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// Copyright 2009 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.

// See malloc.h for overview.
//
// TODO(rsc): double-check stats.

package runtime
#include <stddef.h>
#include <errno.h>
#include <stdlib.h>
#include "go-alloc.h"
#include "runtime.h"
#include "arch.h"
#include "malloc.h"
#include "go-string.h"
#include "interface.h"
#include "go-type.h"

MHeap runtime_mheap;
extern MStats mstats;   // defined in extern.go

extern volatile int32 runtime_MemProfileRate
  __asm__ ("libgo_runtime.runtime.MemProfileRate");

// Allocate an object of at least size bytes.
// Small objects are allocated from the per-thread cache's free lists.
// Large objects (> 32 kB) are allocated straight from the heap.
void*
runtime_mallocgc(uintptr size, uint32 flag, int32 dogc, int32 zeroed)
{
        M *m;
        G *g;
        int32 sizeclass, rate;
        MCache *c;
        uintptr npages;
        MSpan *s;
        void *v;

        m = runtime_m();
        g = runtime_g();
        if(g->status == Gsyscall)
                dogc = 0;
        if(runtime_gcwaiting && g != m->g0 && m->locks == 0 && g->status != Gsyscall) {
                runtime_gosched();
                m = runtime_m();
        }
        if(m->mallocing)
                runtime_throw("malloc/free - deadlock");
        m->mallocing = 1;
        if(size == 0)
                size = 1;

        c = m->mcache;
        c->local_nmalloc++;
        if(size <= MaxSmallSize) {
                // Allocate from mcache free lists.
                sizeclass = runtime_SizeToClass(size);
                size = runtime_class_to_size[sizeclass];
                v = runtime_MCache_Alloc(c, sizeclass, size, zeroed);
                if(v == nil)
                        runtime_throw("out of memory");
                c->local_alloc += size;
                c->local_total_alloc += size;
                c->local_by_size[sizeclass].nmalloc++;
        } else {
                // TODO(rsc): Report tracebacks for very large allocations.

                // Allocate directly from heap.
                npages = size >> PageShift;
                if((size & PageMask) != 0)
                        npages++;
                s = runtime_MHeap_Alloc(&runtime_mheap, npages, 0, !(flag & FlagNoGC));
                if(s == nil)
                        runtime_throw("out of memory");
                size = npages<<PageShift;
                c->local_alloc += size;
                c->local_total_alloc += size;
                v = (void*)(s->start << PageShift);

                // setup for mark sweep
                runtime_markspan(v, 0, 0, true);
        }
        if(!(flag & FlagNoGC))
                runtime_markallocated(v, size, (flag&FlagNoPointers) != 0);

        m->mallocing = 0;

        if(!(flag & FlagNoProfiling) && (rate = runtime_MemProfileRate) > 0) {
                if(size >= (uint32) rate)
                        goto profile;
                if((uint32) m->mcache->next_sample > size)
                        m->mcache->next_sample -= size;
                else {
                        // pick next profile time
                        // If you change this, also change allocmcache.
                        if(rate > 0x3fffffff)   // make 2*rate not overflow
                                rate = 0x3fffffff;
                        m->mcache->next_sample = runtime_fastrand1() % (2*rate);
                profile:
                        runtime_setblockspecial(v, true);
                        runtime_MProf_Malloc(v, size);
                }
        }

        if(dogc && mstats.heap_alloc >= mstats.next_gc)
                runtime_gc(0);
        return v;
}

void*
__go_alloc(uintptr size)
{
        return runtime_mallocgc(size, 0, 0, 1);
}

// Free the object whose base pointer is v.
void
__go_free(void *v)
{
        M *m;
        int32 sizeclass;
        MSpan *s;
        MCache *c;
        uint32 prof;
        uintptr size;

        if(v == nil)
                return;
        
        // If you change this also change mgc0.c:/^sweep,
        // which has a copy of the guts of free.

