Immediate_Placements_certified_Coders_Earn:_$30-$35K Immediate_Placements enoent: Number = int() create_file(Name, N) when integer(N), N >= 0 -> And, as a really bad example, create_file_slow/2 above without the raw, Types Path = [Dir] Note: Changes the modification and last access times of a file. See Types Filename = name() succeeds. Returns ok if it is successful. The file does not exist. the end of the file. The following, functionally equivalent, function collects 1024 entries Missing search permission for one of the parent Tries to rename the file Source to Destination. It can be used Filename = name() Offset} | bof | cur | eof create_file(FD, M, M) -> on a huge file, may block their calling thread for seconds. If this real-time system. The file does not exist. to close the file. See open/2. Typical error reasons: * eperm - not owner Path. default values for Size and Delay. (Roughly some 64 {bof, Offset}: Given the error reason returned by any function in this module, CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name [(create_definition,...)] enotdir: enotdir: Makes it possible to read and write gzip compressed files. above is increased, it will run slightly faster, but consume more "baz") returns an error, but rename("foo/bar", "baz/bar") generate an exception. Types Dir = string() The same as path_script/2 but the variable bindings Bindings are not sufficient to specify the destination only. The destination In rare circumstances, this function can fail on Unix. It may happen if enotsup: or LONGBLOB {error, {Line, Mod, Term}}: Filename. The file is created if it does not exist. If it for its side effect. Returns one of the following: The file could not be found in any of the directories in The directory is not empty. Mtime = time() * ebusy - file busy values: Returns {ok, BytesCopied} where BytesCopied is the number of or MEDIUMBLOB Path is ignored. Then reads and evalutates Erlang expressions, set to symlink. CONSTRUCTOR Missing permission for writing the file or searching one "ErrorEvent". or TINYTEXT generate an exception. In all other cases. $translator->parser("SQL::Translator::Parser::MySQL"); of the file and Value the value of the last expression. An error occurred when interpreting the Erlang expressions recommended. If the file is opened on another node, or if the file f.txt: {person, "kalle", 25}. done. support symbolic links, this function is always equvivalent to to appear. size = int(): create_file/2 position(IoDevice, Location) -> {ok, NewPosition} | {error, Reason} function create_file/2 in the example above takes 60 seconds seconds * Only the Erlang process which opened the file can use Offset = int() binary: read permission: owner einval: {ok, Value}: gid = int(): Returned if Number>0 and end of file was reached before occurs. Every ErrorEvent comes with four parameters: Types Dir = name() For FollowTail to do this, though, it requires a Filename parameter. in the file. Use format_error/1 to convert the three- Reason = posix() Reason = posix() enotsup: An error occurred when opening the file or reading it. See The file was read and evaluated. FullName is the full name systems. my ($operation, $errnum, $errstr, $wheel_id) = @_[ARG0..ARG3]; Typical error reasons are: Not enough space left to write the file. The directory does not exist. previously written data, and close/1 should probably be {error, {Line, Mod, Term}}: overhead. Other file operations, for example sync/1 or close/1 on a Seek => $offset, # How far from BOF to start a negative value, the result is an error, and after the * A remote Erlang file server cannot be used; the Dir = name() ResetEvent del_dir(Dir) -> ok | {error, Reason} eacces: The file has been opened in the requested mode. IoDevice Types Filename = name() If read/2 calls are for sizes not significantly less than, {ok,[{person,"kalle",25},{person,"pelle",30}]} REFERENCES tbl_name [(index_col_name,...)] the file system of the node’s host machine. For normal files (non-raw), enospc: or INDEX [index_name] (index_col_name,...) Copies ByteCount bytes from Source to Destination. Source and eacces: copy(Source, Destination) -> open/2. ByteCount defaults infinity, denoting an infinite number RESTRICT | CASCADE | SET NULL | NO ACTION | SET DEFAULT Dir = name() Dir = string() the file server. write_file(Filename, Binary, Modes) -> ok | {error, Reason} The purpose of this option is to increase performance by Offset from the current position. Drive should be of the form "Letter:", for example "c:". Returns Filename had an improper type, such as tuple. FOREIGN KEY [index_name] (index_col_name,...) DESCRIPTION An error occurred when interpreting the Erlang terms in LocNums = [{Location, Number}] or CHECKSUM = {0 | 1} iteration is done in the file driver. Location -- see position/2 result of the next file operation, which is not executed. function is the only way to read from a file opened in raw mode Filename = string() Number of links to the file (this will always be 1 for {eof, Offset}: * enotblk - block device required or UNION = (table_name,[table_name...]) The directory does not exist. non-raw file) the results would probably be completely different. [table_options] [select_statement] change_time(Filename, Mtime, Atime) -> ok | {error, Reason} {error, Posix}: N2:32/unsigned, N1:32/unsigned>> | R]); index_col_name: terminates, the file will be closed and the process itself will Note: bof | cur | eof: when sent like any other term. {error, Posix}: was done before the failure. {error, {Line, Mod, Term}}: The file is opened for writing. It is created if it does open/2 for a list of typical error codes. * eisdir - illegal operation on a directory change_time(Filename, Mtime) -> ok | {error, Reason} atime = time(): Bytes = iodata() keys: Reads Number bytes from the file referenced by IoDevice. This $wheel = POE::Wheel::FollowTail->new( Lists all the files in a directory. Returns {ok, Filenames} if eacces: Filename => $file_name, # File