- // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file. See the AUTHORS file for names of contributors.
-
- #include <deque>
- #include <dirent.h>
- #include <errno.h>
- #include <fcntl.h>
- #include <pthread.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <sys/mman.h>
- #include <sys/stat.h>
- #include <sys/time.h>
- #include <sys/types.h>
- #include <time.h>
- #include <unistd.h>
- #if defined(LEVELDB_PLATFORM_ANDROID)
- #include <sys/stat.h>
- #endif
- #include "leveldb/env.h"
- #include "leveldb/slice.h"
- #include "port/port.h"
- #include "util/logging.h"
- #include "util/posix_logger.h"
-
- namespace leveldb {
-
- namespace {
-
- static Status IOError(const std::string& context, int err_number) {
- return Status::IOError(context, strerror(err_number));
- }
-
- class PosixSequentialFile: public SequentialFile {
- private:
- std::string filename_;
- FILE* file_;
-
- public:
- PosixSequentialFile(const std::string& fname, FILE* f)
- : filename_(fname), file_(f) { }
- virtual ~PosixSequentialFile() { fclose(file_); }
-
- virtual Status Read(size_t n, Slice* result, char* scratch) {
- Status s;
- size_t r = fread_unlocked(scratch, 1, n, file_);
- *result = Slice(scratch, r);
- if (r < n) {
- if (feof(file_)) {
- // We leave status as ok if we hit the end of the file
- } else {
- // A partial read with an error: return a non-ok status
- s = IOError(filename_, errno);
- }
- }
- return s;
- }
-
- virtual Status Skip(uint64_t n) {
- if (fseek(file_, n, SEEK_CUR)) {
- return IOError(filename_, errno);
- }
- return Status::OK();
- }
- };
-
- // pread() based random-access
- class PosixRandomAccessFile: public RandomAccessFile {
- private:
- std::string filename_;
- int fd_;
-
- public:
- PosixRandomAccessFile(const std::string& fname, int fd)
- : filename_(fname), fd_(fd) { }
- virtual ~PosixRandomAccessFile() { close(fd_); }
-
- virtual Status Read(uint64_t offset, size_t n, Slice* result,
- char* scratch) const {
- Status s;
- ssize_t r = pread(fd_, scratch, n, static_cast<off_t>(offset));
- *result = Slice(scratch, (r < 0) ? 0 : r);
- if (r < 0) {
- // An error: return a non-ok status
- s = IOError(filename_, errno);
- }
- return s;
- }
- };
-
- // mmap() based random-access
- class PosixMmapReadableFile: public RandomAccessFile {
- private:
- std::string filename_;
- void* mmapped_region_;
- size_t length_;
-
- public:
- // base[0,length-1] contains the mmapped contents of the file.
- PosixMmapReadableFile(const std::string& fname, void* base, size_t length)
- : filename_(fname), mmapped_region_(base), length_(length) { }
- virtual ~PosixMmapReadableFile() { munmap(mmapped_region_, length_); }
-
- virtual Status Read(uint64_t offset, size_t n, Slice* result,
- char* scratch) const {
- Status s;
- if (offset + n > length_) {
- *result = Slice();
- s = IOError(filename_, EINVAL);
- } else {
- *result = Slice(reinterpret_cast<char*>(mmapped_region_) + offset, n);
- }
- return s;
- }
- };
-
- // 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 {
- 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;
- }
-
- 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();
- }
- }
-
- 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;
- }
- 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);
- }
- }
-
- fd_ = -1;
- base_ = NULL;
- limit_ = NULL;
- return s;
- }
-
- virtual Status Flush() {
- return Status::OK();
- }
-
- virtual Status Sync() {
- Status s;
-
- if (pending_sync_) {
- // Some unmapped data was not synced
- pending_sync_ = false;
- if (fdatasync(fd_) < 0) {
- s = IOError(filename_, 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;
- }
- };
-
- static int LockOrUnlock(int fd, bool lock) {
- errno = 0;
- struct flock f;
- memset(&f, 0, sizeof(f));
- f.l_type = (lock ? F_WRLCK : F_UNLCK);
- f.l_whence = SEEK_SET;
- f.l_start = 0;
- f.l_len = 0; // Lock/unlock entire file
- return fcntl(fd, F_SETLK, &f);
- }
-
- class PosixFileLock : public FileLock {
- public:
- int fd_;
- };
-
- class PosixEnv : public Env {
- public:
- PosixEnv();
- virtual ~PosixEnv() {
- fprintf(stderr, "Destroying Env::Default()\n");
- exit(1);
- }
-
- virtual Status NewSequentialFile(const std::string& fname,
- SequentialFile** result) {
- FILE* f = fopen(fname.c_str(), "r");
- if (f == NULL) {
- *result = NULL;
- return IOError(fname, errno);
- } else {
- *result = new PosixSequentialFile(fname, f);
- return Status::OK();
- }
- }
-
- virtual Status NewRandomAccessFile(const std::string& fname,
- RandomAccessFile** result) {
- *result = NULL;
- Status s;
- int fd = open(fname.c_str(), O_RDONLY);
- if (fd < 0) {
- s = IOError(fname, errno);
- } else if (sizeof(void*) >= 8) {
- // Use mmap when virtual address-space is plentiful.