        m = runtime_m();
        if(m->mallocing)
                runtime_throw("malloc/free - deadlock");
        m->mallocing = 1;

        if(!runtime_mlookup(v, nil, nil, &s)) {
                // runtime_printf("free %p: not an allocated block\n", v);
                runtime_throw("free runtime_mlookup");
        }
        prof = runtime_blockspecial(v);

        // Find size class for v.
        sizeclass = s->sizeclass;
        c = m->mcache;
        if(sizeclass == 0) {
                // Large object.
                size = s->npages<<PageShift;
                *(uintptr*)(s->start<<PageShift) = 1;   // mark as "needs to be zeroed"
                // Must mark v freed before calling unmarkspan and MHeap_Free:
                // they might coalesce v into other spans and change the bitmap further.
                runtime_markfreed(v, size);
                runtime_unmarkspan(v, 1<<PageShift);
                runtime_MHeap_Free(&runtime_mheap, s, 1);
        } else {
                // Small object.
                size = runtime_class_to_size[sizeclass];
                if(size > sizeof(uintptr))
                        ((uintptr*)v)[1] = 1;   // mark as "needs to be zeroed"
                // Must mark v freed before calling MCache_Free:
                // it might coalesce v and other blocks into a bigger span
                // and change the bitmap further.
                runtime_markfreed(v, size);
                c->local_by_size[sizeclass].nfree++;
                runtime_MCache_Free(c, v, sizeclass, size);
        }
        c->local_alloc -= size;
        if(prof)
                runtime_MProf_Free(v, size);
        m->mallocing = 0;
}

int32
runtime_mlookup(void *v, byte **base, uintptr *size, MSpan **sp)
{
        uintptr n, i;
        byte *p;
        MSpan *s;

        runtime_m()->mcache->local_nlookup++;
        s = runtime_MHeap_LookupMaybe(&runtime_mheap, v);
        if(sp)
                *sp = s;
        if(s == nil) {
                runtime_checkfreed(v, 1);
                if(base)
                        *base = nil;
                if(size)
                        *size = 0;
                return 0;
        }

        p = (byte*)((uintptr)s->start<<PageShift);
        if(s->sizeclass == 0) {
                // Large object.
                if(base)
                        *base = p;
                if(size)
                        *size = s->npages<<PageShift;
                return 1;
        }

        if((byte*)v >= (byte*)s->limit) {
                // pointers past the last block do not count as pointers.
                return 0;
        }

        n = runtime_class_to_size[s->sizeclass];
        if(base) {
                i = ((byte*)v - p)/n;
                *base = p + i*n;
        }
        if(size)
                *size = n;

        return 1;
}

MCache*
runtime_allocmcache(void)
{
        int32 rate;
        MCache *c;

        runtime_lock(&runtime_mheap);
        c = runtime_FixAlloc_Alloc(&runtime_mheap.cachealloc);
        mstats.mcache_inuse = runtime_mheap.cachealloc.inuse;
        mstats.mcache_sys = runtime_mheap.cachealloc.sys;
        runtime_unlock(&runtime_mheap);

        // Set first allocation sample size.
        rate = runtime_MemProfileRate;
        if(rate > 0x3fffffff)   // make 2*rate not overflow
                rate = 0x3fffffff;
        if(rate != 0)
                c->next_sample = runtime_fastrand1() % (2*rate);

        return c;
}

void
runtime_purgecachedstats(M* m)
{
        MCache *c;

        // Protected by either heap or GC lock.
        c = m->mcache;
        mstats.heap_alloc += c->local_cachealloc;
        c->local_cachealloc = 0;
        mstats.heap_objects += c->local_objects;
        c->local_objects = 0;
        mstats.nmalloc += c->local_nmalloc;
        c->local_nmalloc = 0;
        mstats.nfree += c->local_nfree;
        c->local_nfree = 0;
        mstats.nlookup += c->local_nlookup;
        c->local_nlookup = 0;
        mstats.alloc += c->local_alloc;
        c->local_alloc= 0;
        mstats.total_alloc += c->local_total_alloc;
        c->local_total_alloc= 0;
}

extern uintptr runtime_sizeof_C_MStats
  __asm__ ("libgo_runtime.runtime.Sizeof_C_MStats");

