1 files changed, 191 insertions, 0 deletions
diff --git a/klm/lm/binary_format.cc b/klm/lm/binary_format.cc
new file mode 100644
index 00000000..2a075b6b
--- /dev/null
+++ b/klm/lm/binary_format.cc
@@ -0,0 +1,191 @@
+#include "lm/binary_format.hh"
+
+#include "lm/lm_exception.hh"
+#include "util/file_piece.hh"
+
+#include <limits>
+#include <string>
+
+#include <fcntl.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+namespace lm {
+namespace ngram {
+namespace {
+const char kMagicBeforeVersion[] = "mmap lm http://kheafield.com/code format version";
+const char kMagicBytes[] = "mmap lm http://kheafield.com/code format version 1\n\0";
+const long int kMagicVersion = 1;
+
+// Test values.  
+struct Sanity {
+  char magic[sizeof(kMagicBytes)];
+  float zero_f, one_f, minus_half_f;
+  WordIndex one_word_index, max_word_index;
+  uint64_t one_uint64;
+
+  void SetToReference() {
+    std::memcpy(magic, kMagicBytes, sizeof(magic));
+    zero_f = 0.0; one_f = 1.0; minus_half_f = -0.5;
+    one_word_index = 1;
+    max_word_index = std::numeric_limits<WordIndex>::max();
+    one_uint64 = 1;
+  }
+};
+
+const char *kModelNames[3] = {"hashed n-grams with probing", "hashed n-grams with sorted uniform find", "bit packed trie"};
+
+std::size_t Align8(std::size_t in) {
+  std::size_t off = in % 8;
+  if (!off) return in;
+  return in + 8 - off;
+}
+
+std::size_t TotalHeaderSize(unsigned char order) {
+  return Align8(sizeof(Sanity) + sizeof(FixedWidthParameters) + sizeof(uint64_t) * order);
+}
+
+void ReadLoop(int fd, void *to_void, std::size_t size) {
+  uint8_t *to = static_cast<uint8_t*>(to_void);
+  while (size) {
+    ssize_t ret = read(fd, to, size);
+    if (ret == -1) UTIL_THROW(util::ErrnoException, "Failed to read from binary file");
+    if (ret == 0) UTIL_THROW(util::ErrnoException, "Binary file too short");
+    to += ret;
+    size -= ret;
+  }
+}
+
+void WriteHeader(void *to, const Parameters &params) {
+  Sanity header = Sanity();
+  header.SetToReference();
+  memcpy(to, &header, sizeof(Sanity));
+  char *out = reinterpret_cast<char*>(to) + sizeof(Sanity);
+
+  *reinterpret_cast<FixedWidthParameters*>(out) = params.fixed;
+  out += sizeof(FixedWidthParameters);
+
+  uint64_t *counts = reinterpret_cast<uint64_t*>(out);
+  for (std::size_t i = 0; i < params.counts.size(); ++i) {
+    counts[i] = params.counts[i];
+  }
+}
+
+} // namespace
+namespace detail {
+
+bool IsBinaryFormat(int fd) {
+  const off_t size = util::SizeFile(fd);
+  if (size == util::kBadSize || (size <= static_cast<off_t>(sizeof(Sanity)))) return false;
+  // Try reading the header.  
+  util::scoped_memory memory;
+  try {
+    util::MapRead(util::LAZY, fd, 0, sizeof(Sanity), memory);
+  } catch (const util::Exception &e) {
+    return false;
+  }
+  Sanity reference_header = Sanity();
+  reference_header.SetToReference();
+  if (!memcmp(memory.get(), &reference_header, sizeof(Sanity))) return true;
+  if (!memcmp(memory.get(), kMagicBeforeVersion, strlen(kMagicBeforeVersion))) {
+    char *end_ptr;
+    const char *begin_version = static_cast<const char*>(memory.get()) + strlen(kMagicBeforeVersion);
+    long int version = strtol(begin_version, &end_ptr, 10);
+    if ((end_ptr != begin_version) && version != kMagicVersion) {
+      UTIL_THROW(FormatLoadException, "Binary file has version " << version << " but this implementation expects version " << kMagicVersion << " so you'll have to rebuild your binary LM from the ARPA.  Sorry.");
+    }
+    UTIL_THROW(FormatLoadException, "File looks like it should be loaded with mmap, but the test values don't match.  Try rebuilding the binary format LM using the same code revision, compiler, and architecture.");
+  }
+  return false;
+}
+
+void ReadHeader(int fd, Parameters &out) {
+  if ((off_t)-1 == lseek(fd, sizeof(Sanity), SEEK_SET)) UTIL_THROW(util::ErrnoException, "Seek failed in binary file");
+  ReadLoop(fd, &out.fixed, sizeof(out.fixed));
+  if (out.fixed.probing_multiplier < 1.0)
+    UTIL_THROW(FormatLoadException, "Binary format claims to have a probing multiplier of " << out.fixed.probing_multiplier << " which is < 1.0.");
+
+  out.counts.resize(static_cast<std::size_t>(out.fixed.order));
+  ReadLoop(fd, &*out.counts.begin(), sizeof(uint64_t) * out.fixed.order);
+}
+
+void MatchCheck(ModelType model_type, const Parameters &params) {
+  if (params.fixed.model_type != model_type) {
+    if (static_cast<unsigned int>(params.fixed.model_type) >= (sizeof(kModelNames) / sizeof(const char *)))
+      UTIL_THROW(FormatLoadException, "The binary file claims to be model type " << static_cast<unsigned int>(params.fixed.model_type) << " but this is not implemented for in this inference code.");
+    UTIL_THROW(FormatLoadException, "The binary file was built for " << kModelNames[params.fixed.model_type] << " but the inference code is trying to load " << kModelNames[model_type]);
+  }
+}
+
+uint8_t *SetupBinary(const Config &config, const Parameters &params, std::size_t memory_size, Backing &backing) {
+  const off_t file_size = util::SizeFile(backing.file.get());
+  // The header is smaller than a page, so we have to map the whole header as well.  
