2 Unix SMB/Netbios implementation.
4 file read prediction routines
5 Copyright (C) Andrew Tridgell 1992-1995
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 extern int DEBUGLEVEL;
28 /* variables used by the read prediction module */
29 static int rp_fd = -1;
30 static int rp_offset = 0;
31 static int rp_length = 0;
32 static int rp_alloced = 0;
33 static int rp_predict_fd = -1;
34 static int rp_predict_offset = 0;
35 static int rp_predict_length = 0;
36 static int rp_timeout = 5;
37 static time_t rp_time = 0;
38 static char *rp_buffer = NULL;
39 static BOOL predict_skip=False;
40 time_t smb_last_time=(time_t)0;
42 /****************************************************************************
43 handle read prediction on a file
44 ****************************************************************************/
45 int read_predict(int fd,int offset,char *buf,char **ptr,int num)
48 int possible = rp_length - (offset - rp_offset);
50 possible = MIN(possible,num);
52 /* give data if possible */
54 offset >= rp_offset &&
56 smb_last_time-rp_time < rp_timeout)
60 memcpy(buf,rp_buffer + (offset-rp_offset),possible);
62 *ptr = rp_buffer + (offset-rp_offset);
63 DEBUG(5,("read-prediction gave %d bytes of %d\n",ret,num));
71 /* prepare the next prediction */
73 rp_predict_offset = offset + num;
74 rp_predict_length = num;
82 /****************************************************************************
84 ****************************************************************************/
85 void do_read_prediction()
87 static int readsize = 0;
89 if (predict_skip) return;
91 if (rp_predict_fd == -1)
94 rp_fd = rp_predict_fd;
95 rp_offset = rp_predict_offset;
101 readsize = lp_readsize();
102 readsize = MAX(readsize,1024);
105 rp_predict_length = MIN(rp_predict_length,2*readsize);
106 rp_predict_length = MAX(rp_predict_length,1024);
107 rp_offset = (rp_offset/1024)*1024;
108 rp_predict_length = (rp_predict_length/1024)*1024;
110 if (rp_predict_length > rp_alloced)
112 rp_buffer = Realloc(rp_buffer,rp_predict_length);
113 rp_alloced = rp_predict_length;
116 DEBUG(0,("can't allocate read-prediction buffer\n"));
124 if (lseek(rp_fd,rp_offset,SEEK_SET) != rp_offset) {
130 rp_length = read(rp_fd,rp_buffer,rp_predict_length);
131 rp_time = time(NULL);
136 /****************************************************************************
137 invalidate read-prediction on a fd
138 ****************************************************************************/
139 void invalidate_read_prediction(int fd)
143 if (rp_predict_fd == fd)