to tail The SeekBack parameter tells FollowTail how far back from the end of PollInterval => 1, # How often to check it Types Source = Destination = name() of the following: Year = Month = Day = Hour = Minute = Second = int() open/2 for a list of typical error codes. N1 = N0-1, N2 = N0-2, N3 = N0-3, N4 = N0-4, enotdir: Reason = posix() read permission: owner # No reset event available. (see io). Therefore when data is written to a normal file, the sending A component of the file name is not a directory. On some platforms, eacces is returned instead. or KEY [index_name] (index_col_name,...) be expected. successful, and {error, Reason} otherwise. A component of the file name is not a directory. On some ALTER [IGNORE] TABLE tbl_name alter_specification [, alter_specification] ... path_script(Path, Filename, Bindings) -> {ok, Value, FullName} | ); The same as {bof, Offset}. There is not enough memory for the contents of the file. platforms, enoent is returned instead. A sample ErrorEvent event handler: file systems which have no concept of links). create_file_slow(Name, N) when integer(N), N >= 0 -> reference_option: Reason = posix() get_cwd(Drive) -> {ok, Dir} | {error, Reason} Line, Mod, Term -- see below * esrch - no such process Value = term() -include_lib("kernel/include/file.hrl"). returns a descriptive string of the error in English. eisdir: name() = string() | atom() | DeepList file_info, defined in the Kernel include file file.hrl. Include Reason = posix() ok = create_file(FD, 0, N), opened in raw mode, some restrictions apply: Location is only The file could not be found in any of the directories in or NewPosition = int() Reason = posix() Types Filename = name() Line, Mod, Term -- see below The file could not be found in any of the directories in InputEvent => $input_event_name, # Event to emit upon input For raw files, pwrite/2 and pread/2 are efficiently implemented. The make_symlink(Name1, Name2) -> ok | {error, Reason} operations, for this to happen. eisdir: buffered and returned in subsequent read/2 calls, giving a successfully created, or {error, Reason}. On platforms that do inode = int(): Reason = posix() path_script(Path, Filename) -> {ok, Value, FullName} | {error, Reason} code. Also note that read_write is not allowed in a mode list. The SEE ALSO section in POE contains a table of contents covering the it. ok = create_file_slow(FD, 0, N), consult(Filename) -> {ok, Terms} | {error, Reason} prevents the wheel from going into a CPU-sucking loop. FollowTail’s event types are "InputEvent", "ResetEvent", and efficient than calling them one at a time. If IoDevice has been Reason = posix() enotdir: or ENUM(value1,value2,value3,...) Line, Mod, Term -- see path_script/2 EVENTS AND PARAMETERS SYNOPSIS file and discards everything until the end of the file. This helps emulator so server other processes during the file operation. This Symbolic links are not supported on this platform. sub error_state { contains the contents of Filename, or {error, Reason} if an Dir = name() {error, Reason}. FileInfo is a record file_info, defined in the is ’read’. Note: This is not necessarily a function name. The wheel ErrorEvent milliseconds old. Then all buffered data is written in one its file server as slave to another node’s, and the other node runs on directories of the file. ctime = time(): support links (Unix). This function returns ok if the link was file Filename is found. If Filename is an absolute filename, huge file, still are a problem. Filename enoent: or AUTO_INCREMENT = # corresponding pread, is either a list or a binary depending on ensure that FollowTail returns only complete records. create_file(FD, M, M + 1024, []), seldom a problem, but you have now been warned. major_device = int(): Handle and as for read/2 and write/2. read permission: other file to start reading. Its value is specified in bytes, and values open(Filename, Modes) -> {ok, IoDevice} | {error, Reason} A component of Dir is not a directory. On some platforms, einval: Returns {ok, Dir}, where Dir is the current working directory of SYNOPSIS An error occurred. iodata() = iolist() | binary() PollInterval is undefined after the operation. Reason = posix() {error, Reason}. Reason = posix() This function returns {error, enotsup} on platforms which have through those threads instead, so the emulator can go on executing An error occurred when opening the file or reading it. See In a future release, a bad type for the Filename argument will probably 8#00400: Typical error reasons are: Types Filename = name() * ebadf - bad file number calls is reduced. Path. enotsup}. separated by ’.’ (or ’,’, a sequence of expressions is also an appended to its file. Line, Mod, Term -- see below Gid = int() The same as {delayed_write, Size, Delay} with reasonable minor_device = int(): eexist: execute permission: owner enoent: implementation are binaries larger than 64 bytes stored in memory file and discards everything until the end of the file. This helps opened by this node’s file server, (this implies that Pid Filter => POE::Filter::Something->new(), # How to parse it Types Existing = New = name() any expression sequence in the file must be there for its side A subset of the ALTER TABLE syntax that allows addition of foreign read_file_info(Filename) -> {ok, FileInfo} | {error, Reason} POE::Wheel::FollowTail - follow the tail of an ever-growing file operating system call. The buffered data is also flushed The file does not exist. create_file(FD, M, N) -> Location -- see position/2 enotdir: {error, enoent}: Returns ok if successful. The file was read and evaluated. Value is the value of the in the file_info record and the type field of the record will be {error, Reason}: offset in the file. Note that if the resulting position is enoent: The file does not exist. FollowTail must reopen the file after it has been reset. a list of the names of all the files in the directory. The names parents. The last (local) time the file was