/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/MemoryReporting.h"

#include "nsCache.h"

#include <limits.h>

#include "nscore.h"

#include "nsDiskCacheBinding.h"

#include "nsCacheService.h"

using namespace mozilla;

/******************************************************************************

 *  static hash table callback functions

 *

 *****************************************************************************/

struct HashTableEntry : PLDHashEntryHdr {

    nsDiskCacheBinding *  mBinding;

};

static PLDHashNumber

HashKey(const void *key)

{

    return (PLDHashNumber) NS_PTR_TO_INT32(key);

}

static bool

MatchEntry(const PLDHashEntryHdr *       header,

           const void *                  key)

{

    HashTableEntry * hashEntry = (HashTableEntry *) header;

    return (hashEntry->mBinding->mRecord.HashNumber() == (PLDHashNumber) NS_PTR_TO_INT32(key));

}

static void

MoveEntry(PLDHashTable *           /* table */,

          const PLDHashEntryHdr *     src,

          PLDHashEntryHdr       *     dst)

{

    new (KnownNotNull, dst) HashTableEntry(std::move(*(HashTableEntry*)src));

    // No need to delete `src`.

}

static void

ClearEntry(PLDHashTable *      /* table */,

           PLDHashEntryHdr *      header)

{

    ((HashTableEntry *)header)->mBinding = nullptr;

}

/******************************************************************************

 *  Utility Functions

 *****************************************************************************/

nsDiskCacheBinding *

GetCacheEntryBinding(nsCacheEntry * entry)

{

    return (nsDiskCacheBinding *) entry->Data();

}

/******************************************************************************

 *  nsDiskCacheBinding

 *****************************************************************************/

NS_IMPL_ISUPPORTS0(nsDiskCacheBinding)

nsDiskCacheBinding::nsDiskCacheBinding(nsCacheEntry* entry, nsDiskCacheRecord * record)

    :   mCacheEntry(entry)

    ,   mStreamIO(nullptr)

    ,   mDeactivateEvent(nullptr)

{

    NS_ASSERTION(record->ValidRecord(), "bad record");

    PR_INIT_CLIST(this);

    mRecord     = *record;

    mDoomed     = entry->IsDoomed();

    mGeneration = record->Generation();    // 0 == uninitialized, or data & meta using block files

}

nsDiskCacheBinding::~nsDiskCacheBinding()

{

    // Grab the cache lock since the binding is stored in nsCacheEntry::mData

    // and it is released using nsCacheService::ReleaseObject_Locked() which

    // releases the object outside the cache lock.

    nsCacheServiceAutoLock lock;

    NS_ASSERTION(PR_CLIST_IS_EMPTY(this), "binding deleted while still on list");

    if (!PR_CLIST_IS_EMPTY(this))

        PR_REMOVE_LINK(this);       // XXX why are we still on a list?

    // sever streamIO/binding link

    if (mStreamIO) {

        if (NS_FAILED(mStreamIO->ClearBinding()))

            nsCacheService::DoomEntry(mCacheEntry);

        NS_RELEASE(mStreamIO);

    }

}

nsresult

nsDiskCacheBinding::EnsureStreamIO()

{

    if (!mStreamIO) {

        mStreamIO = new nsDiskCacheStreamIO(this);

        if (!mStreamIO)  return NS_ERROR_OUT_OF_MEMORY;

        NS_ADDREF(mStreamIO);

    }

    return NS_OK;

}

/******************************************************************************

 *  nsDiskCacheBindery

 *

 *  Keeps track of bound disk cache entries to detect for collisions.

 *

 *****************************************************************************/

const PLDHashTableOps nsDiskCacheBindery::ops =

{

    HashKey,

    MatchEntry,

    MoveEntry,

    ClearEntry

};

nsDiskCacheBindery::nsDiskCacheBindery()

    : table(&ops, sizeof(HashTableEntry), kInitialTableLength)

    , initialized(false)

{

}

nsDiskCacheBindery::~nsDiskCacheBindery()

{

    Reset();

}

void

nsDiskCacheBindery::Init()

{

    table.ClearAndPrepareForLength(kInitialTableLength);

    initialized = true;

}

void

nsDiskCacheBindery::Reset()

{

    if (initialized) {

        table.ClearAndPrepareForLength(kInitialTableLength);

        initialized = false;

    }

}

nsDiskCacheBinding *

nsDiskCacheBindery::CreateBinding(nsCacheEntry *       entry,

                                  nsDiskCacheRecord *  record)

{

    NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");

    nsCOMPtr<nsISupports> data = entry->Data();

    if (data) {

        NS_ERROR("cache entry already has bind data");

        return nullptr;

    }

    nsDiskCacheBinding * binding = new nsDiskCacheBinding(entry, record);

    if (!binding)  return nullptr;

    // give ownership of the binding to the entry

    entry->SetData(binding);

    // add binding to collision detection system

    nsresult rv = AddBinding(binding);

    if (NS_FAILED(rv)) {

        entry->SetData(nullptr);

        return nullptr;

    }

    return binding;

}

/**

 *  FindActiveEntry :  to find active colliding entry so we can doom it

 */

nsDiskCacheBinding *

nsDiskCacheBindery::FindActiveBinding(uint32_t  hashNumber) const

{

    NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");

