/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * 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 nsMemoryCacheDevice.cpp, released February 22, 2001.
 * 
 * The Initial Developer of the Original Code is Netscape Communications
 * Corporation.  Portions created by Netscape are
 * Copyright (C) 2001 Netscape Communications Corporation.  All
 * Rights Reserved.
 * 
 * Contributor(s): 
 *    Gordon Sheridan, <gordon@netscape.com>
 *    Patrick C. Beard <beard@netscape.com>
 */

#include "nsMemoryCacheDevice.h"
#include "nsCacheService.h"
#include "nsICacheService.h"
#include "nsIComponentManager.h"
#include "nsIServiceManager.h"
#include "nsNetCID.h"
#include "nsIObserverService.h"
#include "nsIPref.h"
#include "nsICacheVisitor.h"
#include "nsITransport.h"
#include <signal.h>


static NS_DEFINE_CID(kStorageTransportCID, NS_STORAGETRANSPORT_CID);

const char *gMemoryDeviceID      = "memory";


nsMemoryCacheDevice::nsMemoryCacheDevice()
    : mInitialized(PR_FALSE),
      mEvictionThreshold(40 * 1024),
      mHardLimit(4 * 1024 * 1024),  // set default memory limit, in case prefs aren't available
      mTotalSize(0),
      mInactiveSize(0),
      mEntryCount(0),
      mMaxEntryCount(0)
{
    PR_INIT_CLIST(&mEvictionList[mostLikelyToEvict]);
    PR_INIT_CLIST(&mEvictionList[leastLikelyToEvict]);
}


nsMemoryCacheDevice::~nsMemoryCacheDevice()
{    
    Shutdown();
}


nsresult
nsMemoryCacheDevice::Init()
{
    if (mInitialized)  return NS_ERROR_ALREADY_INITIALIZED;

    nsresult  rv = mMemCacheEntries.Init();
    
    // set some default memory limits, in case prefs aren't available
    mSoftLimit = mHardLimit * 0.9;

    // XXX Register as a memory pressure observer
    mInitialized = NS_SUCCEEDED(rv);
    return rv;
}


nsresult
nsMemoryCacheDevice::Shutdown()
{
    NS_ASSERTION(mInitialized, "### attempting to shutdown while not initialized.\n");
    NS_ENSURE_TRUE(mInitialized, NS_ERROR_NOT_INITIALIZED);
    
    mMemCacheEntries.Shutdown();

    // evict all entries
    nsCacheEntry * entry, * next;

    for (int i=mostLikelyToEvict; i <= leastLikelyToEvict; ++i) {
        entry = (nsCacheEntry *)PR_LIST_HEAD(&mEvictionList[i]);
        while (entry != &mEvictionList[i]) {
            NS_ASSERTION(entry->IsInUse() == PR_FALSE, "### shutting down with active entries.\n");
            next = (nsCacheEntry *)PR_NEXT_LINK(entry);
            PR_REMOVE_AND_INIT_LINK(entry);
        
            // update statistics
            PRUint32 memoryRecovered = entry->Size();
            mTotalSize    -= memoryRecovered;
            mInactiveSize -= memoryRecovered;
            --mEntryCount;

            delete entry;
            entry = next;
        }
    }

/*
 * we're not factoring in changes to meta data yet...    
 *  NS_ASSERTION(mTotalSize == 0, "### mem cache leaking entries?\n");
 */
    NS_ASSERTION(mInactiveSize == 0, "### mem cache leaking entries?\n");
    NS_ASSERTION(mEntryCount == 0, "### mem cache leaking entries?\n");
    
    mInitialized = PR_FALSE;
    return NS_OK;
}


const char *
nsMemoryCacheDevice::GetDeviceID()
{
    return gMemoryDeviceID;
}


nsCacheEntry *
nsMemoryCacheDevice::FindEntry(nsCString * key)
{
    nsCacheEntry * entry = mMemCacheEntries.GetEntry(key);
    if (!entry)  return nsnull;

    // move entry to the tail of an eviction list
    PR_REMOVE_AND_INIT_LINK(entry);
    PR_APPEND_LINK(entry, &mEvictionList[EvictionList(entry, 0)]);
    
    mInactiveSize -= entry->Size();

    return entry;
}


nsresult
nsMemoryCacheDevice::DeactivateEntry(nsCacheEntry * entry)
{
    if (entry->IsDoomed()) {
#if debug
        // XXX verify we've removed it from mMemCacheEntries & eviction list
#endif
        // update statistics
        mTotalSize    -= entry->Size();
        --mEntryCount;

        delete entry;
        return NS_OK;
    }

    nsCacheEntry * ourEntry = mMemCacheEntries.GetEntry(entry->Key());
    NS_ASSERTION(ourEntry, "DeactivateEntry called for an entry we don't have!");
    NS_ASSERTION(entry == ourEntry, "entry doesn't match ourEntry");
    if (ourEntry != entry)
        return NS_ERROR_INVALID_POINTER;

    mInactiveSize += entry->Size();
    EvictEntriesIfNecessary();

    return NS_OK;
}


nsresult
nsMemoryCacheDevice::BindEntry(nsCacheEntry * entry)
{
	if (!entry->IsDoomed()) {
 	    NS_ASSERTION(PR_CLIST_IS_EMPTY(entry),"entry is already on a list!");
	
