| /* Copyright 2016 The TensorFlow Authors. All Rights Reserved. |
| |
| 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. |
| ==============================================================================*/ |
| |
| #include "tensorflow/core/framework/op_kernel.h" |
| #include "tensorflow/core/framework/tensor.h" |
| #include "tensorflow/core/platform/mutex.h" |
| |
| namespace tensorflow { |
| |
| // This Op takes in a list of strings and a counter (ref). It increments the |
| // counter by 1 and returns the element at that position in the list (circling |
| // around if need to). |
| class ObtainNextOp : public OpKernel { |
| public: |
| explicit ObtainNextOp(OpKernelConstruction* context) : OpKernel(context) {} |
| |
| void Compute(OpKernelContext* ctx) override { |
| const Tensor* list; |
| OP_REQUIRES_OK(ctx, ctx->input("list", &list)); |
| int64 num_elements = list->NumElements(); |
| auto list_flat = list->flat<tstring>(); |
| |
| // Allocate output. |
| Tensor* output_tensor = nullptr; |
| OP_REQUIRES_OK(ctx, ctx->allocate_output("out_element", TensorShape({}), |
| &output_tensor)); |
| |
| // Obtain mutex for the "counter" tensor. |
| mutex* mu; |
| OP_REQUIRES_OK(ctx, ctx->input_ref_mutex("counter", &mu)); |
| mutex_lock l(*mu); |
| // Increment "counter" tensor by 1. |
| Tensor counter_tensor; |
| OP_REQUIRES_OK(ctx, ctx->mutable_input("counter", &counter_tensor, true)); |
| int64* pos = &counter_tensor.scalar<int64>()(); |
| *pos = (*pos + 1) % num_elements; |
| |
| // Assign value to output. |
| output_tensor->scalar<tstring>()() = list_flat(*pos); |
| } |
| }; |
| |
| REGISTER_KERNEL_BUILDER(Name("ObtainNext").Device(DEVICE_CPU), ObtainNextOp); |
| |
| } // namespace tensorflow |