1/* Copyright 2015 The TensorFlow Authors. All Rights Reserved.
2
3Licensed under the Apache License, Version 2.0 (the "License");
4you may not use this file except in compliance with the License.
5You may obtain a copy of the License at
6
7 http://www.apache.org/licenses/LICENSE-2.0
8
9Unless required by applicable law or agreed to in writing, software
10distributed under the License is distributed on an "AS IS" BASIS,
11WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12See the License for the specific language governing permissions and
13limitations under the License.
14==============================================================================*/
15
16#ifndef TENSORFLOW_CORE_FRAMEWORK_READER_OP_KERNEL_H_
17#define TENSORFLOW_CORE_FRAMEWORK_READER_OP_KERNEL_H_
18
19#include <functional>
20#include <string>
21
22#include "tensorflow/core/framework/op_kernel.h"
23#include "tensorflow/core/framework/reader_interface.h"
24#include "tensorflow/core/framework/resource_mgr.h"
25#include "tensorflow/core/framework/resource_op_kernel.h"
26#include "tensorflow/core/platform/mutex.h"
27#include "tensorflow/core/platform/types.h"
28
29namespace tensorflow {
30
31// NOTE: This is now a very thin layer over ResourceOpKernel.
32// TODO(sjhwang): Remove dependencies to this class, then delete this.
33
34// Implementation for ops providing a Reader.
35class ReaderOpKernel : public ResourceOpKernel<ReaderInterface> {
36 public:
37 using ResourceOpKernel::ResourceOpKernel;
38
39 // Must be called by descendants before the first call to Compute() (typically
40 // called during construction). factory must return a ReaderInterface
41 // descendant allocated with new that ReaderOpKernel will take ownership of.
42 void SetReaderFactory(std::function<ReaderInterface*()> factory)
43 TF_LOCKS_EXCLUDED(mu_) {
44 DCHECK(get_resource() == nullptr);
45 mutex_lock l(mu_);
46 factory_ = factory;
47 }
48
49 void Compute(OpKernelContext* context) override {
50 if (!IsCancellable()) {
51 ResourceOpKernel<ReaderInterface>::Compute(context);
52 } else {
53 // Install cancellation
54 CancellationManager* cm = context->cancellation_manager();
55 CancellationToken token = cm->get_cancellation_token();
56 bool already_cancelled =
57 !cm->RegisterCallback(token, [this]() { this->Cancel(); });
58
59 if (!already_cancelled) {
60 ResourceOpKernel<ReaderInterface>::Compute(context);
61 } else {
62 context->SetStatus(errors::Cancelled("read operation was cancelled"));
63 }
64 }
65 }
66
67 private:
68 virtual bool IsCancellable() const { return false; }
69 virtual void Cancel() {}
70
71 Status CreateResource(ReaderInterface** reader)
72 TF_EXCLUSIVE_LOCKS_REQUIRED(mu_) override {
73 *reader = factory_();
74 if (*reader == nullptr) {
75 return errors::ResourceExhausted("Failed to allocate reader");
76 }
77 std::function<ReaderInterface*()> temp = nullptr;
78 factory_.swap(temp);
79 return OkStatus();
80 }
81
82 std::function<ReaderInterface*()> factory_ TF_GUARDED_BY(mu_);
83};
84
85} // namespace tensorflow
86
87#endif // TENSORFLOW_CORE_FRAMEWORK_READER_OP_KERNEL_H_
88