    // find hash entry for key

    auto hashEntry = static_cast<HashTableEntry*>

        (table.Search((void*)(uintptr_t)hashNumber));

    if (!hashEntry) return nullptr;

    // walk list looking for active entry

    NS_ASSERTION(hashEntry->mBinding, "hash entry left with no binding");

    nsDiskCacheBinding * binding = hashEntry->mBinding;

    while (binding->mCacheEntry->IsDoomed()) {

        binding = (nsDiskCacheBinding *)PR_NEXT_LINK(binding);

        if (binding == hashEntry->mBinding)  return nullptr;

    }

    return binding;

}

/**

 *  AddBinding

 *

 *  Called from FindEntry() if we read an entry off of disk

 *      - it may already have a generation number

 *      - a generation number conflict is an error

 *

 *  Called from BindEntry()

 *      - a generation number needs to be assigned

 */

nsresult

nsDiskCacheBindery::AddBinding(nsDiskCacheBinding * binding)

{

    NS_ENSURE_ARG_POINTER(binding);

    NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");

    // find hash entry for key

    auto hashEntry = static_cast<HashTableEntry*>

        (table.Add((void*)(uintptr_t)binding->mRecord.HashNumber(), fallible));

    if (!hashEntry)

        return NS_ERROR_OUT_OF_MEMORY;

    if (hashEntry->mBinding == nullptr) {

        hashEntry->mBinding = binding;

        if (binding->mGeneration == 0)

            binding->mGeneration = 1;   // if generation uninitialized, set it to 1

        return NS_OK;

    }

    // insert binding in generation order

    nsDiskCacheBinding * p  = hashEntry->mBinding;

    bool     calcGeneration = (binding->mGeneration == 0);  // do we need to calculate generation?

    if (calcGeneration)  binding->mGeneration = 1;          // initialize to 1 if uninitialized

    while (true) {

        if (binding->mGeneration < p->mGeneration) {

            // here we are

            PR_INSERT_BEFORE(binding, p);

            if (hashEntry->mBinding == p)

                hashEntry->mBinding = binding;

            break;

        }

        if (binding->mGeneration == p->mGeneration) {

            if (calcGeneration)  ++binding->mGeneration;    // try the next generation

            else {

                NS_ERROR("### disk cache: generations collide!");

                return NS_ERROR_UNEXPECTED;

            }

        }

        p = (nsDiskCacheBinding *)PR_NEXT_LINK(p);

        if (p == hashEntry->mBinding) {

            // end of line: insert here or die

            p = (nsDiskCacheBinding *)PR_PREV_LINK(p);  // back up and check generation

            if (p->mGeneration == 255) {

                NS_WARNING("### disk cache: generation capacity at full");

                return NS_ERROR_UNEXPECTED;

            }

            PR_INSERT_BEFORE(binding, hashEntry->mBinding);

            break;

        }

    }

    return NS_OK;

}

/**

 *  RemoveBinding :  remove binding from collision detection on deactivation

 */

void

nsDiskCacheBindery::RemoveBinding(nsDiskCacheBinding * binding)

{

    NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");

    if (!initialized)   return;

    void* key = (void *)(uintptr_t)binding->mRecord.HashNumber();

    auto hashEntry =

        static_cast<HashTableEntry*>(table.Search((void*)(uintptr_t) key));

    if (!hashEntry) {

        NS_WARNING("### disk cache: binding not in hashtable!");

        return;

    }

    if (binding == hashEntry->mBinding) {

        if (PR_CLIST_IS_EMPTY(binding)) {

            // remove this hash entry

            table.Remove((void*)(uintptr_t) binding->mRecord.HashNumber());

            return;

        }

        // promote next binding to head, and unlink this binding

        hashEntry->mBinding = (nsDiskCacheBinding *)PR_NEXT_LINK(binding);

    }

    PR_REMOVE_AND_INIT_LINK(binding);

}

/**

 * ActiveBindings: return true if any bindings have open descriptors.

 */

bool

nsDiskCacheBindery::ActiveBindings()

{

    NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");

    if (!initialized) return false;

    for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {

        auto entry = static_cast<HashTableEntry*>(iter.Get());

        nsDiskCacheBinding* binding = entry->mBinding;

        nsDiskCacheBinding* head = binding;

        do {

            if (binding->IsActive()) {

                return true;

            }

            binding = (nsDiskCacheBinding *)PR_NEXT_LINK(binding);

        } while (binding != head);

    }

    return false;

}

/**

 * SizeOfExcludingThis: return the amount of heap memory (bytes) being used by

 * the bindery.

 */

size_t

nsDiskCacheBindery::SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf)

{

    NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");

    if (!initialized) return 0;

    size_t size = 0;

    for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {

        auto entry = static_cast<HashTableEntry*>(iter.Get());

        nsDiskCacheBinding* binding = entry->mBinding;

        nsDiskCacheBinding* head = binding;

        do {

            size += aMallocSizeOf(binding);

            if (binding->mStreamIO) {

                size += binding->mStreamIO->SizeOfIncludingThis(aMallocSizeOf);

            }

            // No good way to get at mDeactivateEvent internals for proper

            // size, so we use this as an estimate.

            if (binding->mDeactivateEvent) {

                size += aMallocSizeOf(binding->mDeactivateEvent);

            }

            binding = (nsDiskCacheBinding *)PR_NEXT_LINK(binding);

        } while (binding != head);

    }

    return size;

}