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net_instaweb::FileSystem Class Reference

#include "file_system.h"

Inheritance diagram for net_instaweb::FileSystem:
net_instaweb::AprFileSystem net_instaweb::MemFileSystem net_instaweb::StdioFileSystem

List of all members.

Classes

struct  DirInfo
class  File
struct  FileInfo
class  InputFile
class  OutputFile

Public Member Functions

virtual int MaxPathLength (const StringPiece &base) const
virtual bool ReadFile (const char *filename, GoogleString *buffer, MessageHandler *handler)
virtual bool ReadFile (const char *filename, Writer *writer, MessageHandler *handler)
virtual bool ReadFile (InputFile *input_file, GoogleString *buffer, MessageHandler *handler)
virtual bool ReadFile (InputFile *input_file, Writer *writer, MessageHandler *handler)
virtual bool WriteFile (const char *filename, const StringPiece &buffer, MessageHandler *handler)
virtual bool WriteTempFile (const StringPiece &prefix_name, const StringPiece &buffer, GoogleString *filename, MessageHandler *handler)
bool WriteFileAtomic (const StringPiece &filename, const StringPiece &buffer, MessageHandler *handler)
virtual InputFileOpenInputFile (const char *filename, MessageHandler *handler)=0
OutputFileOpenOutputFile (const char *filename, MessageHandler *handler)
 Automatically creates sub-directories to filename.
OutputFileOpenOutputFileForAppend (const char *filename, MessageHandler *handler)
OutputFileOpenTempFile (const StringPiece &prefix_name, MessageHandler *handler)
virtual bool Close (File *file, MessageHandler *handler)
 Closes the File and cleans up memory.
virtual bool RemoveFile (const char *filename, MessageHandler *handler)=0
 Like POSIX 'rm'.
bool RenameFile (const char *old_filename, const char *new_filename, MessageHandler *handler)
virtual bool MakeDir (const char *directory_path, MessageHandler *handler)=0
virtual bool RemoveDir (const char *directory_path, MessageHandler *handler)=0
 Like POSIX 'rmdir', remove a directory only if it is empty.
virtual BoolOrError Exists (const char *path, MessageHandler *handler)=0
 Like POSIX 'test -e', checks if path exists (is a file, directory, etc.).
virtual BoolOrError IsDir (const char *path, MessageHandler *handler)=0
 Like POSIX 'test -d', checks if path exists and refers to a directory.
virtual bool RecursivelyMakeDir (const StringPiece &directory_path, MessageHandler *handler)
virtual bool ListContents (const StringPiece &dir, StringVector *files, MessageHandler *handler)=0
virtual bool Atime (const StringPiece &path, int64 *timestamp_sec, MessageHandler *handler)=0
virtual bool Mtime (const StringPiece &path, int64 *timestamp_sec, MessageHandler *handler)=0
 Modified time. Time the file contents were modified.
virtual void GetDirInfo (const StringPiece &path, DirInfo *dirinfo, MessageHandler *handler)
virtual bool Size (const StringPiece &path, int64 *size, MessageHandler *handler)=0
virtual BoolOrError TryLock (const StringPiece &lock_name, MessageHandler *handler)=0
virtual BoolOrError TryLockWithTimeout (const StringPiece &lock_name, int64 timeout_millis, MessageHandler *handler)
virtual bool Unlock (const StringPiece &lock_name, MessageHandler *handler)=0

Protected Member Functions

virtual OutputFileOpenOutputFileHelper (const char *filename, bool append, MessageHandler *handler)=0
virtual OutputFileOpenTempFileHelper (const StringPiece &filename, MessageHandler *handler)=0
virtual bool RenameFileHelper (const char *old_filename, const char *new_filename, MessageHandler *handler)=0

Detailed Description

Provides abstract file system interface. This isolation layer helps us:


Member Function Documentation

virtual bool net_instaweb::FileSystem::Atime ( const StringPiece &  path,
int64 *  timestamp_sec,
MessageHandler handler 
) [pure virtual]

Stores in *timestamp_sec the timestamp (in seconds since the epoch) of the last time the file was accessed (through one of our Read methods, or by someone else accessing the filesystem directly). Returns true on success, false on failure.

Todo:
TODO(abliss): replace this with a single Stat() function.

Implemented in net_instaweb::MemFileSystem, net_instaweb::AprFileSystem, and net_instaweb::StdioFileSystem.

virtual void net_instaweb::FileSystem::GetDirInfo ( const StringPiece &  path,
DirInfo dirinfo,
MessageHandler handler 
) [virtual]

Given a directory path, list the files in the directory and all subdirectories along with total size, inode count, and list of empty directories (useful for cache cleaning). The files/directories in the 'files' and 'empty_dirs' members of dirinfo will have the 'path' input parameter prepended to them. We assume no circular links. If the files or directories are modified while we traverse, we are not guaranteed to represent their final state. The path name should NOT end in a "/".

Todo:
TODO(abliss): unify all slash-ending assumptions
virtual bool net_instaweb::FileSystem::ListContents ( const StringPiece &  dir,
StringVector *  files,
MessageHandler handler 
) [pure virtual]

Like POSIX 'ls -a', lists all files and directories under the given directory (but omits "." and ".."). Full paths (not just filenames) will be pushed onto the back of the supplied vector (without clearing it). Returns true on success (even if the dir was empty), false on error (even if some files were pushed onto the vector). This is generally not threadsafe! Use a mutex.

