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Diffstat (limited to 'lib/system/gc.nim')
| -rw-r--r-- | lib/system/gc.nim | 647 |
1 files changed, 647 insertions, 0 deletions
diff --git a/lib/system/gc.nim b/lib/system/gc.nim new file mode 100644 index 000000000..f91b8843e --- /dev/null +++ b/lib/system/gc.nim @@ -0,0 +1,647 @@ +# +# +# Nimrod's Runtime Library +# (c) Copyright 2009 Andreas Rumpf +# +# See the file "copying.txt", included in this +# distribution, for details about the copyright. +# + + +# Garbage Collector +# +# The basic algorithm is *Deferrent Reference Counting* with cycle detection. +# Special care has been taken to avoid recursion as far as possible to avoid +# stack overflows when traversing deep datastructures. This is comparable to +# an incremental and generational GC. It should be well-suited for soft real +# time applications (like games). +# +# Future Improvements: +# * Support for multi-threading. However, locks for the reference counting +# might turn out to be too slow. + +const + CycleIncrease = 2 # is a multiplicative increase + InitialCycleThreshold = 4*1024*1024 # X MB because cycle checking is slow + ZctThreshold = 256 # we collect garbage if the ZCT's size + # reaches this threshold + # this seems to be a good value + +const + rcIncrement = 0b1000 # so that lowest 3 bits are not touched + # NOTE: Most colors are currently unused + rcBlack = 0b000 # cell is colored black; in use or free + rcGray = 0b001 # possible member of a cycle + rcWhite = 0b010 # member of a garbage cycle + rcPurple = 0b011 # possible root of a cycle + rcZct = 0b100 # in ZCT + rcRed = 0b101 # Candidate cycle undergoing sigma-computation + rcOrange = 0b110 # Candidate cycle awaiting epoch boundary + rcShift = 3 # shift by rcShift to get the reference counter + colorMask = 0b111 +type + TWalkOp = enum + waZctDecRef, waPush, waCycleDecRef + + TFinalizer {.compilerproc.} = proc (self: pointer) + # A ref type can have a finalizer that is called before the object's + # storage is freed. + + TGcStat {.final, pure.} = object + stackScans: int # number of performed stack scans (for statistics) + cycleCollections: int # number of performed full collections + maxThreshold: int # max threshold that has been set + maxStackSize: int # max stack size + maxStackCells: int # max stack cells in ``decStack`` + cycleTableSize: int # max entries in cycle table + + TGcHeap {.final, pure.} = object # this contains the zero count and + # non-zero count table + zct: TCellSeq # the zero count table + decStack: TCellSeq # cells in the stack that are to decref again + cycleRoots: TCellSet + tempStack: TCellSeq # temporary stack for recursion elimination + stat: TGcStat + +var + stackBottom: pointer + gch: TGcHeap + cycleThreshold: int = InitialCycleThreshold + recGcLock: int = 0 + # we use a lock to prevend the garbage collector to be triggered in a + # finalizer; the collector should not call itself this way! Thus every + # object allocated by a finalizer will not trigger a garbage collection. + # This is wasteful but safe. This is a lock against recursive garbage + # collection, not a lock for threads! + +proc unsureAsgnRef(dest: ppointer, src: pointer) {.compilerproc.} + # unsureAsgnRef updates the reference counters only if dest is not on the + # stack. It is used by the code generator if it cannot decide wether a + # reference is in the stack or not (this can happen for var parameters). +#proc growObj(old: pointer, newsize: int): pointer {.compilerproc.} +proc newObj(typ: PNimType, size: int): pointer {.compilerproc.} +proc newSeq(typ: PNimType, len: int): pointer {.compilerproc.} + +proc addZCT(s: var TCellSeq, c: PCell) {.noinline.} = + if (c.refcount and rcZct) == 0: + c.refcount = c.refcount and not colorMask or rcZct + add(s, c) + +proc cellToUsr(cell: PCell): pointer {.inline.