media/libdatasource/include/datasource/NuCachedSource2.h

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * 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.
 */

#ifndef NU_CACHED_SOURCE_2_H_

#define NU_CACHED_SOURCE_2_H_

#include <media/DataSource.h>
#include <media/stagefright/foundation/ABase.h>
#include <media/stagefright/foundation/AHandlerReflector.h>

namespace android {

struct ALooper;
struct PageCache;

struct NuCachedSource2 : public DataSource {
    static sp<NuCachedSource2> Create(
            const sp<DataSource> &source,
            const char *cacheConfig = NULL,
            bool disconnectAtHighwatermark = false);

    virtual status_t initCheck() const;

    virtual ssize_t readAt(off64_t offset, void *data, size_t size);

    virtual void close();

    virtual void disconnect();

    virtual status_t getSize(off64_t *size);
    virtual uint32_t flags();

    virtual String8 getUri();

    virtual String8 getMIMEType() const;

    virtual String8 toString() {
        return mName;
    }

    status_t getAvailableSize(off64_t offset, off64_t *size);

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

    size_t cachedSize();
    size_t approxDataRemaining(status_t *finalStatus) const;

    void resumeFetchingIfNecessary();

    // The following methods are supported only if the
    // data source is HTTP-based; otherwise, ERROR_UNSUPPORTED
    // is returned.
    status_t getEstimatedBandwidthKbps(int32_t *kbps);
    status_t setCacheStatCollectFreq(int32_t freqMs);

    static void RemoveCacheSpecificHeaders(
            KeyedVector<String8, String8> *headers,
            String8 *cacheConfig,
            bool *disconnectAtHighwatermark);

protected:
    virtual ~NuCachedSource2();

private:
    friend struct AHandlerReflector<NuCachedSource2>;

    NuCachedSource2(
            const sp<DataSource> &source,
            const char *cacheConfig,
            bool disconnectAtHighwatermark);

    enum {
        kPageSize                       = 65536,
        kDefaultHighWaterThreshold      = 20 * 1024 * 1024,
        kDefaultLowWaterThreshold       = 4 * 1024 * 1024,

        // Read data after a 15 sec timeout whether we're actively
        // fetching or not.
        kDefaultKeepAliveIntervalUs     = 15000000,
    };

    enum {
        kWhatFetchMore  = 'fetc',
        kWhatRead       = 'read',
    };

    enum {
        kMaxNumRetries = 10,
    };

    sp<DataSource> mSource;
    sp<AHandlerReflector<NuCachedSource2> > mReflector;
    sp<ALooper> mLooper;
    String8 mName;

    Mutex mSerializer;
    mutable Mutex mLock;
    Condition mCondition;

    PageCache *mCache;
    off64_t mCacheOffset;
    status_t mFinalStatus;
    off64_t mLastAccessPos;
    sp<AMessage> mAsyncResult;
    bool mFetching;
    bool mDisconnecting;
    int64_t mLastFetchTimeUs;

    int32_t mNumRetriesLeft;

    size_t mHighwaterThresholdBytes;
    size_t mLowwaterThresholdBytes;

    // If the keep-alive interval is 0, keep-alives are disabled.
    int64_t mKeepAliveIntervalUs;

    bool mDisconnectAtHighwatermark;

    void onMessageReceived(const sp<AMessage> &msg);
    void onFetch();
    void onRead(const sp<AMessage> &msg);

    void fetchInternal();
    ssize_t readInternal(off64_t offset, void *data, size_t size);
    status_t seekInternal_l(off64_t offset);

    size_t approxDataRemaining_l(off64_t offset, status_t *finalStatus) const;

    void restartPrefetcherIfNecessary_l(
            bool ignoreLowWaterThreshold = false, bool force = false);

    void updateCacheParamsFromSystemProperty();
    void updateCacheParamsFromString(const char *s);

    DISALLOW_EVIL_CONSTRUCTORS(NuCachedSource2);
};

}  // namespace android

#endif  // NU_CACHED_SOURCE_2_H_