1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
|
/*
*
* Copyright 2015 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#ifndef GRPCPP_IMPL_CODEGEN_PROTO_BUFFER_READER_H
#define GRPCPP_IMPL_CODEGEN_PROTO_BUFFER_READER_H
#include <type_traits>
#include <grpc/impl/codegen/byte_buffer_reader.h>
#include <grpc/impl/codegen/grpc_types.h>
#include <grpc/impl/codegen/slice.h>
#include <grpcpp/impl/codegen/byte_buffer.h>
#include <grpcpp/impl/codegen/config_protobuf.h>
#include <grpcpp/impl/codegen/core_codegen_interface.h>
#include <grpcpp/impl/codegen/serialization_traits.h>
#include <grpcpp/impl/codegen/status.h>
/// This header provides an object that reads bytes directly from a
/// grpc::ByteBuffer, via the ZeroCopyInputStream interface
namespace grpc {
extern CoreCodegenInterface* g_core_codegen_interface;
/// This is a specialization of the protobuf class ZeroCopyInputStream
/// The principle is to get one chunk of data at a time from the proto layer,
/// with options to backup (re-see some bytes) or skip (forward past some bytes)
///
/// Read more about ZeroCopyInputStream interface here:
/// https://developers.google.com/protocol-buffers/docs/reference/cpp/google.protobuf.io.zero_copy_stream#ZeroCopyInputStream
class ProtoBufferReader : public ::grpc::protobuf::io::ZeroCopyInputStream {
public:
/// Constructs buffer reader from \a buffer. Will set \a status() to non ok
/// if \a buffer is invalid (the internal buffer has not been initialized).
explicit ProtoBufferReader(ByteBuffer* buffer)
: byte_count_(0), backup_count_(0), status_() {
/// Implemented through a grpc_byte_buffer_reader which iterates
/// over the slices that make up a byte buffer
if (!buffer->Valid() ||
!g_core_codegen_interface->grpc_byte_buffer_reader_init(
&reader_, buffer->c_buffer())) {
status_ = Status(StatusCode::INTERNAL,
"Couldn't initialize byte buffer reader");
}
}
~ProtoBufferReader() override {
if (status_.ok()) {
g_core_codegen_interface->grpc_byte_buffer_reader_destroy(&reader_);
}
}
/// Give the proto library a chunk of data from the stream. The caller
/// may safely read from data[0, size - 1].
bool Next(const void** data, int* size) override {
if (!status_.ok()) {
return false;
}
/// If we have backed up previously, we need to return the backed-up slice
if (backup_count_ > 0) {
*data = GRPC_SLICE_START_PTR(*slice_) + GRPC_SLICE_LENGTH(*slice_) -
backup_count_;
GPR_CODEGEN_ASSERT(backup_count_ <= INT_MAX);
*size = static_cast<int>(backup_count_);
backup_count_ = 0;
return true;
}
/// Otherwise get the next slice from the byte buffer reader
if (!g_core_codegen_interface->grpc_byte_buffer_reader_peek(&reader_,
&slice_)) {
return false;
}
*data = GRPC_SLICE_START_PTR(*slice_);
// On win x64, int is only 32bit
GPR_CODEGEN_ASSERT(GRPC_SLICE_LENGTH(*slice_) <= INT_MAX);
byte_count_ += * size = static_cast<int>(GRPC_SLICE_LENGTH(*slice_));
return true;
}
/// Returns the status of the buffer reader.
Status status() const { return status_; }
/// The proto library calls this to indicate that we should back up \a count
/// bytes that have already been returned by the last call of Next.
/// So do the backup and have that ready for a later Next.
void BackUp(int count) override {
GPR_CODEGEN_ASSERT(count <= static_cast<int>(GRPC_SLICE_LENGTH(*slice_)));
backup_count_ = count;
}
/// The proto library calls this to skip over \a count bytes. Implement this
/// using Next and BackUp combined.
bool Skip(int count) override {
const void* data;
int size;
while (Next(&data, &size)) {
if (size >= count) {
BackUp(size - count);
return true;
}
// size < count;
count -= size;
}
// error or we have too large count;
return false;
}
/// Returns the total number of bytes read since this object was created.
int64_t ByteCount() const override { return byte_count_ - backup_count_; }
// These protected members are needed to support internal optimizations.
// they expose internal bits of grpc core that are NOT stable. If you have
// a use case needs to use one of these functions, please send an email to
// https://groups.google.com/forum/#!forum/grpc-io.
protected:
void set_byte_count(int64_t byte_count) { byte_count_ = byte_count; }
int64_t backup_count() { return backup_count_; }
void set_backup_count(int64_t backup_count) { backup_count_ = backup_count; }
grpc_byte_buffer_reader* reader() { return &reader_; }
grpc_slice* slice() { return slice_; }
grpc_slice** mutable_slice_ptr() { return &slice_; }
private:
int64_t byte_count_; ///< total bytes read since object creation
int64_t backup_count_; ///< how far backed up in the stream we are
grpc_byte_buffer_reader reader_; ///< internal object to read \a grpc_slice
///< from the \a grpc_byte_buffer
grpc_slice* slice_; ///< current slice passed back to the caller
Status status_; ///< status of the entire object
};
} // namespace grpc
#endif // GRPCPP_IMPL_CODEGEN_PROTO_BUFFER_READER_H
|
