString, tySequence}: fvGC
elif containsGarbageCollectedRef(t): fvInvalid
else: fvBlob
proc typeNeedsNoDeepCopy(t: PType): bool =
var t = t.skipTypes(abstractInst)
# for the tconvexhull example (and others) we're a bit lax here and pretend
# seqs and strings are *by value* only and 'shallow' doesn't exist!
if t.kind == tyString: return true
# note that seq[T] is fine, but 'var seq[T]' is not, so we need to skip 'var'
# for the stricter check and likewise we can skip 'seq' for a less
# strict check:
if t.kind in {tyVar, tyLent, tySequence}: t = t.elementType
result = not containsGarbageCollectedRef(t)
proc addLocalVar(g: ModuleGraph; varSection, varInit: PNode; idgen: IdGenerator; owner: PSym; typ: PType;
v: PNode; useShallowCopy=false): PSym =
result = newSym(skTemp, getIdent(g.cache, genPrefix), idgen, owner, varSection.info,
owner.options)
result.typ = typ
incl(result.flags, sfFromGeneric)
var vpart = newNodeI(nkIdentDefs, varSection.info, 3)
vpart[0] = newSymNode(result)
vpart[1] = newNodeI(nkEmpty, varSection.info)
vpart[2] = if varInit.isNil: v else: vpart[1]
varSection.add vpart
if varInit != nil:
if g.config.selectedGC in {gcArc, gcOrc, gcAtomicArc}:
# inject destructors pass will do its own analysis
varInit.add newFastMoveStmt(g, newSymNode(result), v)
else:
if useShallowCopy and typeNeedsNoDeepCopy(typ) or optTinyRtti in g.config.globalOptions:
varInit.add newFastMoveStmt(g, newSymNode(result), v)
else:
let deepCopyCall = newNodeI(nkCall, varInit.info, 3)
deepCopyCall[0] = newSymNode(getSysMagic(g, varSection.info, "deepCopy", mDeepCopy))
deepCopyCall[1] = newSymNode(result)
deepCopyCall[2] = v
varInit.add deepCopyCall
discard """
We generate roughly this:
proc f_wrapper(thread, args) =
barrierEnter(args.barrier) # for parallel statement
var a = args.a # thread transfer; deepCopy or shallowCopy or no copy
# depending on whether we're in a 'parallel' statement
var b = args.b
var fv = args.fv
fv.owner = thread # optional
nimArgsPassingDone() # signal parent that the work is done
#
args.fv.blob = f(a, b, ...)
nimFlowVarSignal(args.fv)
# - or -
f(a, b, ...)
barrierLeave(args.barrier) # for parallel statement
stmtList:
var scratchObj
scratchObj.a = a
scratchObj.b = b
nimSpawn(f_wrapper, addr scratchObj)
scratchObj.fv # optional
"""
proc castToVoidPointer(g: ModuleGraph, n: PNode, fvField: PNode): PNode =
if g.config.backend == backendCpp:
result = fvField
else:
let ptrType = getSysType(g, n.info, tyPointer)
result = newNodeI(nkCast, fvField.info)
result.add newNodeI(nkEmpty, fvField.info)
result.add fvField
result.typ = ptrType
proc createWrapperProc(g: ModuleGraph; f: PNode; threadParam, argsParam: PSym;
varSection, varInit, call, barrier, fv: PNode;
idgen: IdGenerator;
spawnKind: TSpawnResult, result: PSym) =
var body = newNodeI(nkStmtList, f.info)
var threadLocalBarrier: PSym = nil
if barrier != nil:
var varSection2 = newNodeI(nkVarSection, barrier.info)
threadLocalBarrier = addLocalVar(g, varSection2, nil, idgen, result,
barrier.typ, barrier)
body.add varSection2
body.add callCodegenProc(g, "barrierEnter", threadLocalBarrier.info,
threadLocalBarrier.newSymNode)
var threadLocalProm: PSym = nil
if spawnKind == srByVar:
threadLocalProm = addLocalVar(g, varSection, nil, idgen, result, fv.typ, fv)
elif fv != nil:
internalAssert g.config, fv.typ.kind == tyGenericInst
threadLocalProm = addLocalVar(g, varSection, nil, idgen, result, fv.typ, fv)
body.add varSection
body.add varInit
if fv != nil and spawnKind != srByVar:
# generate:
# fv.owner = threadParam
body.add newAsgnStmt(indirectAccess(threadLocalProm.newSymNode,
"owner", fv.info, g.cache), threadParam.newSymNode)
body.add callCodegenProc(g, "nimArgsPassingDone", threadParam.info,
threadParam.newSymNode)
