gpu/src/GrResourceCache.cpp

/*
    Copyright 2010 Google Inc.

    Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
 */


#include "GrResourceCache.h"
#include "GrResource.h"

GrResourceEntry::GrResourceEntry(const GrResourceKey& key, GrResource* resource)
        : fKey(key), fResource(resource) {
    fLockCount = 0;
    fPrev = fNext = NULL;

    // we assume ownership of the resource, and will unref it when we die
    GrAssert(resource);
}

GrResourceEntry::~GrResourceEntry() {
    fResource->unref();
}

#if GR_DEBUG
void GrResourceEntry::validate() const {
    GrAssert(fLockCount >= 0);
    GrAssert(fResource);
    fResource->validate();
}
#endif

///////////////////////////////////////////////////////////////////////////////

GrResourceCache::GrResourceCache(int maxCount, size_t maxBytes) :
        fMaxCount(maxCount),
        fMaxBytes(maxBytes) {
    fEntryCount          = 0;
    fEntryBytes          = 0;
    fClientDetachedCount = 0;
    fClientDetachedBytes = 0;

    fHead = fTail = NULL;
}

GrResourceCache::~GrResourceCache() {
    GrAutoResourceCacheValidate atcv(this);

    this->removeAll();
}

void GrResourceCache::getLimits(int* maxResources, size_t* maxResourceBytes) const{
    if (maxResources) {
        *maxResources = fMaxCount;
    }
    if (maxResourceBytes) {
        *maxResourceBytes = fMaxBytes;
    }
}

void GrResourceCache::setLimits(int maxResources, size_t maxResourceBytes) {
    bool smaller = (maxResources < fMaxCount) || (maxResourceBytes < fMaxBytes);

    fMaxCount = maxResources;
    fMaxBytes = maxResourceBytes;

    if (smaller) {
        this->purgeAsNeeded();
    }
}

void GrResourceCache::internalDetach(GrResourceEntry* entry,
                                    bool clientDetach) {
    GrResourceEntry* prev = entry->fPrev;
    GrResourceEntry* next = entry->fNext;

    if (prev) {
        prev->fNext = next;
    } else {
        fHead = next;
    }
    if (next) {
        next->fPrev = prev;
    } else {
        fTail = prev;
    }

    // update our stats
    if (clientDetach) {
        fClientDetachedCount += 1;
        fClientDetachedBytes += entry->resource()->sizeInBytes();
    } else {
        fEntryCount -= 1;
        fEntryBytes -= entry->resource()->sizeInBytes();
    }
}

void GrResourceCache::attachToHead(GrResourceEntry* entry,
                                  bool clientReattach) {
    entry->fPrev = NULL;
    entry->fNext = fHead;
    if (fHead) {
        fHead->fPrev = entry;
    }
    fHead = entry;
    if (NULL == fTail) {
        fTail = entry;
    }

    // update our stats
    if (clientReattach) {
        fClientDetachedCount -= 1;
        fClientDetachedBytes -= entry->resource()->sizeInBytes();
    } else {
        fEntryCount += 1;
        fEntryBytes += entry->resource()->sizeInBytes();
    }
}

class GrResourceCache::Key {
    typedef GrResourceEntry T;

    const GrResourceKey& fKey;
public:
    Key(const GrResourceKey& key) : fKey(key) {}

    uint32_t getHash() const { return fKey.hashIndex(); }

    static bool LT(const T& entry, const Key& key) {
        return entry.key() < key.fKey;
    }
    static bool EQ(const T& entry, const Key& key) {
        return entry.key() == key.fKey;
    }
#if GR_DEBUG
    static uint32_t GetHash(const T& entry) {
        return entry.key().hashIndex();
    }
    static bool LT(const T& a, const T& b) {
        return a.key() < b.key();
    }
    static bool EQ(const T& a, const T& b) {
        return a.key() == b.key();
    }
#endif
};

GrResourceEntry* GrResourceCache::findAndLock(const GrResourceKey& key) {
    GrAutoResourceCacheValidate atcv(this);

    GrResourceEntry* entry = fCache.find(key);
    if (entry) {
        this->internalDetach(entry, false);
        this->attachToHead(entry, false);
        // mark the entry as "busy" so it doesn't get purged
        entry->lock();
    }
    return entry;
}

