1 files changed, 224 insertions, 0 deletions
diff --git a/klm/util/file_piece.cc b/klm/util/file_piece.cc
new file mode 100644
index 00000000..2b439499
--- /dev/null
+++ b/klm/util/file_piece.cc
@@ -0,0 +1,224 @@
+#include "util/file_piece.hh"
+
+#include "util/exception.hh"
+
+#include <iostream>
+#include <string>
+#include <limits>
+
+#include <assert.h>
+#include <cstdlib>
+#include <ctype.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+namespace util {
+
+EndOfFileException::EndOfFileException() throw() {
+  *this << "End of file";
+}
+EndOfFileException::~EndOfFileException() throw() {}
+
+ParseNumberException::ParseNumberException(StringPiece value) throw() {
+  *this << "Could not parse \"" << value << "\" into a float";
+}
+
+int OpenReadOrThrow(const char *name) {
+  int ret = open(name, O_RDONLY);
+  if (ret == -1) UTIL_THROW(ErrnoException, "in open (" << name << ") for reading");
+  return ret;
+}
+
+off_t SizeFile(int fd) {
+  struct stat sb;
+  if (fstat(fd, &sb) == -1 || (!sb.st_size && !S_ISREG(sb.st_mode))) return kBadSize;
+  return sb.st_size;
+}
+
+FilePiece::FilePiece(const char *name, std::ostream *show_progress, off_t min_buffer) : 
+  file_(OpenReadOrThrow(name)), total_size_(SizeFile(file_.get())), page_(sysconf(_SC_PAGE_SIZE)),
+  progress_(total_size_ == kBadSize ? NULL : show_progress, std::string("Reading ") + name, total_size_) {
+  Initialize(name, show_progress, min_buffer);
+}
+
+FilePiece::FilePiece(const char *name, int fd, std::ostream *show_progress, off_t min_buffer) : 
+  file_(fd), total_size_(SizeFile(file_.get())), page_(sysconf(_SC_PAGE_SIZE)),
+  progress_(total_size_ == kBadSize ? NULL : show_progress, std::string("Reading ") + name, total_size_) {
+  Initialize(name, show_progress, min_buffer);
+}
+
+void FilePiece::Initialize(const char *name, std::ostream *show_progress, off_t min_buffer) {
+  if (total_size_ == kBadSize) {
+    fallback_to_read_ = true;
+    if (show_progress) 
+      *show_progress << "File " << name << " isn't normal.  Using slower read() instead of mmap().  No progress bar." << std::endl;
+  } else {
+    fallback_to_read_ = false;
+  }
+  default_map_size_ = page_ * std::max<off_t>((min_buffer / page_ + 1), 2);
+  position_ = NULL;
+  position_end_ = NULL;
+  mapped_offset_ = 0;
+  at_end_ = false;
+  Shift();
+}
+
+float FilePiece::ReadFloat() throw(EndOfFileException, ParseNumberException) {
+  SkipSpaces();
+  while (last_space_ < position_) {
+    if (at_end_) {
+      // Hallucinate a null off the end of the file.
+      std::string buffer(position_, position_end_);
+      char *end;
+      float ret = std::strtof(buffer.c_str(), &end);
+      if (buffer.c_str() == end) throw ParseNumberException(buffer);
+      position_ += end - buffer.c_str();
+      return ret;
+    }
+    Shift();
+  }
+  char *end;
+  float ret = std::strtof(position_, &end);
+  if (end == position_) throw ParseNumberException(ReadDelimited());
+  position_ = end;
+  return ret;
+}
+
+void FilePiece::SkipSpaces() throw (EndOfFileException) {
+  for (; ; ++position_) {
+    if (position_ == position_end_) Shift();
+    if (!isspace(*position_)) return;
+  }
+}
+
+const char *FilePiece::FindDelimiterOrEOF() throw (EndOfFileException) {
+  for (const char *i = position_; i <= last_space_; ++i) {
+    if (isspace(*i)) return i;
+  }
+  while (!at_end_) {
+    size_t skip = position_end_ - position_;
+    Shift();
+    for (const char *i = position_ + skip; i <= last_space_; ++i) {
+      if (isspace(*i)) return i;
+    }
+  }
+  return position_end_;
+}
+
+StringPiece FilePiece::ReadLine(char delim) throw (EndOfFileException) {
+  const char *start = position_;
+  do {
+    for (const char *i = start; i < position_end_; ++i) {
+      if (*i == delim) {
+        StringPiece ret(position_, i - position_);
+        position_ = i + 1;
+        return ret;
+      }
+    }
+    size_t skip = position_end_ - position_;
+    Shift();
+    start = position_ + skip;
+  } while (!at_end_);
+  StringPiece ret(position_, position_end_ - position_);
+  position_ = position_end_;
+  return position_;
+}
+
+void FilePiece::Shift() throw(EndOfFileException) {
+  if (at_end_) throw EndOfFileException();
+  off_t desired_begin = position_ - data_.begin() + mapped_offset_;
+  progress_.Set(desired_begin);
+
+  if (!fallback_to_read_) MMapShift(desired_begin);
+  // Notice an mmap failure might set the fallback.  
