/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "nsXPCOM.h"
#include "nsMemoryImpl.h"
#include "nsThreadUtils.h"

#include "nsIObserver.h"
#include "nsIObserverService.h"
#include "nsIServiceManager.h"
#include "nsISupportsArray.h"

#include "prmem.h"
#include "prcvar.h"
#include "pratom.h"

#include "nsAlgorithm.h"
#include "nsAutoLock.h"
#include "nsCOMPtr.h"
#include "nsString.h"

#if defined(XP_WIN)
#include <windows.h>
#endif

#if defined (NS_OSSO)
#include <osso-mem.h>
#include <fcntl.h>
#include <unistd.h>
static const char kHighMark[] = "/sys/kernel/high_watermark";
#endif

// Some platforms notify you when system memory is low, others do not.
// In the case of those that do not, we want to post low memory
// notifications from IsLowMemory().  For those that can notify us, that
// code usually lives in toolkit.
#ifdef WINCE
#define NOTIFY_LOW_MEMORY
#endif

#ifdef WINCE_WINDOWS_MOBILE
#include "aygshell.h"
#endif

#include "nsITimer.h"

static nsMemoryImpl sGlobalMemory;

NS_IMPL_QUERY_INTERFACE1(nsMemoryImpl, nsIMemory)

NS_IMETHODIMP_(void*)
nsMemoryImpl::Alloc(PRSize size)
{
    return NS_Alloc(size);
}

NS_IMETHODIMP_(void*)
nsMemoryImpl::Realloc(void* ptr, PRSize size)
{
    return NS_Realloc(ptr, size);
}

NS_IMETHODIMP_(void)
nsMemoryImpl::Free(void* ptr)
{
    NS_Free(ptr);
}

NS_IMETHODIMP
nsMemoryImpl::HeapMinimize(PRBool aImmediate)
{
    return FlushMemory(NS_LITERAL_STRING("heap-minimize").get(), aImmediate);
}

/* this magic number is something greater than 40mb
 * and after all, 40mb should be good enough for any web app
 * unless it's part of an office suite.
 */
static const int kRequiredMemory = 0x3000000;

NS_IMETHODIMP
nsMemoryImpl::IsLowMemory(PRBool *result)
{
#if defined(WINCE_WINDOWS_MOBILE)
    *result = PR_FALSE;
    // See bug 475595 -- this is incorrect right now, and causes a big
    // perf hit since GlobalMemoryStatus has to grab a kernel VM lock
    // and do a bunch of munging through VM pages to get the data
    // that's requested.  We call IsLowMemory in some performance
    // critical code (e.g. during painting), so that's bad.
    MEMORYSTATUS stat;
    GlobalMemoryStatus(&stat);
    *result = (stat.dwMemoryLoad >= 98);
#elif defined(WINCE)
    // Bug 525323 - GlobalMemoryStatus kills perf on WinCE.
    *result = PR_FALSE;
#elif defined(XP_WIN)
    MEMORYSTATUSEX stat;
    stat.dwLength = sizeof stat;
    GlobalMemoryStatusEx(&stat);
    *result = (stat.ullAvailPageFile < kRequiredMemory) &&
        ((float)stat.ullAvailPageFile / stat.ullTotalPageFile) < 0.1;
#elif defined(NS_OSSO)
    static int osso_highmark_fd = -1;
    if (osso_highmark_fd == -1) {
        osso_highmark_fd = open (kHighMark, O_RDONLY);

        if (osso_highmark_fd == -1) {
            NS_ERROR("can't find the osso highmark file");    
            *result = PR_FALSE;
            return NS_OK;
        }
    }

    // be kind, rewind.
    lseek(osso_highmark_fd, 0L, SEEK_SET);

    int c = 0;
    read (osso_highmark_fd, &c, 1);

    *result = (c == '1');
#else
    *result = PR_FALSE;
#endif

#ifdef NOTIFY_LOW_MEMORY
    if (*result) {
        sGlobalMemory.FlushMemory(NS_LITERAL_STRING("low-memory").get(), PR_FALSE);
    }
#endif
    return NS_OK;
}

