/*
 * COPYRIGHT:       See COPYING in the top level directory
 * PROJECT:         ReactOS kernel
 * FILE:            ntoskrnl/mm/balance.c
 * PURPOSE:         kernel memory managment functions
 *
 * PROGRAMMERS:     David Welch (welch@cwcom.net)
 *                  Cameron Gutman (cameron.gutman@reactos.org)
 */

/* INCLUDES *****************************************************************/

#include <ntoskrnl.h>
#define NDEBUG
#include <debug.h>

#include "ARM3/miarm.h"

/* TYPES ********************************************************************/
typedef struct _MM_ALLOCATION_REQUEST
{
    PFN_NUMBER Page;
    LIST_ENTRY ListEntry;
    KEVENT Event;
}
MM_ALLOCATION_REQUEST, *PMM_ALLOCATION_REQUEST;
/* GLOBALS ******************************************************************/

MM_MEMORY_CONSUMER MiMemoryConsumers[MC_MAXIMUM];
static ULONG MiMinimumAvailablePages;
static LIST_ENTRY AllocationListHead;
static KSPIN_LOCK AllocationListLock;
static ULONG MiMinimumPagesPerRun;

static CLIENT_ID MiBalancerThreadId;
static HANDLE MiBalancerThreadHandle = NULL;
static KEVENT MiBalancerEvent;
static KTIMER MiBalancerTimer;

static LONG PageOutThreadActive;

/* FUNCTIONS ****************************************************************/

CODE_SEG("INIT")
VOID
NTAPI
MmInitializeBalancer(ULONG NrAvailablePages, ULONG NrSystemPages)
{
    memset(MiMemoryConsumers, 0, sizeof(MiMemoryConsumers));
    InitializeListHead(&AllocationListHead);
    KeInitializeSpinLock(&AllocationListLock);

    /* Set up targets. */
    MiMinimumAvailablePages = 256;
    MiMinimumPagesPerRun = 256;
    MiMemoryConsumers[MC_USER].PagesTarget = NrAvailablePages / 2;
}

CODE_SEG("INIT")
VOID
NTAPI
MmInitializeMemoryConsumer(
    ULONG Consumer,
    NTSTATUS (*Trim)(ULONG Target, ULONG Priority, PULONG NrFreed))
{
    MiMemoryConsumers[Consumer].Trim = Trim;
}

VOID
NTAPI
MiZeroPhysicalPage(
    IN PFN_NUMBER PageFrameIndex
);

NTSTATUS
NTAPI
MmReleasePageMemoryConsumer(ULONG Consumer, PFN_NUMBER Page)
{
    if (Page == 0)
    {
        DPRINT1("Tried to release page zero.\n");
        KeBugCheck(MEMORY_MANAGEMENT);
    }

    (void)InterlockedDecrementUL(&MiMemoryConsumers[Consumer].PagesUsed);

    MmDereferencePage(Page);

    return(STATUS_SUCCESS);
}

ULONG
NTAPI
MiTrimMemoryConsumer(ULONG Consumer, ULONG InitialTarget)
{
    ULONG Target = InitialTarget;
    ULONG NrFreedPages = 0;
    NTSTATUS Status;

    /* Make sure we can trim this consumer */
    if (!MiMemoryConsumers[Consumer].Trim)
    {
        /* Return the unmodified initial target */
        return InitialTarget;
    }

    if (MmAvailablePages < MiMinimumAvailablePages)
    {
        /* Global page limit exceeded */
        Target = (ULONG)max(Target, MiMinimumAvailablePages - MmAvailablePages);
    }
    else if (MiMemoryConsumers[Consumer].PagesUsed > MiMemoryConsumers[Consumer].PagesTarget)
    {
        /* Consumer page limit exceeded */
        Target = max(Target, MiMemoryConsumers[Consumer].PagesUsed - MiMemoryConsumers[Consumer].PagesTarget);
    }

    if (Target)
    {
        /* Now swap the pages out */
        Status = MiMemoryConsumers[Consumer].Trim(Target, MmAvailablePages < MiMinimumAvailablePages, &NrFreedPages);

        DPRINT("Trimming consumer %lu: Freed %lu pages with a target of %lu pages\n", Consumer, NrFreedPages, Target);

        if (!NT_SUCCESS(Status))
        {
            KeBugCheck(MEMORY_MANAGEMENT);
        }
    }

    /* Return the page count needed to be freed to meet the initial target */
    return (InitialTarget > NrFreedPages) ? (InitialTarget - NrFreedPages) : 0;
}

NTSTATUS
MmTrimUserMemory(ULONG Target, ULONG Priority, PULONG NrFreedPages)
{
    PFN_NUMBER CurrentPage;
    NTSTATUS Status;

