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Diffstat (limited to 'src/leveldb/util/env_posix.cc')
-rw-r--r-- | src/leveldb/util/env_posix.cc | 706 |
1 files changed, 706 insertions, 0 deletions
diff --git a/src/leveldb/util/env_posix.cc b/src/leveldb/util/env_posix.cc new file mode 100644 index 0000000000..4676bc2240 --- /dev/null +++ b/src/leveldb/util/env_posix.cc @@ -0,0 +1,706 @@ +// 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. +#if !defined(LEVELDB_PLATFORM_WINDOWS) + +#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/resource.h> +#include <sys/stat.h> +#include <sys/time.h> +#include <sys/types.h> +#include <time.h> +#include <unistd.h> +#include <deque> +#include <limits> +#include <set> +#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" +#include "util/env_posix_test_helper.h" + +namespace leveldb { + +namespace { + +static int open_read_only_file_limit = -1; +static int mmap_limit = -1; + +static Status IOError(const std::string& context, int err_number) { + return Status::IOError(context, strerror(err_number)); +} + +// Helper class to limit resource usage to avoid exhaustion. +// Currently used to limit read-only file descriptors and mmap file usage +// so that we do not end up running out of file descriptors, virtual memory, +// or running into kernel performance problems for very large databases. +class Limiter { + public: + // Limit maximum number of resources to |n|. + Limiter(intptr_t n) { + SetAllowed(n); + } + + // If another resource 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 resource 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<intptr_t>(allowed_.Acquire_Load()); + } + + // REQUIRES: mu_ must be held + void SetAllowed(intptr_t v) { + allowed_.Release_Store(reinterpret_cast<void*>(v)); + } + + Limiter(const Limiter&); + void operator=(const Limiter&); +}; + +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(); + } + + virtual std::string GetName() const { return filename_; } +}; + +// pread() based random-access +class PosixRandomAccessFile: public RandomAccessFile { + private: + std::string filename_; + bool temporary_fd_; // If true, fd_ is -1 and we open on every read. + int fd_; + Limiter* limiter_; + + public: + PosixRandomAccessFile(const std::string& fname, int fd, Limiter* limiter) + : filename_(fname), fd_(fd), limiter_(limiter) { + temporary_fd_ = !limiter->Acquire(); + if (temporary_fd_) { + // Open file on every access. + close(fd_); + fd_ = -1; + } + } + + virtual ~PosixRandomAccessFile() { + if (!temporary_fd_) { + close(fd_); + limiter_->Release(); + } + } + + virtual Status Read(uint64_t offset, size_t n, Slice* result, + char* scratch) const { + int fd = fd_; + if (temporary_fd_) { + fd = open(filename_.c_str(), O_RDONLY); + if (fd < 0) { + return IOError(filename_, errno); + } + } + + 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); + } + if (temporary_fd_) { + // Close the temporary file descriptor opened earlier. + close(fd); + } + return s; + } + + virtual std::string GetName() const { return filename_; } +}; + +// mmap() based random-access +class PosixMmapReadableFile: public RandomAccessFile { + private: + std::string filename_; + void* mmapped_region_; + size_t length_; + Limiter* limiter_; + + public: + // base[0,length-1] contains the mmapped contents of the file. + PosixMmapReadableFile(const std::string& fname, void* base, size_t length, + Limiter* 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<char*>(mmapped_region_) + offset, n); + } + return s; + } + + virtual std::string GetName() const { return filename_; } +}; + +class PosixWritableFile : public WritableFile { + private: + std::string filename_; + FILE* file_; + + public: + 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) { + 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 result; + if (fclose(file_) != 0) { + result = IOError(filename_, errno); + } + file_ = NULL; + return