} = + # convert object (=pointer to refcount) to pointer to userdata + result = cast[pointer](cast[TAddress](cell)+%TAddress(sizeof(TCell))) + +proc usrToCell(usr: pointer): PCell {.inline.} = + # convert pointer to userdata to object (=pointer to refcount) + result = cast[PCell](cast[TAddress](usr)-%TAddress(sizeof(TCell))) + +proc canbeCycleRoot(c: PCell): bool {.inline.} = + result = ntfAcyclic notin c.typ.flags + +proc extGetCellType(c: pointer): PNimType {.compilerproc.} = + # used for code generation concerning debugging + result = usrToCell(c).typ + +proc internRefcount(p: pointer): int {.exportc: "getRefcount".} = + result = int(usrToCell(p).refcount) shr rcShift + +proc GC_disable() = inc(recGcLock) +proc GC_enable() = + if recGcLock > 0: dec(recGcLock) + +proc GC_setStrategy(strategy: TGC_Strategy) = + case strategy + of gcThroughput: nil + of gcResponsiveness: nil + of gcOptimizeSpace: nil + of gcOptimizeTime: nil + +proc GC_enableMarkAndSweep() = + cycleThreshold = InitialCycleThreshold + +proc GC_disableMarkAndSweep() = + cycleThreshold = high(cycleThreshold)-1 + # set to the max value to suppress the cycle detector + +# this that has to equals zero, otherwise we have to round up UnitsPerPage: +when BitsPerPage mod (sizeof(int)*8) != 0: + {.error: "(BitsPerPage mod BitsPerUnit) should be zero!".} + +when debugGC: + proc writeCell(msg: CString, c: PCell) = + var kind = -1 + if c.typ != nil: kind = ord(c.typ.kind) + when debugGC: + c_fprintf(c_stdout, "[GC] %s: %p %d rc=%ld from %s(%ld)\n", + msg, c, kind, c.refcount shr rcShift, c.filename, c.line) + else: + c_fprintf(c_stdout, "[GC] %s: %p %d rc=%ld\n", + msg, c, kind, c.refcount shr rcShift) + +when traceGC: + # traceGC is a special switch to enable extensive debugging + type + TCellState = enum + csAllocated, csZctFreed, csCycFreed + var + states: array[TCellState, TCellSet] + + proc traceCell(c: PCell, state: TCellState) = + case state + of csAllocated: + if c in states[csAllocated]: + writeCell("attempt to alloc an already allocated cell", c) + assert(false) + excl(states[csCycFreed], c) + excl(states[csZctFreed], c) + of csZctFreed: + if c in states[csZctFreed]: + writeCell("attempt to free zct cell twice", c) + assert(false) + if c in states[csCycFreed]: + writeCell("attempt to free with zct, but already freed with cyc", c) + assert(false) + if c notin states[csAllocated]: + writeCell("attempt to free not an allocated cell", c) + assert(false) + excl(states[csAllocated], c) + of csCycFreed: + if c notin states[csAllocated]: + writeCell("attempt to free a not allocated cell", c) + assert(false) + if c in states[csCycFreed]: + writeCell("attempt to free cyc cell twice", c) + assert(false) + if c in states[csZctFreed]: + writeCell("attempt to free with cyc, but already freed with zct", c) + assert(false) + excl(states[csAllocated], c) + incl(states[state], c) + + proc writeLeakage() = + var z = 0 + var y = 0 + var e = 0 + for c in elements(states[csAllocated]): + inc(e) + if c in states[csZctFreed]: inc(z) + elif c in states[csCycFreed]: inc(z) + else: writeCell("leak", c) + cfprintf(cstdout, "Allocations: %ld; ZCT freed: %ld; CYC freed: %ld\n", + e, z, y) + +template gcTrace(cell, state: expr): stmt = + when traceGC: traceCell(cell, state) + +# ----------------------------------------------------------------------------- + +# forward declarations: +proc collectCT(gch: var TGcHeap) +proc IsOnStack(p: pointer): bool {.noinline.} +proc forAllChildren(cell: PCell, op: TWalkOp) +proc doOperation(p: pointer, op: TWalkOp) +proc forAllChildrenAux(dest: Pointer, mt: PNimType, op: TWalkOp) +# we need the prototype here for debugging purposes + +proc prepareDealloc(cell: PCell) = + if cell.typ.finalizer != nil: + # the finalizer could invoke something that + # allocates memory; this could trigger a garbage + # collection. Since we are already collecting we + # prevend recursive entering here by a lock. + # XXX: we should set the cell's children to nil! + inc(recGcLock) + (cast[TFinalizer](cell.typ.finalizer))(cellToUsr(cell)) + dec(recGcLock) + +proc setStackBottom(theStackBottom: pointer) {.compilerproc.