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Clean up env_posix.cc.

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General cleanup principles:
* Use override when applicable.
* Remove static when redundant (methods and  globals in anonymous
  namespaces).
* Use const on class members where possible.
* Standardize on "status" for Status local variables.
* Renames where clarity can be improved.
* Qualify standard library names with std:: when possible, to
  distinguish from POSIX names.
* Qualify POSIX names with the global namespace (::) when possible, to
  distinguish from standard library names.

This also refactors the background thread synchronization logic so that
it's statically analyzable.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=219212089
This commit is contained in:
costan 2018-10-29 16:17:46 -07:00 committed by Victor Costan
parent a7dc502e9f
commit 1cb3840881
1 changed files with 338 additions and 293 deletions
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565
util/env_posix.cc
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@ -3,22 +3,21 @@
// found in the LICENSE file. See the AUTHORS file for names of contributors. // found in the LICENSE file. See the AUTHORS file for names of contributors.
#include <dirent.h> #include <dirent.h>
#include <errno.h>
#include <fcntl.h> #include <fcntl.h>
#include <pthread.h> #include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h> #include <sys/mman.h>
#include <sys/resource.h> #include <sys/resource.h>
#include <sys/stat.h> #include <sys/stat.h>
#include <sys/time.h> #include <sys/time.h>
#include <sys/types.h> #include <sys/types.h>
#include <time.h>
#include <unistd.h> #include <unistd.h>
#include <atomic> #include <atomic>
#include <cerrno>
#include <cstddef> #include <cstddef>
#include <cstdint> #include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring> #include <cstring>
#include <limits> #include <limits>
#include <queue> #include <queue>
@ -26,6 +25,7 @@
#include <string> #include <string>
#include <thread> #include <thread>
#include <type_traits> #include <type_traits>
#include <utility>
#include "leveldb/env.h" #include "leveldb/env.h"
#include "leveldb/slice.h" #include "leveldb/slice.h"
@ -45,16 +45,22 @@ namespace leveldb {
namespace { namespace {
static int open_read_only_file_limit = -1; // Set by EnvPosixTestHelper::SetReadOnlyMMapLimit() and MaxOpenFiles().
static int mmap_limit = -1; int g_open_read_only_file_limit = -1;
// Up to 1000 mmap regions for 64-bit binaries; none for 32-bit.
constexpr const int kDefaultMmapLimit = (sizeof(void*) >= 8) ? 1000 : 0;
// Can be set using EnvPosixTestHelper::SetReadOnlyMMapLimit.
int g_mmap_limit = kDefaultMmapLimit;
constexpr const size_t kWritableFileBufferSize = 65536; constexpr const size_t kWritableFileBufferSize = 65536;
static Status PosixError(const std::string& context, int err_number) { Status PosixError(const std::string& context, int error_number) {
if (err_number == ENOENT) { if (error_number == ENOENT) {
return Status::NotFound(context, strerror(err_number)); return Status::NotFound(context, std::strerror(error_number));
} else { } else {
return Status::IOError(context, strerror(err_number)); return Status::IOError(context, std::strerror(error_number));
} }
} }
@ -97,124 +103,147 @@ class Limiter {
std::atomic<int> acquires_allowed_; std::atomic<int> acquires_allowed_;
}; };
class PosixSequentialFile: public SequentialFile { // Implements sequential read access in a file using read().
private: //
std::string filename_; // Instances of this class are thread-friendly but not thread-safe, as required
int fd_; // by the SequentialFile API.
class PosixSequentialFile final : public SequentialFile {
public: public:
PosixSequentialFile(const std::string& fname, int fd) PosixSequentialFile(std::string filename, int fd)
: filename_(fname), fd_(fd) {} : fd_(fd), filename_(filename) {}
virtual ~PosixSequentialFile() { close(fd_); } ~PosixSequentialFile() override { close(fd_); }
virtual Status Read(size_t n, Slice* result, char* scratch) { Status Read(size_t n, Slice* result, char* scratch) override {
Status s; Status status;
while (true) { while (true) {
ssize_t r = read(fd_, scratch, n); ::ssize_t read_size = ::read(fd_, scratch, n);
if (r < 0) { if (read_size < 0) { // Read error.
