Filesystem wrapper, an analogue of boost::filesystem. More...

Detailed Description

Filesystem wrapper, an analogue of boost::filesystem.

These methods abstract accesses to filesystems like boost::filesystem and std::filesystem in C++1z(?). We should not directly call POSIX or Windows filesystem APIs in other modules. Instead, all of them should go through this package.

Why this package exists: The best case scenario for us is the standard C++ library provides filesystem abstraction. However, the spec (based on Boost filesystem ver2) didn't get into even C++14, let alone its implmentations. Thus, we can't rely on it at all. Boost filesystem has a few issues, too. First, it is changing and has some issue when C++11 is enabled. Furthermore, the filesystem package is NOT a header-only module in boost. We do not want to introduce additional dependencies to the gigantic boost shared library, which might not be available or has versioning issues in some environment. Rather, we just need only a small subset of functionalities in those libraries because our usage of filesystem is quite minimal and simplistic. Hence, we do it ourselves.

Direct File I/O: Another goal to have this package is to abstract Direct I/O (O_DIRECT in linux and FILE_FLAG_NO_BUFFERING in Windows). We need them to bypass filesystem-level caching, but these are not in C++ standards at all and won't be (if it happens, Linus would get a heart attack: https://lkml.org/lkml/2007/1/10/233 ).

Class/method designs: Basically, we clone Boost filesystem's class/method into this package when we find a need for some filesystem API access in our code. Due to our specialized needs, we might simplify the API. Our goal is not to duplicate all Boost filesystem classes. Just add what we need.

Classes
struct	DeviceEmulationOptions
	Set of configurations to emulate slower devices for some experiments. More...

class	DirectIoFile
	Represents an I/O stream on one file without filesystem caching. More...

struct	FileStatus
	Analogue of boost::filesystem::file_status. More...

class	Path
	Analogue of boost::filesystem::path. More...

struct	SpaceInfo
	Analogue of boost::filesystem::space_info. More...

Typedefs
typedef assorted::FixedString< 508 >	FixedPath
	Represents a fixed (thus can be placed in shared memory) path string. More...

Enumerations
enum	FileType { kStatusError = 0, kFileNotFound, kRegularFile, kDirectoryFile, kTypeUnknown }
	Analogue of boost::filesystem::file_type. More...

enum	FilePermission { kNoPerms = 0, kOwnerRead = 0400, kOwnerWrite = 0200, kOwnerExe = 0100, kOwnerAll = 0700, kGroupRead = 040, kGroupWrite = 020, kGroupExe = 010, kGroupAll = 070, kOthersRead = 04, kOthersWrite = 02, kOthersExe = 01, kOthersAll = 07, kAllAll = kOwnerAll\|kGroupAll\|kOthersAll, kPermsNotKnown = 0xFFFF }
	Analogue of boost::filesystem::perm. More...

Functions
FileStatus	status (const Path &p)
	Returns the status of the file. More...

bool	exists (const Path &p)
	Returns if the file exists. More...

bool	is_directory (const Path &p)
	Returns if the file is a directory. More...

bool	is_regular_file (const Path &p)
	Returns if the file is a regular file. More...

Path	current_path ()
	Returns the current working directory. More...

Path	home_path ()
	Returns the absolute path of the home directory of the user running this process. More...

Path	absolute (const std::string &p)
	Returns the absolue path of the specified path. More...

bool	create_directories (const Path &p, bool sync=false)
	Recursive mkdir (mkdirs). More...

bool	create_directory (const Path &p, bool sync=false)
	mkdir. More...

uint64_t	file_size (const Path &p)
	Returns size of the file. More...

bool	remove (const Path &p)
	Deletes a regular file or an empty directory. More...

uint64_t	remove_all (const Path &p)
	Recursively deletes a directory. More...

SpaceInfo	space (const Path &p)
	Returns free space information for the device the file is on. More...

std::string	unique_name (uint64_t differentiator=0)
	Equivalent to unique_path("%%%%-%%%%-%%%%-%%%%"). More...

std::string	unique_name (const std::string &model, uint64_t differentiator=0)
	Returns a randomly generated file name with the given template. More...

bool	fsync (const Path &path, bool sync_parent_directory=false)
	Makes the content and metadata of the file durable all the way up to devices. More...

bool	atomic_rename (const Path &old_path, const Path &new_path)
	Renames the old file to the new file with the POSIX atomic-rename semantics. More...

bool	durable_atomic_rename (const Path &old_path, const Path &new_path)
	fsync() on source file before rename, then fsync() on the parent folder after rename. More...