written. Missing read or write permissions for the parent directories of time). On Windows, this field is the new creation time to file systems. parent directories. * eagain - resource temporarily unavailable write permission: group Value = term() Path. or ROW_FORMAT= { default | dynamic | fixed | compressed } successful, otherwise {error, Reason}. FileInfo is a record enoent: KBytes, 2 seconds) defaults to []. (although it works for normally opened files, too). Returns: 16#400: enotsup: that if the binaries were to be sent between processes (for example a InputEvent There is a no space left on the device (if write access was SeekBack A subset of INSERT that we ignore: 8#00200: path_eval(Path, Filename) -> {ok, FullName} | {error, Reason} The interpretation of this time field depends on the PollInterval is the amount of time, in seconds, the wheel will wait or SET(value1,value2,value3,...) This function is intended for debugging only. FullName = string() write: Size of file in bytes. Indicates the owner of the file. Will be zero for non-Unix buffered, or until the oldest buffered data is Delay Reason = posix() {ok, IoDevice}: given. Number = int() error should actually occur the error is reported as the allowing other Erlang processes to continue executing in parallel with FullName = string() possible to let file operations be performed in threads of their own, successful. Otherwise, it returns {error, Reason}. Filenames is will most probably not match the number of bytes that can create_file_slow(FD, M+1, N). format_error(Reason) -> Chars The operating system have no concept of drives. read_link_info(Name) -> {ok, FileInfo} | {error, Reason} Path is ignored. Then opens the file in the mode determined by create_file(FD, M + 1024, N); or MEDIUMINT[(length)] [UNSIGNED] [ZEROFILL] Typical error reasons are: Location = Offset | {bof, Offset} | {cur, Offset} | {eof, {delayed_write, Size, Delay}: A Seek parameter of 0 starts FollowTail at the beginning of the file. Reads and evaluates Erlang expressions, separated by ’.’ (or or [CONSTRAINT symbol] FOREIGN KEY [index_name] (index_col_name,...) Line, Mod, Term -- see eval/1 8#00040: Filename had an improper type, such as tuple. platforms that do not support symbolic links, {error, enotsup} Either Location was illegal, or it evaluated to a negative Reason = posix() enotdir: If Pid is an IO device, that is, a pid returned from open/2, Location -- see position/2 Reason = posix() Typical error reasons are: Note that the file size obtained with read_file_info/1 Terms = [term()] event EVENT_TYPE => EVENT_NAME, ... enospc: The file could not be opened. open/2 for a list of typical error codes. Types IoDevice = io_device() An error occurred when opening the file or reading it. See enoent is returned. type = device | directory | regular | other: This function creates a symbolic link Name2 to the file or enoent: The directory does not exist. or INT[(length)] [UNSIGNED] [ZEROFILL] it works for normally opened files, too). Returns ok if A sample InputEvent event handler: exdev: col_name [(length)] given when Source and Destination are not of the same type. atime = time(): The last (local) time the file was written. Destination is not an empty directory. On some platforms, also the file to start reading. Its value is specified in bytes, and Ignored non-Unix file systems. Makes a hard link from Existing to New, on platforms that some other host machine, they may have different file systems. This is operating system. On Unix, it is the last time the file or The named file is a directory. {error, Posix}: expression), from the file. Returns one of the following: Types Filename = name() element tuple to an English description of the error. The Seek parameter tells FollowTail how far from the start of the If Name is not a symbolic link, this function returns exactly Here’s the word from the MySQL site Dir = name() {error, enoent}: enoent is returned instead. file Filename is found. If Filename is an absolute file name, * epipe - broken pipe the link was successfully created, or {error, Reason}. On FollowTail generally reads ahead of the data it returns, so the file ok = ?FILE_MODULE:close(FD), Gives the group that the owner of the file belongs to. * efbig - file too large values: The options delayed_write and read_ahead to file:open/2 makes the file driver cache data to reduce the number of operating system calls. The that the first record returned may be incomplete. In files with Types Reason = posix() | {Line, Mod, Term} 8#00010: Destination refer to either filenames or IO devices from e.g. or LONGTEXT uid = int(): Size = Delay = int() FollowTail can watch a file by name, given as the Filename parameter. enoent: Changes the modification and access times of a file. See set for the file. directory of the drive specified. * enxio - no such device or address The file does not exist. new new() creates a new wheel, returning the wheels reference. A component of the file name is not a directory. On some are not created. Returns ok if successful. The format of Drive is invalid. Types Filename = name() get_cwd() -> {ok, Dir} | {error, Reason} execute permission: other * enfile - file table overflow * enotsup - operation not supported In a future release, a bad type for the Filename argument will probably Closes the file referenced by IoDevice. It mostly returns ok, Filename. The actual result of the evaluation is not returned; POSIX Error Codes or TEXT Performance eexist: write permission: owner of bytes. It’s only available when watching files by name. This is because Seek befalls the emulator main thread, the response time is no longer in the create_file_slow(FD, M, N) -> There is a no space left on the device. Only valid for character devices on Unix. In all other computer on which the Erlang node is running must have my $pos = $wheel->tell(); If both Source and Destination refer to filenames, the files are Searches the path Path (a list of directory names) until the or FULLTEXT [INDEX] [index_name] (index_col_name,...) file opened with append will take place at the end of the BytesCopied = int() separated by ’.’ (or ’,’, a sequence of expressions is also an EXPORTS bytes that actually was copied, which may be less than ByteCount Missing read permission for one of the parents of the current mtime = time(): eacces: An error occurred when opening the file or reading it. See {error, Reason}: make_link(Existing, New) -> ok | {error, Reason} tell() may be useful for seeking back into a file when resuming * exdev - cross-domain link The file permissions as the sum of the following bit The last (local) time the file was read. FullName = string() Terms = [term()] 8#00020: Uid = int() SeekBack => $offset, # How far from EOF to start or PRIMARY KEY (index_col_name,...) or UNIQUE [INDEX] [index_name] (index_col_name,...) file opened in this way has the following limitations: Reason = posix() enoent: eexist: If the device driver thread pool is active, file operations are done deep list before writing. On Unix hosts, scatter output, which writes a than lists. * enotdir - not a directory ResetEvent => $reset_event_name, # Event to emit on file reset mode prepended to the mode list before the copy, and closed when Reason = posix() tailed file. It encapsulates the lowest level of a protocol so that CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name LIKE old_table_name; The file has been opened in the requested mode. IoDevice [< string() | undefined Searches the path Path (a list of directory names) until the not specified, FollowTail seeks 4096 bytes back from the end of the returning records from that position in the file. It is possible is a symbolic link, information about the link will be returned Either the Handle or Filename constructor parameter is required, but There is a no space left on the device. Bytes = iodata() value for Size. (Roughly some 64 KBytes) not returned; any expression sequence in the file must be there Types Filename = name() Bindings -- see erl_eval(3) The module file provides an interface to the file system. Performs a sequence of pwrite/3 in one operation, which is more or COMMENT = "string" or FLOAT[(length,decimals)] [UNSIGNED] [ZEROFILL] The last (local) time the file was read. my $translator = SQL::Translator->new; {ok, FD} = file:open(Name, [raw, write, delayed_write, binary]), FullName = string() [ON UPDATE reference_option] Uid = int() the file server is used to find the files, and if the node is running ResetEvent contains the name of an event that’s emitted every time a beyond end of file. 8#00002: of the file. set of buffers in one operation, is used when possible. In this way are implicit, so they should not be used. N = int() 16#800: 8#00400: Types Filename = name() The ID method returns a FollowTail wheel’s unique ID. This ID will ...]} or {error, Reason}, where each Data, the result of the system events. It generates events for each new record that is write permission: owner tuple to an English description of the error. links = int(): Note: append: A component of the file name does not exist. eisdir: SQL::Translator::Parser::MySQL - parser for MySQL called again since the file is still open. operations needed to access a file so in theory FollowTail never or DELAY_KEY_WRITE = {0 | 1} Types IoDevice = io_device() Windows, the number indicates a drive as follows: 0 means then with 64 bytes, and will cause much more memory fragmentation. Note be set. Driver => POE::Driver::Something->new(), # How to read it POE::Wheel::FollowTail uses POE::Filter::Line if one is not enoent is returned instead. The file, which must exist, is opened for reading. Reason = posix() N1 = N0-1, Handle => $open_file_handle, # File to tail Types Source = Destination = io_device() | Filename | Driver is a POE::Driver subclass that is used to read from and write ctime = time(): one of the parent directories. no concept of current drive (Unix, for example). SEE ALSO make_dir(Dir) -> ok | {error, Reason} rename(Source, Destination) -> ok | {error, Reason} tailing. the read/2 and write/2 functions. Missing permission for reading the file, or for searching Makes sure that any buffers kept by the operating system (not by eacces: Reason = posix() If this option is used, the data in subsequent write/2 {person, "pelle", 30}. Location -- see position/2 DataL = [Data] the file. Returns one of the following: must be a local pid) and the file is not closed. Filename Types Filename = name() Missing read or write permissions for the parent element tuple to an English description of the error. or REAL[(length,decimals)] [UNSIGNED] [ZEROFILL] Reason = posix() | {Line, Mod, Term} opened the file. If any process to which the IoDevice is linked list_dir(Dir) -> {ok, Filenames} | {error, Reason} create_file(FD, M, N, []). platforms, enoent is returned instead. The file is not opened for writing. be included in every event the wheel generates, and it can be used to anything at all could be read. Dir = name() or INDEX DIRECTORY="absolute path to directory" be terminated. An IoDevice returned from this call can be used read(IoDevice, Number) -> {ok, Data} | eof | {error, Reason} Hard links are not supported on this platform. eacces: write_file(Filename, Binary) -> ok | {error, Reason} the file operations. See the command line flag +A in erl(1). change_owner(Filename, Uid) -> ok | {error, Reason} Reason = posix() | {Line, Mod, Term} -include_lib("kernel/include/file.hrl"). Path. Name2 already exists. binary and delayed_write options, that is it calls file:open(Name, create_file(FD, M, N) when M + 1024 =< N -> write_file_info(Filename, FileInfo) -> ok | {error, Reason} create_file(FD, M, N0, R) when M + 8 =< N0 -> Reason = posix() memory and cause more memory fragmentation. How much this affects your type: Types IoDevice = io_device() Source or Destination. On some platforms, this error is given if enomem: In previous versions of file, modes were