if (errno == EINTR) { if (errno == EINTR) {
continue; // Retry continue; // Retry
} }
s = PosixError(filename_, errno); status = PosixError(filename_, errno);
break; break;
} }
*result = Slice(scratch, r); *result = Slice(scratch, read_size);
break; break;
} }
return s; return status;
} }
virtual Status Skip(uint64_t n) { Status Skip(uint64_t n) override {
if (lseek(fd_, n, SEEK_CUR) == static_cast<off_t>(-1)) { if (::lseek(fd_, n, SEEK_CUR) == static_cast<off_t>(-1)) {
return PosixError(filename_, errno); return PosixError(filename_, errno);
} }
return Status::OK(); return Status::OK();
} }
private:
const int fd_;
const std::string filename_;
}; };
// pread() based random-access // Implements random read access in a file using pread().
class PosixRandomAccessFile: public RandomAccessFile { //
private: // Instances of this class are thread-safe, as required by the RandomAccessFile
std::string filename_; // API. Instances are immutable and Read() only calls thread-safe library
bool temporary_fd_; // If true, fd_ is -1 and we open on every read. // functions.
int fd_; class PosixRandomAccessFile final : public RandomAccessFile {
Limiter* limiter_;
public: public:
PosixRandomAccessFile(const std::string& fname, int fd, Limiter* limiter) // The new instance takes ownership of |fd|. |fd_limiter| must outlive this
: filename_(fname), fd_(fd), limiter_(limiter) { // instance, and will be used to determine if .
temporary_fd_ = !limiter->Acquire(); PosixRandomAccessFile(std::string filename, int fd, Limiter* fd_limiter)
if (temporary_fd_) { : has_permanent_fd_(fd_limiter->Acquire()),
// Open file on every access. fd_(has_permanent_fd_ ? fd : -1),
close(fd_); fd_limiter_(fd_limiter),
fd_ = -1; filename_(std::move(filename)) {
if (!has_permanent_fd_) {
assert(fd_ == -1);
::close(fd); // The file will be opened on every read.
} }
} }
virtual ~PosixRandomAccessFile() { ~PosixRandomAccessFile() override {
if (!temporary_fd_) { if (has_permanent_fd_) {
close(fd_); assert(fd_ != -1);
limiter_->Release(); ::close(fd_);
fd_limiter_->Release();
} }
} }
virtual Status Read(uint64_t offset, size_t n, Slice* result, Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const { char* scratch) const override {
int fd = fd_; int fd = fd_;
if (temporary_fd_) { if (!has_permanent_fd_) {
fd = open(filename_.c_str(), O_RDONLY); fd = ::open(filename_.c_str(), O_RDONLY);
if (fd < 0) { if (fd < 0) {
return PosixError(filename_, errno); return PosixError(filename_, errno);
} }
} }
Status s; assert(fd != -1);
ssize_t r = pread(fd, scratch, n, static_cast<off_t>(offset));
*result = Slice(scratch, (r < 0) ? 0 : r); Status status;
if (r < 0) { ssize_t read_size = ::pread(fd, scratch, n, static_cast<off_t>(offset));
// An error: return a non-ok status *result = Slice(scratch, (read_size < 0) ? 0 : read_size);
s = PosixError(filename_, errno); if (read_size < 0) {
// An error: return a non-ok status.
status = PosixError(filename_, errno);
} }
if (temporary_fd_) { if (!has_permanent_fd_) {
// Close the temporary file descriptor opened earlier. // Close the temporary file descriptor opened earlier.
close(fd); assert(fd != fd_);
::close(fd);
} }
return s; return status;
} }
private:
const bool has_permanent_fd_; // If false, the file is opened on every read.
const int fd_; // -1 if has_permanent_fd_ is false.