/*static*/ nsresult
nsMemoryImpl::Create(nsISupports* outer, const nsIID& aIID, void **aResult)
{
    NS_ENSURE_NO_AGGREGATION(outer);
    return sGlobalMemory.QueryInterface(aIID, aResult);
}

nsresult
nsMemoryImpl::FlushMemory(const PRUnichar* aReason, PRBool aImmediate)
{
    nsresult rv;

    if (aImmediate) {
        // They've asked us to run the flusher *immediately*. We've
        // got to be on the UI main thread for us to be able to do
        // that...are we?
        if (!NS_IsMainThread()) {
            NS_ERROR("can't synchronously flush memory: not on UI thread");
            return NS_ERROR_FAILURE;
        }
    }

    PRInt32 lastVal = PR_AtomicSet(&sIsFlushing, 1);
    if (lastVal)
        return NS_OK;

    PRIntervalTime now = PR_IntervalNow();

    // Run the flushers immediately if we can; otherwise, proxy to the
    // UI thread an run 'em asynchronously.
    if (aImmediate) {
        rv = RunFlushers(aReason);
    }
    else {
        // Don't broadcast more than once every 1000ms to avoid being noisy
        if (PR_IntervalToMicroseconds(now - sLastFlushTime) > 1000) {
            sFlushEvent.mReason = aReason;
            rv = NS_DispatchToMainThread(&sFlushEvent, NS_DISPATCH_NORMAL);
        }
    }

    sLastFlushTime = now;
    return rv;
}

nsresult
nsMemoryImpl::RunFlushers(const PRUnichar* aReason)
{
    nsCOMPtr<nsIObserverService> os = do_GetService("@mozilla.org/observer-service;1");
    if (os) {

        // Instead of:
        //  os->NotifyObservers(this, "memory-pressure", aReason);
        // we are going to do this manually to see who/what is
        // deallocating.

        nsCOMPtr<nsISimpleEnumerator> e;
        os->EnumerateObservers("memory-pressure", getter_AddRefs(e));

        if ( e ) {
          nsCOMPtr<nsIObserver> observer;
          PRBool loop = PR_TRUE;

          while (NS_SUCCEEDED(e->HasMoreElements(&loop)) && loop) 
          {
              e->GetNext(getter_AddRefs(observer));

              if (!observer)
                  continue;

              observer->Observe(observer, "memory-pressure", aReason);
          }
        }
    }

    // Run built-in system flushers
#ifdef WINCE_WINDOWS_MOBILE

    // This function tries to free up memory for an application.
    // If necessary, the shell closes down other applications by
    // sending WM_CLOSE messages.  We ask for 4MB.

    SHCloseApps(1024 * 1024 * 4);

#endif

    sIsFlushing = 0;
    return NS_OK;
}

// XXX need NS_IMPL_STATIC_ADDREF/RELEASE
NS_IMETHODIMP_(nsrefcnt) nsMemoryImpl::FlushEvent::AddRef() { return 2; }
NS_IMETHODIMP_(nsrefcnt) nsMemoryImpl::FlushEvent::Release() { return 1; }
NS_IMPL_QUERY_INTERFACE1(nsMemoryImpl::FlushEvent, nsIRunnable)

NS_IMETHODIMP
nsMemoryImpl::FlushEvent::Run()
{
    sGlobalMemory.RunFlushers(mReason);
    return NS_OK;
}

PRInt32
nsMemoryImpl::sIsFlushing = 0;

PRIntervalTime
nsMemoryImpl::sLastFlushTime = 0;

nsMemoryImpl::FlushEvent
nsMemoryImpl::sFlushEvent;

XPCOM_API(void*)
NS_Alloc(PRSize size)
{
    if (size > PR_INT32_MAX)
        return nsnull;

    void* result = PR_Malloc(size);
    if (! result) {
        // Request an asynchronous flush
        sGlobalMemory.FlushMemory(NS_LITERAL_STRING("alloc-failure").get(), PR_FALSE);
    }
    return result;
}

XPCOM_API(void*)
NS_Realloc(void* ptr, PRSize size)
{
    if (size > PR_INT32_MAX)
        return nsnull;

    void* result = PR_Realloc(ptr, size);
    if (! result && size != 0) {
        // Request an asynchronous flush
        sGlobalMemory.FlushMemory(NS_LITERAL_STRING("alloc-failure").get(), PR_FALSE);
    }
    return result;
}

XPCOM_API(void)
NS_Free(void* ptr)
{
    PR_Free(ptr);
}

nsresult
NS_GetMemoryManager(nsIMemory* *result)
{
    return sGlobalMemory.QueryInterface(NS_GET_IID(nsIMemory), (void**) result);
}