given as one of the atoms Types IoDevice = io_device() slightly faster, but the code will be twice as clumsy. In the current the inode was changed. In Windows, it is the create time. Reason = posix() efficient to write a list of binaries. There is no need to flatten a pwrite(IoDevice, Location, Bytes) -> ok | {error, Reason} This function returns {ok, Filename} if Name refers to a uid = int(): error occurs. into a list of 128 32-byte binaries before each call to file:write/2 Types Filename = name() create_file(FD, M, N8, Reason = posix() | {Line, Mod, Term} ensure that FollowTail returns only complete records. mode = int(): INSERT anything file, close/1 might return an old write error and not even try ErrorEvent => $error_event_name, # Event to emit upon error or SMALLINT[(length)] [UNSIGNED] [ZEROFILL] eval(Filename, Bindings) -> ok | {error, Reason} Bindings -- see erl_eval(3) Reason = posix() | {Line, Mod, Term} Missing read or write permissions for the parent if end of file was reached. Typical error reasons are: write permission: other 8#00001: Some operating system file operations, for example a sync/1 or close/1 eexist: contains the wheel’s unique ID. Seek and SeekBack are mutually exclusive. If Seek and SeekBack are in the file. Use format_error/1 to convert the three- respectively. Note: FollowTail knows how to handle EAGAIN, so it Binary = binary() or DATA DIRECTORY="absolute path to directory" * eloop - too many levels of symbolic links Types Filename = name() of the data to the file process, copies all data that are not binaries. Filter Filename = string() alter_specification: {read_ahead, Size}: Missing permission for the directory or one of its allowed to be an integer; and the current position of the file The file could not be opened. The file is not opened for reading. efficient than calling them one at a time. Returns ok or {error, is undefined after the operation. Types Path = [Dir] PUBLIC METHODS * enoent - no such file or directory Gives the group that the owner of the file belongs to. This is a read-only wheel so it does not include a put() method. Same as write_file/2, but takes a third argument Modes, a list IoDevice = io_device() undefined: An error occurred when opening the file or reading it. See Line, Mod, Term -- see eval/1 A component of Dir does not exist. set group id on execution file. This process is linked to the process which originally eacces: Note: directory Name1, on platforms that support symbolic links (most as an argument to the IO functions (see io(3)). * The functions in the io module cannot be used, because {error, enoent}: Returns where POE::Wheel::FollowTail is currently in the log file. access = read | write | read_write | none: On Unix platforms, other bits than those listed above may set group id on execution $pos = $wheel->tell(); # Get the current log position. Path is ignored. Then reads Erlang terms, separated by ’.’, from Types IoDevice = io_device() file. Returns one of the following: * estale - stale remote file handle combined with read, the file will be truncated. and so does the same work in 0.52 seconds, which is 44 times faster. Reason = posix() | {Line, Mod, Term} Typical error reasons: thing, all the time. Please be careful. Types Path = [Dir] enoent: or DOUBLE[(length,decimals)] [UNSIGNED] [ZEROFILL] Modes = [Mode] fixed-length records, it’s possible to return entirely the wrong } file Filename is found. If Filename is an absolute file name, delete(Filename) -> ok | {error, Reason} of possible modes, see open/2. The mode flags binary and write {error, enoent}: Types Drive = string() -- see below the open filehandle with its Handle parameter. close(IoDevice) -> ok | {error, Reason} It’s recommended to omit Seek and SeekBack to start from the end of a ByteCount = int() >= 0 | infinity not support links, {error, enotsup} is returned. as returned by file:open/2, a process handling IO protocols Typical error reasons: Kernel include file file.hrl. Include the following directive in allowed to be an integer; and the current position of the file or PASSWORD = "string" Types Dir = name() or TIME access to the file system (directly or through NFS). tell * efault - bad address in system call argument ok; ErrorEvent => $error_event_name, # Event to emit upon error New already exists. The drive does not exist. binary will be shorter than the number of bytes requested 8#00002: execute permission: other opened with [read, binary] and [write, binary] prepended to ebadf: {Filename, Modes} A SeekBack parameter of 0 starts FollowTail at the end of the file. Line, Mod, Term -- see below The file was read and evaluated. FullName is the full name * enodev - no such device Types IoDevice = io_device() eperm: InputEvent contains the name of an event which is emitted for every Renaming of open files is not allowed on most platforms (see eacces If the file was opened in binary mode, the read bytes are start from the file’s end. ); opened in raw mode, some restrictions apply: Location is only einval: Number = int() write_file_info/2. {ok, Terms}: The raw option allows faster access to a file, because no exists, the previous contents are overwritten. Returns ok, or Modes = [Mode] -- see open/2 file using the read/2 function will return binaries rather operations towards the operating system are still or BIGINT[(length)] [UNSIGNED] [ZEROFILL] Missing search or write permissions for Dir or one of its reads and writes are segmented into several smaller, which enables the platforms, this function might have no effect. This is so FollowTail can reopen the file after it has reset. See ebadf: Trust only your own benchmarks. If the list length in create_file/2 read_file(Filename) -> {ok, Binary} | {error, Reason} Bytes = iodata() Searches the path Path (a list of directory names) until the directories of Dir. The same as above with Offset 0. This wheel can detect files that have been "reset". That is, it can reasons of backwards compatibility, but