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Annotation of fam/fam/NetConnection.h, Revision 1.1.1.1

1.1       trev        1: //  Copyright (C) 1999 Silicon Graphics, Inc.  All Rights Reserved.
                      2: //
                      3: //  This program is free software; you can redistribute it and/or modify it
                      4: //  under the terms of version 2 of the GNU General Public License as
                      5: //  published by the Free Software Foundation.
                      6: //
                      7: //  This program is distributed in the hope that it would be useful, but
                      8: //  WITHOUT ANY WARRANTY; without even the implied warranty of
                      9: //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  Further, any
                     10: //  license provided herein, whether implied or otherwise, is limited to
                     11: //  this program in accordance with the express provisions of the GNU
                     12: //  General Public License.  Patent licenses, if any, provided herein do not
                     13: //  apply to combinations of this program with other product or programs, or
                     14: //  any other product whatsoever.  This program is distributed without any
                     15: //  warranty that the program is delivered free of the rightful claim of any
                     16: //  third person by way of infringement or the like.  See the GNU General
                     17: //  Public License for more details.
                     18: //
                     19: //  You should have received a copy of the GNU General Public License along
                     20: //  with this program; if not, write the Free Software Foundation, Inc., 59
                     21: //  Temple Place - Suite 330, Boston MA 02111-1307, USA.
                     22:
                     23: #ifndef NetConnection_included
                     24: #define NetConnection_included
                     25:
                     26: #include <sys/types.h>
                     27: #include "Boolean.h"
                     28: #include <limits.h>
                     29:
                     30: //  NetConnection is an abstract base class that implements an event
                     31: //  driven, flow controlled reliable datagram connection over an
                     32: //  already open stream socket.
                     33: //
                     34: //  The incoming and outgoing data streams are broken into messages.
                     35: //  The format of a message is four bytes of message length (MSB
                     36: //  first) followed by "length" bytes of data.  The last byte of data
                     37: //  should be NUL ('\0').
                     38: //
                     39: //  The mprintf() function outputs a message using printf-style
                     40: //  formatting.  It appends a NUL byte to the message and prepends the
                     41: //  message length.  It also automatically flushes the message.  If
                     42: //  the connection has closed, mprintf() returns immediately.
                     43: //
                     44: //  When a complete message is received, the pure virtual function
                     45: //  input_msg() is called with the length and the address of the
                     46: //  message.  If EOF is read on the connection, input_msg() is called
                     47: //  with a NULL address and count (analogous to read(2) returning 0
                     48: //  bytes).
                     49: //
                     50: //  NetConnection implements flow control.  Whenever the output buffer
                     51: //  is empty, read events are accepted from the Scheduler.  Whenever
                     52: //  the output buffer can't be flushed, reading is suspended, and the
                     53: //  Scheduler watches for the connection to be writable.  This means
                     54: //  that input is only accepted when it's possible to send a reply.
                     55: //  The unblock handler, if any, is called whenever output becomes
                     56: //  unblocked.
                     57:
                     58: class NetConnection {
                     59:
                     60: public:
                     61:
                     62:     typedef void (*UnblockHandler)(void *closure);
                     63:
                     64:     NetConnection(int fd, UnblockHandler, void *closure);
                     65:
                     66:     virtual ~NetConnection();
                     67:     bool ready_for_output() const;
                     68:     void ready_for_input(bool);
                     69:     int get_fd() const { return fd; }
                     70:
                     71: protected:
                     72:
                     73:     virtual bool input_msg(const char *data, unsigned nbytes) = 0;
                     74:     void mprintf(const char *format, ...);
                     75:
                     76: private:
                     77:
                     78:     enum { MAXMSGSIZE = PATH_MAX + 40 };
                     79:     typedef u_int32_t Length;
                     80:     typedef struct msgList_s {
                     81:         char msg[MAXMSGSIZE+5];  //  + 4 for 32-bit length, + 1 for overflow
                     82:         int len;
                     83:         msgList_s * next;
                     84:     } msgList_t;
                     85:
                     86:     msgList_t *omsgList;
                     87:     msgList_t *omsgListTail;
                     88:
                     89:     int fd;
                     90:     bool iready, oready;
                     91:     char ibuf[MAXMSGSIZE+5];     //  + 4 for 32-bit length, + 1 for overflow
                     92:     char *iend;
                     93:     char *itail;
                     94:     UnblockHandler unblock_handler;
                     95:     void *closure;
                     96:
                     97:     void set_handlers(bool new_iready, bool new_oready);
                     98:     void shutdown(bool = true);
                     99:
                    100:     //  Input
                    101:
                    102:     void input();
                    103:     void deliver_input();
                    104:     static void read_handler(int fd, void *closure);
                    105:
                    106:     //  Output
                    107:
                    108:     void flush();
                    109:     static void write_handler(int fd, void *closure);
                    110:
                    111:     NetConnection(const NetConnection&); // Do not copy
                    112:     NetConnection& operator = (const NetConnection&);	 //  or assign.
                    113:
                    114: };
                    115:
                    116: #endif /* !NetConnection_included */