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605 rader
15 KiB
605 rader
15 KiB
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <time.h>
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#include <unistd.h>
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#include <deque>
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#include <set>
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#include "leveldb/env.h"
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#include "leveldb/slice.h"
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#include "port/port.h"
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#include "util/logging.h"
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#include "util/mutexlock.h"
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#include "util/posix_logger.h"
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namespace leveldb {
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namespace {
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static Status IOError(const std::string& context, int err_number) {
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return Status::IOError(context, strerror(err_number));
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}
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class PosixSequentialFile: public SequentialFile {
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private:
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std::string filename_;
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FILE* file_;
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public:
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PosixSequentialFile(const std::string& fname, FILE* f)
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: filename_(fname), file_(f) { }
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virtual ~PosixSequentialFile() { fclose(file_); }
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virtual Status Read(size_t n, Slice* result, char* scratch) {
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Status s;
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size_t r = fread_unlocked(scratch, 1, n, file_);
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*result = Slice(scratch, r);
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if (r < n) {
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if (feof(file_)) {
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// We leave status as ok if we hit the end of the file
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} else {
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// A partial read with an error: return a non-ok status
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s = IOError(filename_, errno);
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}
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}
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return s;
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}
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virtual Status Skip(uint64_t n) {
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if (fseek(file_, n, SEEK_CUR)) {
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return IOError(filename_, errno);
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}
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return Status::OK();
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}
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};
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// pread() based random-access
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class PosixRandomAccessFile: public RandomAccessFile {
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private:
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std::string filename_;
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int fd_;
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public:
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PosixRandomAccessFile(const std::string& fname, int fd)
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: filename_(fname), fd_(fd) { }
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virtual ~PosixRandomAccessFile() { close(fd_); }
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virtual Status Read(uint64_t offset, size_t n, Slice* result,
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char* scratch) const {
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Status s;
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ssize_t r = pread(fd_, scratch, n, static_cast<off_t>(offset));
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*result = Slice(scratch, (r < 0) ? 0 : r);
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if (r < 0) {
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// An error: return a non-ok status
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s = IOError(filename_, errno);
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}
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return s;
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}
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};
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// Helper class to limit mmap file usage so that we do not end up
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// running out virtual memory or running into kernel performance
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// problems for very large databases.
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class MmapLimiter {
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public:
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// Up to 1000 mmaps for 64-bit binaries; none for smaller pointer sizes.
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MmapLimiter() {
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SetAllowed(sizeof(void*) >= 8 ? 1000 : 0);
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}
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// If another mmap slot is available, acquire it and return true.
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// Else return false.
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bool Acquire() {
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if (GetAllowed() <= 0) {
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return false;
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}
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MutexLock l(&mu_);
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intptr_t x = GetAllowed();
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if (x <= 0) {
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return false;
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} else {
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SetAllowed(x - 1);
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return true;
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}
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}
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// Release a slot acquired by a previous call to Acquire() that returned true.
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void Release() {
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MutexLock l(&mu_);
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SetAllowed(GetAllowed() + 1);
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}
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private:
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port::Mutex mu_;
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port::AtomicPointer allowed_;
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intptr_t GetAllowed() const {
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return reinterpret_cast<intptr_t>(allowed_.Acquire_Load());
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}
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// REQUIRES: mu_ must be held
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void SetAllowed(intptr_t v) {
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allowed_.Release_Store(reinterpret_cast<void*>(v));
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}
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MmapLimiter(const MmapLimiter&);
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void operator=(const MmapLimiter&);
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};
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// mmap() based random-access
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class PosixMmapReadableFile: public RandomAccessFile {
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private:
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std::string filename_;
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void* mmapped_region_;
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size_t length_;
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MmapLimiter* limiter_;
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public:
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// base[0,length-1] contains the mmapped contents of the file.
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PosixMmapReadableFile(const std::string& fname, void* base, size_t length,
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MmapLimiter* limiter)
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: filename_(fname), mmapped_region_(base), length_(length),
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limiter_(limiter) {
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}
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virtual ~PosixMmapReadableFile() {
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munmap(mmapped_region_, length_);
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limiter_->Release();
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}
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virtual Status Read(uint64_t offset, size_t n, Slice* result,
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char* scratch) const {
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Status s;
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if (offset + n > length_) {
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*result = Slice();
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s = IOError(filename_, EINVAL);
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} else {
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*result = Slice(reinterpret_cast<char*>(mmapped_region_) + offset, n);
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}
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return s;
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}
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};
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class PosixWritableFile : public WritableFile {
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private:
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std::string filename_;
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FILE* file_;
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public:
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PosixWritableFile(const std::string& fname, FILE* f)
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: filename_(fname), file_(f) { }
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~PosixWritableFile() {
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if (file_ != NULL) {
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// Ignoring any potential errors
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fclose(file_);
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}
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}
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virtual Status Append(const Slice& data) {
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size_t r = fwrite_unlocked(data.data(), 1, data.size(), file_);
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if (r != data.size()) {
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return IOError(filename_, errno);
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}
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return Status::OK();
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}
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virtual Status Close() {
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Status result;
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if (fclose(file_) != 0) {
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result = IOError(filename_, errno);
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}
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file_ = NULL;
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return result;
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}
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virtual Status Flush() {
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if (fflush_unlocked(file_) != 0) {
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return IOError(filename_, errno);
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}
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return Status::OK();
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}
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Status SyncDirIfManifest() {
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const char* f = filename_.c_str();
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const char* sep = strrchr(f, '/');
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Slice basename;
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std::string dir;
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if (sep == NULL) {
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dir = ".";
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basename = f;
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} else {
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dir = std::string(f, sep - f);
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basename = sep + 1;
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}
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Status s;
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if (basename.starts_with("MANIFEST")) {
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int fd = open(dir.c_str(), O_RDONLY);
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if (fd < 0) {
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s = IOError(dir, errno);
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} else {
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if (fsync(fd) < 0) {
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s = IOError(dir, errno);
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}
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close(fd);
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}
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}
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return s;
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}
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virtual Status Sync() {
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// Ensure new files referred to by the manifest are in the filesystem.
