ceph/src/librbd/io/ReadResult.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3
   4 #ifndef CEPH_LIBRBD_IO_READ_RESULT_H
   5 #define CEPH_LIBRBD_IO_READ_RESULT_H
   6
   7 #include "include/int_types.h"
   8 #include "include/buffer_fwd.h"
   9 #include "include/Context.h"
  10 #include "librbd/io/Types.h"
  11 #include "osdc/Striper.h"
  12 #include <sys/uio.h>
  13 #include <boost/variant/variant.hpp>
  14
  15 struct CephContext;
  16
  17 namespace librbd {
  18 namespace io {
  19
  20 struct AioCompletion;
  21 template <typename> struct ObjectReadRequest;
  22
  23 class ReadResult {
  24 private:
  25   struct C_ReadRequest : public Context {
  26     AioCompletion *aio_completion;
  27     bufferlist bl;
  28
  29     C_ReadRequest(AioCompletion *aio_completion);
  30
  31     void finish(int r) override;
  32   };
  33
  34 public:
  35
  36   struct C_ImageReadRequest : public C_ReadRequest {
  37     Extents image_extents;
  38
  39     C_ImageReadRequest(AioCompletion *aio_completion,
  40                        const Extents image_extents)
  41       : C_ReadRequest(aio_completion), image_extents(image_extents) {
  42     }
  43
  44     void finish(int r) override;
  45   };
  46
  47   struct C_SparseReadRequestBase : public C_ReadRequest {
  48     C_SparseReadRequestBase(AioCompletion *aio_completion)
  49       : C_ReadRequest(aio_completion) {
  50     }
  51
  52     using C_ReadRequest::finish;
  53     void finish(ExtentMap &extent_map, const Extents &buffer_extents,
  54                 uint64_t offset, size_t length, bufferlist &bl, int r);
  55   };
  56
  57   template <typename ImageCtxT>
  58   struct C_SparseReadRequest : public C_SparseReadRequestBase {
  59     ObjectReadRequest<ImageCtxT> *request;
  60
  61     C_SparseReadRequest(AioCompletion *aio_completion)
  62       : C_SparseReadRequestBase(aio_completion) {
  63     }
  64
  65     void finish(int r) override {
  66       C_SparseReadRequestBase::finish(request->get_extent_map(),
  67                                       request->get_buffer_extents(),
  68                                       request->get_offset(),
  69                                       request->get_length(), request->data(),
  70                                       r);
  71     }
  72   };
  73
  74   ReadResult();
  75   ReadResult(char *buf, size_t buf_len);
  76   ReadResult(const struct iovec *iov, int iov_count);
  77   ReadResult(ceph::bufferlist *bl);
  78
  79   void set_clip_length(size_t length);
  80   void assemble_result(CephContext *cct);
  81
  82 private:
  83   struct Empty {
  84   };
  85
  86   struct Linear {
  87     char *buf;
  88     size_t buf_len;
  89
  90     Linear(char *buf, size_t buf_len) : buf(buf), buf_len(buf_len) {
  91     }
  92   };
  93
  94   struct Vector {
  95     const struct iovec *iov;
  96     int iov_count;
  97
  98     Vector(const struct iovec *iov, int iov_count)
  99       : iov(iov), iov_count(iov_count) {
 100     }
 101   };
 102
 103   struct Bufferlist {
 104     ceph::bufferlist *bl;
 105
 106     Bufferlist(ceph::bufferlist *bl) : bl(bl) {
 107     }
 108   };
 109
 110   typedef boost::variant<Empty,
 111                          Linear,
 112                          Vector,
 113                          Bufferlist> Buffer;
 114   struct SetClipLengthVisitor;
 115   struct AssembleResultVisitor;
 116
 117   Buffer m_buffer;
 118   Striper::StripedReadResult m_destriper;
 119
 120 };
 121
 122 } // namespace io
 123 } // namespace librbd
 124
 125 #endif // CEPH_LIBRBD_IO_READ_RESULT_H
 126