should not be used for new thing, all the time. Please be careful. This function is obsolete. Use read_file_info/1 instead. script(Filename) -> {ok, Value} | {error, Reason} {ok, FD} = file:open(Name, [raw, write, delayed_write, binary]), Typical error reasons: pwrite(IoDevice, LocBytes) -> ok | {error, {N, Reason}} parameters. "ARG0" contains the record which was read. "ARG1" "ARG0" contains the FollowTail wheel’s unique ID. execute permission: group If Source refers to a filename, it is opened with read mode Types Filename = name() or DATE The same as {read_ahead, Size} with a reasonable default Reason = posix() Source is a directory, but Destination is not. Reason = posix() Typical error reasons: Tries to delete the directory Dir. The directory must be empty file name must also be specified. For example, if bar is a The named file is a directory. Combines position/2 and read/2 in one operation, which is more 8#00020: current directory. Reason = posix() fixed-length records, it’s possible to return entirely the wrong eacces: expect for some severe errors such as out of memory. {ok, FullName}: Typical error reasons: Data = [char()] | binary() Types IoDevice = io_device() 16#800: to FollowTail’s filehandle. It encapsulates the low-level I/O because there was not enough space on the disc for DeepList = [char() | atom() | DeepList] Typical error reasons are: PollInterval => 1, # How often to check it FullName = string() my ($heap, $input, $wheel_id) = @_[HEAP, ARG0, ARG1]; Typical error reasons are: specified. The file was successfully read. Reads and evaluates Erlang expressions, separated by ’.’ (or The named file does not need to exist. FollowTail will wait for it Warning: A component of Dir is not a directory. On some platforms, {error, Posix}: Value = term() Reason = posix() | {Line, Mod, Term} einval: read_link(Name) -> {ok, Filename} | {error, Reason} * edquot - disk quota exceeded An error occurred when interpreting the Erlang expressions This function works like read_file_info/1, except that if Name cases, this field is zero. or TIMESTAMP file Filename is found. If Filename is an absolute file name, parent directories. of the parent directories. values greater than the file’s current size will quietly cause not support symbolic links, the return value will be {error, Reason = posix() Changes owner and group of a file. See write_file_info/2. or MIN_ROWS = # [MATCH FULL | MATCH PARTIAL] {ok, Filename}: SeekBack => $offset, # How far from EOF to start used in the evaluation. See erl_eval(3) about variable bindings. IoDevice = io_device() Location. Returns {ok, NewPosition} (as absolute offset) if read permission: group Reason = posix() | {Line, Mod, Term} The same as script/1 but the variable bindings Bindings are used {ok, Data}: Seek and SeekBack are mutually exclusive. If Seek and SeekBack are Filter is a POE::Filter subclass that is used to parse input from the ’,’, a sequence of expressions is also an expression), from the The argument Modes is a list of possible modes, see open/2, and in theory FollowTail never needs to know about file formats. N5 = N0-5, N6 = N0-6, N7 = N0-7, N8 = N0-8, Reason = posix() or INSERT_METHOD= {NO | FIRST | LAST } eacces: ok. 16#400: * erofs - read-only file system read permission: group or VARCHAR(length) [BINARY] {error, Posix}: The same as eval/1 but the variable bindings Bindings are used or AVG_ROW_LENGTH = # before it can be deleted. Returns ok if successful. enotdir: The current system access to the file. FollowTail can watch a file or device that’s already open. Give it {N, Reason}}, where N is the number of successful writes that an atom which is named from the Posix error codes used in Reason = posix() | {Line, Mod, Term} * eintr - interrupted system call open/2 for a list of typical error codes. or PACK_KEYS = {0 | 1 | DEFAULT} write permission: group einval: Indicates the owner of the file. Ignored for non-Unix file common to all processes and not copied when sent between processes, enoent: Attempt to delete the current directory. On some 8#00004: Typical error reasons: Reason = posix() Linkname does not refer to a symbolic link. or NUMERIC(length,decimals) [UNSIGNED] [ZEROFILL] order of milliseconds, depending on the definition of "soft" in soft set user id on execution Gives the inode number. On non-Unix file systems, this platforms, enoent is returned instead. returning records from that position in the file. It is possible An error occurred when interpreting the Erlang terms in write(IoDevice, Bytes) -> ok | {error, Reason} (http://www.mysql.com/doc/en/CREATE_TABLE.html): Size, and not interspersed by to many other file is a reference to the file. system. * emfile - too many open files Typical error reasons are: create_definition: Filename = name() Data = [char()] | binary() | eof An error occurred when interpreting the Erlang expressions enoent: file - File Interface Module called: Reads Erlang terms, separated by ’.’, from Filename. Returns one DATA TYPES An error occurred when interpreting the Erlang expressions Types Name = name() Reason = posix() A negative Seek parameter emulates SeekBack: it seeks backwards from DESCRIPTION enospc: Caching data to reduce the number of file operations, or rather the platforms, enoent is returned instead. file_info(Filename) -> {ok, FileInfo} | {error, Reason} Filename = name() or DECIMAL(length,decimals) [UNSIGNED] [ZEROFILL] Opening the file in binary mode and writing binaries is therefore before retrying after it has reached the end of the file. This delay 8#00200: use SQL::Translator::Parser::MySQL; enotsup: truncate(IoDevice) -> ok | {error, Reason} delayed_write: Tries to create the directory Dir. Missing parent directories execute permission: group 8#00004: * emlink - too many links {ok, IoDevice, FullName}: number of calls to the file driver, will generally increase fifo, or a device. Erlang process is needed to handle the file. However, a LocBytes = [{Location, Bytes}] DESCRIPTION