result; + } + + virtual Status Flush() { + if (fflush_unlocked(file_) != 0) { + return IOError(filename_, errno); + } + return Status::OK(); + } + + Status SyncDirIfManifest() { + const char* f = filename_.c_str(); + const char* sep = strrchr(f, '/'); + Slice basename; + std::string dir; + if (sep == NULL) { + dir = "."; + basename = f; + } else { + dir = std::string(f, sep - f); + basename = sep + 1; + } + Status s; + if (basename.starts_with("MANIFEST")) { + int fd = open(dir.c_str(), O_RDONLY); + if (fd < 0) { + s = IOError(dir, errno); + } else { + if (fsync(fd) < 0 && errno != EINVAL) { + s = IOError(dir, errno); + } + close(fd); + } + } + return s; + } + + virtual Status Sync() { + // Ensure new files referred to by the manifest are in the filesystem. + Status s = SyncDirIfManifest(); + if (!s.ok()) { + return s; + } + if (fflush_unlocked(file_) != 0 || + fdatasync(fileno(file_)) != 0) { + s = Status::IOError(filename_, strerror(errno)); + } + return s; + } + + virtual std::string GetName() const { return filename_; } +}; + +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<std::string> 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() { + char msg[] = "Destroying Env::Default()\n"; + fwrite(msg, 1, sizeof(msg), stderr); + abort(); + } + + 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, &fd_limit_); + } + return s; + } + + virtual Status NewWritableFile(const std::string& fname, + WritableFile** result) { + Status s; + FILE* f = fopen(fname.c_str(), "w"); + if (f == NULL) { + *result = NULL; + s = IOError(fname, errno); + } else { + *result = new PosixWritableFile(fname, f); + } + return s; + } + + virtual Status NewAppendableFile(const std::string& fname, + WritableFile** result) { + Status s; + FILE* f = fopen(fname.c_str(), "a"); + if (f == NULL) { + *result = NULL; + s = IOError(fname, errno); + } else { + *result = new PosixWritableFile(fname, f); + } + 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 (!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<PosixFileLock*>(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<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)); + abort(); + } + } + + // BGThread() is the body of the background thread + void BGThread(); + static void* BGThreadWrapper(void* arg) { + reinterpret_cast<PosixEnv*>(arg)->BGThread(); + return NULL; + } + + 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_; + + PosixLockTable locks_; + Limiter mmap_limit_; + Limiter fd_limit_; +}; + +// Return the maximum number of concurrent mmaps. +static int MaxMmaps() { + if (mmap_limit >= 0) { + return mmap_limit; + } + // Up to 1000 mmaps for 64-bit binaries; none for smaller pointer sizes. + mmap_limit = sizeof(void*) >= 8 ? 1000 : 0; + return mmap_limit; +} + +// Return the maximum number of read-only files to keep open. +static intptr_t MaxOpenFiles() { + if (open_read_only_file_limit >= 0) { + return open_read_only_file_limit; + } + struct rlimit rlim; + if (getrlimit(RLIMIT_NOFILE, &rlim)) { + // getrlimit failed, fallback to hard-coded default. + open_read_only_file_limit = 50; + } else if (rlim.rlim_cur == RLIM_INFINITY) { + open_read_only_file_limit = std::numeric_limits<int>::max(); + } else { + // Allow use of 20% of available file descriptors for read-only files. + open_read_only_file_limit = rlim.rlim_cur / 5; + } + return open_read_only_file_limit; +} + +PosixEnv::PosixEnv() + : started_bgthread_(false), + mmap_limit_(MaxMmaps()), + fd_limit_(MaxOpenFiles()) { + 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; } + +void EnvPosixTestHelper::SetReadOnlyFDLimit(int limit) { + assert(default_env == NULL); + open_read_only_file_limit = limit; +} + +void EnvPosixTestHelper::SetReadOnlyMMapLimit(int limit) { + assert(default_env == NULL); + mmap_limit = limit; +} + +Env* Env::Default() { + pthread_once(&once, InitDefaultEnv); + return default_env; +} + +} // namespace leveldb + +#endif |