Implemented in net_instaweb::MemFileSystem, net_instaweb::AprFileSystem, and net_instaweb::StdioFileSystem.

virtual bool net_instaweb::FileSystem::MakeDir ( const char *  directory_path,
MessageHandler handler 
) [pure virtual]

Like POSIX 'mkdir', makes a directory only if parent directory exists. Fails if directory_name already exists or parent directory doesn't exist.

Implemented in net_instaweb::MemFileSystem, net_instaweb::AprFileSystem, and net_instaweb::StdioFileSystem.

virtual int net_instaweb::FileSystem::MaxPathLength ( const StringPiece &  base) const [virtual]

Returns the maximum possible length of a path in a given directory. Note that this is the total, and there may be further constraints on each level. It also depends on the base path.

Default implementation defensively returns 8192.

Reimplemented in net_instaweb::AprFileSystem, and net_instaweb::StdioFileSystem.

OutputFile* net_instaweb::FileSystem::OpenOutputFileForAppend ( const char *  filename,
MessageHandler handler 
) [inline]

Open a file to append to it. Automatically creates sub-directories to filename.

virtual OutputFile* net_instaweb::FileSystem::OpenOutputFileHelper ( const char *  filename,
bool  append,
MessageHandler handler 
) [protected, pure virtual]

These interfaces must be defined by implementers of FileSystem. They may assume the directory already exists.

Implemented in net_instaweb::MemFileSystem, net_instaweb::AprFileSystem, and net_instaweb::StdioFileSystem.

OutputFile* net_instaweb::FileSystem::OpenTempFile ( const StringPiece &  prefix_name,
MessageHandler handler 
) [inline]

Opens a temporary file to write, with the specified prefix. If successful, the filename can be obtained from File::filename(). Automatically creates sub-directories to filename.

NULL is returned on failure.

virtual bool net_instaweb::FileSystem::ReadFile ( const char *  filename,
GoogleString buffer,
MessageHandler handler 
) [virtual]

High level support to read/write entire files in one shot. The input_file versions accept a NULL input_file, in which case they report failure. All routines close the file.

virtual bool net_instaweb::FileSystem::RecursivelyMakeDir ( const StringPiece &  directory_path,
MessageHandler handler 
) [virtual]

Like POSIX 'mkdir -p', makes all directories up to this one recursively. Fails if we do not have permission to make any directory in chain.

Reimplemented in net_instaweb::MemFileSystem.

bool net_instaweb::FileSystem::RenameFile ( const char *  old_filename,
const char *  new_filename,
MessageHandler handler 
) [inline]

Like POSIX 'mv', except it automatically creates sub-directories for new_filename.

virtual bool net_instaweb::FileSystem::Size ( const StringPiece &  path,
int64 *  size,
MessageHandler handler 
) [pure virtual]

Given a file, computes its size in bytes and store it in *size. Returns true on success, false on failure. Behavior is undefined if path refers to a directory. This function has different behavior depending on the underlying implementation. Memory-based implementations will report the size of the file, while disk-based implementations should return the actual allocated size on disk.

Todo:
TODO(abliss): replace this with a single Stat() function.

Implemented in net_instaweb::MemFileSystem, net_instaweb::AprFileSystem, and net_instaweb::StdioFileSystem.

virtual BoolOrError net_instaweb::FileSystem::TryLock ( const StringPiece &  lock_name,
MessageHandler handler 
) [pure virtual]

Attempts to obtain a global (cross-process, cross-thread) lock of the given name (which should be a valid filename, not otherwise used, in an extant directory). If someone else has this lock, returns False immediately. If anything goes wrong, returns Error. On success, returns True: then you must call Unlock when you are done.

Implemented in net_instaweb::MemFileSystem, net_instaweb::AprFileSystem, and net_instaweb::StdioFileSystem.

virtual BoolOrError net_instaweb::FileSystem::TryLockWithTimeout ( const StringPiece &  lock_name,
int64  timeout_millis,
MessageHandler handler 
) [inline, virtual]

Like TryLock, but may attempt to break the lock if it appears to be staler than the given number of milliseconds. (The default implementation never actually breaks locks.) If you obtain a lock through this method, there are no hard guarantees that nobody else has it too. <blink> If you use this function, your lock becomes "best-effort". </blink>

Reimplemented in net_instaweb::MemFileSystem, net_instaweb::AprFileSystem, and net_instaweb::StdioFileSystem.

virtual bool net_instaweb::FileSystem::Unlock ( const StringPiece &  lock_name,
MessageHandler handler 
) [pure virtual]

Attempts to release a lock previously obtained through TryLock. If your thread did not prevously obtain the lock, the behavior is undefined. Returns true if we successfully release the lock. Returns false if we were unable to release the lock (e.g. somebody came along and write-protected the lockfile). You might try again, or start using a different lock name.

Implemented in net_instaweb::MemFileSystem, net_instaweb::AprFileSystem, and net_instaweb::StdioFileSystem.

bool net_instaweb::FileSystem::WriteFileAtomic ( const StringPiece &  filename,
const StringPiece &  buffer,
MessageHandler handler 
)

Write a temp file first and then copy to filename so that the file cannot be read after being partially written. Temp file name is based on filename.

Todo:
TODO(sligocki): Use thoughout code where appropriate.
virtual bool net_instaweb::FileSystem::WriteTempFile ( const StringPiece &  prefix_name,
const StringPiece &  buffer,
GoogleString filename,
MessageHandler handler 
) [virtual]

Writes given data to a temp file in one shot, storing the filename in filename on success. Returns false and clears filename on failure.


The documentation for this class was generated from the following file:
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