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      1 /* Copyright 2016 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 #include "tensorflow/core/util/memmapped_file_system_writer.h"
     16 
     17 #include <algorithm>
     18 
     19 namespace tensorflow {
     20 
     21 Status MemmappedFileSystemWriter::InitializeToFile(Env* env,
     22                                                    const string& filename) {
     23   auto status = env->NewWritableFile(filename, &output_file_);
     24   if (status.ok()) {
     25     output_file_offset_ = 0;
     26   }
     27   return status;
     28 }
     29 
     30 Status MemmappedFileSystemWriter::SaveTensor(const Tensor& tensor,
     31                                              const string& element_name) {
     32   if (!output_file_) {
     33     return errors::FailedPrecondition(
     34         "MemmappedEnvWritter: saving tensor into not opened file");
     35   }
     36   if (!MemmappedFileSystem::IsWellFormedMemmappedPackageFilename(
     37           element_name)) {
     38     return errors::InvalidArgument(
     39         "MemmappedEnvWritter: element_name is invalid: must have memmapped ",
     40         "package prefix ", MemmappedFileSystem::kMemmappedPackagePrefix,
     41         " and include [A-Za-z0-9_.]");
     42   }
     43   const auto tensor_data = tensor.tensor_data();
     44   if (tensor_data.empty()) {
     45     return errors::InvalidArgument(
     46         "MemmappedEnvWritter: saving tensor with 0 size");
     47   }
     48   // Adds pad for correct alignment after memmapping.
     49   TF_RETURN_IF_ERROR(AdjustAlignment(Allocator::kAllocatorAlignment));
     50   AddToDirectoryElement(element_name);
     51   const auto result = output_file_->Append(tensor_data);
     52   if (result.ok()) {
     53     output_file_offset_ += tensor_data.size();
     54   }
     55   return result;
     56 }
     57 
     58 Status MemmappedFileSystemWriter::SaveProtobuf(
     59     const protobuf::MessageLite& message, const string& element_name) {
     60   if (!output_file_) {
     61     return errors::FailedPrecondition(
     62         "MemmappedEnvWritter: saving protobuf into not opened file");
     63   }
     64   if (!MemmappedFileSystem::IsWellFormedMemmappedPackageFilename(
     65           element_name)) {
     66     return errors::InvalidArgument(
     67         "MemmappedEnvWritter: element_name is invalid: must have memmapped "
     68         "package prefix ",
     69         MemmappedFileSystem::kMemmappedPackagePrefix,
     70         " and include [A-Za-z0-9_.]");
     71   }
     72   AddToDirectoryElement(element_name);
     73   const string encoded = message.SerializeAsString();
     74   const auto res = output_file_->Append(encoded);
     75   if (res.ok()) {
     76     output_file_offset_ += encoded.size();
     77   }
     78   return res;
     79 }
     80 
     81 namespace {
     82 
     83 StringPiece EncodeUint64LittleEndian(uint64 val, char* output_buffer) {
     84   for (unsigned int i = 0; i < sizeof(uint64); ++i) {
     85     output_buffer[i] = (val >> i * 8);
     86   }
     87   return {output_buffer, sizeof(uint64)};
     88 }
     89 
     90 }  // namespace
     91 
     92 Status MemmappedFileSystemWriter::FlushAndClose() {
     93   if (!output_file_) {
     94     return errors::FailedPrecondition(
     95         "MemmappedEnvWritter: flushing into not opened file");
     96   }
     97   const string dir = directory_.SerializeAsString();
     98   TF_RETURN_IF_ERROR(output_file_->Append(dir));
     99 
    100   // Write the directory offset.
    101   char buffer[sizeof(uint64)];
    102   TF_RETURN_IF_ERROR(output_file_->Append(
    103       EncodeUint64LittleEndian(output_file_offset_, buffer)));
    104 
    105   // Flush and close the file.
    106   TF_RETURN_IF_ERROR(output_file_->Flush());
    107   TF_RETURN_IF_ERROR(output_file_->Close());
    108   output_file_.reset();
    109   return Status::OK();
    110 }
    111 
    112 Status MemmappedFileSystemWriter::AdjustAlignment(uint64 alignment) {
    113   const uint64 alignment_rest = output_file_offset_ % alignment;
    114   const uint64 to_write_for_alignment =
    115       (alignment_rest == 0) ? 0 : alignment - (output_file_offset_ % alignment);
    116   static constexpr uint64 kFillerBufferSize = 16;
    117   const char kFillerBuffer[kFillerBufferSize] = {};
    118   for (uint64 rest = to_write_for_alignment; rest > 0;) {
    119     StringPiece sp(kFillerBuffer, std::min(rest, kFillerBufferSize));
    120     TF_RETURN_IF_ERROR(output_file_->Append(sp));
    121     rest -= sp.size();
    122     output_file_offset_ += sp.size();
    123   }
    124   return Status::OK();
    125 }
    126 
    127 void MemmappedFileSystemWriter::AddToDirectoryElement(const string& name) {
    128   MemmappedFileSystemDirectoryElement* new_directory_element =
    129       directory_.add_element();
    130   new_directory_element->set_offset(output_file_offset_);
    131   new_directory_element->set_name(name);
    132 }
    133 
    134 }  // namespace tensorflow
    135