Limiter* const fd_limiter_;
const std::string filename_;
}; };
// mmap() based random-access // Implements random read access in a file using mmap().
class PosixMmapReadableFile: public RandomAccessFile { //
private: // Instances of this class are thread-safe, as required by the RandomAccessFile
std::string filename_; // API. Instances are immutable and Read() only calls thread-safe library
void* mmapped_region_; // functions.
size_t length_; class PosixMmapReadableFile final : public RandomAccessFile {
Limiter* limiter_;
public: public:
// base[0,length-1] contains the mmapped contents of the file. // mmap_base[0, length-1] points to the memory-mapped contents of the file. It
PosixMmapReadableFile(const std::string& fname, void* base, size_t length, // must be the result of a successful call to mmap(). This instances takes
Limiter* limiter) // over the ownership of the region.
: filename_(fname), mmapped_region_(base), length_(length), //
limiter_(limiter) { // |mmap_limiter| must outlive this instance. The caller must have already
// aquired the right to use one mmap region, which will be released when this
// instance is destroyed.
PosixMmapReadableFile(std::string filename, char* mmap_base, size_t length,
Limiter* mmap_limiter)
: mmap_base_(mmap_base), length_(length), mmap_limiter_(mmap_limiter),
filename_(std::move(filename)) {}
~PosixMmapReadableFile() override {
::munmap(static_cast<void*>(mmap_base_), length_);
mmap_limiter_->Release();
} }
virtual ~PosixMmapReadableFile() { Status Read(uint64_t offset, size_t n, Slice* result,
munmap(mmapped_region_, length_); char* scratch) const override {
limiter_->Release();
}
virtual Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const {
Status s;
if (offset + n > length_) { if (offset + n > length_) {
*result = Slice(); *result = Slice();
s = PosixError(filename_, EINVAL); return PosixError(filename_, EINVAL);
} else {
*result = Slice(reinterpret_cast<char*>(mmapped_region_) + offset, n);
} }
return s;
*result = Slice(mmap_base_ + offset, n);
return Status::OK();
} }
private:
char* const mmap_base_;
const size_t length_;
Limiter* const mmap_limiter_;
const std::string filename_;
}; };
class PosixWritableFile final : public WritableFile { class PosixWritableFile final : public WritableFile {
@ -378,30 +407,39 @@ class PosixWritableFile final : public WritableFile {
const std::string dirname_; // The directory of filename_. const std::string dirname_; // The directory of filename_.
}; };
static int LockOrUnlock(int fd, bool lock) { int LockOrUnlock(int fd, bool lock) {
errno = 0; errno = 0;
struct flock f; struct ::flock file_lock_info;
memset(&f, 0, sizeof(f)); std::memset(&file_lock_info, 0, sizeof(file_lock_info));
f.l_type = (lock ? F_WRLCK : F_UNLCK); file_lock_info.l_type = (lock ? F_WRLCK : F_UNLCK);
f.l_whence = SEEK_SET; file_lock_info.l_whence = SEEK_SET;
f.l_start = 0; file_lock_info.l_start = 0;
f.l_len = 0; // Lock/unlock entire file file_lock_info.l_len = 0; // Lock/unlock entire file.
return fcntl(fd, F_SETLK, &f); return ::fcntl(fd, F_SETLK, &file_lock_info);
} }
// Instances are thread-safe because they are immutable.
class PosixFileLock : public FileLock { class PosixFileLock : public FileLock {
public: public:
int fd_; PosixFileLock(int fd, std::string filename)
std::string name_; : fd_(fd), filename_(std::move(filename)) {}
int fd() const { return fd_; }
const std::string& filename() const { return filename_; }
private:
const int fd_;
const std::string filename_;
}; };
// Set of locked files. We keep a separate set instead of just // Tracks the files locked by PosixEnv::LockFile().