		// append entry to the eviction list
        PR_APPEND_LINK(entry, &mEvictionList[EvictionList(entry, 0)]);

        // add entry to hashtable of mem cache entries
        nsresult  rv = mMemCacheEntries.AddEntry(entry);
        if (NS_FAILED(rv)) {
            PR_REMOVE_AND_INIT_LINK(entry);
            return rv;
        }
	}

    // add size of entry to memory totals
    ++mEntryCount;
    if (mMaxEntryCount < mEntryCount) mMaxEntryCount = mEntryCount;

    mTotalSize += entry->Size();
    EvictEntriesIfNecessary();
    
    return NS_OK;
}


void
nsMemoryCacheDevice::DoomEntry(nsCacheEntry * entry)
{
    // XXX debug code to verify we have entry
    mMemCacheEntries.RemoveEntry(entry);

    // remove entry from our eviction list
    PR_REMOVE_AND_INIT_LINK(entry);
}


nsresult
nsMemoryCacheDevice::GetTransportForEntry( nsCacheEntry *    entry,
                                           nsCacheAccessMode mode,
                                           nsITransport   ** transport )
{
    NS_ENSURE_ARG_POINTER(entry);
    NS_ENSURE_ARG_POINTER(transport);

    nsCOMPtr<nsISupports> data;

    nsresult rv = entry->GetData(getter_AddRefs(data));
    if (NS_FAILED(rv))
        return rv;

    if (data)
        return CallQueryInterface(data, transport);
    else {
        // create a new transport for this entry
        rv = nsComponentManager::CreateInstance(kStorageTransportCID,
                                                nsnull,
                                                NS_GET_IID(nsITransport),
                                                (void **) transport);
        if (NS_FAILED(rv)) return rv;

        entry->SetData(*transport);
        return NS_OK;
    }
}


nsresult
nsMemoryCacheDevice::GetFileForEntry( nsCacheEntry *    entry,
                                      nsIFile **        result )
{
    return NS_ERROR_NOT_IMPLEMENTED;
}


nsresult
nsMemoryCacheDevice::OnDataSizeChange( nsCacheEntry * entry, PRInt32 deltaSize)
{
    if (entry->IsStreamData()) {
        // we have the right to refuse or pre-evict
    }

    // adjust our totals
    mTotalSize    += deltaSize;
    
    if (!entry->IsDoomed()) {
        // move entry to the tail of the appropriate eviction list
        PR_REMOVE_AND_INIT_LINK(entry);
        PR_APPEND_LINK(entry, &mEvictionList[EvictionList(entry, deltaSize)]);
    }

    EvictEntriesIfNecessary();

    return NS_OK;
}


void
nsMemoryCacheDevice::AdjustMemoryLimits(PRUint32  softLimit, PRUint32  hardLimit)
{
    mSoftLimit = softLimit;
    mHardLimit = hardLimit;
    EvictEntriesIfNecessary();
}


void
nsMemoryCacheDevice::EvictEntry(nsCacheEntry * entry)
{
    // remove entry from our hashtable
    mMemCacheEntries.RemoveEntry(entry);
    
    // remove entry from the eviction list
    PR_REMOVE_AND_INIT_LINK(entry);
    
    // update statistics
    PRUint32 memoryRecovered = entry->Size();
    mTotalSize    -= memoryRecovered;
    mInactiveSize -= memoryRecovered;
    --mEntryCount;

    delete entry;
}


void
nsMemoryCacheDevice::EvictEntriesIfNecessary(void)
{
    nsCacheEntry * entry, * next;

    if ((mTotalSize < mHardLimit) && (mInactiveSize < mSoftLimit))
        return;

    for (int i=mostLikelyToEvict; i<=leastLikelyToEvict; ++i) {
        entry = (nsCacheEntry *)PR_LIST_HEAD(&mEvictionList[i]);
        while (entry != &mEvictionList[i]) {
            if (entry->IsInUse()) {
                entry = (nsCacheEntry *)PR_NEXT_LINK(entry);
                continue;
            }

            next = (nsCacheEntry *)PR_NEXT_LINK(entry);
            EvictEntry(entry);
            entry = next;

            if ((mTotalSize < mHardLimit) && (mInactiveSize < mSoftLimit))
                return;
        }
    }
}


int
nsMemoryCacheDevice::EvictionList(nsCacheEntry * entry, PRUint32  deltaSize)
{
    PRUint32  size = entry->Size() + deltaSize;
    if ((size > mEvictionThreshold) || (entry->ExpirationTime() != 0))
        return mostLikelyToEvict;
    
    return leastLikelyToEvict;
}


nsresult
nsMemoryCacheDevice::Visit(nsICacheVisitor * visitor)
{
    nsMemoryCacheDeviceInfo * deviceInfo = new nsMemoryCacheDeviceInfo(this);
    nsCOMPtr<nsICacheDeviceInfo> deviceRef(deviceInfo);
    if (!deviceInfo) return NS_ERROR_OUT_OF_MEMORY;