} = + stackBottom = theStackBottom + +proc PossibleRoot(gch: var TGcHeap, c: PCell) {.inline.} = + if canbeCycleRoot(c): incl(gch.cycleRoots, c) + +proc decRef(c: PCell) {.inline.} = + when stressGC: + if c.refcount <% rcIncrement: + writeCell("broken cell", c) + assert(c.refcount >=% rcIncrement) + c.refcount = c.refcount -% rcIncrement + if c.refcount <% rcIncrement: + addZCT(gch.zct, c) + elif canBeCycleRoot(c): + incl(gch.cycleRoots, c) + +proc incRef(c: PCell) {.inline.} = + c.refcount = c.refcount +% rcIncrement + if canBeCycleRoot(c): + incl(gch.cycleRoots, c) + +proc nimGCref(p: pointer) {.compilerproc, inline.} = incRef(usrToCell(p)) +proc nimGCunref(p: pointer) {.compilerproc, inline.} = decRef(usrToCell(p)) + +proc asgnRef(dest: ppointer, src: pointer) {.compilerproc, inline.} = + # the code generator calls this proc! + assert(not isOnStack(dest)) + # BUGFIX: first incRef then decRef! + if src != nil: incRef(usrToCell(src)) + if dest^ != nil: decRef(usrToCell(dest^)) + dest^ = src + +proc asgnRefNoCycle(dest: ppointer, src: pointer) {.compilerproc, inline.} = + # the code generator calls this proc if it is known at compile time that no + # cycle is possible. + if src != nil: + var c = usrToCell(src) + c.refcount = c.refcount +% rcIncrement + if dest^ != nil: + var c = usrToCell(dest^) + c.refcount = c.refcount -% rcIncrement + if c.refcount <% rcIncrement: + addZCT(gch.zct, c) + dest^ = src + +proc unsureAsgnRef(dest: ppointer, src: pointer) = + if not IsOnStack(dest): + if src != nil: incRef(usrToCell(src)) + if dest^ != nil: decRef(usrToCell(dest^)) + dest^ = src + +proc initGC() = + when traceGC: + for i in low(TCellState)..high(TCellState): Init(states[i]) + gch.stat.stackScans = 0 + gch.stat.cycleCollections = 0 + gch.stat.maxThreshold = 0 + gch.stat.maxStackSize = 0 + gch.stat.maxStackCells = 0 + gch.stat.cycleTableSize = 0 + # init the rt + init(gch.zct) + init(gch.tempStack) + Init(gch.cycleRoots) + Init(gch.decStack) + new(gOutOfMem) # reserve space for the EOutOfMemory exception here! + +proc forAllSlotsAux(dest: pointer, n: ptr TNimNode, op: TWalkOp) = + var d = cast[TAddress](dest) + case n.kind + of nkNone: assert(false) + of nkSlot: forAllChildrenAux(cast[pointer](d +% n.offset), n.typ, op) + of nkList: + for i in 0..n.len-1: forAllSlotsAux(dest, n.sons[i], op) + of nkCase: + var m = selectBranch(dest, n) + if m != nil: forAllSlotsAux(dest, m, op) + +proc forAllChildrenAux(dest: Pointer, mt: PNimType, op: TWalkOp) = + var d = cast[TAddress](dest) + if dest == nil: return # nothing to do + if ntfNoRefs notin mt.flags: + case mt.Kind + of tyArray, tyArrayConstr, tyOpenArray: + for i in 0..(mt.size div mt.base.size)-1: + forAllChildrenAux(cast[pointer](d +% i *% mt.base.size), mt.base, op) + of tyRef, tyString, tySequence: # leaf: + doOperation(cast[ppointer](d)^, op) + of tyObject, tyTuple, tyPureObject: + forAllSlotsAux(dest, mt.node, op) + else: nil + +proc forAllChildren(cell: PCell, op: TWalkOp) = + assert(cell != nil) + assert(cell.typ != nil) + case cell.typ.Kind + of tyRef: # common case + forAllChildrenAux(cellToUsr(cell), cell.typ.base, op) + of tySequence: + var d = cast[TAddress](cellToUsr(cell)) + var s = cast[PGenericSeq](d) + if s != nil: + for i in 0..s.len-1: + forAllChildrenAux(cast[pointer](d +% i *% cell.typ.base.size +% + GenericSeqSize), cell.typ.base, op) + of tyString: nil + else: assert(false) + +proc checkCollection {.inline.