- uint64_t size;
- s = GetFileSize(fname, &size);
- if (s.ok()) {
- void* base = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
- if (base != MAP_FAILED) {
- *result = new PosixMmapReadableFile(fname, base, size);
- } else {
- s = IOError(fname, errno);
- }
- }
- close(fd);
- } else {
- *result = new PosixRandomAccessFile(fname, fd);
- }
- return s;
- }
-
- 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) {
- *result = NULL;
- s = IOError(fname, errno);
- } else {
- *result = new PosixMmapFile(fname, fd, page_size_);
- }
- return s;
- }
-
- virtual bool FileExists(const std::string& fname) {
- return access(fname.c_str(), F_OK) == 0;
- }
-
- virtual Status GetChildren(const std::string& dir,
- std::vector<std::string>* result) {
- result->clear();
- DIR* d = opendir(dir.c_str());
- if (d == NULL) {
- return IOError(dir, errno);
- }
- struct dirent* entry;
- while ((entry = readdir(d)) != NULL) {
- result->push_back(entry->d_name);
- }
- closedir(d);
- return Status::OK();
- }
-
- virtual Status DeleteFile(const std::string& fname) {
- Status result;
- if (unlink(fname.c_str()) != 0) {
- result = IOError(fname, errno);
- }
- return result;
- };
-
- virtual Status CreateDir(const std::string& name) {
- Status result;
- if (mkdir(name.c_str(), 0755) != 0) {
- result = IOError(name, errno);
- }
- return result;
- };
-
- virtual Status DeleteDir(const std::string& name) {
- Status result;
- if (rmdir(name.c_str()) != 0) {
- result = IOError(name, errno);
- }
- return result;
- };
-
- virtual Status GetFileSize(const std::string& fname, uint64_t* size) {
- Status s;
- struct stat sbuf;
- if (stat(fname.c_str(), &sbuf) != 0) {
- *size = 0;
- s = IOError(fname, errno);
- } else {
- *size = sbuf.st_size;
- }
- return s;
- }
-
- virtual Status RenameFile(const std::string& src, const std::string& target) {
- Status result;
- if (rename(src.c_str(), target.c_str()) != 0) {
- result = IOError(src, errno);
- }
- return result;
- }
-
- virtual Status LockFile(const std::string& fname, FileLock** lock) {
- *lock = NULL;
- Status result;
- int fd = open(fname.c_str(), O_RDWR | O_CREAT, 0644);
- if (fd < 0) {
- result = IOError(fname, errno);
- } else if (LockOrUnlock(fd, true) == -1) {
- result = IOError("lock " + fname, errno);
- close(fd);
- } else {
- PosixFileLock* my_lock = new PosixFileLock;
- my_lock->fd_ = fd;
- *lock = my_lock;
- }
- return result;
- }
-
- virtual Status UnlockFile(FileLock* lock) {
- PosixFileLock* my_lock = reinterpret_cast<PosixFileLock*>(lock);
- Status result;
- if (LockOrUnlock(my_lock->fd_, false) == -1) {
- result = IOError("unlock", errno);
- }
- close(my_lock->fd_);
- delete my_lock;
- return result;
- }
-
- virtual void Schedule(void (*function)(void*), void* arg);
-
- virtual void StartThread(void (*function)(void* arg), void* arg);
-
- virtual Status GetTestDirectory(std::string* result) {
- const char* env = getenv("TEST_TMPDIR");
- if (env && env[0] != '\0') {
- *result = env;
- } else {
- char buf[100];
- snprintf(buf, sizeof(buf), "/tmp/leveldbtest-%d", int(geteuid()));
- *result = buf;
- }
- // Directory may already exist
- CreateDir(*result);
- return Status::OK();
- }
-
- static uint64_t gettid() {
- pthread_t tid = pthread_self();
- uint64_t thread_id = 0;
- memcpy(&thread_id, &tid, std::min(sizeof(thread_id), sizeof(tid)));
- return thread_id;
- }
-