+  std::size_t total_map = TotalHeaderSize(params.counts.size()) + memory_size;
+  if (file_size != util::kBadSize && static_cast<uint64_t>(file_size) < total_map)
+    UTIL_THROW(FormatLoadException, "Binary file has size " << file_size << " but the headers say it should be at least " << total_map);
+
+  util::MapRead(config.load_method, backing.file.get(), 0, total_map, backing.memory);
+
+  if (config.enumerate_vocab && !params.fixed.has_vocabulary)
+    UTIL_THROW(FormatLoadException, "The decoder requested all the vocabulary strings, but this binary file does not have them.  You may need to rebuild the binary file with an updated version of build_binary.");
+
+  if (config.enumerate_vocab) {
+    if ((off_t)-1 == lseek(backing.file.get(), total_map, SEEK_SET))
+      UTIL_THROW(util::ErrnoException, "Failed to seek in binary file to vocab words");
+  }
+  return reinterpret_cast<uint8_t*>(backing.memory.get()) + TotalHeaderSize(params.counts.size());
+}
+
+uint8_t *SetupZeroed(const Config &config, ModelType model_type, const std::vector<uint64_t> &counts, std::size_t memory_size, Backing &backing) {
+  if (config.probing_multiplier <= 1.0) UTIL_THROW(FormatLoadException, "probing multiplier must be > 1.0");
+  if (config.write_mmap) {
+    std::size_t total_map = TotalHeaderSize(counts.size()) + memory_size;
+    // Write out an mmap file.  
+    backing.memory.reset(util::MapZeroedWrite(config.write_mmap, total_map, backing.file), total_map, util::scoped_memory::MMAP_ALLOCATED);
+
+    Parameters params;
+    params.counts = counts;
+    params.fixed.order = counts.size();
+    params.fixed.probing_multiplier = config.probing_multiplier;
+    params.fixed.model_type = model_type;
+    params.fixed.has_vocabulary = config.include_vocab;
+
+    WriteHeader(backing.memory.get(), params);
+
+    if (params.fixed.has_vocabulary) {
+      if ((off_t)-1 == lseek(backing.file.get(), total_map, SEEK_SET))
+        UTIL_THROW(util::ErrnoException, "Failed to seek in binary file " << config.write_mmap << " to vocab words");
+    }
+    return reinterpret_cast<uint8_t*>(backing.memory.get()) + TotalHeaderSize(counts.size());
+  } else {
+    backing.memory.reset(util::MapAnonymous(memory_size), memory_size, util::scoped_memory::MMAP_ALLOCATED);
+    return reinterpret_cast<uint8_t*>(backing.memory.get());
+  } 
+}
+
+void ComplainAboutARPA(const Config &config, ModelType model_type) {
+  if (config.write_mmap || !config.messages) return;
+  if (config.arpa_complain == Config::ALL) {
+    *config.messages << "Loading the LM will be faster if you build a binary file." << std::endl;
+  } else if (config.arpa_complain == Config::EXPENSIVE && model_type == TRIE_SORTED) {
+    *config.messages << "Building " << kModelNames[model_type] << " from ARPA is expensive.  Save time by building a binary format." << std::endl;
+  }
+}
+
+} // namespace detail
+
+bool RecognizeBinary(const char *file, ModelType &recognized) {
+  util::scoped_fd fd(util::OpenReadOrThrow(file));
+  if (!detail::IsBinaryFormat(fd.get())) return false;
+  Parameters params;
+  detail::ReadHeader(fd.get(), params);
+  recognized = params.fixed.model_type;
+  return true;
+}
+
+} // namespace ngram
+} // namespace lm