} = + # checks if a collection should be done + if recGcLock == 0: + collectCT(gch) + +proc newObj(typ: PNimType, size: int): pointer = + # generates a new object and sets its reference counter to 0 + assert(typ.kind in {tyRef, tyString, tySequence}) + checkCollection() + var res = cast[PCell](rawAlloc(allocator, size + sizeof(TCell))) + zeroMem(res, size+sizeof(TCell)) + assert((cast[TAddress](res) and (MemAlign-1)) == 0) + # now it is buffered in the ZCT + res.typ = typ + when debugGC: + if framePtr != nil and framePtr.prev != nil: + res.filename = framePtr.prev.filename + res.line = framePtr.prev.line + res.refcount = rcZct # refcount is zero, but mark it to be in the ZCT + assert(isAllocatedPtr(allocator, res)) + # its refcount is zero, so add it to the ZCT: + block addToZCT: + # we check the last 8 entries (cache line) for a slot + # that could be reused + var L = gch.zct.len + var d = gch.zct.d + for i in countdown(L-1, max(0, L-8)): + var c = d[i] + if c.refcount >=% rcIncrement: + c.refcount = c.refcount and not colorMask + d[i] = res + break addToZCT + add(gch.zct, res) + when logGC: writeCell("new cell", res) + gcTrace(res, csAllocated) + result = cellToUsr(res) + +proc newSeq(typ: PNimType, len: int): pointer = + result = newObj(typ, addInt(mulInt(len, typ.base.size), GenericSeqSize)) + cast[PGenericSeq](result).len = len + cast[PGenericSeq](result).space = len + +proc growObj(old: pointer, newsize: int): pointer = + checkCollection() + var ol = usrToCell(old) + assert(ol.typ != nil) + assert(ol.typ.kind in {tyString, tySequence}) + var res = cast[PCell](rawAlloc(allocator, newsize + sizeof(TCell))) + var elemSize = 1 + if ol.typ.kind != tyString: + elemSize = ol.typ.base.size + + var oldsize = cast[PGenericSeq](old).len*elemSize + GenericSeqSize + copyMem(res, ol, oldsize + sizeof(TCell)) + zeroMem(cast[pointer](cast[TAddress](res)+% oldsize +% sizeof(TCell)), + newsize-oldsize) + assert((cast[TAddress](res) and (MemAlign-1)) == 0) + assert(res.refcount shr rcShift <=% 1) + #if res.refcount <% rcIncrement: + # add(gch.zct, res) + #else: # XXX: what to do here? + # decRef(ol) + if (ol.refcount and colorMask) == rcZct: + var j = gch.zct.len-1 + var d = gch.zct.d + while j >= 0: + if d[j] == ol: + d[j] = res + break + dec(j) + if canBeCycleRoot(ol): excl(gch.cycleRoots, ol) + when logGC: + writeCell("growObj old cell", ol) + writeCell("growObj new cell", res) + gcTrace(ol, csZctFreed) + gcTrace(res, csAllocated) + when reallyDealloc: rawDealloc(allocator, ol) + else: + assert(ol.typ != nil) + zeroMem(ol, sizeof(TCell)) + result = cellToUsr(res) + +# ---------------- cycle collector ------------------------------------------- + +proc doOperation(p: pointer, op: TWalkOp) = + if p == nil: return + var c: PCell = usrToCell(p) + assert(c != nil) + case op # faster than function pointers because of easy prediction + of waZctDecRef: + assert(c.refcount >=% rcIncrement) + c.refcount = c.refcount -% rcIncrement + when logGC: writeCell("decref (from doOperation)", c) + if c.refcount <% rcIncrement: addZCT(gch.zct, c) + of waPush: + add(gch.tempStack, c) + of waCycleDecRef: + assert(c.refcount >=% rcIncrement) + c.refcount = c.refcount -% rcIncrement + +# we now use a much simpler and non-recursive algorithm for cycle removal +proc collectCycles(gch: var TGcHeap) = + var tabSize = 0 + for c in elements(gch.cycleRoots): + inc(tabSize) + forallChildren(c, waCycleDecRef) + gch.stat.cycleTableSize = max(gch.stat.cycleTableSize, tabSize) + + # restore reference counts (a depth-first traversal is needed): + var marker: TCellSet + Init(marker) + for c in elements(gch.cycleRoots): + if c.refcount >=% rcIncrement: + if not containsOrIncl(marker, c): + gch.tempStack.len = 0 + forAllChildren(c, waPush) + while gch.tempStack.len > 0: + dec(gch.tempStack.len) + var d = gch.tempStack.d[gch.tempStack.len] + d.refcount = d.refcount +% rcIncrement + if d in gch.cycleRoots and not containsOrIncl(marker, d): + forAllChildren(d, waPush) + # remove cycles: + for c in elements(gch.cycleRoots): + if c.refcount <% rcIncrement: + gch.tempStack.len = 0 + forAllChildren(c, waPush) + while gch.tempStack.len > 0: + dec(gch.tempStack.len) + var d = gch.tempStack.d[gch.tempStack.len] + if d.refcount <% rcIncrement: + if d notin gch.cycleRoots: # d is leaf of c and not part of cycle + addZCT(gch.zct, d) + when logGC: writeCell("add to ZCT (from cycle collector)", d) + prepareDealloc(c) + gcTrace(c, csCycFreed) + when logGC: writeCell("cycle collector dealloc cell", c) + when reallyDealloc: rawDealloc(allocator, c) + else: + assert(c.typ != nil) + zeroMem(c, sizeof(TCell)) + Deinit(gch.cycleRoots) + Init(gch.cycleRoots) + +proc gcMark(p: pointer) {.inline.} = + # the addresses are not as objects on the stack, so turn them to objects: + var cell = usrToCell(p) + var c = cast[TAddress](cell) + if c >% PageSize: + # fast check: does it look like a cell? + if isAllocatedPtr(allocator, cell): + # mark the cell: + cell.refcount = cell.refcount +% rcIncrement + add(gch.decStack, cell) + +# ----------------- stack management -------------------------------------- +# inspired from Smart Eiffel + +proc stackSize(): int {.noinline.} = + var stackTop: array[0..1, pointer] + result = abs(cast[int](addr(stackTop[0])) - cast[int](stackBottom)) + +when defined(sparc): # For SPARC architecture. + proc isOnStack(p: pointer): bool = + var stackTop: array [0..1, pointer] + var b = cast[TAddress](stackBottom) + var a = cast[TAddress](addr(stackTop[0])) + var x = cast[TAddress](p) + result = x >=% a and x <=% b + + proc markStackAndRegisters(gch: var TGcHeap) {.noinline, cdecl.} = + when defined(sparcv9): + asm """"flushw \n" """ + else: + asm """"ta 0x3 ! ST_FLUSH_WINDOWS\n" """ + + var + max = stackBottom + sp: PPointer + stackTop: array[0..1, pointer] + sp = addr(stackTop[0]) + # Addresses decrease as the stack grows. + while sp <= max: + gcMark(sp^) + sp = cast[ppointer](cast[TAddress](sp) +% sizeof(pointer)) + +elif defined(ELATE): + {.error: "stack marking code is to be written for this architecture".} + +elif defined(hppa) or defined(hp9000) or defined(hp9000s300) or + defined(hp9000s700) or defined(hp9000s800) or defined(hp9000s820): + # --------------------------------------------------------------------------- + # Generic code for architectures where addresses increase as the stack grows. + # --------------------------------------------------------------------------- + proc isOnStack(p: pointer): bool = + var stackTop: array [0..1, pointer] + var a = cast[TAddress](stackBottom) + var b = cast[TAddress](addr(stackTop[0])) + var x = cast[TAddress](p) + result = x >=% a and x <=% b + + var + jmpbufSize {.importc: "sizeof(jmp_buf)", nodecl.}: int + # a little hack to get the size of a TJmpBuf in the generated C code + # in a platform independant way + + proc markStackAndRegisters(gch: var TGcHeap) {.noinline, cdecl.} = + var registers: C_JmpBuf + if c_setjmp(registers) == 0'i32: # To fill the C stack with registers. + var max = cast[TAddress](stackBottom) + var sp = cast[TAddress](addr(registers)) +% jmpbufSize -% sizeof(pointer) + # sp will traverse the JMP_BUF as well (jmp_buf size is added, + # otherwise sp would be below the registers structure). + while sp >=% max: + gcMark(cast[ppointer](sp)^) + sp = sp -% sizeof(pointer) + +else: + # --------------------------------------------------------------------------- + # Generic code for architectures where addresses decrease as the stack grows. + # --------------------------------------------------------------------------- + proc isOnStack(p: pointer): bool = + var stackTop: array [0..1, pointer] + var b = cast[TAddress](stackBottom) + var a = cast[TAddress](addr(stackTop[0])) + var x = cast[TAddress](p) + result = x >=% a and x <=% b + + proc markStackAndRegisters(gch: var TGcHeap) {.noinline, cdecl.