- virtual Status NewLogger(const std::string& fname, Logger** result) {
- FILE* f = fopen(fname.c_str(), "w");
- if (f == NULL) {
- *result = NULL;
- return IOError(fname, errno);
- } else {
- *result = new PosixLogger(f, &PosixEnv::gettid);
- return Status::OK();
- }
- }
-
- virtual uint64_t NowMicros() {
- struct timeval tv;
- gettimeofday(&tv, NULL);
- return static_cast<uint64_t>(tv.tv_sec) * 1000000 + tv.tv_usec;
- }
-
- virtual void SleepForMicroseconds(int micros) {
- usleep(micros);
- }
-
- private:
- void PthreadCall(const char* label, int result) {
- if (result != 0) {
- fprintf(stderr, "pthread %s: %s\n", label, strerror(result));
- exit(1);
- }
- }
-
- // BGThread() is the body of the background thread
- void BGThread();
- static void* BGThreadWrapper(void* arg) {
- reinterpret_cast<PosixEnv*>(arg)->BGThread();
- return NULL;
- }
-
- size_t page_size_;
- pthread_mutex_t mu_;
- pthread_cond_t bgsignal_;
- pthread_t bgthread_;
- bool started_bgthread_;
-
- // Entry per Schedule() call
- struct BGItem { void* arg; void (*function)(void*); };
- typedef std::deque<BGItem> BGQueue;
- BGQueue queue_;
- };
-
- PosixEnv::PosixEnv() : page_size_(getpagesize()),
- started_bgthread_(false) {
- PthreadCall("mutex_init", pthread_mutex_init(&mu_, NULL));
- PthreadCall("cvar_init", pthread_cond_init(&bgsignal_, NULL));
- }
-
- void PosixEnv::Schedule(void (*function)(void*), void* arg) {
- PthreadCall("lock", pthread_mutex_lock(&mu_));
-
- // Start background thread if necessary
- if (!started_bgthread_) {
- started_bgthread_ = true;
- PthreadCall(
- "create thread",
- pthread_create(&bgthread_, NULL, &PosixEnv::BGThreadWrapper, this));
- }
-
- // If the queue is currently empty, the background thread may currently be
- // waiting.
- if (queue_.empty()) {
- PthreadCall("signal", pthread_cond_signal(&bgsignal_));
- }
-
- // Add to priority queue
- queue_.push_back(BGItem());
- queue_.back().function = function;
- queue_.back().arg = arg;
-
- PthreadCall("unlock", pthread_mutex_unlock(&mu_));
- }
-
- void PosixEnv::BGThread() {
- while (true) {
- // Wait until there is an item that is ready to run
- PthreadCall("lock", pthread_mutex_lock(&mu_));
- while (queue_.empty()) {
- PthreadCall("wait", pthread_cond_wait(&bgsignal_, &mu_));
- }
-
- void (*function)(void*) = queue_.front().function;
- void* arg = queue_.front().arg;
- queue_.pop_front();
-
- PthreadCall("unlock", pthread_mutex_unlock(&mu_));
- (*function)(arg);
- }
- }
-
- namespace {
- struct StartThreadState {
- void (*user_function)(void*);
- void* arg;
- };
- }
- static void* StartThreadWrapper(void* arg) {
- StartThreadState* state = reinterpret_cast<StartThreadState*>(arg);
- state->user_function(state->arg);
- delete state;
- return NULL;
- }
-
- void PosixEnv::StartThread(void (*function)(void* arg), void* arg) {
- pthread_t t;
- StartThreadState* state = new StartThreadState;
- state->user_function = function;
- state->arg = arg;
- PthreadCall("start thread",
- pthread_create(&t, NULL, &StartThreadWrapper, state));
- }
-
- } // namespace
-
- static pthread_once_t once = PTHREAD_ONCE_INIT;
- static Env* default_env;
- static void InitDefaultEnv() { default_env = new PosixEnv; }
-
- Env* Env::Default() {
- pthread_once(&once, InitDefaultEnv);
- return default_env;
- }
-
- } // namespace leveldb
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