// relying on fcntrl(F_SETLK) since fcntl(F_SETLK) does not provide //
// any protection against multiple uses from the same process. // We maintain a separate set instead of relying on fcntrl(F_SETLK) because
// fcntl(F_SETLK) does not provide any protection against multiple uses from the
// same process.
//
// Instances are thread-safe because all member data is guarded by a mutex.
class PosixLockTable { class PosixLockTable {
private:
port::Mutex mu_;
std::set<std::string> locked_files_ GUARDED_BY(mu_);
public: public:
bool Insert(const std::string& fname) LOCKS_EXCLUDED(mu_) { bool Insert(const std::string& fname) LOCKS_EXCLUDED(mu_) {
mu_.Lock(); mu_.Lock();
@ -414,217 +452,225 @@ class PosixLockTable {
locked_files_.erase(fname); locked_files_.erase(fname);
mu_.Unlock(); mu_.Unlock();
} }
private:
port::Mutex mu_;
std::set<std::string> locked_files_ GUARDED_BY(mu_);
}; };
class PosixEnv : public Env { class PosixEnv : public Env {
public: public:
PosixEnv(); PosixEnv();
virtual ~PosixEnv() { ~PosixEnv() override {
char msg[] = "Destroying Env::Default()\n"; static char msg[] = "PosixEnv singleton destroyed. Unsupported behavior!\n";
fwrite(msg, 1, sizeof(msg), stderr); std::fwrite(msg, 1, sizeof(msg), stderr);
abort(); std::abort();
} }
virtual Status NewSequentialFile(const std::string& fname, Status NewSequentialFile(const std::string& filename,
SequentialFile** result) { SequentialFile** result) override {
int fd = open(fname.c_str(), O_RDONLY); int fd = ::open(filename.c_str(), O_RDONLY);
if (fd < 0) { if (fd < 0) {
*result = nullptr; *result = nullptr;
return PosixError(fname, errno); return PosixError(filename, errno);
} else { }
*result = new PosixSequentialFile(fname, fd);
*result = new PosixSequentialFile(filename, fd);
return Status::OK(); return Status::OK();
} }
}
virtual Status NewRandomAccessFile(const std::string& fname, Status NewRandomAccessFile(const std::string& filename,
RandomAccessFile** result) { RandomAccessFile** result) override {
*result = nullptr; *result = nullptr;
Status s; int fd = ::open(filename.c_str(), O_RDONLY);
int fd = open(fname.c_str(), O_RDONLY);
if (fd < 0) { if (fd < 0) {
s = PosixError(fname, errno); return PosixError(filename, errno);
} else if (mmap_limit_.Acquire()) {
uint64_t size;
s = GetFileSize(fname, &size);
if (s.ok()) {
void* base = mmap(nullptr, size, PROT_READ, MAP_SHARED, fd, 0);
if (base != MAP_FAILED) {
*result = new PosixMmapReadableFile(fname, base, size, &mmap_limit_);
} else {
s = PosixError(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, if (!mmap_limiter_.Acquire()) {
WritableFile** result) { *result = new PosixRandomAccessFile(filename, fd, &fd_limiter_);
Status s; return Status::OK();
int fd = open(fname.c_str(), O_TRUNC | O_WRONLY | O_CREAT, 0644); }
uint64_t file_size;
Status status = GetFileSize(filename, &file_size);
if (status.ok()) {
void* mmap_base = ::mmap(/*addr=*/nullptr, file_size, PROT_READ,
MAP_SHARED, fd, 0);
if (mmap_base != MAP_FAILED) {
*result = new PosixMmapReadableFile(
filename, reinterpret_cast<char*>(mmap_base), file_size,
&mmap_limiter_);
} else {
status = PosixError(filename, errno);
}
}
::close(fd);
if (!status.ok()) {
mmap_limiter_.Release();
}
return status;
}
Status NewWritableFile(const std::string& filename,
WritableFile** result) override {
int fd = ::open(filename.c_str(), O_TRUNC | O_WRONLY | O_CREAT, 0644);
if (fd < 0) { if (fd < 0) {
*result = nullptr; *result = nullptr;
s = PosixError(fname, errno); return PosixError(filename, errno);
} else {
*result = new PosixWritableFile(fname, fd);
}
return s;
} }
