diff options
Diffstat (limited to 'util/env_posix.cc')
| -rw-r--r-- | util/env_posix.cc | 176 |
1 files changed, 27 insertions, 149 deletions
diff --git a/util/env_posix.cc b/util/env_posix.cc index 3e2925d..e1cbebd 100644 --- a/util/env_posix.cc +++ b/util/env_posix.cc @@ -175,147 +175,43 @@ class PosixMmapReadableFile: public RandomAccessFile { } }; -// We preallocate up to an extra megabyte and use memcpy to append new -// data to the file. This is safe since we either properly close the -// file before reading from it, or for log files, the reading code -// knows enough to skip zero suffixes. -class PosixMmapFile : public WritableFile { +class PosixWritableFile : public WritableFile { private: std::string filename_; - int fd_; - size_t page_size_; - size_t map_size_; // How much extra memory to map at a time - char* base_; // The mapped region - char* limit_; // Limit of the mapped region - char* dst_; // Where to write next (in range [base_,limit_]) - char* last_sync_; // Where have we synced up to - uint64_t file_offset_; // Offset of base_ in file - - // Have we done an munmap of unsynced data? - bool pending_sync_; - - // Roundup x to a multiple of y - static size_t Roundup(size_t x, size_t y) { - return ((x + y - 1) / y) * y; - } - - size_t TruncateToPageBoundary(size_t s) { - s -= (s & (page_size_ - 1)); - assert((s % page_size_) == 0); - return s; - } - - bool UnmapCurrentRegion() { - bool result = true; - if (base_ != NULL) { - if (last_sync_ < limit_) { - // Defer syncing this data until next Sync() call, if any - pending_sync_ = true; - } - if (munmap(base_, limit_ - base_) != 0) { - result = false; - } - file_offset_ += limit_ - base_; - base_ = NULL; - limit_ = NULL; - last_sync_ = NULL; - dst_ = NULL; - - // Increase the amount we map the next time, but capped at 1MB - if (map_size_ < (1<<20)) { - map_size_ *= 2; - } - } - return result; - } - - bool MapNewRegion() { - assert(base_ == NULL); - if (ftruncate(fd_, file_offset_ + map_size_) < 0) { - return false; - } - void* ptr = mmap(NULL, map_size_, PROT_READ | PROT_WRITE, MAP_SHARED, - fd_, file_offset_); - if (ptr == MAP_FAILED) { - return false; - } - base_ = reinterpret_cast<char*>(ptr); - limit_ = base_ + map_size_; - dst_ = base_; - last_sync_ = base_; - return true; - } + FILE* file_; public: - PosixMmapFile(const std::string& fname, int fd, size_t page_size) - : filename_(fname), - fd_(fd), - page_size_(page_size), - map_size_(Roundup(65536, page_size)), - base_(NULL), - limit_(NULL), - dst_(NULL), - last_sync_(NULL), - file_offset_(0), - pending_sync_(false) { - assert((page_size & (page_size - 1)) == 0); - } - - - ~PosixMmapFile() { - if (fd_ >= 0) { - PosixMmapFile::Close(); + PosixWritableFile(const std::string& fname, FILE* f) + : filename_(fname), file_(f) { } + + ~PosixWritableFile() { + if (file_ != NULL) { + // Ignoring any potential errors + fclose(file_); } } virtual Status Append(const Slice& data) { - const char* src = data.data(); - size_t left = data.size(); - while (left > 0) { - assert(base_ <= dst_); - assert(dst_ <= limit_); - size_t avail = limit_ - dst_; - if (avail == 0) { - if (!UnmapCurrentRegion() || - !MapNewRegion()) { - return IOError(filename_, errno); - } - } - - size_t n = (left <= avail) ? left : avail; - memcpy(dst_, src, n); - dst_ += n; - src += n; - left -= n; + size_t r = fwrite_unlocked(data.data(), 1, data.size(), file_); + if (r != data.size()) { + return IOError(filename_, errno); } return Status::OK(); } virtual Status Close() { - Status s; - size_t unused = limit_ - dst_; - if (!UnmapCurrentRegion()) { - s = IOError(filename_, errno); - } else if (unused > 0) { - // Trim the extra space at the end of the file - if (ftruncate(fd_, file_offset_ - unused) < 0) { - s = IOError(filename_, errno); - } - } - - if (close(fd_) < 0) { - if (s.ok()) { - s = IOError(filename_, errno); - } + Status result; + if (fclose(file_) != 0) { + result = IOError(filename_, errno); } - - fd_ = -1; - base_ = NULL; - limit_ = NULL; - return s; + file_ = NULL; + return result; } virtual Status Flush() { + if (fflush_unlocked(file_) != 0) { + return IOError(filename_, errno); + } return Status::OK(); } @@ -352,26 +248,10 @@ class PosixMmapFile : public WritableFile { if (!s.ok()) { return s; } - - if (pending_sync_) { - // Some unmapped data was not synced - pending_sync_ = false; - if (fdatasync(fd_) < 0) { - s = IOError(filename_, errno); - } + if (fflush_unlocked(file_) != 0 || + fdatasync(fileno(file_)) != 0) { + s = Status::IOError(filename_, strerror(errno)); } - - if (dst_ > last_sync_) { - // Find the beginnings of the pages that contain the first and last - // bytes to be synced. - size_t p1 = TruncateToPageBoundary(last_sync_ - base_); - size_t p2 = TruncateToPageBoundary(dst_ - base_ - 1); - last_sync_ = dst_; - if (msync(base_ + p1, p2 - p1 + page_size_, MS_SYNC) < 0) { - s = IOError(filename_, errno); - } - } - return s; } }; @@ -462,12 +342,12 @@ class PosixEnv : public Env { virtual Status NewWritableFile(const std::string& fname, WritableFile** result) { Status s; - const int fd = open(fname.c_str(), O_CREAT | O_RDWR | O_TRUNC, 0644); - if (fd < 0) { + FILE* f = fopen(fname.c_str(), "w"); + if (f == NULL) { *result = NULL; s = IOError(fname, errno); } else { - *result = new PosixMmapFile(fname, fd, page_size_); + *result = new PosixWritableFile(fname, f); } return s; } @@ -630,7 +510,6 @@ class PosixEnv : public Env { return NULL; } - size_t page_size_; pthread_mutex_t mu_; pthread_cond_t bgsignal_; pthread_t bgthread_; @@ -645,8 +524,7 @@ class PosixEnv : public Env { MmapLimiter mmap_limit_; }; -PosixEnv::PosixEnv() : page_size_(getpagesize()), - started_bgthread_(false) { +PosixEnv::PosixEnv() : started_bgthread_(false) { PthreadCall("mutex_init", pthread_mutex_init(&mu_, NULL)); PthreadCall("cvar_init", pthread_cond_init(&bgsignal_, NULL)); } |