#define MaxArena32 (2U<<30)

void
runtime_mallocinit(void)
{
        byte *p;
        uintptr arena_size, bitmap_size;
        extern byte end[];
        byte *want;

        runtime_sizeof_C_MStats = sizeof(MStats);

        runtime_InitSizes();

        // Set up the allocation arena, a contiguous area of memory where
        // allocated data will be found.  The arena begins with a bitmap large
        // enough to hold 4 bits per allocated word.
        if(sizeof(void*) == 8) {
                // On a 64-bit machine, allocate from a single contiguous reservation.
                // 16 GB should be big enough for now.
                //
                // The code will work with the reservation at any address, but ask
                // SysReserve to use 0x000000f800000000 if possible.
                // Allocating a 16 GB region takes away 36 bits, and the amd64
                // doesn't let us choose the top 17 bits, so that leaves the 11 bits
                // in the middle of 0x00f8 for us to choose.  Choosing 0x00f8 means
                // that the valid memory addresses will begin 0x00f8, 0x00f9, 0x00fa, 0x00fb.
                // None of the bytes f8 f9 fa fb can appear in valid UTF-8, and
                // they are otherwise as far from ff (likely a common byte) as possible.
                // Choosing 0x00 for the leading 6 bits was more arbitrary, but it
                // is not a common ASCII code point either.  Using 0x11f8 instead
                // caused out of memory errors on OS X during thread allocations.
                // These choices are both for debuggability and to reduce the
                // odds of the conservative garbage collector not collecting memory
                // because some non-pointer block of memory had a bit pattern
                // that matched a memory address.
                //
                // Actually we reserve 17 GB (because the bitmap ends up being 1 GB)
                // but it hardly matters: fc is not valid UTF-8 either, and we have to
                // allocate 15 GB before we get that far.
                arena_size = (uintptr)(16LL<<30);
                bitmap_size = arena_size / (sizeof(void*)*8/4);
                p = runtime_SysReserve((void*)(0x00f8ULL<<32), bitmap_size + arena_size);
                if(p == nil)
                        runtime_throw("runtime: cannot reserve arena virtual address space");
        } else {
                // On a 32-bit machine, we can't typically get away
                // with a giant virtual address space reservation.
                // Instead we map the memory information bitmap
                // immediately after the data segment, large enough
                // to handle another 2GB of mappings (256 MB),
                // along with a reservation for another 512 MB of memory.
                // When that gets used up, we'll start asking the kernel
                // for any memory anywhere and hope it's in the 2GB
                // following the bitmap (presumably the executable begins
                // near the bottom of memory, so we'll have to use up
                // most of memory before the kernel resorts to giving out
                // memory before the beginning of the text segment).
                //
                // Alternatively we could reserve 512 MB bitmap, enough
                // for 4GB of mappings, and then accept any memory the
                // kernel threw at us, but normally that's a waste of 512 MB
                // of address space, which is probably too much in a 32-bit world.
                bitmap_size = MaxArena32 / (sizeof(void*)*8/4);
                arena_size = 512<<20;
                
                // SysReserve treats the address we ask for, end, as a hint,
                // not as an absolute requirement.  If we ask for the end
                // of the data segment but the operating system requires
                // a little more space before we can start allocating, it will
                // give out a slightly higher pointer.  Except QEMU, which
                // is buggy, as usual: it won't adjust the pointer upward.
                // So adjust it upward a little bit ourselves: 1/4 MB to get
                // away from the running binary image and then round up
                // to a MB boundary.
                want = (byte*)(((uintptr)end + (1<<18) + (1<<20) - 1)&~((1<<20)-1));
                if(0xffffffff - (uintptr)want <= bitmap_size + arena_size)
                  want = 0;
                p = runtime_SysReserve(want, bitmap_size + arena_size);
                if(p == nil)
                        runtime_throw("runtime: cannot reserve arena virtual address space");
        }
        if((uintptr)p & (((uintptr)1<<PageShift)-1))
                runtime_throw("runtime: SysReserve returned unaligned address");

        runtime_mheap.bitmap = p;
        runtime_mheap.arena_start = p + bitmap_size;
        runtime_mheap.arena_used = runtime_mheap.arena_start;
        runtime_mheap.arena_end = runtime_mheap.arena_start + arena_size;

