release/src/router/mysql/storage/ndb/src/common/transporter/SendBuffer.hpp

   1 /* Copyright (c) 2003-2005 MySQL AB
   2
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; version 2 of the License.
   6
   7    This program is distributed in the hope that it will be useful,
   8    but WITHOUT ANY WARRANTY; without even the implied warranty of
   9    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10    GNU General Public License for more details.
  11
  12    You should have received a copy of the GNU General Public License
  13    along with this program; if not, write to the Free Software
  14    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA */
  15
  16 //****************************************************************************
  17 //
  18 //  NAME
  19 //      SendBuffer
  20 //
  21 //  DESCRIPTION
  22 //      The SendBuffer is a circular buffer storing signals waiting to be sent.
  23 //      The signals can be of variable size and are copied into the buffer
  24 //      in Protocol 6 format. There will be two SendBuffer instances
  25 //      (priority level A and B) for each transporter using a buffer for
  26 //      sending. The buffering will in most cases be done to send as big
  27 //      packages as possible over TCP/IP.
  28 //
  29 //***************************************************************************/
  30 #ifndef SendBuffer_H
  31 #define SendBuffer_H
  32
  33 #include "TransporterDefinitions.hpp"
  34 #include <TransporterCallback.hpp>
  35
  36 #ifdef DEBUG_TRANSPORTER
  37 #include <ndb_global.h>
  38 #endif
  39
  40 class SendBuffer {
  41   friend class TCP_Transporter;
  42 public:
  43   // Set member variables
  44   SendBuffer(Uint32 bufSize);
  45
  46   // Deallocate the buffer memory
  47   ~SendBuffer();
  48
  49   // Allocate memory for the buffer and initialize the buffer pointers
  50   bool initBuffer(Uint32 aRemoteNodeId);
  51
  52   // Number of bytes remaining in the buffer
  53   Uint32 bufferSizeRemaining() const;
  54
  55   // Number of bytes of data in the buffer
  56   int bufferSize();
  57
  58   // Empty the buffer
  59   void emptyBuffer();
  60
  61   /**
  62    * The transporter calls updateBuffer after a retrieve followed by
  63    * a successful send, to update the cirkular buffer pointers.
  64    * updateBuffer is called with the number of bytes really sent,
  65    * it may be that it is less than what was retrived from the buffer.
  66    * If that is the case there will be an incomplete message (slack)
  67    * in the SendBuffer.
  68    *
  69    * Returns  0 if buffer empty
  70    *    else ~0
  71    */
  72   Uint32 bytesSent(Uint32 len);
  73
  74 #ifdef DEBUG_TRANSPORTER
  75   // Prints the buffer status on the screen. Can be used for testing purposes.
  76   void print();
  77 #endif
  78
  79   Uint32* getInsertPtr(Uint32 bytes);
  80   void updateInsertPtr(Uint32 bytes);
  81
  82 private:
  83
  84   Uint32   sizeOfBuffer;  // Length, in number of bytes, of the buffer memory
  85   Uint32   dataSize;      // Number of bytes in buffer
  86
  87   Uint32 * startOfBuffer; // Pointer to the start of the buffer memory
  88   Uint32 * endOfBuffer;   // Pointer to end of buffer
  89
  90   Uint32 * insertPtr;     // Where to insert next
  91
  92   char *   sendPtr;           // Where data to send starts
  93   Uint32   sendDataSize;      // Num bytes to send
  94
  95   Uint32   theRemoteNodeId;
  96 };
  97
  98 inline
  99 Uint32
 100 SendBuffer::bytesSent(Uint32 bytes) {
 101
 102   if(bytes > dataSize){
 103 #ifdef DEBUG_TRANSPORTER
 104     printf("bytes(%d) > dataSize(%d)\n", bytes, dataSize);
 105 #endif
 106     abort();
 107     // reportError(0 ,theRemoteNodeId, TE_INVALID_MESSAGE_LENGTH);
 108     return 0;
 109   }//if
 110
 111   if(bytes > sendDataSize){
 112 #ifdef DEBUG_TRANSPORTER
 113     printf("bytes(%d) > sendDataSize(%d)\n", bytes, sendDataSize);
 114 #endif
 115     abort();
 116     //reportError(0,theRemoteNodeId, TE_INVALID_MESSAGE_LENGTH);
 117     return 0;
 118   }//if
 119
 120   dataSize     -= bytes;
 121   sendPtr      += bytes;
 122   sendDataSize -= bytes;
 123
 124   if(sendDataSize == 0){
 125     if(sendPtr > (char*)insertPtr){
 126       sendPtr = (char *)startOfBuffer;
 127       sendDataSize = dataSize;
 128     } else {
 129       sendPtr = ((char*)insertPtr) - dataSize;
 130       sendDataSize = dataSize;
 131     }
 132   }
 133
 134   if(dataSize == 0)
 135     return 0;
 136   return ~0;
 137 }
 138
 139 inline
 140 Uint32*
 141 SendBuffer::getInsertPtr(Uint32 len){
 142   if (bufferSizeRemaining() < len){
 143     return 0;
 144   }
 145
 146   const char * const tmpInsertPtr = (char *) insertPtr;
 147
 148   if(tmpInsertPtr >= sendPtr){
 149     // Is there enough space at the end of the buffer?
 150     if ((tmpInsertPtr + len) < (char*)endOfBuffer){
 151       sendDataSize += len;
 152       return insertPtr;
 153     } else {
 154       // We have passed the end of the cirkular buffer,
 155       // must start from the beginning
 156       // Is there enough space in the beginning of the buffer?
 157       if ((Uint32)(sendPtr - (char *)startOfBuffer) <= len){
 158         // Not enough space available, insert failed
 159         return 0;
 160       } else {
 161         // There is space available at the beginning of the buffer
 162         // We start from the beginning, set endOfData and insertPtr
 163         insertPtr = startOfBuffer;
 164         if(sendDataSize != 0){
 165           return insertPtr;
 166         }
 167         sendPtr      = (char *)startOfBuffer;
 168         sendDataSize = len;
 169         return insertPtr;
 170       }
 171     }
 172   } else {
 173     // sendPtr > insertPtr
 174     // Is there enought room
 175     if((tmpInsertPtr + len) < sendPtr){
 176       return insertPtr;
 177     }
 178     return 0;
 179   }
 180 }
 181
 182 inline
 183 void
 184 SendBuffer::updateInsertPtr(Uint32 lenBytes){
 185   dataSize  += lenBytes;
 186   insertPtr += (lenBytes / 4);
 187 }
 188
 189 #endif // Define of SendBuffer_H