    PRBool keepGoing;
    nsresult rv = visitor->VisitDevice(gMemoryDeviceID, deviceInfo, &keepGoing);
    if (NS_FAILED(rv)) return rv;

    if (!keepGoing)
        return NS_OK;

    nsCacheEntry *              entry;
    nsCOMPtr<nsICacheEntryInfo> entryRef;

    for (int i=mostLikelyToEvict; i <= leastLikelyToEvict; ++i) {
        entry = (nsCacheEntry *)PR_LIST_HEAD(&mEvictionList[i]);
        while (entry != &mEvictionList[i]) {
            nsCacheEntryInfo * entryInfo = new nsCacheEntryInfo(entry);
            if (!entryInfo) return NS_ERROR_OUT_OF_MEMORY;
            entryRef = entryInfo;

            rv = visitor->VisitEntry(gMemoryDeviceID, entryInfo, &keepGoing);
            entryInfo->DetachEntry();
            if (NS_FAILED(rv)) return rv;
            if (!keepGoing) break;

            entry = (nsCacheEntry *)PR_NEXT_LINK(entry);
        }
    }
    return NS_OK;
}


nsresult
nsMemoryCacheDevice::EvictEntries(const char * clientID)
{
    nsCacheEntry * entry;
    PRUint32 prefixLength = (clientID ? nsCRT::strlen(clientID) : 0);

    for (int i=mostLikelyToEvict; i<=leastLikelyToEvict; ++i) {
        PRCList * elem = PR_LIST_HEAD(&mEvictionList[i]);
        while (elem != &mEvictionList[i]) {
            entry = (nsCacheEntry *)elem;
            elem = PR_NEXT_LINK(elem);
            
            const char * key = entry->Key()->get();
            if (clientID && nsCRT::strncmp(clientID, key, prefixLength) != 0)
                continue;
            
            if (entry->IsInUse()) {
                nsresult rv = nsCacheService::GlobalInstance()->DoomEntry_Locked(entry);
                if (NS_FAILED(rv)) return rv;
            } else {
                EvictEntry(entry);
            }
        }
    }
    return NS_OK;
}


void
nsMemoryCacheDevice::SetCapacity(PRUint32  capacity)
{
    PRUint32 hardLimit = capacity * 1024;  // convert k into bytes
    PRUint32 softLimit = hardLimit * 0.9;
    AdjustMemoryLimits(softLimit, hardLimit);
}


/******************************************************************************
 * nsMemoryCacheDeviceInfo - for implementing about:cache
 *****************************************************************************/


NS_IMPL_ISUPPORTS1(nsMemoryCacheDeviceInfo, nsICacheDeviceInfo);


NS_IMETHODIMP
nsMemoryCacheDeviceInfo::GetDescription(char ** result)
{
    NS_ENSURE_ARG_POINTER(result);
    *result = nsCRT::strdup("Memory cache device");
    if (!*result) return NS_ERROR_OUT_OF_MEMORY;
    return NS_OK;
}


NS_IMETHODIMP
nsMemoryCacheDeviceInfo::GetUsageReport(char ** result)
{
    NS_ENSURE_ARG_POINTER(result);
    *result = nsCRT::strdup("Memory cache usage report:");
    if (!*result) return NS_ERROR_OUT_OF_MEMORY;
    return NS_OK;
}


NS_IMETHODIMP
nsMemoryCacheDeviceInfo::GetEntryCount(PRUint32 * result)
{
    NS_ENSURE_ARG_POINTER(result);
    // XXX compare calculated count vs. mEntryCount
    *result = mDevice->mEntryCount;
    return NS_OK;
}


NS_IMETHODIMP
nsMemoryCacheDeviceInfo::GetTotalSize(PRUint32 * result)
{
    NS_ENSURE_ARG_POINTER(result);
    *result = mDevice->mTotalSize;
    return NS_OK;
}


NS_IMETHODIMP
nsMemoryCacheDeviceInfo::GetMaximumSize(PRUint32 * result)
{
    NS_ENSURE_ARG_POINTER(result);
    *result = mDevice->mHardLimit;
    return NS_OK;
}