From 58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9 Mon Sep 17 00:00:00 2001 From: Ilya Zhuravlev Date: Tue, 23 Oct 2012 01:18:44 +0400 Subject: Add dummy and LevelDB database backends --- src/leveldb/util/env_posix.cc | 698 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 698 insertions(+) create mode 100644 src/leveldb/util/env_posix.cc (limited to 'src/leveldb/util/env_posix.cc') diff --git a/src/leveldb/util/env_posix.cc b/src/leveldb/util/env_posix.cc new file mode 100644 index 000000000..78e09c95c --- /dev/null +++ b/src/leveldb/util/env_posix.cc @@ -0,0 +1,698 @@ +// 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#if defined(LEVELDB_PLATFORM_ANDROID) +#include +#endif +#include "leveldb/env.h" +#include "leveldb/slice.h" +#include "port/port.h" +#include "util/logging.h" +#include "util/mutexlock.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(offset)); + *result = Slice(scratch, (r < 0) ? 0 : r); + if (r < 0) { + // An error: return a non-ok status + s = IOError(filename_, errno); + } + return s; + } +}; + +// Helper class to limit mmap file usage so that we do not end up +// running out virtual memory or running into kernel performance +// problems for very large databases. +class MmapLimiter { + public: + // Up to 1000 mmaps for 64-bit binaries; none for smaller pointer sizes. + MmapLimiter() { + SetAllowed(sizeof(void*) >= 8 ? 1000 : 0); + } + + // If another mmap slot is available, acquire it and return true. + // Else return false. + bool Acquire() { + if (GetAllowed() <= 0) { + return false; + } + MutexLock l(&mu_); + intptr_t x = GetAllowed(); + if (x <= 0) { + return false; + } else { + SetAllowed(x - 1); + return true; + } + } + + // Release a slot acquired by a previous call to Acquire() that returned true. + void Release() { + MutexLock l(&mu_); + SetAllowed(GetAllowed() + 1); + } + + private: + port::Mutex mu_; + port::AtomicPointer allowed_; + + intptr_t GetAllowed() const { + return reinterpret_cast(allowed_.Acquire_Load()); + } + + // REQUIRES: mu_ must be held + void SetAllowed(intptr_t v) { + allowed_.Release_Store(reinterpret_cast(v)); + } + + MmapLimiter(const MmapLimiter&); + void operator=(const MmapLimiter&); +}; + +// mmap() based random-access +class PosixMmapReadableFile: public RandomAccessFile { + private: + std::string filename_; + void* mmapped_region_; + size_t length_; + MmapLimiter* limiter_; + + public: + // base[0,length-1] contains the mmapped contents of the file. + PosixMmapReadableFile(const std::string& fname, void* base, size_t length, + MmapLimiter* limiter) + : filename_(fname), mmapped_region_(base), length_(length), + limiter_(limiter) { + } + + virtual ~PosixMmapReadableFile() { + munmap(mmapped_region_, length_); + limiter_->Release(); + } + + 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(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(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_; + std::string name_; +}; + +// Set of locked files. We keep a separate set instead of just +// relying on fcntrl(F_SETLK) since fcntl(F_SETLK) does not provide +// any protection against multiple uses from the same process. +class PosixLockTable { + private: + port::Mutex mu_; + std::set locked_files_; + public: + bool Insert(const std::string& fname) { + MutexLock l(&mu_); + return locked_files_.insert(fname).second; + } + void Remove(const std::string& fname) { + MutexLock l(&mu_); + locked_files_.erase(fname); + } +}; + +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 (mmap_limit_.Acquire()) { + 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, &mmap_limit_); + } else { + s = IOError(fname, errno); + } + } + close(fd); + if (!s.ok()) { + mmap_limit_.Release(); + } + } 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* 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 (!locks_.Insert(fname)) { + close(fd); + result = Status::IOError("lock " + fname, "already held by process"); + } else if (LockOrUnlock(fd, true) == -1) { + result = IOError("lock " + fname, errno); + close(fd); + locks_.Remove(fname); + } else { + PosixFileLock* my_lock = new PosixFileLock; + my_lock->fd_ = fd; + my_lock->name_ = fname; + *lock = my_lock; + } + return result; + } + + virtual Status UnlockFile(FileLock* lock) { + PosixFileLock* my_lock = reinterpret_cast(lock); + Status result; + if (LockOrUnlock(my_lock->fd_, false) == -1) { + result = IOError("unlock", errno); + } + locks_.Remove(my_lock->name_); + 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(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(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 BGQueue; + BGQueue queue_; + + PosixLockTable locks_; + MmapLimiter mmap_limit_; +}; + +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(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 -- cgit v1.2.3