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      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 #include "tensorflow/core/lib/io/record_writer.h"
     17 
     18 #include "tensorflow/core/lib/core/coding.h"
     19 #include "tensorflow/core/lib/hash/crc32c.h"
     20 #include "tensorflow/core/lib/io/compression.h"
     21 #include "tensorflow/core/platform/env.h"
     22 
     23 namespace tensorflow {
     24 namespace io {
     25 namespace {
     26 bool IsZlibCompressed(RecordWriterOptions options) {
     27   return options.compression_type == RecordWriterOptions::ZLIB_COMPRESSION;
     28 }
     29 }  // namespace
     30 
     31 RecordWriterOptions RecordWriterOptions::CreateRecordWriterOptions(
     32     const string& compression_type) {
     33   RecordWriterOptions options;
     34   if (compression_type == "ZLIB") {
     35     options.compression_type = io::RecordWriterOptions::ZLIB_COMPRESSION;
     36 #if defined(IS_SLIM_BUILD)
     37     LOG(ERROR) << "Compression is not supported but compression_type is set."
     38                << " No compression will be used.";
     39 #else
     40     options.zlib_options = io::ZlibCompressionOptions::DEFAULT();
     41 #endif  // IS_SLIM_BUILD
     42   } else if (compression_type == compression::kGzip) {
     43     options.compression_type = io::RecordWriterOptions::ZLIB_COMPRESSION;
     44 #if defined(IS_SLIM_BUILD)
     45     LOG(ERROR) << "Compression is not supported but compression_type is set."
     46                << " No compression will be used.";
     47 #else
     48     options.zlib_options = io::ZlibCompressionOptions::GZIP();
     49 #endif  // IS_SLIM_BUILD
     50   } else if (compression_type != compression::kNone) {
     51     LOG(ERROR) << "Unsupported compression_type:" << compression_type
     52                << ". No compression will be used.";
     53   }
     54   return options;
     55 }
     56 
     57 RecordWriter::RecordWriter(WritableFile* dest,
     58                            const RecordWriterOptions& options)
     59     : dest_(dest), options_(options) {
     60   if (IsZlibCompressed(options)) {
     61 // We don't have zlib available on all embedded platforms, so fail.
     62 #if defined(IS_SLIM_BUILD)
     63     LOG(FATAL) << "Zlib compression is unsupported on mobile platforms.";
     64 #else   // IS_SLIM_BUILD
     65     ZlibOutputBuffer* zlib_output_buffer = new ZlibOutputBuffer(
     66         dest, options.zlib_options.input_buffer_size,
     67         options.zlib_options.output_buffer_size, options.zlib_options);
     68     Status s = zlib_output_buffer->Init();
     69     if (!s.ok()) {
     70       LOG(FATAL) << "Failed to initialize Zlib inputbuffer. Error: "
     71                  << s.ToString();
     72     }
     73     dest_ = zlib_output_buffer;
     74 #endif  // IS_SLIM_BUILD
     75   } else if (options.compression_type == RecordWriterOptions::NONE) {
     76     // Nothing to do
     77   } else {
     78     LOG(FATAL) << "Unspecified compression type :" << options.compression_type;
     79   }
     80 }
     81 
     82 RecordWriter::~RecordWriter() {
     83   if (dest_ != nullptr) {
     84     Status s = Close();
     85     if (!s.ok()) {
     86       LOG(ERROR) << "Could not finish writing file: " << s;
     87     }
     88   }
     89 }
     90 
     91 static uint32 MaskedCrc(const char* data, size_t n) {
     92   return crc32c::Mask(crc32c::Value(data, n));
     93 }
     94 
     95 Status RecordWriter::WriteRecord(StringPiece data) {
     96   // Format of a single record:
     97   //  uint64    length
     98   //  uint32    masked crc of length
     99   //  byte      data[length]
    100   //  uint32    masked crc of data
    101   char header[sizeof(uint64) + sizeof(uint32)];
    102   core::EncodeFixed64(header + 0, data.size());
    103   core::EncodeFixed32(header + sizeof(uint64),
    104                       MaskedCrc(header, sizeof(uint64)));
    105   char footer[sizeof(uint32)];
    106   core::EncodeFixed32(footer, MaskedCrc(data.data(), data.size()));
    107 
    108   TF_RETURN_IF_ERROR(dest_->Append(StringPiece(header, sizeof(header))));
    109   TF_RETURN_IF_ERROR(dest_->Append(data));
    110   return dest_->Append(StringPiece(footer, sizeof(footer)));
    111 }
    112 
    113 Status RecordWriter::Close() {
    114 #if !defined(IS_SLIM_BUILD)
    115   if (IsZlibCompressed(options_)) {
    116     Status s = dest_->Close();
    117     delete dest_;
    118     dest_ = nullptr;
    119     return s;
    120   }
    121 #endif  // IS_SLIM_BUILD
    122   return Status::OK();
    123 }
    124 
    125 Status RecordWriter::Flush() {
    126   if (IsZlibCompressed(options_)) {
    127     return dest_->Flush();
    128   }
    129   return Status::OK();
    130 }
    131 
    132 }  // namespace io
    133 }  // namespace tensorflow
    134