if spawnKind == srByVar:
body.add newAsgnStmt(genDeref(threadLocalProm.newSymNode), call)
elif fv != nil:
let fk = flowVarKind(g.config, fv.typ.firstGenericParam)
if fk == fvInvalid:
localError(g.config, f.info, "cannot create a flowVar of type: " &
typeToString(fv.typ.firstGenericParam))
body.add newAsgnStmt(indirectAccess(threadLocalProm.newSymNode,
if fk == fvGC: "data" else: "blob", fv.info, g.cache), call)
if fk == fvGC:
let incRefCall = newNodeI(nkCall, fv.info, 2)
incRefCall[0] = newSymNode(getSysMagic(g, fv.info, "GCref", mGCref))
incRefCall[1] = indirectAccess(threadLocalProm.newSymNode,
"data", fv.info, g.cache)
body.add incRefCall
if barrier == nil:
# by now 'fv' is shared and thus might have beeen overwritten! we need
# to use the thread-local view instead:
let castExpr = castToVoidPointer(g, f, threadLocalProm.newSymNode)
body.add callCodegenProc(g, "nimFlowVarSignal", threadLocalProm.info,
castExpr)
else:
body.add call
if barrier != nil:
body.add callCodegenProc(g, "barrierLeave", threadLocalBarrier.info,
threadLocalBarrier.newSymNode)
var params = newNodeI(nkFormalParams, f.info)
params.add newNodeI(nkEmpty, f.info)
params.add threadParam.newSymNode
params.add argsParam.newSymNode
var t = newType(tyProc, idgen, threadParam.owner)
t.rawAddSon nil
t.rawAddSon threadParam.typ
t.rawAddSon argsParam.typ
t.n = newNodeI(nkFormalParams, f.info)
t.n.add newNodeI(nkEffectList, f.info)
t.n.add threadParam.newSymNode
t.n.add argsParam.newSymNode
let emptyNode = newNodeI(nkEmpty, f.info)
result.ast = newProcNode(nkProcDef, f.info, body = body,
params = params, name = newSymNode(result), pattern = emptyNode,
genericParams = emptyNode, pragmas = emptyNode,
exceptions = emptyNode)
result.typ = t
proc createCastExpr(argsParam: PSym; objType: PType; idgen: IdGenerator): PNode =
result = newNodeI(nkCast, argsParam.info)
result.add newNodeI(nkEmpty, argsParam.info)
result.add newSymNode(argsParam)
result.typ = newType(tyPtr, idgen, objType.owner)
result.typ.rawAddSon(objType)
template checkMagicProcs(g: ModuleGraph, n: PNode, formal: PNode) =
if (formal.typ.kind == tyVarargs and formal.typ.elementType.kind in {tyTyped, tyUntyped}) or
formal.typ.kind in {tyTyped, tyUntyped}:
localError(g.config, n.info, "'spawn'ed function cannot have a 'typed' or 'untyped' parameter")
proc setupArgsForConcurrency(g: ModuleGraph; n: PNode; objType: PType;
idgen: IdGenerator; owner: PSym; scratchObj: PSym,
castExpr, call,
varSection, varInit, result: PNode) =
let formals = n[0].typ.n
let tmpName = getIdent(g.cache, genPrefix)
for i in 1..<n.len:
# we pick n's type here, which hopefully is 'tyArray' and not
# 'tyOpenArray':
var argType = n[i].typ.skipTypes(abstractInst)
if i < formals.len:
if formals[i].typ.kind in {tyVar, tyLent}:
localError(g.config, n[i].info, "'spawn'ed function cannot have a 'var' parameter")
checkMagicProcs(g, n[i], formals[i])
if formals[i].typ.kind in {tyTypeDesc, tyStatic}:
continue
#elif containsTyRef(argType):
# localError(n[i].info, "'spawn'ed function cannot refer to 'ref'/closure")
let fieldname = if i < formals.len: formals[i].sym.name else: tmpName
var field = newSym(skField, fieldname, idgen, objType.owner, n.info, g.config.options)
field.typ = argType
discard objType.addField(field, g.cache, idgen)
result.add newFastAsgnStmt(newDotExpr(scratchObj, field), n[i])
let temp = addLocalVar(g, varSection, varInit, idgen, owner, argType,
indirectAccess(castExpr, field, n.info))
call.add(newSymNode(temp))
proc setupArgsForParallelism(g: ModuleGraph; n: PNode; objType: PType;
idgen: IdGenerator;
owner: PSym; scratchObj: PSym;
castExpr, call,
varSection, varInit, result: PNode) =
let formals = n[0].typ.n
let tmpName = getIdent(g.cache, genPrefix)
