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Diffstat (limited to 'lib/std/tasks.nim')
| -rw-r--r-- | lib/std/tasks.nim | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/lib/std/tasks.nim b/lib/std/tasks.nim new file mode 100644 index 000000000..7e59747f5 --- /dev/null +++ b/lib/std/tasks.nim @@ -0,0 +1,312 @@ +# +# +# Nim's Runtime Library +# (c) Copyright 2021 Nim contributors +# +# See the file "copying.txt", included in this +# distribution, for details about the copyright. +# + +## This module provides basic primitives for creating parallel programs. +## A `Task` should be only owned by a single Thread, it cannot be shared by threads. + +import std/[macros, isolation, typetraits] + +when defined(nimPreviewSlimSystem): + import std/assertions + +export isolation + + +when compileOption("threads"): + from std/effecttraits import isGcSafe + + +# +# proc hello(a: int, b: string) = +# echo $a & b +# +# let literal = "Nim" +# let t = toTask(hello(521, literal)) +# +# +# is roughly converted to +# +# type +# ScratchObj_369098780 = object +# a: int +# b: string +# +# let scratch_369098762 = cast[ptr ScratchObj_369098780](c_calloc(csize_t 1, +# csize_t sizeof(ScratchObj_369098780))) +# if scratch_369098762.isNil: +# raise newException(OutOfMemDefect, "Could not allocate memory") +# block: +# var isolate_369098776 = isolate(521) +# scratch_369098762.a = extract(isolate_369098776) +# var isolate_369098778 = isolate(literal) +# scratch_369098762.b = extract(isolate_369098778) +# proc hello_369098781(args`gensym3: pointer) {.nimcall.} = +# let objTemp_369098775 = cast[ptr ScratchObj_369098780](args`gensym3) +# let :tmp_369098777 = objTemp_369098775.a +# let :tmp_369098779 = objTemp_369098775.b +# hello(a = :tmp_369098777, b = :tmp_369098779) +# +# proc destroyScratch_369098782(args`gensym3: pointer) {.nimcall.} = +# let obj_369098783 = cast[ptr ScratchObj_369098780](args`gensym3) +# =destroy(obj_369098783[]) +# let t = Task(callback: hello_369098781, args: scratch_369098762, destroy: destroyScratch_369098782) +# + + +type + Task* = object ## `Task` contains the callback and its arguments. + callback: proc (args, res: pointer) {.nimcall, gcsafe.} + args: pointer + destroy: proc (args: pointer) {.nimcall, gcsafe.} + + +proc `=copy`*(x: var Task, y: Task) {.error.} + +const arcLike = defined(gcArc) or defined(gcAtomicArc) or defined(gcOrc) +when defined(nimAllowNonVarDestructor) and arcLike: + proc `=destroy`*(t: Task) {.inline, gcsafe.} = + ## Frees the resources allocated for a `Task`. + if t.args != nil: + if t.destroy != nil: + t.destroy(t.args) + deallocShared(t.args) +else: + proc `=destroy`*(t: var Task) {.inline, gcsafe.} = + ## Frees the resources allocated for a `Task`. + if t.args != nil: + if t.destroy != nil: + t.destroy(t.args) + deallocShared(t.args) + +proc invoke*(task: Task; res: pointer = nil) {.inline, gcsafe.} = + ## Invokes the `task`. + assert task.callback != nil + task.callback(task.args, res) + +template checkIsolate(scratchAssignList: seq[NimNode], procParam, scratchDotExpr: NimNode) = + # block: + # var isoTempA = isolate(521) + # scratch.a = extract(isolateA) + # var isoTempB = isolate(literal) + # scratch.b = extract(isolateB) + let isolatedTemp = genSym(nskTemp, "isoTemp") + scratchAssignList.add newVarStmt(isolatedTemp, newCall(newIdentNode("isolate"), procParam)) + scratchAssignList.add newAssignment(scratchDotExpr, + newCall(newIdentNode("extract"), isolatedTemp)) + +template addAllNode(assignParam: NimNode, procParam: NimNode) = + let scratchDotExpr = newDotExpr(scratchIdent, formalParams[i][0]) + + checkIsolate(scratchAssignList, procParam, scratchDotExpr) + + let tempNode = genSym(kind = nskTemp, ident = formalParams[i][0].strVal) + callNode.add nnkExprEqExpr.newTree(formalParams[i][0], tempNode) + tempAssignList.add newLetStmt(tempNode, newDotExpr(objTemp, formalParams[i][0])) + scratchRecList.add newIdentDefs(newIdentNode(formalParams[i][0].strVal), assignParam) + +proc analyseRootSym(s: NimNode): NimNode = + result = s + while true: + case result.kind + of nnkBracketExpr, nnkDerefExpr, nnkHiddenDeref, + nnkAddr, nnkHiddenAddr, + nnkObjDownConv, nnkObjUpConv: + result = result[0] + of nnkDotExpr, nnkCheckedFieldExpr, nnkHiddenStdConv, nnkHiddenSubConv: + result = result[1] + else: + break + +macro toTask*(e: typed{nkCall | nkInfix | nkPrefix | nkPostfix | nkCommand | nkCallStrLit}): Task = + ## Converts the call and its arguments to `Task`. + runnableExamples: + proc hello(a: int) = echo a + + let b = toTask hello(13) + assert b is Task + + let retType = getTypeInst(e) + let returnsVoid = retType.typeKind == ntyVoid + + let rootSym = analyseRootSym(e[0]) + expectKind rootSym, nnkSym + + when compileOption("threads"): + if not isGcSafe(rootSym): + error("'toTask' takes a GC safe call expression", e) + + if hasClosure(rootSym): + error("closure call is not allowed", e) + + if e.len > 1: + let scratchIdent = genSym(kind = nskTemp, ident = "scratch") + let impl = e[0].getTypeInst + + when defined(nimTasksDebug): + echo impl.treeRepr + echo e.treeRepr + let formalParams = impl[0] + + var + scratchRecList = newNimNode(nnkRecList) + scratchAssignList: seq[NimNode] + tempAssignList: seq[NimNode] + callNode: seq[NimNode] + + let + objTemp = genSym(nskTemp, ident = "objTemp") + + for i in 1 ..