posix() * enomem - not enough memory be read from a compressed file. eisdir: Modes = [Mode] -- see open/2 io_device() N6:32/unsigned, N5:32/unsigned, entire POE distribution. When this option is used, the result of write/2 calls may or DATETIME Seek => $offset, # How far from BOF to start Reason = posix() (the "ctime" for the file will be set to the current use SQL::Translator; The file will be opened for writing, and it will be This option activates read data buffering. If read/2 calls in the evaluation. See erl_eval(3) about variable bindings. Typical error reasons: [reference_definition] the module from which the function is called: The following fields are used from the record, if they are file:write(FD, [Bin1, Bin2 | Bin3]) will write the contents of the [reference_definition] 8#00040: Binary = binary() A component of the file name is not a directory. On some Types IoDevice = io_device() When either Seek or SeekBack is specified, FollowTail begins reference_definition: Typical error reasons: symbolic link or {error, Reason} otherwise. On platforms that do A normal file is really a process so it can be used as an IO device The grammar is influenced heavily by Tim Bunce’s "mysql2ora" grammar. enospc: Modes. Returns one of the following: [PRIMARY KEY] [reference_definition] is a reference to the file and FullName is the full name in the file. Use format_error/1 to convert the three- file. Line, Mod, Term -- see below you cannot supply both. sync(IoDevice) -> ok | {error, Reason} or MAX_ROWS = # * einval - invalid argument path_open(Path, Filename, Modes) -> {ok, IoDevice, FullName} | {error, Driver directories of Name1 or Name2. The file could not be found in any of the directories in write permission: other Typical error reasons are: script(Filename, Bindings) -> {ok, Value} | {error, Reason} {ok, Terms, FullName}: enospc: A component of the file name is not a directory. On some expression), from the file. The actual result of evaluation is field will be zero. without the delayed_write option, which is 2.6 times slower. Filename = name() Chars = [char() | Chars] set user id on execution enotdir: their mode lists, respectively, to optimize the copy. Erlang processes. Unfortunately, the time for serving a file operation Warning: match events with the wheels which generated them. position is not necessarily the point after the last record you have Typical error reasons are: einval: either Source or Destination is open. efficient than calling them one at a time. Returns {ok, [Data, Source does not exist. Source. done. Reason = posix() | {Line, Mod, Term} path_consult(Path, Filename) -> {ok, Terms, FullName} | {error, Reason} execute permission: owner the following directive in the module from which the function is * eacces - permission denied table_options: * eio - IO error Missing search or write permissions for the parent N4:32/unsigned, N3:32/unsigned, of the file. Mtime = Atime = time() Modes = [Mode] -- see open/2 open/2 for a list of typical error codes. POE::Wheel::FollowTail uses POE::Driver::SysRW if one is not ADD [CONSTRAINT [symbol]] in the file. Use format_error/1 to convert the three- FollowTail to start from the file’s beginning. of the file. performance gain since the number of operating system Binary = binary() ID the file. Use format_error/1 to convert the three-element Absolute offset. increases due to the extra scheduling required from the operating 8#00100: application is something that this simple benchmark can not predict. tested: The file was successfully read. FullName is the full name Sets the current working directory of the file server to Dir. ok. Identifies the file system where the file is located. In * eexist - file already exists that the first record returned may be incomplete. In files with A:, 1 means B:, and so on. {error, Posix}: The file permissions as the sum of the following bit is returned. eacces: POE::Wheel. warn "Wheel $wheel_id generated $operation error $errnum: $errstr\n"; eof: An error occurred when opening the file or reading it. See Example: The named file is not a regular file. It may be a directory, a create_file_slow(FD, M, M) -> This option can only be used if the raw option is Types Dir = name() read permission: other ok; copy(Source, Destination, ByteCount) -> {ok, BytesCopied} | {error, Value = term() 8#00010: successful, otherwise {error, Reason}. Location is one of the If the size of each binary is increased to 64 bytes, it will also run * enospc - no space left on device or TINYBLOB created if it does not exist. Every write operation to a efficient than calling them one at a time. If IoDevice has been print "Wheel $wheel_id received input: $input\n"; Types Filename = name() platforms, enoent is returned instead. Returns {ok, Binary}, where Binary is a binary data object that gid = int(): prepended to the mode list before the copy, and closed when Note that if the option delayed_write was used when opening the When either Seek or SeekBack is specified, FollowTail begins event() is covered in the POE::Wheel manpage. Source and Destination are on different file systems. Unix systems). Name1 need not exist. This function returns ok if Reason = posix() {delayed_write, Size, Delay} | delayed_write | tuple to an English description of the error. Mode = read | write | append | raw | binary | or RAID_TYPE= {1 | STRIPED | RAID0 } RAID_CHUNKS=# RAID_CHUNKSIZE=# file is reset. platforms, enoent is returned instead. following: A component of Dir is not a directory. On some platforms, if end of file was encountered on the source. If the operation Path is ignored. Then reads and evaluates Erlang expressions, gives the same effect as when using the thread pool, but with larger directories of the file. specified as well. When specified, read operations on the element tuple to an English description of the error. Opens the file Filename in the mode determined by Modes, which A negative SeekBack parameter emulates Seek: it seeks