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Status s = SyncDirIfManifest();
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if (!s.ok()) {
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return s;
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}
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if (fflush_unlocked(file_) != 0 ||
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fdatasync(fileno(file_)) != 0) {
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s = Status::IOError(filename_, strerror(errno));
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}
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return s;
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}
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};
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static int LockOrUnlock(int fd, bool lock) {
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errno = 0;
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struct flock f;
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memset(&f, 0, sizeof(f));
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f.l_type = (lock ? F_WRLCK : F_UNLCK);
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f.l_whence = SEEK_SET;
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f.l_start = 0;
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f.l_len = 0; // Lock/unlock entire file
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return fcntl(fd, F_SETLK, &f);
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}
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class PosixFileLock : public FileLock {
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public:
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int fd_;
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std::string name_;
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};
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// Set of locked files. We keep a separate set instead of just
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// relying on fcntrl(F_SETLK) since fcntl(F_SETLK) does not provide
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// any protection against multiple uses from the same process.
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class PosixLockTable {
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private:
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port::Mutex mu_;
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std::set<std::string> locked_files_;
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public:
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bool Insert(const std::string& fname) {
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MutexLock l(&mu_);
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return locked_files_.insert(fname).second;
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}
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void Remove(const std::string& fname) {
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MutexLock l(&mu_);
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locked_files_.erase(fname);
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}
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};
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class PosixEnv : public Env {
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public:
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PosixEnv();
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virtual ~PosixEnv() {
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char msg[] = "Destroying Env::Default()\n";
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fwrite(msg, 1, sizeof(msg), stderr);
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abort();
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}
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virtual Status NewSequentialFile(const std::string& fname,
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SequentialFile** result) {
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FILE* f = fopen(fname.c_str(), "r");
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if (f == NULL) {
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*result = NULL;
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return IOError(fname, errno);
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} else {
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*result = new PosixSequentialFile(fname, f);
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return Status::OK();
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}
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}
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virtual Status NewRandomAccessFile(const std::string& fname,
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RandomAccessFile** result) {
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*result = NULL;
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Status s;
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int fd = open(fname.c_str(), O_RDONLY);
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if (fd < 0) {
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s = IOError(fname, errno);
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} else if (mmap_limit_.Acquire()) {
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uint64_t size;
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s = GetFileSize(fname, &size);
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if (s.ok()) {
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void* base = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
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if (base != MAP_FAILED) {
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*result = new PosixMmapReadableFile(fname, base, size, &mmap_limit_);
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} else {
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s = IOError(fname, errno);
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}
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}
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close(fd);
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if (!s.ok()) {
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mmap_limit_.Release();
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}
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} else {
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*result = new PosixRandomAccessFile(fname, fd);
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}
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return s;
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}
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virtual Status NewWritableFile(const std::string& fname,
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WritableFile** result) {
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Status s;
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FILE* f = fopen(fname.c_str(), "w");
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if (f == NULL) {
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*result = NULL;
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s = IOError(fname, errno);
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} else {
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*result = new PosixWritableFile(fname, f);
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}
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return s;
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}
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virtual bool FileExists(const std::string& fname) {
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return access(fname.c_str(), F_OK) == 0;
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}
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virtual Status GetChildren(const std::string& dir,
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std::vector<std::string>* result) {
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result->clear();
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DIR* d = opendir(dir.c_str());
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if (d == NULL) {
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return IOError(dir, errno);
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}
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struct dirent* entry;
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while ((entry = readdir(d)) != NULL) {
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result->push_back(entry->d_name);
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}
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closedir(d);
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return Status::OK();
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}
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virtual Status DeleteFile(const std::string& fname) {
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Status result;
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if (unlink(fname.c_str()) != 0) {
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result = IOError(fname, errno);
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}
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return result;
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}
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virtual Status CreateDir(const std::string& name) {
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Status result;
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if (mkdir(name.c_str(), 0755) != 0) {
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result = IOError(name, errno);
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}
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return result;
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}
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virtual Status DeleteDir(const std::string& name) {
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Status result;
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if (rmdir(name.c_str()) != 0) {
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result = IOError(name, errno);
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}
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return result;
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}
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virtual Status GetFileSize(const std::string& fname, uint64_t* size) {
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Status s;