+  if (fallback_to_read_) ReadShift(desired_begin);
+
+  for (last_space_ = position_end_ - 1; last_space_ >= position_; --last_space_) {
+    if (isspace(*last_space_))  break;
+  }
+}
+
+void FilePiece::MMapShift(off_t desired_begin) throw() {
+  // Use mmap.  
+  off_t ignore = desired_begin % page_;
+  // Duplicate request for Shift means give more data.  
+  if (position_ == data_.begin() + ignore) {
+    default_map_size_ *= 2;
+  }
+  // Local version so that in case of failure it doesn't overwrite the class variable.  
+  off_t mapped_offset = desired_begin - ignore;
+
+  off_t mapped_size;
+  if (default_map_size_ >= static_cast<size_t>(total_size_ - mapped_offset)) {
+    at_end_ = true;
+    mapped_size = total_size_ - mapped_offset;
+  } else {
+    mapped_size = default_map_size_;
+  }
+
+  // Forcibly clear the existing mmap first.  
+  data_.reset();
+  data_.reset(mmap(NULL, mapped_size, PROT_READ, MAP_PRIVATE, *file_, mapped_offset), mapped_size, scoped_memory::MMAP_ALLOCATED);
+  if (data_.get() == MAP_FAILED) {
+    fallback_to_read_ = true;
+    if (desired_begin) {
+      if (((off_t)-1) == lseek(*file_, desired_begin, SEEK_SET)) UTIL_THROW(ErrnoException, "mmap failed even though it worked before.  lseek failed too, so using read isn't an option either.");
+    }
+    return;
+  }
+  mapped_offset_ = mapped_offset;
+  position_ = data_.begin() + ignore;
+  position_end_ = data_.begin() + mapped_size;
+}
+
+void FilePiece::ReadShift(off_t desired_begin) throw() {
+  assert(fallback_to_read_);
+  if (data_.source() != scoped_memory::MALLOC_ALLOCATED) {
+    // First call.
+    data_.reset();
+    data_.reset(malloc(default_map_size_), default_map_size_, scoped_memory::MALLOC_ALLOCATED);
+    if (!data_.get()) UTIL_THROW(ErrnoException, "malloc failed for " << default_map_size_);
+    position_ = data_.begin();
+    position_end_ = position_;
+  } 
+  
+  // Bytes [data_.begin(), position_) have been consumed.  
+  // Bytes [position_, position_end_) have been read into the buffer.  
+
+  // Start at the beginning of the buffer if there's nothing useful in it.  
+  if (position_ == position_end_) {
+    mapped_offset_ += (position_end_ - data_.begin());
+    position_ = data_.begin();
+    position_end_ = position_;
+  }
+
+  std::size_t already_read = position_end_ - data_.begin();
+
+  if (already_read == default_map_size_) {
+    if (position_ == data_.begin()) {
+      // Buffer too small.  
+      std::size_t valid_length = position_end_ - position_;
+      default_map_size_ *= 2;
+      data_.call_realloc(default_map_size_);
+      if (!data_.get()) UTIL_THROW(ErrnoException, "realloc failed for " << default_map_size_);
+      position_ = data_.begin();
+      position_end_ = position_ + valid_length;
+    } else {
+      size_t moving = position_end_ - position_;
+      memmove(data_.get(), position_, moving);
+      position_ = data_.begin();
+      position_end_ = position_ + moving;
+      already_read = moving;
+    }
+  }
+
+  ssize_t read_return = read(file_.get(), static_cast<char*>(data_.get()) + already_read, default_map_size_ - already_read);
+  if (read_return == -1) UTIL_THROW(ErrnoException, "read failed");
+  if (read_return == 0) at_end_ = true;
+  position_end_ += read_return;
+}
+
+} // namespace util