1 /* Copyright 2015 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_LIB_IO_RECORD_WRITER_H_
17 #define TENSORFLOW_CORE_LIB_IO_RECORD_WRITER_H_
18
19 #include "tensorflow/core/lib/core/coding.h"
20 #include "tensorflow/core/lib/core/status.h"
21 #include "tensorflow/core/lib/core/stringpiece.h"
22 #include "tensorflow/core/lib/hash/crc32c.h"
23 #if !defined(IS_SLIM_BUILD)
24 #include "tensorflow/core/lib/io/snappy/snappy_compression_options.h"
25 #include "tensorflow/core/lib/io/snappy/snappy_outputbuffer.h"
26 #include "tensorflow/core/lib/io/zlib_compression_options.h"
27 #include "tensorflow/core/lib/io/zlib_outputbuffer.h"
28 #endif // IS_SLIM_BUILD
29 #include "tensorflow/core/platform/cord.h"
30 #include "tensorflow/core/platform/macros.h"
31 #include "tensorflow/core/platform/types.h"
32
33 namespace tensorflow {
34
35 class WritableFile;
36
37 namespace io {
38
39 struct RecordWriterOptions {
40 public:
41 enum CompressionType {
42 NONE = 0,
43 ZLIB_COMPRESSION = 1,
44 SNAPPY_COMPRESSION = 2
45 };
46 CompressionType compression_type = NONE;
47
48 static RecordWriterOptions CreateRecordWriterOptions(
49 const string& compression_type);
50
51 #if !defined(IS_SLIM_BUILD)
52 // Options specific to compression.
53 tensorflow::io::ZlibCompressionOptions zlib_options;
54 tensorflow::io::SnappyCompressionOptions snappy_options;
55 #endif // IS_SLIM_BUILD
56 };
57
58 class RecordWriter {
59 public:
60 // Format of a single record:
61 // uint64 length
62 // uint32 masked crc of length
63 // byte data[length]
64 // uint32 masked crc of data
65 static constexpr size_t kHeaderSize = sizeof(uint64) + sizeof(uint32);
66 static constexpr size_t kFooterSize = sizeof(uint32);
67
68 // Create a writer that will append data to "*dest".
69 // "*dest" must be initially empty.
70 // "*dest" must remain live while this Writer is in use.
71 explicit RecordWriter(WritableFile* dest, const RecordWriterOptions& options =
72 RecordWriterOptions());
73
74 // Calls Close() and logs if an error occurs.
75 //
76 // TODO(jhseu): Require that callers explicitly call Close() and remove the
77 // implicit Close() call in the destructor.
78 ~RecordWriter();
79
80 Status WriteRecord(StringPiece data);
81
82 #if defined(TF_CORD_SUPPORT)
83 Status WriteRecord(const absl::Cord& data);
84 #endif
85
86 // Flushes any buffered data held by underlying containers of the
87 // RecordWriter to the WritableFile. Does *not* flush the
88 // WritableFile.
89 Status Flush();
90
91 // Writes all output to the file. Does *not* close the WritableFile.
92 //
93 // After calling Close(), any further calls to `WriteRecord()` or `Flush()`
94 // are invalid.
95 Status Close();
96
97 // Utility method to populate TFRecord headers. Populates record-header in
98 // "header[0,kHeaderSize-1]". The record-header is based on data[0, n-1].
99 inline static void PopulateHeader(char* header, const char* data, size_t n);
100
101 #if defined(TF_CORD_SUPPORT)
102 inline static void PopulateHeader(char* header, const absl::Cord& data);
103 #endif
104
105 // Utility method to populate TFRecord footers. Populates record-footer in
106 // "footer[0,kFooterSize-1]". The record-footer is based on data[0, n-1].
107 inline static void PopulateFooter(char* footer, const char* data, size_t n);
108
109 #if defined(TF_CORD_SUPPORT)
110 inline static void PopulateFooter(char* footer, const absl::Cord& data);
111 #endif
112
113 private:
114 WritableFile* dest_;
115 RecordWriterOptions options_;
116
MaskedCrc(const char * data,size_t n)117 inline static uint32 MaskedCrc(const char* data, size_t n) {
118 return crc32c::Mask(crc32c::Value(data, n));
119 }
120
121 #if defined(TF_CORD_SUPPORT)
MaskedCrc(const absl::Cord & data)122 inline static uint32 MaskedCrc(const absl::Cord& data) {
123 return crc32c::Mask(crc32c::Value(data));
124 }
125 #endif
126
127 TF_DISALLOW_COPY_AND_ASSIGN(RecordWriter);
128 };
129
PopulateHeader(char * header,const char * data,size_t n)130 void RecordWriter::PopulateHeader(char* header, const char* data, size_t n) {
131 core::EncodeFixed64(header + 0, n);
132 core::EncodeFixed32(header + sizeof(uint64),
133 MaskedCrc(header, sizeof(uint64)));
134 }
135
PopulateFooter(char * footer,const char * data,size_t n)136 void RecordWriter::PopulateFooter(char* footer, const char* data, size_t n) {
137 core::EncodeFixed32(footer, MaskedCrc(data, n));
138 }
139
140 #if defined(TF_CORD_SUPPORT)
PopulateHeader(char * header,const absl::Cord & data)141 void RecordWriter::PopulateHeader(char* header, const absl::Cord& data) {
142 core::EncodeFixed64(header + 0, data.size());
143 core::EncodeFixed32(header + sizeof(uint64),
144 MaskedCrc(header, sizeof(uint64)));
145 }
146
PopulateFooter(char * footer,const absl::Cord & data)147 void RecordWriter::PopulateFooter(char* footer, const absl::Cord& data) {
148 core::EncodeFixed32(footer, MaskedCrc(data));
149 }
150 #endif
151
152 } // namespace io
153 } // namespace tensorflow
154
155 #endif // TENSORFLOW_CORE_LIB_IO_RECORD_WRITER_H_
156