bdb_blobcache.cpp

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    m_CacheAttrDB->key = key;
    m_CacheAttrDB->version = version;
    m_CacheAttrDB->subkey = (m_TimeStampFlag & fTrackSubKey) ? subkey : "";

    EBDB_ErrCode ret = m_CacheAttrDB->Fetch();
    if (ret != eBDB_Ok) {
        return 0;
    }
    
    return (int) m_CacheAttrDB->time_stamp;
}


void CBDB_Cache::Purge(time_t           access_timeout,
                       EKeepVersions    keep_last_version)
{
    CFastMutexGuard guard(x_BDB_BLOB_CacheMutex);

    if (keep_last_version == eDropAll && access_timeout == 0) {
        x_TruncateDB();
        return;
    }

    // Search the database for obsolete cache entries

    vector<SCacheDescr> cache_entries;

    {{
    CBDB_FileCursor cur(*m_CacheAttrDB);
    cur.SetCondition(CBDB_FileCursor::eFirst);


    CTime time_stamp(CTime::eCurrent);
    time_t curr = (int)time_stamp.GetTimeT();
    int timeout = GetTimeout();

    while (cur.Fetch() == eBDB_Ok) {
        time_t db_time_stamp = m_CacheAttrDB->time_stamp;
        int version = m_CacheAttrDB->version;
        const char* key = m_CacheAttrDB->key;
        int overflow = m_CacheAttrDB->overflow;
        const char* subkey = m_CacheAttrDB->subkey;

        if (curr - timeout > db_time_stamp) {
            cache_entries.push_back(
                            SCacheDescr(key, version, subkey, overflow));
        }

    } // while
    }}

    CBDB_Transaction trans(*m_Env);
    m_CacheDB->SetTransaction(&trans);
    m_CacheAttrDB->SetTransaction(&trans);

    ITERATE(vector<SCacheDescr>, it, cache_entries) {
        x_DropBlob(it->key.c_str(), 
                   it->version, 
                   it->subkey.c_str(), 
                   it->overflow);
    }

    trans.Commit();

}


void CBDB_Cache::Purge(const string&    key,
                       const string&    subkey,
                       time_t           access_timeout,
                       EKeepVersions    keep_last_version)
{
    CFastMutexGuard guard(x_BDB_BLOB_CacheMutex);

    if (key.empty() || 
        (keep_last_version == eDropAll && access_timeout == 0)) {
        x_TruncateDB();
        return;
    }

    // Search the database for obsolete cache entries
    vector<SCacheDescr> cache_entries;


    {{

    CBDB_FileCursor cur(*m_CacheAttrDB);
    cur.SetCondition(CBDB_FileCursor::eEQ);

    cur.From << key;

    CTime time_stamp(CTime::eCurrent);
    time_t curr = (int)time_stamp.GetTimeT();
    int timeout = GetTimeout();

    while (cur.Fetch() == eBDB_Ok) {
        time_t db_time_stamp = m_CacheAttrDB->time_stamp;
        int version = m_CacheAttrDB->version;
        const char* x_key = m_CacheAttrDB->key;
        int overflow = m_CacheAttrDB->overflow;
        string x_subkey = (const char*) m_CacheAttrDB->subkey;

        if (subkey.empty()) {
            
        }

        if ( (curr - timeout > db_time_stamp) ||
            (subkey.empty() || (subkey == x_subkey)) 
           ) {
            cache_entries.push_back(
                            SCacheDescr(x_key, version, x_subkey, overflow));
        }

    } // while

    }}

    CBDB_Transaction trans(*m_Env);
    m_CacheDB->SetTransaction(&trans);
    m_CacheAttrDB->SetTransaction(&trans);

    ITERATE(vector<SCacheDescr>, it, cache_entries) {
        x_DropBlob(it->key.c_str(), 
                   it->version, 
                   it->subkey.c_str(), 
                   it->overflow);
    }
    
    trans.Commit();

