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
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
|
//
//
// Copyright 2018 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_SUPPORT_CALLBACK_COMMON_H
#define GRPCPP_SUPPORT_CALLBACK_COMMON_H
#include <functional>
#include <grpc/grpc.h>
#include <grpc/impl/grpc_types.h>
#include <grpc/support/log.h>
#include <grpcpp/impl/call.h>
#include <grpcpp/impl/codegen/channel_interface.h>
#include <grpcpp/impl/completion_queue_tag.h>
#include <grpcpp/support/config.h>
#include <grpcpp/support/status.h>
namespace grpc {
namespace internal {
/// An exception-safe way of invoking a user-specified callback function
// TODO(vjpai): decide whether it is better for this to take a const lvalue
// parameter or an rvalue parameter, or if it even matters
template <class Func, class... Args>
void CatchingCallback(Func&& func, Args&&... args) {
#if GRPC_ALLOW_EXCEPTIONS
try {
func(std::forward<Args>(args)...);
} catch (...) {
// nothing to return or change here, just don't crash the library
}
#else // GRPC_ALLOW_EXCEPTIONS
func(std::forward<Args>(args)...);
#endif // GRPC_ALLOW_EXCEPTIONS
}
template <class Reactor, class Func, class... Args>
Reactor* CatchingReactorGetter(Func&& func, Args&&... args) {
#if GRPC_ALLOW_EXCEPTIONS
try {
return func(std::forward<Args>(args)...);
} catch (...) {
// fail the RPC, don't crash the library
return nullptr;
}
#else // GRPC_ALLOW_EXCEPTIONS
return func(std::forward<Args>(args)...);
#endif // GRPC_ALLOW_EXCEPTIONS
}
// The contract on these tags is that they are single-shot. They must be
// constructed and then fired at exactly one point. There is no expectation
// that they can be reused without reconstruction.
class CallbackWithStatusTag : public grpc_completion_queue_functor {
public:
// always allocated against a call arena, no memory free required
static void operator delete(void* /*ptr*/, std::size_t size) {
GPR_ASSERT(size == sizeof(CallbackWithStatusTag));
}
// This operator should never be called as the memory should be freed as part
// of the arena destruction. It only exists to provide a matching operator
// delete to the operator new so that some compilers will not complain (see
// https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
// there are no tests catching the compiler warning.
static void operator delete(void*, void*) { GPR_ASSERT(false); }
CallbackWithStatusTag(grpc_call* call, std::function<void(Status)> f,
CompletionQueueTag* ops)
: call_(call), func_(std::move(f)), ops_(ops) {
grpc_call_ref(call);
functor_run = &CallbackWithStatusTag::StaticRun;
// A client-side callback should never be run inline since they will always
// have work to do from the user application. So, set the parent's
// inlineable field to false
inlineable = false;
}
~CallbackWithStatusTag() {}
Status* status_ptr() { return &status_; }
// force_run can not be performed on a tag if operations using this tag
// have been sent to PerformOpsOnCall. It is intended for error conditions
// that are detected before the operations are internally processed.
void force_run(Status s) {
status_ = std::move(s);
Run(true);
}
private:
grpc_call* call_;
std::function<void(Status)> func_;
CompletionQueueTag* ops_;
Status status_;
static void StaticRun(grpc_completion_queue_functor* cb, int ok) {
static_cast<CallbackWithStatusTag*>(cb)->Run(static_cast<bool>(ok));
}
void Run(bool ok) {
void* ignored = ops_;
if (!ops_->FinalizeResult(&ignored, &ok)) {
// The tag was swallowed
return;
}
GPR_ASSERT(ignored == ops_);
// Last use of func_ or status_, so ok to move them out
auto func = std::move(func_);
auto status = std::move(status_);
func_ = nullptr; // reset to clear this out for sure
status_ = Status(); // reset to clear this out for sure
CatchingCallback(std::move(func), std::move(status));
grpc_call_unref(call_);
}
};
/// CallbackWithSuccessTag can be reused multiple times, and will be used in
/// this fashion for streaming operations. As a result, it shouldn't clear
/// anything up until its destructor
class CallbackWithSuccessTag : public grpc_completion_queue_functor {
public:
// always allocated against a call arena, no memory free required
static void operator delete(void* /*ptr*/, std::size_t size) {
GPR_ASSERT(size == sizeof(CallbackWithSuccessTag));
}
// This operator should never be called as the memory should be freed as part
// of the arena destruction. It only exists to provide a matching operator
// delete to the operator new so that some compilers will not complain (see
// https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
// there are no tests catching the compiler warning.
static void operator delete(void*, void*) { GPR_ASSERT(false); }
CallbackWithSuccessTag() : call_(nullptr) {}
CallbackWithSuccessTag(const CallbackWithSuccessTag&) = delete;
CallbackWithSuccessTag& operator=(const CallbackWithSuccessTag&) = delete;
~CallbackWithSuccessTag() { Clear(); }
// Set can only be called on a default-constructed or Clear'ed tag.
// It should never be called on a tag that was constructed with arguments
// or on a tag that has been Set before unless the tag has been cleared.
// can_inline indicates that this particular callback can be executed inline
// (without needing a thread hop) and is only used for library-provided server
// callbacks.
void Set(grpc_call* call, std::function<void(bool)> f,
CompletionQueueTag* ops, bool can_inline) {
GPR_ASSERT(call_ == nullptr);
grpc_call_ref(call);
call_ = call;
func_ = std::move(f);
ops_ = ops;
functor_run = &CallbackWithSuccessTag::StaticRun;
inlineable = can_inline;
}
void Clear() {
if (call_ != nullptr) {
grpc_call* call = call_;
call_ = nullptr;
func_ = nullptr;
grpc_call_unref(call);
}
}
CompletionQueueTag* ops() { return ops_; }
// force_run can not be performed on a tag if operations using this tag
// have been sent to PerformOpsOnCall. It is intended for error conditions
// that are detected before the operations are internally processed.
void force_run(bool ok) { Run(ok); }
/// check if this tag is currently set
// NOLINTNEXTLINE(google-explicit-constructor)
operator bool() const { return call_ != nullptr; }
private:
grpc_call* call_;
std::function<void(bool)> func_;
CompletionQueueTag* ops_;
static void StaticRun(grpc_completion_queue_functor* cb, int ok) {
static_cast<CallbackWithSuccessTag*>(cb)->Run(static_cast<bool>(ok));
}
void Run(bool ok) {
void* ignored = ops_;
// Allow a "false" return value from FinalizeResult to silence the
// callback, just as it silences a CQ tag in the async cases
#ifndef NDEBUG
auto* ops = ops_;
#endif
bool do_callback = ops_->FinalizeResult(&ignored, &ok);
GPR_DEBUG_ASSERT(ignored == ops);
if (do_callback) {
CatchingCallback(func_, ok);
}
}
};
} // namespace internal
} // namespace grpc
#endif // GRPCPP_SUPPORT_CALLBACK_COMMON_H
|
