1 2 // Licensed under the Apache License, Version 2.0 (the "License"); 3 // you may not use this file except in compliance with the License. 4 // You may obtain a copy of the License at 5 // 6 // http://www.apache.org/licenses/LICENSE-2.0 7 // 8 // Unless required by applicable law or agreed to in writing, software 9 // distributed under the License is distributed on an "AS IS" BASIS, 10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 11 // See the License for the specific language governing permissions and 12 // limitations under the License. 13 // 14 // Copyright 2005-2010 Google, Inc. 15 // Author: sorenj (at) google.com (Jeffrey Sorensen) 16 17 #ifndef FST_LIB_MAPPED_FILE_H_ 18 #define FST_LIB_MAPPED_FILE_H_ 19 20 #include <unistd.h> 21 #include <sys/mman.h> 22 23 #include <fst/fst.h> 24 #include <iostream> 25 #include <fstream> 26 #include <sstream> 27 28 DECLARE_int32(fst_arch_alignment); // defined in mapped-file.h 29 30 namespace fst { 31 32 // A memory region is a simple abstraction for allocated memory or data from 33 // mmap'ed files. If mmap equals NULL, then data represents an owned region of 34 // size bytes. Otherwise, mmap and size refer to the mapping and data is a 35 // casted pointer to a region contained within [mmap, mmap + size). 36 // If size is 0, then mmap refers and data refer to a block of memory managed 37 // externally by some other allocator. 38 struct MemoryRegion { 39 void *data; 40 void *mmap; 41 size_t size; 42 }; 43 44 class MappedFile { 45 public: 46 virtual ~MappedFile(); 47 48 void* mutable_data() const { 49 return reinterpret_cast<void*>(region_.data); 50 } 51 52 const void* data() const { 53 return reinterpret_cast<void*>(region_.data); 54 } 55 56 // Returns a MappedFile object that contains the contents of the input 57 // stream s starting from the current file position with size bytes. 58 // The file name must also be provided in the FstReadOptions as opts.source 59 // or else mapping will fail. If mapping is not possible, then a MappedFile 60 // object with a new[]'ed block of memory will be created. 61 static MappedFile* Map(istream* s, const FstReadOptions& opts, size_t size); 62 63 // Creates a MappedFile object with a new[]'ed block of memory of size. 64 // RECOMMENDED FOR INTERNAL USE ONLY, may change in future releases. 65 static MappedFile* Allocate(size_t size); 66 67 // Creates a MappedFile object pointing to a borrowed reference to data. 68 // This block of memory is not owned by the MappedFile object and will not 69 // be freed. 70 // RECOMMENDED FOR INTERNAL USE ONLY, may change in future releases. 71 static MappedFile* Borrow(void *data); 72 73 static const int kArchAlignment; 74 75 private: 76 explicit MappedFile(const MemoryRegion ®ion); 77 78 MemoryRegion region_; 79 DISALLOW_COPY_AND_ASSIGN(MappedFile); 80 }; 81 } // namespace fst 82 83 #endif // FST_LIB_MAPPED_FILE_H_ 84
