1 /*

     2  * Copyright (c) 2001, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef _BUFFER_

    26 #define _BUFFER_

    27 

    28 // A Buffer is the backing store for the IOBuf abstraction and

    29 // supports producer-consumer filling and draining.

    30 

    31 class Buffer {

    32 public:

    33   Buffer(int bufSize);

    34   ~Buffer();

    35 

    36   char* fillPos();   // Position of the place where buffer should be filled

    37   int   remaining(); // Number of bytes that can be placed starting at fillPos

    38   int   size();      // Size of the buffer

    39   // Move up fill position by amount (decreases remaining()); returns

    40   // false if not enough space

    41   bool  incrFillPos(int amt);

    42 

    43   // Read single byte (0..255); returns -1 if no data available.

    44   int   readByte();

    45   // Read multiple bytes, non-blocking (this buffer does not define a

    46   // fill mechanism), into provided buffer. Returns number of bytes read.

    47   int   readBytes(char* buf, int len);

    48 

    49   // Access to drain position. Be very careful using this.

    50   char* drainPos();

    51   int   drainRemaining();

    52   bool  incrDrainPos(int amt);

    53 

    54   // Compact buffer, removing already-consumed input. This must be

    55   // called periodically to yield the illusion of an infinite buffer.

    56   void  compact();

    57 

    58 private:

    59   Buffer(const Buffer&);

    60   Buffer& operator=(const Buffer&);

    61 

    62   char* buf;

    63   int   sz;

    64   int   fill;

    65   int   drain;

    66 };

    67 

    68 #endif // #defined _BUFFER_