bool	rename (const Path &old_path, const Path &new_path)
	Just a synonym of atomic_rename() to avoid confusion. More...

bool	operator== (const Path &lhs, const Path &rhs)

bool	operator== (const Path &lhs, const std::string &rhs)

bool	operator== (const std::string &lhs, const Path &rhs)

bool	operator!= (const Path &lhs, const Path &rhs)

bool	operator!= (const Path &lhs, const std::string &rhs)

bool	operator!= (const std::string &lhs, const Path &rhs)

bool	operator< (const Path &lhs, const Path &rhs)

bool	operator<= (const Path &lhs, const Path &rhs)

bool	operator> (const Path &lhs, const Path &rhs)

bool	operator>= (const Path &lhs, const Path &rhs)

bool	is_odirect_aligned (uint64_t value)

bool	is_odirect_aligned (const void *ptr)

std::ostream &	operator<< (std::ostream &o, const DirectIoFile &v)

std::ostream &	operator<< (std::ostream &o, const SpaceInfo &v)

std::ostream &	operator<< (std::ostream &o, const Path &v)

Variables
const uint64_t	kOdirectAlignment = 0x1000

Function Documentation

bool foedus::fs::is_odirect_aligned ( uint64_t value )

inline

Definition at line 37 of file direct_io_file.cpp.

Referenced by foedus::fs::DirectIoFile::read(), foedus::fs::DirectIoFile::read_raw(), foedus::fs::DirectIoFile::seek(), foedus::fs::DirectIoFile::truncate(), foedus::fs::DirectIoFile::write(), and foedus::fs::DirectIoFile::write_raw().

                                                {
   return (value % kOdirectAlignment) == 0;
 }

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bool foedus::fs::is_odirect_aligned ( const void * ptr )

inline

Definition at line 40 of file direct_io_file.cpp.

                                                 {
   return (reinterpret_cast<uintptr_t>(ptr) % kOdirectAlignment) == 0;
 }

bool foedus::fs::operator!=	(	const Path &	lhs,
		const Path &	rhs
	)

inline

Definition at line 89 of file path.hpp.

References foedus::fs::Path::compare().

89 {return lhs.compare(rhs) != 0;}

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bool foedus::fs::operator!=	(	const Path &	lhs,
		const std::string &	rhs
	)

inline

Definition at line 90 of file path.hpp.

References foedus::fs::Path::compare().

90 {return lhs.compare(rhs) != 0;}

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bool foedus::fs::operator!=	(	const std::string &	lhs,
		const Path &	rhs
	)

inline

Definition at line 91 of file path.hpp.

References foedus::fs::Path::compare().

91 {return rhs.compare(lhs) != 0;}

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bool foedus::fs::operator<	(	const Path &	lhs,
		const Path &	rhs
	)

inline

Definition at line 93 of file path.hpp.

References foedus::fs::Path::compare().

93 {return lhs.compare(rhs) < 0;}

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std::ostream& foedus::fs::operator<<	(	std::ostream &	o,
		const Path &	v
	)

Definition at line 84 of file path.cpp.

References foedus::fs::Path::string().

                                                      {
   o << v.string();
   return o;
 }

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std::ostream& foedus::fs::operator<<	(	std::ostream &	o,
		const SpaceInfo &	v
	)

Definition at line 193 of file filesystem.cpp.

References foedus::fs::SpaceInfo::available_, foedus::fs::SpaceInfo::capacity_, and foedus::fs::SpaceInfo::free_.

                                                           {
   o << "SpaceInfo: available_=" << v.available_ << ", capacity_=" << v.capacity_
     << ", free_=" << v.free_;
   return o;
 }

std::ostream& foedus::fs::operator<<	(	std::ostream &	o,
		const DirectIoFile &	v
	)

Definition at line 388 of file direct_io_file.cpp.

References foedus::fs::DirectIoFile::get_current_offset(), foedus::fs::DirectIoFile::get_descriptor(), foedus::fs::DirectIoFile::get_path(), foedus::fs::DirectIoFile::is_read(), and foedus::fs::DirectIoFile::is_write().

                                                              {
   o << "<DirectIoFile>"
     << "<path>" << v.get_path() << "</path>"
     << "<descriptor>" << v.get_descriptor() << "</descriptor>"
     << "<read>" << v.is_read() << "</read>"
     << "<write>" << v.is_write() << "</write>"
     << "<current_offset>" << v.get_current_offset() << "</current_offset>"
     << "</DirectIoFile>";
   return o;
 }