ceph/src/librbd/io/ReadResult.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3
   4 #include "librbd/io/ReadResult.h"
   5 #include "include/buffer.h"
   6 #include "common/dout.h"
   7 #include "librbd/io/AioCompletion.h"
   8 #include <boost/variant/apply_visitor.hpp>
   9 #include <boost/variant/static_visitor.hpp>
  10
  11 #define dout_subsys ceph_subsys_rbd
  12 #undef dout_prefix
  13 #define dout_prefix *_dout << "librbd::io::ReadResult: " << this \
  14                            << " " << __func__ << ": "
  15
  16 namespace librbd {
  17 namespace io {
  18
  19 struct ReadResult::SetClipLengthVisitor : public boost::static_visitor<void> {
  20   size_t length;
  21
  22   explicit SetClipLengthVisitor(size_t length) : length(length) {
  23   }
  24
  25   void operator()(Linear &linear) const {
  26     ceph_assert(length <= linear.buf_len);
  27     linear.buf_len = length;
  28   }
  29
  30   template <typename T>
  31   void operator()(T &t) const {
  32   }
  33 };
  34
  35 struct ReadResult::AssembleResultVisitor : public boost::static_visitor<void> {
  36   CephContext *cct;
  37   Striper::StripedReadResult &destriper;
  38
  39   AssembleResultVisitor(CephContext *cct, Striper::StripedReadResult &destriper)
  40     : cct(cct), destriper(destriper) {
  41   }
  42
  43   void operator()(Empty &empty) const {
  44     ldout(cct, 20) << "dropping read result" << dendl;
  45   }
  46
  47   void operator()(Linear &linear) const {
  48     ldout(cct, 20) << "copying resulting bytes to "
  49                    << reinterpret_cast<void*>(linear.buf) << dendl;
  50     destriper.assemble_result(cct, linear.buf, linear.buf_len);
  51   }
  52
  53   void operator()(Vector &vector) const {
  54     bufferlist bl;
  55     destriper.assemble_result(cct, bl, true);
  56
  57     ldout(cct, 20) << "copying resulting " << bl.length() << " bytes to iovec "
  58                    << reinterpret_cast<const void*>(vector.iov) << dendl;
  59
  60     bufferlist::iterator it = bl.begin();
  61     size_t length = bl.length();
  62     size_t offset = 0;
  63     int idx = 0;
  64     for (; offset < length && idx < vector.iov_count; idx++) {
  65       size_t len = std::min(vector.iov[idx].iov_len, length - offset);
  66       it.copy(len, static_cast<char *>(vector.iov[idx].iov_base));
  67       offset += len;
  68     }
  69     ceph_assert(offset == bl.length());
  70   }
  71
  72   void operator()(Bufferlist &bufferlist) const {
  73     bufferlist.bl->clear();
  74     destriper.assemble_result(cct, *bufferlist.bl, true);
  75
  76     ldout(cct, 20) << "moved resulting " << bufferlist.bl->length() << " "
  77                    << "bytes to bl " << reinterpret_cast<void*>(bufferlist.bl)
  78                    << dendl;
  79   }
  80 };
  81
  82 ReadResult::C_ImageReadRequest::C_ImageReadRequest(
  83     AioCompletion *aio_completion, const Extents image_extents)
  84   : aio_completion(aio_completion), image_extents(image_extents) {
  85   aio_completion->add_request();
  86 }
  87
  88 void ReadResult::C_ImageReadRequest::finish(int r) {
  89   CephContext *cct = aio_completion->ictx->cct;
  90   ldout(cct, 10) << "C_ImageReadRequest: r=" << r
  91                  << dendl;
  92   if (r >= 0) {
  93     size_t length = 0;
  94     for (auto &image_extent : image_extents) {
  95       length += image_extent.second;
  96     }
  97     ceph_assert(length == bl.length());
  98
  99     aio_completion->lock.Lock();
 100     aio_completion->read_result.m_destriper.add_partial_result(
 101       cct, bl, image_extents);
 102     aio_completion->lock.Unlock();
 103     r = length;
 104   }
 105
 106   aio_completion->complete_request(r);
 107 }
 108
 109 ReadResult::C_ObjectReadRequest::C_ObjectReadRequest(
 110     AioCompletion *aio_completion, uint64_t object_off, uint64_t object_len,
 111     Extents&& buffer_extents)
 112   : aio_completion(aio_completion), object_off(object_off),
 113     object_len(object_len), buffer_extents(std::move(buffer_extents)) {
 114   aio_completion->add_request();
 115 }
 116
 117 void ReadResult::C_ObjectReadRequest::finish(int r) {
 118   CephContext *cct = aio_completion->ictx->cct;
 119   ldout(cct, 10) << "C_ObjectReadRequest: r=" << r
 120                  << dendl;
 121
 122   if (r == -ENOENT) {
 123     r = 0;
 124   }
 125   if (r >= 0) {
 126     ldout(cct, 10) << " got " << extent_map
 127                    << " for " << buffer_extents
 128                    << " bl " << bl.length() << dendl;
 129     // handle the case where a sparse-read wasn't issued
 130     if (extent_map.empty()) {
 131       extent_map[object_off] = bl.length();
 132     }
 133
 134     aio_completion->lock.Lock();
 135     aio_completion->read_result.m_destriper.add_partial_sparse_result(
 136       cct, bl, extent_map, object_off, buffer_extents);
 137     aio_completion->lock.Unlock();
 138
 139     r = object_len;
 140   }
 141
 142   aio_completion->complete_request(r);
 143 }
 144
 145 ReadResult::ReadResult() : m_buffer(Empty()) {
 146 }
 147
 148 ReadResult::ReadResult(char *buf, size_t buf_len)
 149   : m_buffer(Linear(buf, buf_len)) {
 150 }
 151
 152 ReadResult::ReadResult(const struct iovec *iov, int iov_count)
 153   : m_buffer(Vector(iov, iov_count)) {
 154 }
 155
 156 ReadResult::ReadResult(ceph::bufferlist *bl)
 157   : m_buffer(Bufferlist(bl)) {
 158 }
 159
 160 void ReadResult::set_clip_length(size_t length) {
 161   boost::apply_visitor(SetClipLengthVisitor(length), m_buffer);
 162 }
 163
 164 void ReadResult::assemble_result(CephContext *cct) {
 165   boost::apply_visitor(AssembleResultVisitor(cct, m_destriper), m_buffer);
 166 }
 167
 168 } // namespace io
 169 } // namespace librbd
 170