XRootD
XrdXrootdPgwCtl.cc
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1 /******************************************************************************/
2 /* */
3 /* X r d X r o o t d P g w C t l . c c */
4 /* */
5 /* (c) 2021 by the Board of Trustees of the Leland Stanford, Jr., University */
6 /* Produced by Andrew Hanushevsky for Stanford University under contract */
7 /* DE-AC02-76-SFO0515 with the Department of Energy */
8 /* */
9 /* This file is part of the XRootD software suite. */
10 /* */
11 /* XRootD is free software: you can redistribute it and/or modify it under */
12 /* the terms of the GNU Lesser General Public License as published by the */
13 /* Free Software Foundation, either version 3 of the License, or (at your */
14 /* option) any later version. */
15 /* */
16 /* XRootD is distributed in the hope that it will be useful, but WITHOUT */
17 /* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or */
18 /* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public */
19 /* License for more details. */
20 /* */
21 /* You should have received a copy of the GNU Lesser General Public License */
22 /* along with XRootD in a file called COPYING.LESSER (LGPL license) and file */
23 /* COPYING (GPL license). If not, see <http://www.gnu.org/licenses/>. */
24 /* */
25 /* The copyright holder's institutional names and contributor's names may not */
26 /* be used to endorse or promote products derived from this software without */
27 /* specific prior written permission of the institution or contributor. */
28 /******************************************************************************/
29 
30 #include <cstring>
31 
33 #include "XrdSys/XrdSysPlatform.hh"
37 
38 /******************************************************************************/
39 /* S t a t i c M e m b e r s */
40 /******************************************************************************/
41 
42 const char *XrdXrootdPgwCtl::TraceID = "pgwCtl";
43 
44 namespace
45 {
46 static const int pgPageSize = XrdProto::kXR_pgPageSZ;
47 static const int pgPageMask = XrdProto::kXR_pgPageSZ-1;
48 }
49 
50 /******************************************************************************/
51 /* C o n s t r u c t o r */
52 /******************************************************************************/
53 
55  : XrdXrootdPgwBadCS(pid), dataBuff(0), dataBLen(0), fixSRD(0)
56 {
57 
58 // Clear the response area
59 //
60  memset(&resp, 0, sizeof(resp));
61 
62 // Setup response fields that stay constant for the life of the object
63 //
65  resp.bdy.resptype = XrdProto::kXR_FinalResult; // No partials
66 
67 // Setup the iovec assuming full usage
68 //
69  kXR_unt32 *csP = csVec;
70  for (int i = 0; i < maxIOVN; i += 2)
71  {ioVec[i ].iov_base = csP++;
72  ioVec[i ].iov_len = sizeof(kXR_unt32);
73  ioVec[i+1].iov_len = pgPageSize;
74  };
75 }
76 
77 /******************************************************************************/
78 /* A d v a n c e */
79 /******************************************************************************/
80 
82 {
83 // Check if we have anything to advance here
84 //
85  if (iovRem <= 0)
86  {iovNum = 0;
87  iovLen = 0;
88  return false;
89  }
90 
91 // Readjust values for first data iov element as the previous one may not have
92 // bin for a full page (unaligned read). We just do it categorically.
93 //
94  ioVec[1].iov_base = dataBuff;
95  ioVec[1].iov_len = pgPageSize;
96 
97 // Compute number of iovec element we will use for the next read.
98 //
99  if (iovRem > iovNum) iovRem -= iovNum;
100  else {iovNum = iovRem;
101  iovRem = 0;
102  if (endLen)
103  {ioVec[iovNum-1].iov_len = endLen;
104  fixSRD = iovNum-1;
105  }
106  }
107 
108 // Compute bytes read by this frame
109 //
110  int n = iovNum>>1;
111  iovLen = ioVec[iovNum-1].iov_len + (n*crcSZ);
112  if (n > 1) iovLen += (n-1)*pgPageSize;
113 
114 // Indicate there is more to do
115 //
116  return true;
117 }
118 
119 /******************************************************************************/
120 /* S e t u p */
121 /******************************************************************************/
122 
123 const char *XrdXrootdPgwCtl::Setup(XrdBuffer *buffP, kXR_int64 fOffs, int totlen)
124 {
126  int csNum, iovMax;
127 
128 // Reset short length in the iovec from the last use.