    (*NrFreedPages) = 0;

    DPRINT1("MM BALANCER: %s\n", Priority ? "Paging out!" : "Removing access bit!");

    CurrentPage = MmGetLRUFirstUserPage();
    while (CurrentPage != 0 && Target > 0)
    {
        if (Priority)
        {
            Status = MmPageOutPhysicalAddress(CurrentPage);
            if (NT_SUCCESS(Status))
            {
                DPRINT("Succeeded\n");
                Target--;
                (*NrFreedPages)++;
            }
        }
        else
        {
            /* When not paging-out agressively, just reset the accessed bit */
            PEPROCESS Process = NULL;
            PVOID Address = NULL;
            BOOLEAN Accessed = FALSE;

            /*
             * We have a lock-ordering problem here. We cant lock the PFN DB before the Process address space.
             * So we must use circonvoluted loops.
             * Well...
             */
            while (TRUE)
            {
                KAPC_STATE ApcState;
                KIRQL OldIrql = MiAcquirePfnLock();
                PMM_RMAP_ENTRY Entry = MmGetRmapListHeadPage(CurrentPage);
                while (Entry)
                {
                    if (RMAP_IS_SEGMENT(Entry->Address))
                    {
                        Entry = Entry->Next;
                        continue;
                    }

                    /* Check that we didn't treat this entry before */
                    if (Entry->Address < Address)
                    {
                        Entry = Entry->Next;
                        continue;
                    }

                    if ((Entry->Address == Address) && (Entry->Process <= Process))
                    {
                        Entry = Entry->Next;
                        continue;
                    }

                    break;
                }

                if (!Entry)
                {
                    MiReleasePfnLock(OldIrql);
                    break;
                }

                Process = Entry->Process;
                Address = Entry->Address;

                MiReleasePfnLock(OldIrql);

                KeStackAttachProcess(&Process->Pcb, &ApcState);

                MmLockAddressSpace(&Process->Vm);

                /* Be sure this is still valid. */
                PMMPTE Pte = MiAddressToPte(Address);
                if (Pte->u.Hard.Valid)
                {
                    Accessed = Accessed || Pte->u.Hard.Accessed;
                    Pte->u.Hard.Accessed = 0;

                    /* There is no need to invalidate, the balancer thread is never on a user process */
                    //KeInvalidateTlbEntry(Address);
                }

                MmUnlockAddressSpace(&Process->Vm);

                KeUnstackDetachProcess(&ApcState);
            }

            if (!Accessed)
            {
                /* Nobody accessed this page since the last time we check. Time to clean up */

                Status = MmPageOutPhysicalAddress(CurrentPage);
                // DPRINT1("Paged-out one page: %s\n", NT_SUCCESS(Status) ? "Yes" : "No");
                (void)Status;
            }

            /* Done for this page. */
            Target--;
        }

        CurrentPage = MmGetLRUNextUserPage(CurrentPage, TRUE);
    }

    if (CurrentPage)
    {
        KIRQL OldIrql = MiAcquirePfnLock();
        MmDereferencePage(CurrentPage);
        MiReleasePfnLock(OldIrql);
    }

    return STATUS_SUCCESS;
}

static BOOLEAN
MiIsBalancerThread(VOID)
{
    return (MiBalancerThreadHandle != NULL) &&
           (PsGetCurrentThreadId() == MiBalancerThreadId.UniqueThread);
}

VOID
NTAPI
MmRebalanceMemoryConsumers(VOID)
{
    if (InterlockedCompareExchange(&PageOutThreadActive, 0, 1) == 0)
    {
        KeSetEvent(&MiBalancerEvent, IO_NO_INCREMENT, FALSE);
    }
}

NTSTATUS
NTAPI
MmRequestPageMemoryConsumer(ULONG Consumer, BOOLEAN CanWait,
                            PPFN_NUMBER AllocatedPage)
{
    PFN_NUMBER Page;

    /* Update the target */
    InterlockedIncrementUL(&MiMemoryConsumers[Consumer].PagesUsed);

    /*
     * Actually allocate the page.
     */
    Page = MmAllocPage(Consumer);
    if (Page == 0)
    {
        KeBugCheck(NO_PAGES_AVAILABLE);
    }
    *AllocatedPage = Page;

    return(STATUS_SUCCESS);
}


VOID NTAPI
MiBalancerThread(PVOID Unused)
{
    PVOID WaitObjects[2];
    NTSTATUS Status;
    ULONG i;

    WaitObjects[0] = &MiBalancerEvent;
    WaitObjects[1] = &MiBalancerTimer;

    while (1)
    {
        Status = KeWaitForMultipleObjects(2,
                                          WaitObjects,
                                          WaitAny,
                                          Executive,
                                          KernelMode,
                                          FALSE,
                                          NULL,
                                          NULL);

        if (Status == STATUS_WAIT_0 || Status == STATUS_WAIT_1)
        {
            ULONG InitialTarget = 0;