        // Initialize the rest of the allocator.        
        runtime_MHeap_Init(&runtime_mheap, runtime_SysAlloc);
        runtime_m()->mcache = runtime_allocmcache();

        // See if it works.
        runtime_free(runtime_malloc(1));
}

void*
runtime_MHeap_SysAlloc(MHeap *h, uintptr n)
{
        byte *p;

        if(n <= (uintptr)(h->arena_end - h->arena_used)) {
                // Keep taking from our reservation.
                p = h->arena_used;
                runtime_SysMap(p, n);
                h->arena_used += n;
                runtime_MHeap_MapBits(h);
                return p;
        }
        
        // On 64-bit, our reservation is all we have.
        if(sizeof(void*) == 8)
                return nil;

        // On 32-bit, once the reservation is gone we can
        // try to get memory at a location chosen by the OS
        // and hope that it is in the range we allocated bitmap for.
        p = runtime_SysAlloc(n);
        if(p == nil)
                return nil;

        if(p < h->arena_start || (uintptr)(p+n - h->arena_start) >= MaxArena32) {
                runtime_printf("runtime: memory allocated by OS not in usable range\n");
                runtime_SysFree(p, n);
                return nil;
        }

        if(p+n > h->arena_used) {
                h->arena_used = p+n;
                if(h->arena_used > h->arena_end)
                        h->arena_end = h->arena_used;
                runtime_MHeap_MapBits(h);
        }
        
        return p;
}

// Runtime stubs.

void*
runtime_mal(uintptr n)
{
        return runtime_mallocgc(n, 0, 1, 1);
}

func new(typ *Type) (ret *uint8) {
        uint32 flag = typ->__code&GO_NO_POINTERS ? FlagNoPointers : 0;
        ret = runtime_mallocgc(typ->__size, flag, 1, 1);
}

func Alloc(n uintptr) (p *byte) {
        p = runtime_malloc(n);
}

func Free(p *byte) {
        runtime_free(p);
}

func Lookup(p *byte) (base *byte, size uintptr) {
        runtime_mlookup(p, &base, &size, nil);
}

func GC() {
        runtime_gc(1);
}

func SetFinalizer(obj Eface, finalizer Eface) {
        byte *base;
        uintptr size;
        const FuncType *ft;

        if(obj.__type_descriptor == nil) {
                // runtime·printf("runtime.SetFinalizer: first argument is nil interface\n");
                goto throw;
        }
        if(obj.__type_descriptor->__code != GO_PTR) {
                // runtime_printf("runtime.SetFinalizer: first argument is %S, not pointer\n", *obj.type->string);
                goto throw;
        }
        if(!runtime_mlookup(obj.__object, &base, &size, nil) || obj.__object != base) {
                // runtime_printf("runtime.SetFinalizer: pointer not at beginning of allocated block\n");
                goto throw;
        }
        ft = nil;
        if(finalizer.__type_descriptor != nil) {
                if(finalizer.__type_descriptor->__code != GO_FUNC)
                        goto badfunc;
                ft = (const FuncType*)finalizer.__type_descriptor;
                if(ft->__dotdotdot || ft->__in.__count != 1 || !__go_type_descriptors_equal(*(Type**)ft->__in.__values, obj.__type_descriptor))
                        goto badfunc;
        }

        if(!runtime_addfinalizer(obj.__object, finalizer.__type_descriptor != nil ? *(void**)finalizer.__object : nil, ft)) {
                runtime_printf("runtime.SetFinalizer: finalizer already set\n");
                goto throw;
        }
        return;

badfunc:
        // runtime_printf("runtime.SetFinalizer: second argument is %S, not func(%S)\n", *finalizer.type->string, *obj.type->string);
throw:
        runtime_throw("runtime.SetFinalizer");
}