}


bool CBDB_Cache::x_CheckTimestampExpired()
{
    int timeout = GetTimeout();
    int db_time_stamp = m_CacheAttrDB->time_stamp;
    if (timeout) {
        CTime time_stamp(CTime::eCurrent);
        time_t curr = (int)time_stamp.GetTimeT();
        if (curr - timeout > db_time_stamp) {
            _TRACE("local cache item expired:" 
                   << db_time_stamp << " curr=" << curr 
                   << " diff=" << curr - db_time_stamp);
            return true;
        }
    }
    return false;
}


void CBDB_Cache::x_UpdateAccessTime(const string&  key,
                                    int            version,
                                    const string&  subkey)
{
    CBDB_Transaction trans(*m_Env);
    m_CacheDB->SetTransaction(&trans);
    m_CacheAttrDB->SetTransaction(&trans);

    m_CacheAttrDB->key = key;
    m_CacheAttrDB->version = version;
    m_CacheAttrDB->subkey = (m_TimeStampFlag & fTrackSubKey) ? subkey : "";

    EBDB_ErrCode ret =m_CacheAttrDB->Fetch();
    if (ret != eBDB_Ok) {
        m_CacheAttrDB->overflow = 0;
    }

    CTime time_stamp(CTime::eCurrent);
    m_CacheAttrDB->time_stamp = (unsigned)time_stamp.GetTimeT();

    m_CacheAttrDB->UpdateInsert();

    trans.Commit();
}


void CBDB_Cache::x_TruncateDB()
{
    LOG_POST(Info << "CBDB_BLOB_Cache:: cache database truncated");
    m_CacheDB->Truncate();
    m_CacheAttrDB->Truncate();

    // Scan the directory, delete overflow BLOBs
    // TODO: remove overflow files only matching cache specific name
    //       signatures. Since several caches may live in the same
    //       directory we may delete some "extra" files
    CDir dir(m_Path);
    string ext;
    string ov_("ov_");
    if (dir.Exists()) {
        CDir::TEntries  content(dir.GetEntries());
        ITERATE(CDir::TEntries, it, content) {
            if (!(*it)->IsFile()) {
                if (ext == ov_) {
                    (*it)->Remove();
                }
            }
        }
    }
}


void CBDB_Cache::x_DropBlob(const char*    key,
                            int            version,
                            const char*    subkey,
                            int            overflow)
{
    _ASSERT(key);
    _ASSERT(subkey);

    if (overflow == 1) {
        string path;
        s_MakeOverflowFileName(path, m_Path, key, version, subkey);

        CDirEntry entry(path);
        if (entry.Exists()) {
            entry.Remove();
        }
    }
    m_CacheDB->key = key;
    m_CacheDB->version = version;
    m_CacheDB->subkey = subkey;

    m_CacheDB->Delete(CBDB_RawFile::eIgnoreError);

    m_CacheAttrDB->key = key;
    m_CacheAttrDB->version = version;
    m_CacheAttrDB->subkey = subkey;

    m_CacheAttrDB->Delete(CBDB_RawFile::eIgnoreError);

}



const char* kBDBCacheDriverName = "bdbcache";

/// Class factory for BDB implementation of ICache
///
/// @internal
///
class CBDB_CacheReaderCF : 
    public CSimpleClassFactoryImpl<ICache, CBDB_Cache>
{
public:
    typedef 
      CSimpleClassFactoryImpl<ICache, CBDB_Cache> TParent;
public:
    CBDB_CacheReaderCF() : TParent(kBDBCacheDriverName, 0)
    {
    }
    ~CBDB_CacheReaderCF()
    {
    }
};

void NCBI_BDB_ICacheEntryPoint(
     CPluginManager<ICache>::TDriverInfoList&   info_list,
     CPluginManager<ICache>::EEntryPointRequest method)
{
    CHostEntryPointImpl<CBDB_CacheReaderCF>::
       NCBI_EntryPointImpl(info_list, method);
}