129 //
130  if (fixSRD)
131  {ioVec[fixSRD].iov_len = pgPageSize;
132  fixSRD = 0;
133  }
134 
135 // Compute the layout parameters for the complete read (done once)
136 //
137  if (!(csNum = XrdOucPgrwUtils::recvLayout(layout, fOffs, totlen)))
138  return layout.eWhy;
139 
140 // Compute the maximum number of iov entries for the real buffer size
141 //
142  if (buffP->bsize >= maxBSize) iovMax = (maxBSize/XrdProto::kXR_pgPageSZ)*2;
143  else iovMax = (buffP->bsize/XrdProto::kXR_pgPageSZ)*2;
144 
145 // Verify the logic here, under no circumstance should iovMax be zero
146 //
147  if (!iovMax) return "PgwCtl logic error detected; buffer is too small";
148 
149 // If the buffer has changed, then we must update buffer addresses in the iovec
150 // Note that buffer sizes are always a power of 1K (i.e. 1, 2, 4, 8, etc).
151 // However, the caller is on the hook to make the buffer no less than 4K.
152 //
153  if (buffP->buff != dataBuff || buffP->bsize != dataBLen)
154  {char *dP;
155  dP = dataBuff = buffP->buff; dataBLen = buffP->bsize;
156  for (int i = 1; i < iovMax; i +=2)
157  {ioVec[i].iov_base = dP;
159  }
160  }
161 
162 // Setup control information and preset the initial read.
163 //
164  ioVec[1].iov_base = buffP->buff + layout.bOffset;
165  ioVec[1].iov_len = layout.fLen;
166 
167 // Now setup for subsequent reads which we may not need.
168 //
169  iovRem = csNum<<1;
170  if (iovRem > iovMax)
171  {iovNum = iovMax;
172  iovLen = layout.fLen + ((iovMax/2-1)*pgPageSize) + (iovMax/2*crcSZ);
173  endLen = layout.lLen;
174  } else {
175  iovNum = iovRem;
176  iovLen = layout.sockLen;
177  endLen = 0;
178  if (layout.lLen)
179  {ioVec[iovNum-1].iov_len = layout.lLen;
180  fixSRD = iovNum-1;
181  }
182  }
183  iovRem -= iovNum;
184  lenLeft = layout.sockLen - iovLen;
185 
186 // Reset remaining fields
187 //
188  boReset();
189  info.offset = htonll(fOffs);
190  return 0;
191 }
struct ServerResponseBody_Status bdy
Definition: XProtocol.hh:1261
@ kXR_1stRequest
Definition: XProtocol.hh:111
@ kXR_pgwrite
Definition: XProtocol.hh:138
long long kXR_int64
Definition: XPtypes.hh:98
unsigned int kXR_unt32
Definition: XPtypes.hh:90
int bsize
Definition: XrdBuffer.hh:46
char * buff
Definition: XrdBuffer.hh:45
off_t bOffset
Buffer offset to apply iov[1].iov_base.
int fLen
Length to use for iov[1].iov_len.
int sockLen
Total number of network bytes the iovec will handle.
const char * eWhy
Reason for failure when zero is returned.
int lLen
Length to use for iov[csnum*2-1].iov_len)
static int recvLayout(Layout &layout, off_t offs, int dlen, int bsz=0)
Compute the layout for an iovec that receives network bytes applying.
ServerResponseStatus resp
static const int crcSZ
static const int maxIOVN
XrdXrootdPgwCtl(int pid)
static const int maxBSize
const char * Setup(XrdBuffer *buffP, kXR_int64 fOffs, int totlen)
ServerResponseBody_pgWrite info
static const int kXR_pgPageSZ
Definition: XProtocol.hh:494
@ kXR_FinalResult
Definition: XProtocol.hh:1249