< formalParams.len: + var param = formalParams[i][1] + + if param.kind == nnkBracketExpr and param[0].eqIdent("sink"): + param = param[0] + + if param.typeKind in {ntyExpr, ntyStmt}: + error("'toTask'ed function cannot have a 'typed' or 'untyped' parameter", e) + + case param.kind + of nnkVarTy: + error("'toTask'ed function cannot have a 'var' parameter", e) + of nnkBracketExpr: + if param[0].typeKind == ntyTypeDesc: + callNode.add nnkExprEqExpr.newTree(formalParams[i][0], e[i]) + elif param[0].typeKind in {ntyVarargs, ntyOpenArray}: + if param[1].typeKind in {ntyExpr, ntyStmt}: + error("'toTask'ed function cannot have a 'typed' or 'untyped' parameter", e) + let + seqType = nnkBracketExpr.newTree(newIdentNode("seq"), param[1]) + seqCallNode = newCall("@", e[i]) + addAllNode(seqType, seqCallNode) + else: + addAllNode(param, e[i]) + of nnkBracket, nnkObjConstr: + # passing by static parameters + # so we pass them directly instead of passing by scratchObj + callNode.add nnkExprEqExpr.newTree(formalParams[i][0], e[i]) + of nnkSym, nnkPtrTy, nnkProcTy, nnkTupleConstr: + addAllNode(param, e[i]) + of nnkCharLit..nnkNilLit: + callNode.add nnkExprEqExpr.newTree(formalParams[i][0], e[i]) + else: + error("'toTask'ed function cannot have a parameter of " & $param.kind & " kind", e) + + let scratchObjType = genSym(kind = nskType, ident = "ScratchObj") + let scratchObj = nnkTypeSection.newTree( + nnkTypeDef.newTree( + scratchObjType, + newEmptyNode(), + nnkObjectTy.newTree( + newEmptyNode(), + newEmptyNode(), + scratchRecList + ) + ) + ) + + + let scratchObjPtrType = quote do: + cast[ptr `scratchObjType`](allocShared0(sizeof(`scratchObjType`))) + + let scratchLetSection = newLetStmt(scratchIdent, scratchObjPtrType) + + var stmtList = newStmtList() + stmtList.add(scratchObj) + stmtList.add(scratchLetSection) + stmtList.add(nnkBlockStmt.newTree(newEmptyNode(), newStmtList(scratchAssignList))) + + var functionStmtList = newStmtList() + let funcCall = newCall(e[0], callNode) + functionStmtList.add tempAssignList + + let funcName = genSym(nskProc, rootSym.strVal) + let destroyName = genSym(nskProc, "destroyScratch") + let objTemp2 = genSym(ident = "obj") + let tempNode = quote("@") do: + `=destroy`(@objTemp2[]) + + var funcDecl: NimNode + if returnsVoid: + funcDecl = quote do: + proc `funcName`(args, res: pointer) {.gcsafe, nimcall.} = + let `objTemp` = cast[ptr `scratchObjType`](args) + `functionStmtList` + `funcCall` + else: + funcDecl = quote do: + proc `funcName`(args, res: pointer) {.gcsafe, nimcall.} = + let `objTemp` = cast[ptr `scratchObjType`](args) + `functionStmtList` + cast[ptr `retType`](res)[] = `funcCall` + + result = quote do: + `stmtList` + + `funcDecl` + + proc `destroyName`(args: pointer) {.gcsafe, nimcall.} = + let `objTemp2` = cast[ptr `scratchObjType`](args) + `tempNode` + + Task(callback: `funcName`, args: `scratchIdent`, destroy: `destroyName`) + else: + let funcCall = newCall(e[0]) + let funcName = genSym(nskProc, rootSym.strVal) + + if returnsVoid: + result = quote do: + proc `funcName`(args, res: pointer) {.gcsafe, nimcall.} = + `funcCall` + + Task(callback: `funcName`, args: nil) + else: + result = quote do: + proc `funcName`(args, res: pointer) {.gcsafe, nimcall.} = + cast[ptr `retType`](res)[] = `funcCall` + + Task(callback: `funcName`, args: nil) + + + when defined(nimTasksDebug): + echo result.repr + +runnableExamples: + block: + var num = 0 + proc hello(a: int) = inc num, a + + let b = toTask hello(13) + b.invoke() + assert num == 13 + # A task can be invoked multiple times + b.invoke() + assert num == 26 + + block: + type + Runnable = ref object + data: int + + var data: int + proc hello(a: Runnable) {.nimcall.} = + a.data += 2 + data = a.data + + + when false: + # the parameters of call must be isolated. + let x = Runnable(data: 12) + let b = toTask hello(x) # error ----> expression cannot be isolated: x + b.invoke() + + let b = toTask(hello(Runnable(data: 12))) + b.invoke() + assert data == 14 + b.invoke() + assert data == 16 |