virtual Status NewAppendableFile(const std::string& fname, *result = new PosixWritableFile(filename, fd);
WritableFile** result) { return Status::OK();
Status s; }
int fd = open(fname.c_str(), O_APPEND | O_WRONLY | O_CREAT, 0644);
Status NewAppendableFile(const std::string& filename,
WritableFile** result) override {
int fd = ::open(filename.c_str(), O_APPEND | O_WRONLY | O_CREAT, 0644);
if (fd < 0) { if (fd < 0) {
*result = nullptr; *result = nullptr;
s = PosixError(fname, errno); return PosixError(filename, errno);
} else {
*result = new PosixWritableFile(fname, fd);
}
return s;
} }
virtual bool FileExists(const std::string& fname) { *result = new PosixWritableFile(filename, fd);
return access(fname.c_str(), F_OK) == 0; return Status::OK();
} }
virtual Status GetChildren(const std::string& dir, bool FileExists(const std::string& filename) override {
std::vector<std::string>* result) { return ::access(filename.c_str(), F_OK) == 0;
}
Status GetChildren(const std::string& directory_path,
std::vector<std::string>* result) override {
result->clear(); result->clear();
DIR* d = opendir(dir.c_str()); ::DIR* dir = ::opendir(directory_path.c_str());
if (d == nullptr) { if (dir == nullptr) {
return PosixError(dir, errno); return PosixError(directory_path, errno);
} }
struct dirent* entry; struct ::dirent* entry;
while ((entry = readdir(d)) != nullptr) { while ((entry = ::readdir(dir)) != nullptr) {
result->push_back(entry->d_name); result->emplace_back(entry->d_name);
} }
closedir(d); ::closedir(dir);
return Status::OK(); return Status::OK();
} }
virtual Status DeleteFile(const std::string& fname) { Status DeleteFile(const std::string& filename) override {
Status result; if (::unlink(filename.c_str()) != 0) {
if (unlink(fname.c_str()) != 0) { return PosixError(filename, errno);
result = PosixError(fname, errno);
} }
return result; return Status::OK();
} }
virtual Status CreateDir(const std::string& name) { Status CreateDir(const std::string& dirname) override {
Status result; if (::mkdir(dirname.c_str(), 0755) != 0) {
if (mkdir(name.c_str(), 0755) != 0) { return PosixError(dirname, errno);
result = PosixError(name, errno);
} }
return result; return Status::OK();
} }
virtual Status DeleteDir(const std::string& name) { Status DeleteDir(const std::string& dirname) override {
Status result; if (::rmdir(dirname.c_str()) != 0) {
if (rmdir(name.c_str()) != 0) { return PosixError(dirname, errno);
result = PosixError(name, errno);
} }
return result; return Status::OK();
} }
virtual Status GetFileSize(const std::string& fname, uint64_t* size) { Status GetFileSize(const std::string& filename, uint64_t* size) override {
Status s; struct ::stat file_stat;
struct stat sbuf; if (::stat(filename.c_str(), &file_stat) != 0) {
if (stat(fname.c_str(), &sbuf) != 0) {
*size = 0; *size = 0;
s = PosixError(fname, errno); return PosixError(filename, errno);
} else {
*size = sbuf.st_size;
} }
return s; *size = file_stat.st_size;
return Status::OK();
} }
virtual Status RenameFile(const std::string& src, const std::string& target) { Status RenameFile(const std::string& from, const std::string& to) override {
Status result; if (std::rename(from.c_str(), to.c_str()) != 0) {
if (rename(src.c_str(), target.c_str()) != 0) { return PosixError(from, errno);
result = PosixError(src, errno);
} }
return result; return Status::OK();
} }
virtual Status LockFile(const std::string& fname, FileLock** lock) { Status LockFile(const std::string& filename, FileLock** lock) override {
*lock = nullptr; *lock = nullptr;
Status result;
int fd = open(fname.c_str(), O_RDWR | O_CREAT, 0644); int fd = ::open(filename.c_str(), O_RDWR | O_CREAT, 0644);
if (fd < 0) { if (fd < 0) {
