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Diffstat (limited to 'src/runtime/malloc.go')
| -rw-r--r-- | src/runtime/malloc.go | 837 |
1 files changed, 837 insertions, 0 deletions
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go new file mode 100644 index 000000000..117044944 --- /dev/null +++ b/src/runtime/malloc.go @@ -0,0 +1,837 @@ +// Copyright 2014 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package runtime + +import ( + "unsafe" +) + +const ( + debugMalloc = false + + flagNoScan = _FlagNoScan + flagNoZero = _FlagNoZero + + maxTinySize = _TinySize + tinySizeClass = _TinySizeClass + maxSmallSize = _MaxSmallSize + + pageShift = _PageShift + pageSize = _PageSize + pageMask = _PageMask + + bitsPerPointer = _BitsPerPointer + bitsMask = _BitsMask + pointersPerByte = _PointersPerByte + maxGCMask = _MaxGCMask + bitsDead = _BitsDead + bitsPointer = _BitsPointer + + mSpanInUse = _MSpanInUse + + concurrentSweep = _ConcurrentSweep != 0 +) + +// Page number (address>>pageShift) +type pageID uintptr + +// base address for all 0-byte allocations +var zerobase uintptr + +// Allocate an object of size bytes. +// Small objects are allocated from the per-P cache's free lists. +// Large objects (> 32 kB) are allocated straight from the heap. +func mallocgc(size uintptr, typ *_type, flags uint32) unsafe.Pointer { + if size == 0 { + return unsafe.Pointer(&zerobase) + } + size0 := size + + if flags&flagNoScan == 0 && typ == nil { + gothrow("malloc missing type") + } + + // This function must be atomic wrt GC, but for performance reasons + // we don't acquirem/releasem on fast path. The code below does not have + // split stack checks, so it can't be preempted by GC. + // Functions like roundup/add are inlined. And onM/racemalloc are nosplit. + // If debugMalloc = true, these assumptions are checked below. + if debugMalloc { + mp := acquirem() + if mp.mallocing != 0 { + gothrow("malloc deadlock") + } + mp.mallocing = 1 + if mp.curg != nil { + mp.curg.stackguard0 = ^uintptr(0xfff) | 0xbad + } + } + + c := gomcache() + var s *mspan + var x unsafe.Pointer + if size <= maxSmallSize { + if flags&flagNoScan != 0 && size < maxTinySize { + // Tiny allocator. + // + // Tiny allocator combines several tiny allocation requests + // into a single memory block. The resulting memory block + // is freed when all subobjects are unreachable. The subobjects + // must be FlagNoScan (don't have pointers), this ensures that + // the amount of potentially wasted memory is bounded. + // + // Size of the memory block used for combining (maxTinySize) is tunable. + // Current setting is 16 bytes, which relates to 2x worst case memory + // wastage (when all but one subobjects are unreachable). + // 8 bytes would result in no wastage at all, but provides less + // opportunities for combining. + // 32 bytes provides more opportunities for combining, + // but can lead to 4x worst case wastage. + // The best case winning is 8x regardless of block size. + // + // Objects obtained from tiny allocator must not be freed explicitly. + // So when an object will be freed explicitly, we ensure that + // its size >= maxTinySize. + // + // SetFinalizer has a special case for objects potentially coming + // from tiny allocator, it such case it allows to set finalizers + // for an inner byte of a memory block. + // + // The main targets of tiny allocator are small strings and + // standalone escaping variables. On a json benchmark + // the allocator reduces number of allocations by ~12% and + // reduces heap size by ~20%. + tinysize := uintptr(c.tinysize) + if size <= tinysize { + tiny := unsafe.Pointer(c.tiny) + // Align tiny pointer for required (conservative) alignment. + if size&7 == 0 { + tiny = roundup(tiny, 8) + } else if size&3 == 0 { + tiny = roundup(tiny, 4) + } else if size&1 == 0 { + tiny = roundup(tiny, 2) + } + size1 := size + (uintptr(tiny) - uintptr(unsafe.Pointer(c.tiny))) + if size1 <= tinysize { + // The object fits into existing tiny block. + x = tiny + c.tiny = (*byte)(add(x, size)) + c.tinysize -= uintptr(size1) + c.local_tinyallocs++ + if debugMalloc { + mp := acquirem() + if mp.mallocing == 0 { + gothrow("bad malloc") + } + mp.mallocing = 0 + if mp.curg != nil { + mp.curg.stackguard0 = mp.curg.stack.lo + _StackGuard + } + // Note: one releasem for the acquirem just above. + // The other for the acquirem at start of malloc. + releasem(mp) + releasem(mp) + } + return x + } + } + // Allocate a new maxTinySize block. + s = c.alloc[tinySizeClass] + v := s.freelist + if v == nil { + mp := acquirem() + mp.scalararg[0] = tinySizeClass + onM(mcacheRefill_m) + releasem(mp) + s = c.alloc[tinySizeClass] + v = s.freelist + } + s.freelist = v.next + s.ref++ + //TODO: prefetch v.next + x = unsafe.Pointer(v) + (*[2]uint64)(x)[0] = 0 + (*[2]uint64)(x)[1] = 0 + // See if we need to replace the existing tiny block with the new one + // based on amount of remaining free space. + if maxTinySize-size > tinysize { + c.tiny = (*byte)(add(x, size)) + c.tinysize = uintptr(maxTinySize - size) + } + size = maxTinySize + } else { + var sizeclass int8 + if size <= 1024-8 { + sizeclass = size_to_class8[(size+7)>>3] + } else { + sizeclass = size_to_class128[(size-1024+127)>>7] + } + size = uintptr(class_to_size[sizeclass]) + s = c.alloc[sizeclass] + v := s.freelist + if v == nil { + mp := acquirem() + mp.scalararg[0] = uintptr(sizeclass) + onM(mcacheRefill_m) + releasem(mp) + s = c.alloc[sizeclass] + v = s.freelist + } + s.freelist = v.next + s.ref++ + //TODO: prefetch + x = unsafe.Pointer(v) + if flags&flagNoZero == 0 { + v.next = nil + if size > 2*ptrSize && ((*[2]uintptr)(x))[1] != 0 { + memclr(unsafe.Pointer(v), size) + } + } + } + c.local_cachealloc += intptr(size) + } else { + mp := acquirem() + mp.scalararg[0] = uintptr(size) + mp.scalararg[1] = uintptr(flags) + onM(largeAlloc_m) + s = (*mspan)(mp.ptrarg[0]) + mp.ptrarg[0] = nil + releasem(mp) + x = unsafe.Pointer(uintptr(s.start << pageShift)) + size = uintptr(s.elemsize) + } + + if flags&flagNoScan != 0 { + // All objects are pre-marked as noscan. + goto marked + } + + // If allocating a defer+arg block, now that we've picked a malloc size + // large enough to hold everything, cut the "asked for" size down to + // just the defer header, so that the GC bitmap will record the arg block + // as containing nothing at all (as if it were unused space at the end of + // a malloc block caused by size rounding). + // The defer arg areas are scanned as part of scanstack. + if typ == deferType { + size0 = unsafe.Sizeof(_defer{}) + } + + // From here till marked label marking the object as allocated + // and storing type info in the GC bitmap. + { + arena_start := uintptr(unsafe.Pointer(mheap_.arena_start)) + off := (uintptr(x) - arena_start) / ptrSize + xbits := (*uint8)(unsafe.Pointer(arena_start - off/wordsPerBitmapByte - 1)) + shift := (off % wordsPerBitmapByte) * gcBits + if debugMalloc && ((*xbits>>shift)&(bitMask|bitPtrMask)) != bitBoundary { + println("runtime: bits =", (*xbits>>shift)&(bitMask|bitPtrMask)) + gothrow("bad bits in markallocated") + } + + var ti, te uintptr + var ptrmask *uint8 + if size == ptrSize { + // It's one word and it has pointers, it must be a pointer. + *xbits |= (bitsPointer << 2) << shift + goto marked + } + if typ.kind&kindGCProg != 0 { + nptr := (uintptr(typ.size) + ptrSize - 1) / ptrSize + masksize := nptr + if masksize%2 != 0 { + masksize *= 2 // repeated + } + masksize = masksize * pointersPerByte / 8 // 4 bits per word + masksize++ // unroll flag in the beginning + if masksize > maxGCMask && typ.gc[1] != 0 { + // If the mask is too large, unroll the program directly + // into the GC bitmap. It's 7 times slower than copying + // from the pre-unrolled mask, but saves 1/16 of type size + // memory for the mask. + mp := acquirem() + mp.ptrarg[0] = x + mp.ptrarg[1] = unsafe.Pointer(typ) + mp.scalararg[0] = uintptr(size) + mp.scalararg[1] = uintptr(size0) + onM(unrollgcproginplace_m) + releasem(mp) + goto marked + } + ptrmask = (*uint8)(unsafe.Pointer(uintptr(typ.gc[0]))) + // Check whether the program is already unrolled. + if uintptr(atomicloadp(unsafe.Pointer(ptrmask)))&0xff == 0 { + mp := acquirem() + mp.ptrarg[0] = unsafe.Pointer(typ) + onM(unrollgcprog_m) + releasem(mp) + } + ptrmask = (*uint8)(add(unsafe.Pointer(ptrmask), 1)) // skip the unroll flag byte + } else { + ptrmask = (*uint8)(unsafe.Pointer(typ.gc[0])) // pointer to unrolled mask + } + if size == 2*ptrSize { + *xbits = *ptrmask | bitBoundary + goto marked + } + te = uintptr(typ.size) / ptrSize + // If the type occupies odd number of words, its mask is repeated. + if te%2 == 0 { + te /= 2 + } + // Copy pointer bitmask into the bitmap. + for i := uintptr(0); i < size0; i += 2 * ptrSize { + v := *(*uint8)(add(unsafe.Pointer(ptrmask), ti)) + ti++ + if ti == te { + ti = 0 + } + if i == 0 { + v |= bitBoundary + } + if i+ptrSize == size0 { + v &^= uint8(bitPtrMask << 4) + } + + *xbits = v + xbits = (*byte)(add(unsafe.Pointer(xbits), ^uintptr(0))) + } + if size0%(2*ptrSize) == 0 && size0 < size { + // Mark the word after last object's word as bitsDead. + *xbits = bitsDead << 2 + } + } +marked: + if raceenabled { + racemalloc(x, size) + } + + if debugMalloc { + mp := acquirem() + if mp.mallocing == 0 { + gothrow("bad malloc") + } + mp.mallocing = 0 + if mp.curg != nil { + mp.curg.stackguard0 = mp.curg.stack.lo + _StackGuard + } + // Note: one releasem for the acquirem just above. + // The other for the acquirem at start of malloc. + releasem(mp) + releasem(mp) + } + + if debug.allocfreetrace != 0 { + tracealloc(x, size, typ) + } + + if rate := MemProfileRate; rate > 0 { + if size < uintptr(rate) && int32(size) < c.next_sample { + c.next_sample -= int32(size) + } else { + mp := acquirem() + profilealloc(mp, x, size) + releasem(mp) + } + } + + if memstats.heap_alloc >= memstats.next_gc { + gogc(0) + } + + return x +} + +// implementation of new builtin +func newobject(typ *_type) unsafe.Pointer { + flags := uint32(0) + if typ.kind&kindNoPointers != 0 { + flags |= flagNoScan + } + return mallocgc(uintptr(typ.size), typ, flags) +} + +// implementation of make builtin for slices +func newarray(typ *_type, n uintptr) unsafe.Pointer { + flags := uint32(0) + if typ.kind&kindNoPointers != 0 { + flags |= flagNoScan + } + if int(n) < 0 || (typ.size > 0 && n > maxmem/uintptr(typ.size)) { + panic("runtime: allocation size out of range") + } + return mallocgc(uintptr(typ.size)*n, typ, flags) +} + +// rawmem returns a chunk of pointerless memory. It is +// not zeroed. +func