CBDB_CacheHolder::CBDB_CacheHolder(ICache* blob_cache, ICache* id_cache) 
: m_BlobCache(blob_cache),
  m_IdCache(id_cache)
{}

CBDB_CacheHolder::~CBDB_CacheHolder()
{
    delete m_BlobCache;
    delete m_IdCache;
}

END_NCBI_SCOPE

/*
 * ===========================================================================
 * $Log: bdb_blobcache.cpp,v $
 * Revision 1000.5  2004/06/01 18:37:14  gouriano
 * PRODUCTION: UPGRADED [GCC34_MSVC7] Dev-tree R1.54
 *
 * Revision 1.54  2004/05/25 18:43:51  kuznets
 * Fixed bug in setting cache RAM size, added additional protection when joining
 * existing environment.
 *
 * Revision 1.53  2004/05/24 18:03:03  kuznets
 * CBDB_Cache::Open added parameter to specify RAM cache size
 *
 * Revision 1.52  2004/05/17 20:55:11  gorelenk
 * Added include of PCH ncbi_pch.hpp
 *
 * Revision 1.51  2004/04/28 16:58:56  kuznets
 * Fixed deadlock in CBDB_Cache::Remove
 *
 * Revision 1.50  2004/04/28 12:21:32  kuznets
 * Cleaned up dead code
 *
 * Revision 1.49  2004/04/28 12:11:22  kuznets
 * Replaced static string with char* (fix crash on Linux)
 *
 * Revision 1.48  2004/04/27 19:12:01  kuznets
 * Commented old cache implementation
 *
 * Revision 1.47  2004/03/26 14:54:21  kuznets
 * Transaction checkpoint after database creation
 *
 * Revision 1.46  2004/03/26 14:05:39  kuznets
 * Force transaction checkpoints and turn-off buffering
 *
 * Revision 1.45  2004/03/24 13:51:03  friedman
 * Fixed mutex comments
 *
 * Revision 1.44  2004/03/23 19:22:08  friedman
 * Replaced 'static CFastMutex' with DEFINE_STATIC_FAST_MUTEX
 *
 * Revision 1.43  2004/02/27 17:29:50  kuznets
 * +CBDB_CacheHolder
 *
 * Revision 1.42  2004/02/06 16:16:40  vasilche
 * Fixed delete m_Buffer -> delete[] m_Buffer.
 *
 * Revision 1.41  2004/02/02 21:24:29  vasilche
 * Fixed buffering of overflow file streams - open file in constructor.
 * Fixed processing of timestamps when fTimeStampOnRead flag is not set.
 *
 * Revision 1.40  2004/01/29 20:31:06  vasilche
 * Removed debug messages.
 *
 * Revision 1.39  2004/01/07 18:58:10  vasilche
 * Make message about joining to non-transactional environment a warning.
 *
 * Revision 1.38  2003/12/30 16:29:12  kuznets
 * Fixed a bug in overflow file naming.
 *
 * Revision 1.37  2003/12/29 18:47:20  kuznets
 * Cache opening changed to use free threaded environment.
 *
 * Revision 1.36  2003/12/29 17:08:15  kuznets
 * CBDB_CacheIWriter - using transactions to save BDB data
 *
 * Revision 1.35  2003/12/29 16:53:25  kuznets
 * Made Flush transactional
 *
 * Revision 1.34  2003/12/29 15:39:59  vasilche
 * Fixed subkey value in GetReadStream/GetWriteStream.
 *
 * Revision 1.33  2003/12/29 12:57:15  kuznets
 * Changes in Purge() method to make cursor loop lock independent
 * from the record delete function
 *
 * Revision 1.32  2003/12/16 13:45:11  kuznets
 * ICache implementation made transaction protected
 *
 * Revision 1.31  2003/12/08 16:13:15  kuznets
 * Added plugin mananger support
 *
 * Revision 1.30  2003/11/28 17:35:05  vasilche
 * Fixed new[]/delete discrepancy.
 *
 * Revision 1.29  2003/11/26 13:09:16  kuznets
 * Fixed bug in mutex locking