GrResourceEntry* GrResourceCache::createAndLock(const GrResourceKey& key,
                                              GrResource* resource) {
    GrAutoResourceCacheValidate atcv(this);

    GrResourceEntry* entry = new GrResourceEntry(key, resource);

    this->attachToHead(entry, false);
    fCache.insert(key, entry);

#if GR_DUMP_TEXTURE_UPLOAD
    GrPrintf("--- add resource to cache %p, count=%d bytes= %d %d\n",
             entry, fEntryCount, resource->sizeInBytes(), fEntryBytes);
#endif

    // mark the entry as "busy" so it doesn't get purged
    entry->lock();
    this->purgeAsNeeded();
    return entry;
}

void GrResourceCache::detach(GrResourceEntry* entry) {
    internalDetach(entry, true);
    fCache.remove(entry->fKey, entry);
}

void GrResourceCache::reattachAndUnlock(GrResourceEntry* entry) {
    attachToHead(entry, true);
    fCache.insert(entry->key(), entry);
    unlock(entry);
}

void GrResourceCache::unlock(GrResourceEntry* entry) {
    GrAutoResourceCacheValidate atcv(this);

    GrAssert(entry);
    GrAssert(entry->isLocked());
    GrAssert(fCache.find(entry->key()));

    entry->unlock();
    this->purgeAsNeeded();
}

void GrResourceCache::purgeAsNeeded() {
    GrAutoResourceCacheValidate atcv(this);

    GrResourceEntry* entry = fTail;
    while (entry) {
        if (fEntryCount <= fMaxCount && fEntryBytes <= fMaxBytes) {
            break;
        }

        GrResourceEntry* prev = entry->fPrev;
        if (!entry->isLocked()) {
            // remove from our cache
            fCache.remove(entry->fKey, entry);

            // remove from our llist
            this->internalDetach(entry, false);

#if GR_DUMP_TEXTURE_UPLOAD
            GrPrintf("--- ~resource from cache %p [%d %d]\n", entry->resource(),
                     entry->resource()->width(),
                     entry->resource()->height());
#endif
            delete entry;
        }
        entry = prev;
    }
}

void GrResourceCache::removeAll() {
    GrAssert(!fClientDetachedCount);
    GrAssert(!fClientDetachedBytes);

    GrResourceEntry* entry = fHead;
    while (entry) {
        GrAssert(!entry->isLocked());

        GrResourceEntry* next = entry->fNext;
        delete entry;
        entry = next;
    }

    fCache.removeAll();
    fHead = fTail = NULL;
    fEntryCount = 0;
    fEntryBytes = 0;
}

///////////////////////////////////////////////////////////////////////////////

#if GR_DEBUG
static int countMatches(const GrResourceEntry* head, const GrResourceEntry* target) {
    const GrResourceEntry* entry = head;
    int count = 0;
    while (entry) {
        if (target == entry) {
            count += 1;
        }
        entry = entry->next();
    }
    return count;
}

#if GR_DEBUG
static bool both_zero_or_nonzero(int count, size_t bytes) {
    return (count == 0 && bytes == 0) || (count > 0 && bytes > 0);
}
#endif

void GrResourceCache::validate() const {
    GrAssert(!fHead == !fTail);
    GrAssert(both_zero_or_nonzero(fEntryCount, fEntryBytes));
    GrAssert(both_zero_or_nonzero(fClientDetachedCount, fClientDetachedBytes));
    GrAssert(fClientDetachedBytes <= fEntryBytes);
    GrAssert(fClientDetachedCount <= fEntryCount);
    GrAssert((fEntryCount - fClientDetachedCount) == fCache.count());

    fCache.validate();

    GrResourceEntry* entry = fHead;
    int count = 0;
    size_t bytes = 0;
    while (entry) {
        entry->validate();
        GrAssert(fCache.find(entry->key()));
        count += 1;
        bytes += entry->resource()->sizeInBytes();
        entry = entry->fNext;
    }
    GrAssert(count == fEntryCount - fClientDetachedCount);
    GrAssert(bytes == fEntryBytes  - fClientDetachedBytes);

    count = 0;
    for (entry = fTail; entry; entry = entry->fPrev) {
        count += 1;
    }
    GrAssert(count == fEntryCount - fClientDetachedCount);

    for (int i = 0; i < count; i++) {
        int matches = countMatches(fHead, fCache.getArray()[i]);
        GrAssert(1 == matches);
    }
}
#endif