} = + # We use a jmp_buf buffer that is in the C stack. + # Used to traverse the stack and registers assuming + # that 'setjmp' will save registers in the C stack. + var registers: C_JmpBuf + if c_setjmp(registers) == 0'i32: # To fill the C stack with registers. + var max = cast[TAddress](stackBottom) + var sp = cast[TAddress](addr(registers)) + while sp <=% max: + gcMark(cast[ppointer](sp)^) + sp = sp +% sizeof(pointer) + +# ---------------------------------------------------------------------------- +# end of non-portable code +# ---------------------------------------------------------------------------- + +proc CollectZCT(gch: var TGcHeap) = + # Note: Freeing may add child objects to the ZCT! So essentially we do + # deep freeing, which is bad for incremental operation. In order to + # avoid a deep stack, we move objects to keep the ZCT small. + # This is performance critical! + var L = addr(gch.zct.len) + while L^ > 0: + var c = gch.zct.d[0] + # remove from ZCT: + assert((c.refcount and colorMask) == rcZct) + c.refcount = c.refcount and not colorMask + gch.zct.d[0] = gch.zct.d[L^ - 1] + dec(L^) + if c.refcount <% rcIncrement: + # It may have a RC > 0, if it is in the hardware stack or + # it has not been removed yet from the ZCT. This is because + # ``incref`` does not bother to remove the cell from the ZCT + # as this might be too slow. + # In any case, it should be removed from the ZCT. But not + # freed. **KEEP THIS IN MIND WHEN MAKING THIS INCREMENTAL!** + if canBeCycleRoot(c): excl(gch.cycleRoots, c) + when logGC: writeCell("zct dealloc cell", c) + gcTrace(c, csZctFreed) + # We are about to free the object, call the finalizer BEFORE its + # children are deleted as well, because otherwise the finalizer may + # access invalid memory. This is done by prepareDealloc(): + prepareDealloc(c) + forAllChildren(c, waZctDecRef) + when reallyDealloc: rawDealloc(allocator, c) + else: + assert(c.typ != nil) + zeroMem(c, sizeof(TCell)) + +proc unmarkStackAndRegisters(gch: var TGcHeap) = + var d = gch.decStack.d + for i in 0..gch.decStack.len-1: + assert isAllocatedPtr(allocator, d[i]) + decRef(d[i]) # OPT: cannot create a cycle! + gch.decStack.len = 0 + +proc collectCT(gch: var TGcHeap) = + if gch.zct.len >= ZctThreshold or (cycleGC and + getOccupiedMem() >= cycleThreshold) or stressGC: + gch.stat.maxStackSize = max(gch.stat.maxStackSize, stackSize()) + assert(gch.decStack.len == 0) + markStackAndRegisters(gch) + gch.stat.maxStackCells = max(gch.stat.maxStackCells, gch.decStack.len) + inc(gch.stat.stackScans) + collectZCT(gch) + when cycleGC: + if getOccupiedMem() >= cycleThreshold or stressGC: + collectCycles(gch) + collectZCT(gch) + inc(gch.stat.cycleCollections) + cycleThreshold = max(InitialCycleThreshold, getOccupiedMem() * + cycleIncrease) + gch.stat.maxThreshold = max(gch.stat.maxThreshold, cycleThreshold) + unmarkStackAndRegisters(gch) + +proc GC_fullCollect() = + var oldThreshold = cycleThreshold + cycleThreshold = 0 # forces cycle collection + collectCT(gch) + cycleThreshold = oldThreshold + +proc GC_getStatistics(): string = + GC_disable() + result = "[GC] total memory: " & $(getTotalMem()) & "\n" & + "[GC] occupied memory: " & $(getOccupiedMem()) & "\n" & + "[GC] stack scans: " & $gch.stat.stackScans & "\n" & + "[GC] stack cells: " & $gch.stat.maxStackCells & "\n" & + "[GC] cycle collections: " & $gch.stat.cycleCollections & "\n" & + "[GC] max threshold: " & $gch.stat.maxThreshold & "\n" & + "[GC] zct capacity: " & $gch.zct.cap & "\n" & + "[GC] max cycle table size: " & $gch.stat.cycleTableSize & "\n" & + "[GC] max stack size: " & $gch.stat.maxStackSize + when traceGC: writeLeakage() + GC_enable() |