 *
 * Revision 1.28  2003/11/25 19:36:35  kuznets
 * + ICache implementation
 *
 * Revision 1.27  2003/11/06 14:20:38  kuznets
 * Warnings cleaned up
 *
 * Revision 1.26  2003/10/24 13:54:03  vasilche
 * Rolled back incorrect fix of PendingCount().
 *
 * Revision 1.25  2003/10/24 13:41:23  kuznets
 * Completed PendingCount implementaion
 *
 * Revision 1.24  2003/10/24 12:37:42  kuznets
 * Implemented cache locking using PID guard
 *
 * Revision 1.23  2003/10/23 13:46:38  vasilche
 * Implemented PendingCount() method.
 *
 * Revision 1.22  2003/10/22 19:08:29  vasilche
 * Added Flush() implementation.
 *
 * Revision 1.21  2003/10/21 12:11:27  kuznets
 * Fixed non-updated timestamp in Int cache.
 *
 * Revision 1.20  2003/10/20 20:44:20  vasilche
 * Added return true for overflow file read.
 *
 * Revision 1.19  2003/10/20 20:41:37  kuznets
 * Fixed bug in BlobCache::Read
 *
 * Revision 1.18  2003/10/20 20:35:33  kuznets
 * Blob cache Purge improved.
 *
 * Revision 1.17  2003/10/20 20:34:03  kuznets
 * Fixed bug with writing BLOB overflow attribute
 *
 * Revision 1.16  2003/10/20 20:15:30  kuznets
 * Fixed bug with expiration time retrieval
 *
 * Revision 1.15  2003/10/20 19:58:26  kuznets
 * Fixed bug in int cache expiration algorithm
 *
 * Revision 1.14  2003/10/20 17:53:03  kuznets
 * Dismissed blob cache entry overwrite protection.
 *
 * Revision 1.13  2003/10/20 16:34:20  kuznets
 * BLOB cache Store operation reimplemented to use external files.
 * BDB cache shared between tables by using common environment.
 * Overflow file limit set to 1M (was 2M)
 *
 * Revision 1.12  2003/10/17 14:11:41  kuznets
 * Implemented cached read from berkeley db BLOBs
 *
 * Revision 1.11  2003/10/16 19:29:18  kuznets
 * Added Int cache (AKA id resolution cache)
 *
 * Revision 1.10  2003/10/16 12:08:16  ucko
 * Address GCC 2.95 errors about missing sprintf declaration, and avoid
 * possible buffer overflows, by rewriting s_MakeOverflowFileName to use
 * C++ strings.
 *
 * Revision 1.9  2003/10/16 00:30:57  ucko
 * ios_base -> IOS_BASE (should fix GCC 2.95 build)
 *
 * Revision 1.8  2003/10/15 18:39:13  kuznets
 * Fixed minor incompatibility with the C++ language.
 *
 * Revision 1.7  2003/10/15 18:13:16  kuznets
 * Implemented new cache architecture based on combination of BDB tables
 * and plain files. Fixes the performance degradation in Berkeley DB
 * when it has to work with a lot of overflow pages.
 *
 * Revision 1.6  2003/10/06 16:24:19  kuznets
 * Fixed bug in Purge function
 * (truncated cache files with some parameters combination).
 *
 * Revision 1.5  2003/10/02 20:13:25  kuznets
 * Minor code cleanup
 *
 * Revision 1.4  2003/09/29 16:26:34  kuznets
 * Reflected ERW_Result rename + cleaned up 64-bit compilation
 *
 * Revision 1.3  2003/09/29 15:45:17  kuznets
 * Minor warning fixed
 *
 * Revision 1.2  2003/09/24 15:59:45  kuznets
 * Reflected changes in IReader/IWriter <util/reader_writer.hpp>
 *
 * Revision 1.1  2003/09/24 14:30:17  kuznets
 * Initial revision
 *
 *
 * ===========================================================================
 */