Fasdfs 客户端 有没有提供资源池的必要

• StorageClient 的 do_upload_file 方法

/**    * upload file to storage server    * @param cmd the command code    * @param group_name the group name to upload file to, can be empty    * @param master_filename the master file name to generate the slave file    * @param prefix_name the prefix name to generate the slave file * @param file_ext_name file ext name, do not include dot(.)    * @param file_size the file size    * @param callback the write data callback object    *   @param meta_list meta info array    * @return  2 elements string array if success:<br>    *          <ul><li> results[0]: the group name to store the file</li></ul>    *          <ul><li> results[1]: the new created filename</li></ul>     *         return null if fail    */    protected String[] do_upload_file(byte cmd, String group_name, String master_filename,              String prefix_name, String file_ext_name, long file_size, UploadCallback callback,            NameValuePair[] meta_list) throws IOException, MyException    {        byte[] header;        byte[] ext_name_bs;        String new_group_name;        String remote_filename;        boolean bNewConnection;        Socket storageSocket;        byte[] sizeBytes;        byte[] hexLenBytes;        byte[] masterFilenameBytes;        boolean bUploadSlave;        int offset;        long body_len;        bUploadSlave = ((group_name != null && group_name.length() > 0) &&                         (master_filename != null && master_filename.length() > 0) &&                        (prefix_name != null));        if (bUploadSlave)        {            bNewConnection = this.newUpdatableStorageConnection(group_name, master_filename);        }        else        {            bNewConnection = this.newWritableStorageConnection(group_name);        }        try        {            storageSocket = this.storageServer.getSocket();            ext_name_bs = new byte[ProtoCommon.FDFS_FILE_EXT_NAME_MAX_LEN];            Arrays.fill(ext_name_bs, (byte)0);            if (file_ext_name != null && file_ext_name.length() > 0)            {                byte[] bs = file_ext_name.getBytes(ClientGlobal.g_charset);                int ext_name_len = bs.length;                if (ext_name_len > ProtoCommon.FDFS_FILE_EXT_NAME_MAX_LEN)                {                    ext_name_len = ProtoCommon.FDFS_FILE_EXT_NAME_MAX_LEN;                }                System.arraycopy(bs, 0, ext_name_bs, 0, ext_name_len);            }            if (bUploadSlave)            {                masterFilenameBytes = master_filename.getBytes(ClientGlobal.g_charset);                sizeBytes = new byte[2 * ProtoCommon.FDFS_PROTO_PKG_LEN_SIZE];                body_len = sizeBytes.length + ProtoCommon.FDFS_FILE_PREFIX_MAX_LEN + ProtoCommon.FDFS_FILE_EXT_NAME_MAX_LEN                         + masterFilenameBytes.length + file_size;                hexLenBytes = ProtoCommon.long2buff(master_filename.length());                System.arraycopy(hexLenBytes, 0, sizeBytes, 0, hexLenBytes.length);                offset = hexLenBytes.length;            }            else            {                masterFilenameBytes = null;                sizeBytes = new byte[1 + 1 * ProtoCommon.FDFS_PROTO_PKG_LEN_SIZE];        body_len = sizeBytes.length + ProtoCommon.FDFS_FILE_EXT_NAME_MAX_LEN + file_size;                sizeBytes[0] = (byte)this.storageServer.getStorePathIndex();                offset = 1;            }            hexLenBytes = ProtoCommon.long2buff(file_size);            System.arraycopy(hexLenBytes, 0, sizeBytes, offset, hexLenBytes.length);            OutputStream out = storageSocket.getOutputStream();            header = ProtoCommon.packHeader(cmd, body_len, (byte)0);            byte[] wholePkg = new byte[(int)(header.length + body_len - file_size)];            System.arraycopy(header, 0, wholePkg, 0, header.length);            System.arraycopy(sizeBytes, 0, wholePkg, header.length, sizeBytes.length);            offset = header.length + sizeBytes.length;            if (bUploadSlave)            {                byte[] prefix_name_bs = new byte[ProtoCommon.FDFS_FILE_PREFIX_MAX_LEN];                byte[] bs = prefix_name.getBytes(ClientGlobal.g_charset);                int prefix_name_len = bs.length;                Arrays.fill(prefix_name_bs, (byte)0);                if (prefix_name_len > ProtoCommon.FDFS_FILE_PREFIX_MAX_LEN)                {                    prefix_name_len = ProtoCommon.FDFS_FILE_PREFIX_MAX_LEN;                }                if (prefix_name_len > 0)                {                    System.arraycopy(bs, 0, prefix_name_bs, 0, prefix_name_len);                }                System.arraycopy(prefix_name_bs, 0, wholePkg, offset, prefix_name_bs.length);                offset += prefix_name_bs.length;            }            System.arraycopy(ext_name_bs, 0, wholePkg, offset, ext_name_bs.length);            offset += ext_name_bs.length;            if (bUploadSlave)            {                System.arraycopy(masterFilenameBytes, 0, wholePkg, offset, masterFilenameBytes.length);                offset += masterFilenameBytes.length;            }            out.write(wholePkg);            if ((this.errno=(byte)callback.send(out)) != 0)            {                return null;            }            ProtoCommon.RecvPackageInfo pkgInfo = ProtoCommon.recvPackage(storageSocket.getInputStream(),                                          ProtoCommon.STORAGE_PROTO_CMD_RESP, -1);            this.errno = pkgInfo.errno;            if (pkgInfo.errno != 0)            {                return null;            }            if (pkgInfo.body.length <= ProtoCommon.FDFS_GROUP_NAME_MAX_LEN)            {                throw new MyException("body length: " + pkgInfo.body.length + " <= " + ProtoCommon.FDFS_GROUP_NAME_MAX_LEN);            }            new_group_name = new String(pkgInfo.body, 0, ProtoCommon.FDFS_GROUP_NAME_MAX_LEN).trim();            remote_filename = new String(pkgInfo.body, ProtoCommon.FDFS_GROUP_NAME_MAX_LEN, pkgInfo.body.length - ProtoCommon.FDFS_GROUP_NAME_MAX_LEN);            String[] results = new String[2];            results[0] = new_group_name;            results[1] = remote_filename;            if (meta_list == null || meta_list.length == 0)            {                return results;            }            int result = 0;            try            {                result = this.set_metadata(new_group_name, remote_filename,                                 meta_list, ProtoCommon.STORAGE_SET_METADATA_FLAG_OVERWRITE);            }            catch(IOException ex)            {                result = 5;                throw ex;            }            finally            {                if (result != 0)                {                    this.errno = (byte)result;                    this.delete_file(new_group_name, remote_filename);                    return null;                }            }            return results;        }        catch(IOException ex)        {            if (!bNewConnection)            {                try                {                    this.storageServer.close();                }                catch(IOException ex1)                {                    ex1.printStackTrace();                }                finally                {                    this.storageServer = null;                }            }            throw ex;        }        finally        {            if (bNewConnection)            {                try                {                    this.storageServer.close();                }                catch(IOException ex1)                {                    ex1.printStackTrace();                }                finally                {                    this.storageServer = null;                }            }        }    }

