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-rw-r--r--util/env_posix.cc698
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diff --git a/util/env_posix.cc b/util/env_posix.cc
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+// 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 <set>
+#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/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<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;
+ }
+};
+
+// 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<intptr_t>(allowed_.Acquire_Load());
+ }
+
+ // REQUIRES: mu_ must be held
+ void SetAllowed(intptr_t v) {
+ allowed_.Release_Store(reinterpret_cast<void*>(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<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_;
+ 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() {
+ fprintf(stderr, "Destroying Env::Default()\n");
+ 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);
+ }
+ 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 (!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;
+ }
+
+ 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_;
+
+ 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<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
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-12 22:38:34 +0000