# we need to copy the foreign scratch object fields into local variables
# for correctness: These are called 'threadLocal' here.
for i in 1..<n.len:
let n = n[i]
if i < formals.len and formals[i].typ.kind in {tyStatic, tyTypeDesc}:
continue
checkMagicProcs(g, n, formals[i])
let argType = skipTypes(if i < formals.len: formals[i].typ else: n.typ,
abstractInst)
#if containsTyRef(argType):
# localError(n.info, "'spawn'ed function cannot refer to 'ref'/closure")
let fieldname = if i < formals.len: formals[i].sym.name else: tmpName
var field = newSym(skField, fieldname, idgen, objType.owner, n.info, g.config.options)
if argType.kind in {tyVarargs, tyOpenArray}:
# important special case: we always create a zero-copy slice:
let slice = newNodeI(nkCall, n.info, 4)
slice.typ = n.typ
slice[0] = newSymNode(createMagic(g, idgen, "slice", mSlice))
slice[0].typ = getSysType(g, n.info, tyInt) # fake type
var fieldB = newSym(skField, tmpName, idgen, objType.owner, n.info, g.config.options)
fieldB.typ = getSysType(g, n.info, tyInt)
discard objType.addField(fieldB, g.cache, idgen)
if getMagic(n) == mSlice:
let a = genAddrOf(n[1], idgen)
field.typ = a.typ
discard objType.addField(field, g.cache, idgen)
result.add newFastAsgnStmt(newDotExpr(scratchObj, field), a)
var fieldA = newSym(skField, tmpName, idgen, objType.owner, n.info, g.config.options)
fieldA.typ = getSysType(g, n.info, tyInt)
discard objType.addField(fieldA, g.cache, idgen)
result.add newFastAsgnStmt(newDotExpr(scratchObj, fieldA), n[2])
result.add newFastAsgnStmt(newDotExpr(scratchObj, fieldB), n[3])
let threadLocal = addLocalVar(g, varSection, nil, idgen, owner, fieldA.typ,
indirectAccess(castExpr, fieldA, n.info),
useShallowCopy=true)
slice[2] = threadLocal.newSymNode
else:
let a = genAddrOf(n, idgen)
field.typ = a.typ
discard objType.addField(field, g.cache, idgen)
result.add newFastAsgnStmt(newDotExpr(scratchObj, field), a)
result.add newFastAsgnStmt(newDotExpr(scratchObj, fieldB), genHigh(g, n))
slice[2] = newIntLit(g, n.info, 0)
# the array itself does not need to go through a thread local variable:
slice[1] = genDeref(indirectAccess(castExpr, field, n.info))
let threadLocal = addLocalVar(g, varSection, nil, idgen, owner, fieldB.typ,
indirectAccess(castExpr, fieldB, n.info),
useShallowCopy=true)
slice[3] = threadLocal.newSymNode
call.add slice
elif (let size = computeSize(g.config, argType); size < 0 or size > 16) and
n.getRoot != nil:
# it is more efficient to pass a pointer instead:
let a = genAddrOf(n, idgen)
field.typ = a.typ
discard objType.addField(field, g.cache, idgen)
result.add newFastAsgnStmt(newDotExpr(scratchObj, field), a)
let threadLocal = addLocalVar(g, varSection, nil, idgen, owner, field.typ,
indirectAccess(castExpr, field, n.info),
useShallowCopy=true)
call.add(genDeref(threadLocal.newSymNode))
else:
# boring case
field.typ = argType
discard objType.addField(field, g.cache, idgen)
result.add newFastAsgnStmt(newDotExpr(scratchObj, field), n)
let threadLocal = addLocalVar(g, varSection, varInit,
idgen, owner, field.typ,
indirectAccess(castExpr, field, n.info),
useShallowCopy=true)
call.add(threadLocal.newSymNode)
proc wrapProcForSpawn*(g: ModuleGraph; idgen: IdGenerator; owner: PSym; spawnExpr: PNode; retType: PType;
barrier: PNode = nil, dest: PNode = nil): PNode =
# if 'barrier' != nil, then it is in a 'parallel' section and we
# generate quite different code
let n = spawnExpr[^2]
let spawnKind = spawnResult(retType, barrier!=nil)
case spawnKind
of srVoid:
internalAssert g.config, dest == nil
result = newNodeI(nkStmtList, n.info)
of srFlowVar:
internalAssert g.config, dest == nil
result = newNodeIT(nkStmtListExpr, n.info, retType)
of srByVar:
if dest == nil: localError(g.config, n.info, "'spawn' must not be discarded")
result = newNodeI(nkStmtList, n.info)
if n.kind notin nkCallKinds:
localError(g.config, n.info, "'spawn' takes a call expression; got: " & $n)
return
if optThreadAnalysis in g.config.globalOptions:
if {tfThread, tfNoSideEffect} * n[0].typ.flags == {}:
localError(g.config, n.info, "'spawn' takes a GC safe call expression")
var fn = n[0]
let
name = (if fn.kind == nkSym: fn.sym.name.s else: genPrefix) & "Wrapper"
wrapperProc = newSym(skProc, getIdent(g.cache, name), idgen, owner, fn.info, g.config.options)
threadParam = newSym(skParam, getIdent(g.cache, "thread"), idgen, wrapperProc, n.info, g.config.options)
argsParam = newSym(skParam, getIdent(g.cache, "args"), idgen, wrapperProc, n.info, g.config.options)
wrapperProc.flags.incl sfInjectDestructors
block:
let ptrType = getSysType(g, n.info, tyPointer)
threadParam.typ = ptrType
argsParam.typ = ptrType
argsParam.position = 1
var objType = createObj(g, idgen, owner, n.info)
incl(objType.flags, tfFinal)
let castExpr = createCastExpr(argsParam, objType, idgen)
var scratchObj = newSym(skVar, getIdent(g.cache, "scratch"), idgen, owner, n.info, g.config.options)
block:
scratchObj.typ = objType
incl(scratchObj.flags, sfFromGeneric)
var varSectionB = newNodeI(nkVarSection, n.info)
varSectionB.addVar(scratchObj.newSymNode)
result.add varSectionB
var call = newNodeIT(nkCall, n.info, n.typ)
# templates and macros are in fact valid here due to the nature of
# the transformation:
if fn.kind == nkClosure or (fn.typ != nil and fn.typ.callConv == ccClosure):
localError(g.config, n.info, "closure in spawn environment is not allowed")
if not (fn.kind == nkSym and fn.sym.kind in {skProc, skTemplate, skMacro,
skFunc, skMethod, skConverter}):
# for indirect calls we pass the function pointer in the scratchObj
var argType = n[0].typ.skipTypes(abstractInst)
var field = newSym(skField, getIdent(g.cache, "fn"), idgen, owner, n.info, g.config.options)
field.typ = argType
discard objType.addField(field, g.cache, idgen)
result.add newFastAsgnStmt(newDotExpr(scratchObj, field), n[0])
fn = indirectAccess(castExpr, field, n.info)
elif fn.kind == nkSym and fn.sym.kind == skIterator:
localError(g.config, n.info, "iterator in spawn environment is not allowed")
call.add(fn)
var varSection = newNodeI(nkVarSection, n.info)
var varInit = newNodeI(nkStmtList, n.info)
if barrier.isNil:
setupArgsForConcurrency(g, n, objType, idgen, wrapperProc, scratchObj, castExpr, call,
varSection, varInit, result)
else:
setupArgsForParallelism(g, n, objType, idgen, wrapperProc, scratchObj, castExpr, call,
varSection, varInit, result)
var barrierAsExpr: PNode = nil
if barrier != nil:
let typ = newType(tyPtr, idgen, owner)
typ.rawAddSon(magicsys.getCompilerProc(g, "Barrier").typ)
var field = newSym(skField, getIdent(g.cache, "barrier"), idgen, owner, n.info, g.config.options)
field.typ = typ
discard objType.addField(field, g.cache, idgen)
result.add newFastAsgnStmt(newDotExpr(scratchObj, field), barrier)
barrierAsExpr = indirectAccess(castExpr, field, n.info)
var fvField, fvAsExpr: PNode = nil
if spawnKind == srFlowVar:
var field = newSym(skField, getIdent(g.cache, "fv"), idgen, owner, n.info, g.config.options)
field.typ = retType
discard objType.addField(field, g.cache, idgen)
fvField = newDotExpr(scratchObj, field)
fvAsExpr = indirectAccess(castExpr, field, n.info)
# create flowVar:
result.add newFastAsgnStmt(fvField, callProc(spawnExpr[^1]))
if barrier == nil:
let castExpr = castToVoidPointer(g, n, fvField)
result.add callCodegenProc(g, "nimFlowVarCreateSemaphore", fvField.info, castExpr)
elif spawnKind == srByVar:
var field = newSym(skField, getIdent(g.cache, "fv"), idgen, owner, n.info, g.config.options)
field.typ = newType(tyPtr, idgen, objType.owner)
field.typ.rawAddSon(retType)
discard objType.addField(field, g.cache, idgen)
fvAsExpr = indirectAccess(castExpr, field, n.info)
result.add newFastAsgnStmt(newDotExpr(scratchObj, field), genAddrOf(dest, idgen))
createTypeBoundOps(g, nil, objType, n.info, idgen)
createWrapperProc(g, fn, threadParam, argsParam,
varSection, varInit, call,
barrierAsExpr, fvAsExpr, idgen, spawnKind, wrapperProc)
result.add callCodegenProc(g, "nimSpawn" & $spawnExpr.len, wrapperProc.info,
wrapperProc.newSymNode, genAddrOf(scratchObj.newSymNode, idgen), nil, spawnExpr)
if spawnKind == srFlowVar: result.add fvField
|