rawmem(size uintptr) unsafe.Pointer { + return mallocgc(size, nil, flagNoScan|flagNoZero) +} + +// round size up to next size class +func goroundupsize(size uintptr) uintptr { + if size < maxSmallSize { + if size <= 1024-8 { + return uintptr(class_to_size[size_to_class8[(size+7)>>3]]) + } + return uintptr(class_to_size[size_to_class128[(size-1024+127)>>7]]) + } + if size+pageSize < size { + return size + } + return (size + pageSize - 1) &^ pageMask +} + +func profilealloc(mp *m, x unsafe.Pointer, size uintptr) { + c := mp.mcache + rate := MemProfileRate + if size < uintptr(rate) { + // pick next profile time + // If you change this, also change allocmcache. + if rate > 0x3fffffff { // make 2*rate not overflow + rate = 0x3fffffff + } + next := int32(fastrand1()) % (2 * int32(rate)) + // Subtract the "remainder" of the current allocation. + // Otherwise objects that are close in size to sampling rate + // will be under-sampled, because we consistently discard this remainder. + next -= (int32(size) - c.next_sample) + if next < 0 { + next = 0 + } + c.next_sample = next + } + + mProf_Malloc(x, size) +} + +// force = 1 - do GC regardless of current heap usage +// force = 2 - go GC and eager sweep +func gogc(force int32) { + // The gc is turned off (via enablegc) until the bootstrap has completed. + // Also, malloc gets called in the guts of a number of libraries that might be + // holding locks. To avoid deadlocks during stoptheworld, don't bother + // trying to run gc while holding a lock. The next mallocgc without a lock + // will do the gc instead. + mp := acquirem() + if gp := getg(); gp == mp.g0 || mp.locks > 1 || !memstats.enablegc || panicking != 0 || gcpercent < 0 { + releasem(mp) + return + } + releasem(mp) + mp = nil + + semacquire(&worldsema, false) + + if force == 0 && memstats.heap_alloc < memstats.next_gc { + // typically threads which lost the race to grab + // worldsema exit here when gc is done. + semrelease(&worldsema) + return + } + + // Ok, we're doing it! Stop everybody else + startTime := nanotime() + mp = acquirem() + mp.gcing = 1 + releasem(mp) + onM(stoptheworld) + if mp != acquirem() { + gothrow("gogc: rescheduled") + } + + clearpools() + + // Run gc on the g0 stack. We do this so that the g stack + // we're currently running on will no longer change. Cuts + // the root set down a bit (g0 stacks are not scanned, and + // we don't need to scan gc's internal state). We also + // need to switch to g0 so we can shrink the stack. + n := 1 + if debug.gctrace > 1 { + n = 2 + } + for i := 0; i < n; i++ { + if i > 0 { + startTime = nanotime() + } + // switch to g0, call gc, then switch back + mp.scalararg[0] = uintptr(uint32(startTime)) // low 32 bits + mp.scalararg[1] = uintptr(startTime >> 32) // high 32 bits + if force >= 2 { + mp.scalararg[2] = 1 // eagersweep + } else { + mp.scalararg[2] = 0 + } + onM(gc_m) + } + + // all done + mp.gcing = 0 + semrelease(&worldsema) + onM(starttheworld) + releasem(mp) + mp = nil + + // now that gc is done, kick off finalizer thread if needed + if !concurrentSweep { + // give the queued finalizers, if any, a chance to run + Gosched() + } +} + +// GC runs a garbage collection. +func GC() { + gogc(2) +} + +// linker-provided +var noptrdata struct{} +var enoptrdata struct{} +var noptrbss struct{} +var enoptrbss struct{} + +// SetFinalizer sets the finalizer associated with x to f. +// When the garbage collector finds an unreachable block +// with an associated finalizer, it clears the association and runs +// f(x) in a separate goroutine. This makes x reachable again, but +// now without an associated finalizer. Assuming that SetFinalizer +// is not called again, the next time the garbage collector sees +// that x is unreachable, it will free x. +// +// SetFinalizer(x, nil) clears any finalizer associated with x. +// +// The argument x must be a pointer to an object allocated by +// calling new or by taking the address of a composite literal. +// The argument f must be a function that takes a single argument +// to which x's type can be assigned, and can have arbitrary ignored return +// values. If either of these is not true, SetFinalizer aborts the +// program. +// +// Finalizers are run in dependency order: if A points at B, both have +// finalizers, and they are otherwise unreachable, only the finalizer +// for A runs; once A is freed, the finalizer for B can run. +// If a cyclic structure includes a block with a finalizer, that +// cycle is not guaranteed to be garbage collected and the finalizer +// is not guaranteed to run, because there is no ordering that +// respects the dependencies. +// +// The finalizer for x is scheduled to run at some arbitrary time after +// x becomes unreachable. +// There is no guarantee that finalizers will run before a program exits, +// so typically they are useful only for releasing non-memory resources +// associated with an object during a long-running program. +// For example, an os.File object could use a finalizer to close the +// associated operating system file descriptor when a program discards +// an os.File without calling Close, but it would be a mistake +// to depend on a finalizer to flush an in-memory I/O buffer such as a +// bufio.Writer, because the buffer would not be flushed at program exit. +// +// It is not guaranteed that a finalizer will run if the size of *x is +// zero bytes. +// +// It is not guaranteed that a finalizer will run for objects allocated +// in initializers for package-level variables. Such objects may be +// linker-allocated, not heap-allocated. +// +// A single goroutine runs all finalizers for a program, sequentially. +// If a finalizer must run for a long time, it should do so by starting +// a new goroutine. +func SetFinalizer(obj interface{}, finalizer interface{}) { + e := (*eface)(unsafe.Pointer(&obj)) + etyp := e._type + if etyp == nil { + gothrow("runtime.SetFinalizer: first argument is nil") + } + if etyp.kind&kindMask != kindPtr { + gothrow("runtime.SetFinalizer: first argument is " + *etyp._string + ", not pointer") + } + ot := (*ptrtype)(unsafe.Pointer(etyp)) + if ot.elem == nil { + gothrow("nil elem type!") + } + + // find the containing object + _, base, _ := findObject(e.data) + + if base == nil { + // 0-length objects are okay. + if e.data == unsafe.Pointer(&zerobase) { + return + } + + // Global initializers might be linker-allocated. + // var Foo = &Object{} + // func main() { + // runtime.SetFinalizer(Foo, nil) + // } + // The relevant segments are: noptrdata, data, bss, noptrbss. + // We cannot assume they are in any order or even contiguous, + // due to external linking. + if uintptr(unsafe.Pointer(&noptrdata)) <= uintptr(e.data) && uintptr(e.data) < uintptr(unsafe.Pointer(&enoptrdata)) || + uintptr(unsafe.Pointer(&data)) <= uintptr(e.data) && uintptr(e.data) < uintptr(unsafe.Pointer(&edata)) || + uintptr(unsafe.Pointer(&bss)) <= uintptr(e.data) && uintptr(e.data) < uintptr(unsafe.Pointer(&ebss)) || + uintptr(unsafe.Pointer(&noptrbss)) <= uintptr(e.data) && uintptr(e.data) < uintptr(unsafe.Pointer(&enoptrbss)) { + return + } + gothrow("runtime.SetFinalizer: pointer not in allocated block") + } + + if e.data != base { + // As an implementation detail we allow to set finalizers for an inner byte + // of an object if it could come from tiny alloc (see mallocgc for details). + if ot.elem == nil || ot.elem.kind&kindNoPointers == 0 || ot.elem.size >= maxTinySize { + gothrow("runtime.SetFinalizer: pointer not at beginning of allocated block") + } + } + + f := (*eface)(unsafe.Pointer(&finalizer)) + ftyp := f._type + if ftyp == nil { + // switch to M stack and remove finalizer + mp := acquirem() + mp.ptrarg[0] = e.data + onM(removeFinalizer_m) + releasem(mp) + return + } + + if ftyp.kind&kindMask != kindFunc { + gothrow("runtime.SetFinalizer: second argument is " + *ftyp._string + ", not a function") + } + ft := (*functype)(unsafe.Pointer(ftyp)) + ins := *(*[]*_type)(unsafe.Pointer(&ft.in)) + if ft.dotdotdot || len(ins) != 1 { + gothrow("runtime.SetFinalizer: cannot pass " + *etyp._string + " to finalizer " + *ftyp._string) + } + fint := ins[0] + switch { + case fint == etyp: + // ok - same type + goto okarg + case fint.kind&kindMask == kindPtr: + if (fint.x == nil || fint.x.name == nil || etyp.x == nil || etyp.x.name == nil) && (*ptrtype)(unsafe.Pointer(fint)).elem == ot.elem { + // ok - not same type, but both pointers, + // one or the other is unnamed, and same element type, so assignable. + goto okarg + } + case fint.kind&kindMask == kindInterface: + ityp := (*interfacetype)(unsafe.Pointer(fint)) + if len(ityp.mhdr) == 0 { + // ok - satisfies empty interface + goto okarg + } + if _, ok := assertE2I2(ityp, obj); ok { + goto okarg + } + } + gothrow("runtime.SetFinalizer: cannot pass " + *etyp._string + " to finalizer " + *ftyp._string) +okarg: + // compute size needed for return parameters + nret := uintptr(0) + for _, t := range *(*[]*_type)(unsafe.Pointer(&ft.out)) { + nret = round(nret, uintptr(t.align)) + uintptr(t.size) + } + nret = round(nret, ptrSize) + + // make sure we have a finalizer goroutine + createfing() + + // switch to M stack to add finalizer record + mp := acquirem() + mp.ptrarg[0] = f.data + mp.ptrarg[1] = e.data + mp.scalararg[0] = nret + mp.ptrarg[2] = unsafe.Pointer(fint) + mp.ptrarg[3] = unsafe.Pointer(ot) + onM(setFinalizer_m) + if mp.scalararg[0] != 1 { + gothrow("runtime.SetFinalizer: finalizer already set") + } + releasem(mp) +} + +// round n up to a multiple of a. a must be a power of 2. +func round(n, a uintptr) uintptr { + return (n + a - 1) &^ (a - 1) +} + +// Look up pointer v in heap. Return the span containing the object, +// the start of the object, and the size of the object. If the object +// does not exist, return nil, nil, 0. +func findObject(v unsafe.Pointer) (s *mspan, x unsafe.Pointer, n uintptr) { + c := gomcache() + c.local_nlookup++ + if ptrSize == 4 && c.local_nlookup >= 1<<30 { + // purge cache stats to prevent overflow + lock(&mheap_.lock) + purgecachedstats(c) + unlock(&mheap_.lock) + } + + // find span + arena_start := uintptr(unsafe.Pointer(mheap_.arena_start)) + arena_used := uintptr(unsafe.Pointer(mheap_.arena_used)) + if uintptr(v) < arena_start || uintptr(v) >= arena_used { + return + } + p := uintptr(v) >> pageShift + q := p - arena_start>>pageShift + s = *(**mspan)(add(unsafe.Pointer(mheap_.spans), q*ptrSize)) + if s == nil { + return + } + x = unsafe.Pointer(uintptr(s.start) << pageShift) + + if uintptr(v) < uintptr(x) || uintptr(v) >= uintptr(unsafe.Pointer(s.limit)) || s.state != mSpanInUse { + s = nil + x = nil + return + } + + n = uintptr(s.elemsize) + if s.sizeclass != 0 { + x = add(x, (uintptr(v)-uintptr(x))/n*n) + } + return +} + +var fingCreate uint32 + +func createfing() { + // start the finalizer goroutine exactly once + if fingCreate == 0 && cas(&fingCreate, 0, 1) { + go runfinq() + } +} + +// This is the goroutine that runs all of the finalizers +func runfinq() { + var ( + frame unsafe.Pointer + framecap uintptr + ) + + for { + lock(&finlock) + fb := finq + finq = nil + if fb == nil { + gp := getg() + fing = gp + fingwait = true + gp.issystem = true + goparkunlock(&finlock, "finalizer wait") + gp.issystem = false + continue + } + unlock(&finlock) + if raceenabled { + racefingo() + } + for fb != nil { + for i := int32(0); i < fb.cnt; i++ { + f := (*finalizer)(add(unsafe.Pointer(&fb.fin), uintptr(i)*unsafe.Sizeof(finalizer{}))) + + framesz := unsafe.Sizeof((interface{})(nil)) + uintptr(f.nret) + if framecap < framesz { + // The frame does not contain pointers interesting for GC, + // all not yet finalized objects are stored in finq. + // If we do not mark it as FlagNoScan, + // the last finalized object is not collected. + frame = mallocgc(framesz, nil, flagNoScan) + framecap = framesz + } + + if f.fint == nil { + gothrow("missing type in runfinq") + } + switch f.fint.kind & kindMask { + case kindPtr: + // direct use of pointer + *(*unsafe.Pointer)(frame) = f.arg + case kindInterface: + ityp := (*interfacetype)(unsafe.Pointer(f.fint)) + // set up with empty interface + (*eface)(frame)._type = &f.ot.typ + (*eface)(frame).data = f.arg + if len(ityp.mhdr) != 0 { + // convert to interface with methods + // this conversion is guaranteed to succeed - we checked in SetFinalizer + *(*fInterface)(frame) = assertE2I(ityp, *(*interface{})(frame)) + } + default: + gothrow("bad kind in runfinq") + } + reflectcall(unsafe.Pointer(f.fn), frame, uint32(framesz), uint32(framesz)) + + // drop finalizer queue references to finalized object + f.fn = nil + f.arg = nil + f.ot = nil + } + fb.cnt = 0 + next := fb.next + lock(&finlock) + fb.next = finc + finc = fb + unlock(&finlock) + fb = next + } + } +} + +var persistent struct { + lock mutex + pos unsafe.Pointer + end unsafe.Pointer +} + +// Wrapper around sysAlloc that can allocate small chunks. +// There is no associated free operation. +// Intended for things like function/type/debug-related persistent data. +// If align is 0, uses default align (currently 8). +func persistentalloc(size, align uintptr, stat *uint64) unsafe.Pointer { + const ( + chunk = 256 << 10 + maxBlock = 64 << 10 // VM reservation granularity is 64K on windows + ) + + if align != 0 { + if align&(align-1) != 0 { + gothrow("persistentalloc: align is not a power of 2") + } + if align > _PageSize { + gothrow("persistentalloc: align is too large") + } + } else { + align = 8 + } + + if size >= maxBlock { + return sysAlloc(size, stat) + } + + lock(&persistent.lock) + persistent.pos = roundup(persistent.pos, align) + if uintptr(persistent.pos)+size > uintptr(persistent.end) { + persistent.pos = sysAlloc(chunk, &memstats.other_sys) + if persistent.pos == nil { + unlock(&persistent.lock) + gothrow("runtime: cannot allocate memory") + } + persistent.end = add(persistent.pos, chunk) + } + p := persistent.pos + persistent.pos = add(persistent.pos, size) + unlock(&persistent.lock) + + if stat != &memstats.other_sys { + xadd64(stat, int64(size)) + xadd64(&memstats.other_sys, -int64(size)) + } + return p +} |