• 每次上传时都首先获取一个连接，上传完毕后 自动关闭连接。这里的连接指的是Socket连接。
• 将TrackerClient、TrackerServer、StoragerClient、StoragerServer 做成池的话，也只是对象池，而非资源池，因为真正的资源Socket连接 在Socket客户端已经被关闭，在Socket服务器端可能被缓存。

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Socket客户端创建过程。

• StorageServer 的 构造方法

/** - Constructor - @param ip_addr the ip address of storage server - @param port the port of storage server - @param store_path the store path index on the storage server*/    public StorageServer(String ip_addr, int port, byte store_path) throws IOException    {        super(ClientGlobal.getSocket(ip_addr, port), new InetSocketAddress(ip_addr, port));        if (store_path < 0)        {            this.store_path_index = 256 + store_path;        }        else        {            this.store_path_index = store_path;        }    }

• TrackerServer 的getSocket

/** * get the connected socket * @return the socket*/    public Socket getSocket() throws IOException    {        if (this.sock == null)        {            this.sock = ClientGlobal.getSocket(this.inetSockAddr);        }        return this.sock;    }

• ClientGlobal 的getSocket

/** * construct Socket object * @param addr InetSocketAddress object, including ip address and port * @return connected Socket object*/    public static Socket getSocket(InetSocketAddress addr) throws IOException    {        Socket sock = new Socket();        sock.setSoTimeout(ClientGlobal.g_network_timeout);        sock.connect(addr, ClientGlobal.g_connect_timeout);        return sock;    }

• fastdfs 在客户端没有采用Socket池，而是每次都在客户端创建一个新的Socket连接，而在Socket服务器端也就是图片服务器端连接过来的Socket是被缓存起来的。