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struct stat sbuf;
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if (stat(fname.c_str(), &sbuf) != 0) {
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*size = 0;
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s = IOError(fname, errno);
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} else {
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*size = sbuf.st_size;
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}
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return s;
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}
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virtual Status RenameFile(const std::string& src, const std::string& target) {
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Status result;
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if (rename(src.c_str(), target.c_str()) != 0) {
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result = IOError(src, errno);
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}
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return result;
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}
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virtual Status LockFile(const std::string& fname, FileLock** lock) {
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*lock = NULL;
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Status result;
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int fd = open(fname.c_str(), O_RDWR | O_CREAT, 0644);
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if (fd < 0) {
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result = IOError(fname, errno);
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} else if (!locks_.Insert(fname)) {
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close(fd);
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result = Status::IOError("lock " + fname, "already held by process");
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} else if (LockOrUnlock(fd, true) == -1) {
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result = IOError("lock " + fname, errno);
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close(fd);
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locks_.Remove(fname);
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} else {
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PosixFileLock* my_lock = new PosixFileLock;
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my_lock->fd_ = fd;
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my_lock->name_ = fname;
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*lock = my_lock;
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}
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return result;
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}
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virtual Status UnlockFile(FileLock* lock) {
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PosixFileLock* my_lock = reinterpret_cast<PosixFileLock*>(lock);
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Status result;
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if (LockOrUnlock(my_lock->fd_, false) == -1) {
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result = IOError("unlock", errno);
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}
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locks_.Remove(my_lock->name_);
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close(my_lock->fd_);
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delete my_lock;
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return result;
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}
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virtual void Schedule(void (*function)(void*), void* arg);
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virtual void StartThread(void (*function)(void* arg), void* arg);
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virtual Status GetTestDirectory(std::string* result) {
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const char* env = getenv("TEST_TMPDIR");
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if (env && env[0] != '\0') {
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*result = env;
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} else {
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char buf[100];
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snprintf(buf, sizeof(buf), "/tmp/leveldbtest-%d", int(geteuid()));
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*result = buf;
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}
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// Directory may already exist
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CreateDir(*result);
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return Status::OK();
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}
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static uint64_t gettid() {
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pthread_t tid = pthread_self();
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uint64_t thread_id = 0;
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memcpy(&thread_id, &tid, std::min(sizeof(thread_id), sizeof(tid)));
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return thread_id;
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}
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virtual Status NewLogger(const std::string& fname, Logger** result) {
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FILE* f = fopen(fname.c_str(), "w");
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if (f == NULL) {
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*result = NULL;
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return IOError(fname, errno);
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} else {
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*result = new PosixLogger(f, &PosixEnv::gettid);
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return Status::OK();
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}
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}
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virtual uint64_t NowMicros() {
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struct timeval tv;
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gettimeofday(&tv, NULL);
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return static_cast<uint64_t>(tv.tv_sec) * 1000000 + tv.tv_usec;
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}
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virtual void SleepForMicroseconds(int micros) {
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usleep(micros);
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}
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private:
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void PthreadCall(const char* label, int result) {
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if (result != 0) {
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fprintf(stderr, "pthread %s: %s\n", label, strerror(result));
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abort();
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}
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}
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// BGThread() is the body of the background thread
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void BGThread();
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static void* BGThreadWrapper(void* arg) {
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reinterpret_cast<PosixEnv*>(arg)->BGThread();
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return NULL;
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}
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pthread_mutex_t mu_;
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pthread_cond_t bgsignal_;
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pthread_t bgthread_;
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bool started_bgthread_;
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// Entry per Schedule() call
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struct BGItem { void* arg; void (*function)(void*); };
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typedef std::deque<BGItem> BGQueue;
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BGQueue queue_;
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PosixLockTable locks_;
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MmapLimiter mmap_limit_;
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};
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PosixEnv::PosixEnv() : started_bgthread_(false) {
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PthreadCall("mutex_init", pthread_mutex_init(&mu_, NULL));
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PthreadCall("cvar_init", pthread_cond_init(&bgsignal_, NULL));
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}
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void PosixEnv::Schedule(void (*function)(void*), void* arg) {
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PthreadCall("lock", pthread_mutex_lock(&mu_));
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// Start background thread if necessary
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if (!started_bgthread_) {
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started_bgthread_ = true;
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PthreadCall(
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"create thread",
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pthread_create(&bgthread_, NULL, &PosixEnv::BGThreadWrapper, this));
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}
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// If the queue is currently empty, the background thread may currently be
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// waiting.
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if (queue_.empty()) {
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PthreadCall("signal", pthread_cond_signal(&bgsignal_));
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}
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// Add to priority queue
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queue_.push_back(BGItem());
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queue_.back().function = function;
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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
|