diff options
Diffstat (limited to 'lib/system/arc.nim')
| -rw-r--r-- | lib/system/arc.nim | 128 |
1 files changed, 78 insertions, 50 deletions
diff --git a/lib/system/arc.nim b/lib/system/arc.nim index ed5e9f5ca..d001fcaa5 100644 --- a/lib/system/arc.nim +++ b/lib/system/arc.nim @@ -12,26 +12,6 @@ In this new runtime we simplify the object layouts a bit: The runtime type information is only accessed for the objects that have it and it's always at offset 0 then. The ``ref`` object header is independent from the runtime type and only contains a reference count. - -Object subtyping is checked via the generated 'name'. This should have -comparable overhead to the old pointer chasing approach but has the benefit -that it works across DLL boundaries. - -The generated name is a concatenation of the object names in the hierarchy -so that a subtype check becomes a substring check. For example:: - - type - ObjectA = object of RootObj - ObjectB = object of ObjectA - -ObjectA's ``name`` is "|ObjectA|RootObj|". -ObjectB's ``name`` is "|ObjectB|ObjectA|RootObj|". - -Now to check for ``x of ObjectB`` we need to check -for ``x.typ.name.hasSubstring("|ObjectB|")``. In the actual implementation, -however, we could also use a -hash of ``package & "." & module & "." & name`` to save space. - ]# when defined(gcOrc): @@ -46,6 +26,9 @@ else: rcMask = 0b111 rcShift = 3 # shift by rcShift to get the reference counter +const + orcLeakDetector = defined(nimOrcLeakDetector) + type RefHeader = object rc: int # the object header is now a single RC field. @@ -56,9 +39,21 @@ type # in O(1) without doubly linked lists when defined(nimArcDebug) or defined(nimArcIds): refId: int + when defined(gcOrc) and orcLeakDetector: + filename: cstring + line: int Cell = ptr RefHeader +template setFrameInfo(c: Cell) = + when orcLeakDetector: + if framePtr != nil and framePtr.prev != nil: + c.filename = framePtr.prev.filename + c.line = framePtr.prev.line + else: + c.filename = nil + c.line = 0 + template head(p: pointer): Cell = cast[Cell](cast[int](p) -% sizeof(RefHeader)) @@ -77,6 +72,21 @@ elif defined(nimArcIds): const traceId = -1 +when defined(gcAtomicArc) and hasThreadSupport: + template decrement(cell: Cell): untyped = + discard atomicDec(cell.rc, rcIncrement) + template increment(cell: Cell): untyped = + discard atomicInc(cell.rc, rcIncrement) + template count(x: Cell): untyped = + atomicLoadN(x.rc.addr, ATOMIC_ACQUIRE) shr rcShift +else: + template decrement(cell: Cell): untyped = + dec(cell.rc, rcIncrement) + template increment(cell: Cell): untyped = + inc(cell.rc, rcIncrement) + template count(x: Cell): untyped = + x.rc shr rcShift + proc nimNewObj(size, alignment: int): pointer {.compilerRtl.} = let hdrSize = align(sizeof(RefHeader), alignment) let s = size + hdrSize @@ -89,9 +99,10 @@ proc nimNewObj(size, alignment: int): pointer {.compilerRtl.} = atomicInc gRefId if head(result).refId == traceId: writeStackTrace() - cfprintf(cstderr, "[nimNewObj] %p %ld\n", result, head(result).rc shr rcShift) + cfprintf(cstderr, "[nimNewObj] %p %ld\n", result, head(result).count) when traceCollector: cprintf("[Allocated] %p result: %p\n", result -! sizeof(RefHeader), result) + setFrameInfo head(result) proc nimNewObjUninit(size, alignment: int): pointer {.compilerRtl.} = # Same as 'newNewObj' but do not initialize the memory to zero. @@ -110,21 +121,34 @@ proc nimNewObjUninit(size, alignment: int): pointer {.compilerRtl.} = atomicInc gRefId if head(result).refId == traceId: writeStackTrace() - cfprintf(cstderr, "[nimNewObjUninit] %p %ld\n", result, head(result).rc shr rcShift) + cfprintf(cstderr, "[nimNewObjUninit] %p %ld\n", result, head(result).count) when traceCollector: cprintf("[Allocated] %p result: %p\n", result -! sizeof(RefHeader), result) + setFrameInfo head(result) proc nimDecWeakRef(p: pointer) {.compilerRtl, inl.} = - dec head(p).rc, rcIncrement + decrement head(p) + +proc isUniqueRef*[T](x: ref T): bool {.inline.