result = PosixError(fname, errno); return PosixError(filename, errno);
} else if (!locks_.Insert(fname)) {
close(fd);
result = Status::IOError("lock " + fname, "already held by process");
} else if (LockOrUnlock(fd, true) == -1) {
result = PosixError("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) { if (!locks_.Insert(filename)) {
PosixFileLock* my_lock = reinterpret_cast<PosixFileLock*>(lock); ::close(fd);
Status result; return Status::IOError("lock " + filename, "already held by process");
if (LockOrUnlock(my_lock->fd_, false) == -1) {
result = PosixError("unlock", errno);
}
locks_.Remove(my_lock->name_);
close(my_lock->fd_);
delete my_lock;
return result;
} }
virtual void Schedule(void (*function)(void*), void* arg); if (LockOrUnlock(fd, true) == -1) {
int lock_errno = errno;
::close(fd);
locks_.Remove(filename);
return PosixError("lock " + filename, lock_errno);
}
virtual void StartThread(void (*function)(void* arg), void* arg); *lock = new PosixFileLock(fd, filename);
return Status::OK();
}
virtual Status GetTestDirectory(std::string* result) { Status UnlockFile(FileLock* lock) override {
const char* env = getenv("TEST_TMPDIR"); PosixFileLock* posix_file_lock = static_cast<PosixFileLock*>(lock);
if (LockOrUnlock(posix_file_lock->fd(), false) == -1) {
return PosixError("unlock " + posix_file_lock->filename(), errno);
}
locks_.Remove(posix_file_lock->filename());
::close(posix_file_lock->fd());
delete posix_file_lock;
return Status::OK();
}
void Schedule(void (*background_work_function)(void* background_work_arg),
void* background_work_arg) override;
void StartThread(void (*thread_main)(void* thread_main_arg),
void* thread_main_arg) override;
Status GetTestDirectory(std::string* result) override {
const char* env = std::getenv("TEST_TMPDIR");
if (env && env[0] != '\0') { if (env && env[0] != '\0') {
*result = env; *result = env;
} else { } else {
char buf[100]; char buf[100];
snprintf(buf, sizeof(buf), "/tmp/leveldbtest-%d", int(geteuid())); std::snprintf(buf, sizeof(buf), "/tmp/leveldbtest-%d",
static_cast<int>(::geteuid()));
*result = buf; *result = buf;
} }
// Directory may already exist
// The CreateDir status is ignored because the directory may already exist.
CreateDir(*result); CreateDir(*result);
return Status::OK(); return Status::OK();
} }
virtual Status NewLogger(const std::string& fname, Logger** result) { Status NewLogger(const std::string& filename, Logger** result) override {
FILE* f = fopen(fname.c_str(), "w"); std::FILE* fp = std::fopen(filename.c_str(), "w");
if (f == nullptr) { if (fp == nullptr) {
*result = nullptr; *result = nullptr;
return PosixError(fname, errno); return PosixError(filename, errno);
} else { } else {
*result = new PosixLogger(f); *result = new PosixLogger(fp);
return Status::OK(); return Status::OK();
} }
} }
virtual uint64_t NowMicros() { uint64_t NowMicros() override {
struct timeval tv; static constexpr uint64_t kUsecondsPerSecond = 1000000;
gettimeofday(&tv, nullptr); struct ::timeval tv;
return static_cast<uint64_t>(tv.tv_sec) * 1000000 + tv.tv_usec; ::gettimeofday(&tv, nullptr);
return static_cast<uint64_t>(tv.tv_sec) * kUsecondsPerSecond + tv.tv_usec;
} }
virtual void SleepForMicroseconds(int micros) { void SleepForMicroseconds(int micros) override {
usleep(micros); ::usleep(micros);
} }
private: private:
@ -656,44 +702,41 @@ class PosixEnv : public Env {
std::queue<BackgroundWorkItem> background_work_queue_ std::queue<BackgroundWorkItem> background_work_queue_
GUARDED_BY(background_work_mutex_); GUARDED_BY(background_work_mutex_);
PosixLockTable locks_; PosixLockTable locks_; // Thread-safe.