#if (_MI_PAGING_LEVELS == 2)
            if (!MiIsBalancerThread())
            {
                /* Clean up the unused PDEs */
                ULONG_PTR Address;
                PEPROCESS Process = PsGetCurrentProcess();

                /* Acquire PFN lock */
                KIRQL OldIrql = MiAcquirePfnLock();
                PMMPDE pointerPde;
                for (Address = (ULONG_PTR)MI_LOWEST_VAD_ADDRESS;
                     Address < (ULONG_PTR)MM_HIGHEST_VAD_ADDRESS;
                     Address += PTE_PER_PAGE * PAGE_SIZE)
                {
                    if (MiQueryPageTableReferences((PVOID)Address) == 0)
                    {
                        pointerPde = MiAddressToPde(Address);
                        if (pointerPde->u.Hard.Valid)
                            MiDeletePte(pointerPde, MiPdeToPte(pointerPde), Process, NULL);
                        ASSERT(pointerPde->u.Hard.Valid == 0);
                    }
                }
                /* Release lock */
                MiReleasePfnLock(OldIrql);
            }
#endif
            do
            {
                ULONG OldTarget = InitialTarget;

                /* Trim each consumer */
                for (i = 0; i < MC_MAXIMUM; i++)
                {
                    InitialTarget = MiTrimMemoryConsumer(i, InitialTarget);
                }

                /* No pages left to swap! */
                if (InitialTarget != 0 &&
                        InitialTarget == OldTarget)
                {
                    /* Game over */
                    KeBugCheck(NO_PAGES_AVAILABLE);
                }
            }
            while (InitialTarget != 0);

            if (Status == STATUS_WAIT_0)
                InterlockedDecrement(&PageOutThreadActive);
        }
        else
        {
            DPRINT1("KeWaitForMultipleObjects failed, status = %x\n", Status);
            KeBugCheck(MEMORY_MANAGEMENT);
        }
    }
}

BOOLEAN MmRosNotifyAvailablePage(PFN_NUMBER Page)
{
    PLIST_ENTRY Entry;
    PMM_ALLOCATION_REQUEST Request;
    PMMPFN Pfn1;

    /* Make sure the PFN lock is held */
    MI_ASSERT_PFN_LOCK_HELD();

    if (!MiMinimumAvailablePages)
    {
        /* Dirty way to know if we were initialized. */
        return FALSE;
    }

    Entry = ExInterlockedRemoveHeadList(&AllocationListHead, &AllocationListLock);
    if (!Entry)
        return FALSE;

    Request = CONTAINING_RECORD(Entry, MM_ALLOCATION_REQUEST, ListEntry);
    MiZeroPhysicalPage(Page);
    Request->Page = Page;

    Pfn1 = MiGetPfnEntry(Page);
    ASSERT(Pfn1->u3.e2.ReferenceCount == 0);
    Pfn1->u3.e2.ReferenceCount = 1;
    Pfn1->u3.e1.PageLocation = ActiveAndValid;

    /* This marks the PFN as a ReactOS PFN */
    Pfn1->u4.AweAllocation = TRUE;

    /* Allocate the extra ReactOS Data and zero it out */
    Pfn1->u1.SwapEntry = 0;
    Pfn1->RmapListHead = NULL;

    KeSetEvent(&Request->Event, IO_NO_INCREMENT, FALSE);

    return TRUE;
}

CODE_SEG("INIT")
VOID
NTAPI
MiInitBalancerThread(VOID)
{
    KPRIORITY Priority;
    NTSTATUS Status;
    LARGE_INTEGER Timeout;

    KeInitializeEvent(&MiBalancerEvent, SynchronizationEvent, FALSE);
    KeInitializeTimerEx(&MiBalancerTimer, SynchronizationTimer);

    Timeout.QuadPart = -20000000; /* 2 sec */
    KeSetTimerEx(&MiBalancerTimer,
                 Timeout,
                 2000,         /* 2 sec */
                 NULL);

    Status = PsCreateSystemThread(&MiBalancerThreadHandle,
                                  THREAD_ALL_ACCESS,
                                  NULL,
                                  NULL,
                                  &MiBalancerThreadId,
                                  MiBalancerThread,
                                  NULL);
    if (!NT_SUCCESS(Status))
    {
        KeBugCheck(MEMORY_MANAGEMENT);
    }

    Priority = LOW_REALTIME_PRIORITY + 1;
    NtSetInformationThread(MiBalancerThreadHandle,
                           ThreadPriority,
                           &Priority,
                           sizeof(Priority));

}


/* EOF */