} = + ## Returns true if the object `x` points to is uniquely referenced. Such + ## an object can potentially be passed over to a different thread safely, + ## if great care is taken. This queries the internal reference count of + ## the object which is subject to lots of optimizations! In other words + ## the value of `isUniqueRef` can depend on the used compiler version and + ## optimizer setting. + ## Nevertheless it can be used as a very valuable debugging tool and can + ## be used to specify the constraints of a threading related API + ## via `assert isUniqueRef(x)`. + head(cast[pointer](x)).rc == 0 proc nimIncRef(p: pointer) {.compilerRtl, inl.} = when defined(nimArcDebug): if head(p).refId == traceId: writeStackTrace() - cfprintf(cstderr, "[IncRef] %p %ld\n", p, head(p).rc shr rcShift) + cfprintf(cstderr, "[IncRef] %p %ld\n", p, head(p).count) - inc head(p).rc, rcIncrement + increment head(p) when traceCollector: cprintf("[INCREF] %p\n", head(p)) @@ -154,7 +178,7 @@ proc nimRawDispose(p: pointer, alignment: int) {.compilerRtl.} = when defined(nimOwnedEnabled): if head(p).rc >= rcIncrement: cstderr.rawWrite "[FATAL] dangling references exist\n" - quit 1 + rawQuit 1 when defined(nimArcDebug): # we do NOT really free the memory here in order to reliably detect use-after-frees if freedCells.data == nil: init(freedCells) @@ -193,24 +217,29 @@ proc nimDecRefIsLast(p: pointer): bool {.compilerRtl, inl.} = when defined(nimArcDebug): if cell.refId == traceId: writeStackTrace() - cfprintf(cstderr, "[DecRef] %p %ld\n", p, cell.rc shr rcShift) - - if (cell.rc and not rcMask) == 0: - result = true - when traceCollector: - cprintf("[ABOUT TO DESTROY] %p\n", cell) + cfprintf(cstderr, "[DecRef] %p %ld\n", p, cell.count) + + when defined(gcAtomicArc) and hasThreadSupport: + # `atomicDec` returns the new value + if atomicDec(cell.rc, rcIncrement) == -rcIncrement: + result = true + when traceCollector: + cprintf("[ABOUT TO DESTROY] %p\n", cell) else: - dec cell.rc, rcIncrement - # According to Lins it's correct to do nothing else here. - when traceCollector: - cprintf("[DeCREF] %p\n", cell) + if cell.count == 0: + result = true + when traceCollector: + cprintf("[ABOUT TO DESTROY] %p\n", cell) + else: + decrement cell + # According to Lins it's correct to do nothing else here. + when traceCollector: + cprintf("[DECREF] %p\n", cell) proc GC_unref*[T](x: ref T) = ## New runtime only supports this operation for 'ref T'. - if nimDecRefIsLast(cast[pointer](x)): - # XXX this does NOT work for virtual destructors! - `=destroy`(x[]) - nimRawDispose(cast[pointer](x), T.alignOf) + var y {.cursor.} = x + `=destroy`(y) proc GC_ref*[T](x: ref T) = ## New runtime only supports this operation for 'ref T'. @@ -218,22 +247,21 @@ proc GC_ref*[T](x: ref T) = when not defined(gcOrc): template GC_fullCollect* = - ## Forces a full garbage collection pass. With `--gc:arc` a nop. + ## Forces a full garbage collection pass. With `--mm:arc` a nop. discard template setupForeignThreadGc* = - ## With `--gc:arc` a nop. + ## With `--mm:arc` a nop. discard template tearDownForeignThreadGc* = - ## With `--gc:arc` a nop. + ## With `--mm:arc` a nop. discard -proc isObj(obj: PNimTypeV2, subclass: cstring): bool {.compilerRtl, inl.} = - proc strstr(s, sub: cstring): cstring {.header: "<string.h>", importc.} - - result = strstr(obj.name, subclass) != nil +proc isObjDisplayCheck(source: PNimTypeV2, targetDepth: int16, token: uint32): bool {.compilerRtl, inl.} = + result = targetDepth <= source.depth and source.display[targetDepth] == token -proc chckObj(obj: PNimTypeV2, subclass: cstring) {.compilerRtl.} = - # checks if obj is of type subclass: - if not isObj(obj, subclass): sysFatal(ObjectConversionDefect, "invalid object conversion") +when defined(gcDestructors): + proc nimGetVTable(p: pointer, index: int): pointer + {.compilerRtl, inline, raises: [].} = + result = cast[ptr PNimTypeV2](p).vTable[index] |