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1 //
2 //
3 // Copyright 2016 gRPC authors.
4 //
5 // Licensed under the Apache License, Version 2.0 (the "License");
6 // you may not use this file except in compliance with the License.
7 // You may obtain a copy of the License at
8 //
9 //     http://www.apache.org/licenses/LICENSE-2.0
10 //
11 // Unless required by applicable law or agreed to in writing, software
12 // distributed under the License is distributed on an "AS IS" BASIS,
13 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 // See the License for the specific language governing permissions and
15 // limitations under the License.
16 //
17 //
18 
19 #ifndef GRPC_SRC_CORE_LIB_IOMGR_COMBINER_H
20 #define GRPC_SRC_CORE_LIB_IOMGR_COMBINER_H
21 
22 #include <grpc/support/port_platform.h>
23 
24 #include <stddef.h>
25 
26 #include <grpc/support/atm.h>
27 
28 #include "src/core/lib/debug/trace.h"
29 #include "src/core/lib/iomgr/exec_ctx.h"
30 
31 namespace grpc_core {
32 // TODO(yashkt) : Remove this class and replace it with a class that does not
33 // use ExecCtx
34 class Combiner {
35  public:
36   void Run(grpc_closure* closure, grpc_error_handle error);
37   // TODO(yashkt) : Remove this method
38   void FinallyRun(grpc_closure* closure, grpc_error_handle error);
39   // Force the next combiner execution to be offloaded
40   void ForceOffload();
41   Combiner* next_combiner_on_this_exec_ctx = nullptr;
42   MultiProducerSingleConsumerQueue queue;
43   // either:
44   // a pointer to the initiating exec ctx if that is the only exec_ctx that has
45   // ever queued to this combiner, or NULL. If this is non-null, it's not
46   // dereferencable (since the initiating exec_ctx may have gone out of scope)
47   gpr_atm initiating_exec_ctx_or_null;
48   // state is:
49   // lower bit - zero if orphaned (STATE_UNORPHANED)
50   // other bits - number of items queued on the lock (STATE_ELEM_COUNT_LOW_BIT)
51   gpr_atm state;
52   bool time_to_execute_final_list = false;
53   grpc_closure_list final_list;
54   // TODO(ctiller): delete this when the combiner_offload_to_event_engine
55   // experiment is removed.
56   grpc_closure offload;
57   gpr_refcount refs;
58   std::shared_ptr<grpc_event_engine::experimental::EventEngine> event_engine;
59 };
60 }  // namespace grpc_core
61 
62 // Provides serialized access to some resource.
63 // Each action queued on a combiner is executed serially in a borrowed thread.
64 // The actual thread executing actions may change over time (but there will only
65 // ever be one at a time).
66 
67 // Initialize the lock
68 grpc_core::Combiner* grpc_combiner_create(
69     std::shared_ptr<grpc_event_engine::experimental::EventEngine> event_engine);
70 
71 #ifndef NDEBUG
72 #define GRPC_COMBINER_DEBUG_ARGS \
73   , const char *file, int line, const char *reason
74 #define GRPC_COMBINER_REF(combiner, reason) \
75   grpc_combiner_ref((combiner), __FILE__, __LINE__, (reason))
76 #define GRPC_COMBINER_UNREF(combiner, reason) \
77   grpc_combiner_unref((combiner), __FILE__, __LINE__, (reason))
78 #else
79 #define GRPC_COMBINER_DEBUG_ARGS
80 #define GRPC_COMBINER_REF(combiner, reason) grpc_combiner_ref((combiner))
81 #define GRPC_COMBINER_UNREF(combiner, reason) grpc_combiner_unref((combiner))
82 #endif
83 
84 // Ref/unref the lock, for when we're sharing the lock ownership
85 // Prefer to use the macros above
86 grpc_core::Combiner* grpc_combiner_ref(
87     grpc_core::Combiner* lock GRPC_COMBINER_DEBUG_ARGS);
88 void grpc_combiner_unref(grpc_core::Combiner* lock GRPC_COMBINER_DEBUG_ARGS);
89 
90 bool grpc_combiner_continue_exec_ctx();
91 
92 extern grpc_core::DebugOnlyTraceFlag grpc_combiner_trace;
93 
94 #endif  // GRPC_SRC_CORE_LIB_IOMGR_COMBINER_H
95