Limiter mmap_limit_; Limiter mmap_limiter_; // Thread-safe.
Limiter fd_limit_; Limiter fd_limiter_; // Thread-safe.
}; };
// Return the maximum number of concurrent mmaps. // Return the maximum number of concurrent mmaps.
static int MaxMmaps() { int MaxMmaps() {
if (mmap_limit >= 0) { return g_mmap_limit;
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. // Return the maximum number of read-only files to keep open.
static intptr_t MaxOpenFiles() { int MaxOpenFiles() {
if (open_read_only_file_limit >= 0) { if (g_open_read_only_file_limit >= 0) {
return open_read_only_file_limit; return g_open_read_only_file_limit;
} }
struct rlimit rlim; struct ::rlimit rlim;
if (getrlimit(RLIMIT_NOFILE, &rlim)) { if (::getrlimit(RLIMIT_NOFILE, &rlim)) {
// getrlimit failed, fallback to hard-coded default. // getrlimit failed, fallback to hard-coded default.
open_read_only_file_limit = 50; g_open_read_only_file_limit = 50;
} else if (rlim.rlim_cur == RLIM_INFINITY) { } else if (rlim.rlim_cur == RLIM_INFINITY) {
open_read_only_file_limit = std::numeric_limits<int>::max(); g_open_read_only_file_limit = std::numeric_limits<int>::max();
} else { } else {
// Allow use of 20% of available file descriptors for read-only files. // Allow use of 20% of available file descriptors for read-only files.
open_read_only_file_limit = rlim.rlim_cur / 5; g_open_read_only_file_limit = rlim.rlim_cur / 5;
} }
return open_read_only_file_limit; return g_open_read_only_file_limit;
} }
} // namespace
PosixEnv::PosixEnv() PosixEnv::PosixEnv()
: background_work_cv_(&background_work_mutex_), : background_work_cv_(&background_work_mutex_),
started_background_thread_(false), started_background_thread_(false),
mmap_limit_(MaxMmaps()), mmap_limiter_(MaxMmaps()),
fd_limit_(MaxOpenFiles()) { fd_limiter_(MaxOpenFiles()) {
} }
void PosixEnv::Schedule( void PosixEnv::Schedule(
@ -737,6 +780,8 @@ void PosixEnv::BackgroundThreadMain() {
} }
} }
namespace {
// Wraps an Env instance whose destructor is never created. // Wraps an Env instance whose destructor is never created.
// //
// Intended usage: // Intended usage:
@ -800,12 +845,12 @@ void PosixEnv::StartThread(void (*thread_main)(void* thread_main_arg),
void EnvPosixTestHelper::SetReadOnlyFDLimit(int limit) { void EnvPosixTestHelper::SetReadOnlyFDLimit(int limit) {
PosixDefaultEnv::AssertEnvNotInitialized(); PosixDefaultEnv::AssertEnvNotInitialized();
open_read_only_file_limit = limit; g_open_read_only_file_limit = limit;
} }
void EnvPosixTestHelper::SetReadOnlyMMapLimit(int limit) { void EnvPosixTestHelper::SetReadOnlyMMapLimit(int limit) {
PosixDefaultEnv::AssertEnvNotInitialized(); PosixDefaultEnv::AssertEnvNotInitialized();
mmap_limit = limit; g_mmap_limit = limit;
} }
Env* Env::Default() { Env* Env::Default() {