1 | /* Copyright 2020 The TensorFlow Authors. All Rights Reserved. |
2 | |
3 | Licensed under the Apache License, Version 2.0 (the "License"); |
4 | you may not use this file except in compliance with the License. |
5 | You may obtain a copy of the License at |
6 | |
7 | http://www.apache.org/licenses/LICENSE-2.0 |
8 | |
9 | Unless required by applicable law or agreed to in writing, software |
10 | distributed under the License is distributed on an "AS IS" BASIS, |
11 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
12 | See the License for the specific language governing permissions and |
13 | limitations under the License. |
14 | ==============================================================================*/ |
15 | |
16 | #ifndef TENSORFLOW_CORE_KERNELS_STATELESS_RANDOM_GAMMA_OP_H_ |
17 | #define TENSORFLOW_CORE_KERNELS_STATELESS_RANDOM_GAMMA_OP_H_ |
18 | |
19 | #include "tensorflow/core/framework/op_kernel.h" |
20 | #include "tensorflow/core/lib/core/status.h" |
21 | #include "tensorflow/core/lib/random/philox_random.h" |
22 | |
23 | namespace tensorflow { |
24 | |
25 | namespace functor { |
26 | |
27 | template <typename Device, typename T> |
28 | struct StatelessRandomGammaFunctor { |
29 | static Status Fill(OpKernelContext* ctx, const T* alpha_flat, |
30 | int64_t num_samples, int64_t num_alphas, |
31 | int64_t samples_per_alpha, |
32 | const random::PhiloxRandom& random, T* samples_flat); |
33 | }; |
34 | |
35 | } // namespace functor |
36 | |
37 | // Buffer that holds multiple samples. Operator()(random::PhiloxRandom*) returns |
38 | // a single sample from this buffer. If the buffer is empty, it first generates |
39 | // new samples using the provided distribution. |
40 | // |
41 | // If the call to Distribution::operator() returns samples[0...N-1], then this |
42 | // class returns samples in the following order: |
43 | // |
44 | // samples[N-1], samples[N-2],..., samples[1], samples[0] |
45 | // |
46 | // For comparison, random::SingleSampleAdapter returns samples in |
47 | // the following order: |
48 | // |
49 | // samples[0], samples[1],...,samples[N-2], samples[N-1]. |
50 | // |
51 | template <class Distribution> |
52 | class RandomSampleBuffer { |
53 | public: |
54 | typedef typename Distribution::ResultElementType ResultElementType; |
55 | |
56 | PHILOX_DEVICE_INLINE |
57 | explicit RandomSampleBuffer(Distribution* distribution) |
58 | : distribution_(distribution), remaining_numbers_(0) {} |
59 | |
60 | PHILOX_DEVICE_INLINE |
61 | ResultElementType operator()(random::PhiloxRandom* random) { |
62 | if (remaining_numbers_ == 0) { |
63 | results_ = (*distribution_)(random); |
64 | remaining_numbers_ = Distribution::kResultElementCount; |
65 | } |
66 | |
67 | remaining_numbers_--; |
68 | return results_[remaining_numbers_]; |
69 | } |
70 | |
71 | // Mark this buffer as empty. The next call to operator() will fill it |
72 | // with new random numbers. |
73 | PHILOX_DEVICE_INLINE |
74 | void Clear() { remaining_numbers_ = 0; } |
75 | |
76 | private: |
77 | typedef typename Distribution::ResultType ResultType; |
78 | |
79 | Distribution* distribution_; |
80 | ResultType results_; |
81 | int remaining_numbers_; |
82 | }; |
83 | |
84 | } // namespace tensorflow |
85 | |
86 | #endif // TENSORFLOW_CORE_KERNELS_STATELESS_RANDOM_GAMMA_OP_H_ |
87 | |