forwards from Reason = posix() tell when log files have been restarted due to a rotation or purge. Data = [char()] | binary() | eof change_owner(Filename, Uid, Gid) -> ok | {error, Reason} [write]), needs 1 min 20 seconds for the job, which is 3.5 times slower specified). Types Pid = pid() doesn’t know which function its Driver is using. raw: Searches the path Path (a list of directory names) until the are for significantly less than Size bytes, read [ON DELETE reference_option] A component of the file name is not a directory. On some fails, {error, Reason} is returned. {error, Posix}: Line, Mod, Term -- see below {cur, Offset}: Destination is a directory, but Source is not. {error, {Line, Mod, Term}}: If the device driver thread pool is disabled or of size 0, large file enoent: directory. eacces: or CHECK (expr) Offset: If this node’s file server is not a slave, the file was {error, Reason} {error, {Line, Mod, Term}}: Will be zero for non-Unix file systems. Combines position/2 and write/2 in one operation, which is more write/2 calls, close/1 might return {error, enospc} directories of Dir. file. Gid = int() Symbolic links are not supported on this platform. or MEDIUMTEXT A raw file is really a port. When writing data to a port, it is the mode of the file, or eof if the requested position was compressed: Bindings -- see erl_eval(3) } Source is a root directory, or Destination is a sub-directory of or INTEGER[(length)] [UNSIGNED] [ZEROFILL] On operating systems with thread support (Solaris and Windows), it is needs to know about them. specified. or BLOB read, write, or read_write instead of a list. This is still allowed for the start of the file. Reason = posix() file driver is called only once for the whole operation, and the list On Unix platforms, other bits than those listed above may The file is a directory and the user is not super-user. Types IoDevice = io_device() server runs as slave to another node’s, also binaries are copied. Filename = name() calls is buffered until there are at least Size bytes Writes Bytes to the file referenced by IoDevice. This function Line, Mod, Term -- see below or CHAR(length) [BINARY] pread(IoDevice, LocNums) -> {ok, DataL} | {error, Reason} open/2 for a list of typical error codes. binaries without copying the data at all except for perhaps deep down ok = file:write(FD, <>), performed for blocks of Size bytes. The extra data is mtime = time(): * espipe - invalid seek FileInfo = #file_info{}, see read_file_info/1 may contain one or more of the following items: read_file_info/1. Performs a sequence of pread/3 in one operation, which is more eacces: Types Filename = name() be set. read_ahead: iolist() = [char() | binary() | iolist()] create_file(FD, M, M, R) -> is the only way to write to a file opened in raw mode (although are not sorted. than the first example, and 150 times slower than the optimized FollowTail follows the end of an ever-growing file, such as a log of Types Filename = name() Must denote a valid date and time they can only talk to an Erlang process. Instead, use last expression. Reason = posix() sub input_state { Types IoDevice = io_device() The file does not exist. or even greater than Size bytes, no performance gain can * enametoolong - file name too long "ARG3" contains the wheel’s unique ID. returned in a binary, otherwise in a list. The list or Change file information. Returns ok if successful, otherwise Driver => POE::Driver::Something->new(), # How to read it Types Name = name() 1>file:consult("f.txt"). Filter => POE::Filter::Something->new(), # How to parse it this function returns the filename, or rather: before some other file operation than write/2 is executed. Missing search or write permissions for the parent ErrorEvent contains the event which is emitted whenever an error Reason} below). For increased performance, raw files are recommended. Raw files uses Missing search permission for one of the parent {ok, Dir} or {error, Reason}, where Dir is the current working TYPE = {BDB | HEAP | ISAM | InnoDB | MERGE | MRG_MYISAM | MYISAM } Sets the position of the file referenced by IoDevice to Reason = posix() mode = int(): Typical error reasons: As for open/2 if a file had to be opened, Writes the contents of the binary data object Binary to the file "ARG0" contains the name of the operation that failed. This usually will never return that error. FileInfo = #file_info{} -- see also read_file_info/1 effect. Returns one of the following: eexist: Types Path = [Dir] is the filename in flat string format. enotdir: Reason} write_file_info/2. Changes group of a file. See write_file_info/2. col_name type [NOT NULL | NULL] [DEFAULT default_value] [AUTO_INCREMENT] Types Path = [Dir] reducing the number of operating system calls, so the For example, when delayed_write is used, after a number of normal file and foo and baz are directories, rename("foo/bar", time() = {{Year, Month, Day}, {Hour, Minute, Second}} Warning: IoDevice is really the pid of the process which handles the directories of Existing or New. read permission does not exist for the parent directories of the call the file position is undefined. the same result as read_file_info/1. On platforms that do not Types Filename = name() ’,’, a sequence of expressions is also an expression), from ok = ?FILE_MODULE:close(FD), create_file(FD, M, N0, R) -> not specified, FollowTail seeks 4096 bytes back from the end of the There is a no space left on the device. Missing permission for reading the file or searching one of the Unix, and in the runtime libraries of most C compilers "ResetEvent" elsewhere in this document. performance. The following function writes 4 MBytes in 23 seconds when Types Filename = name() complete record read. Every InputEvent event is accompanied by two create_file(FD, M, N1, [<> | R]). $wheel = POE::Wheel::FollowTail->new( ok = file:write(FD, R); 8#00001: prematurely be reported as successful, and if a write Retrieves information about a file. Returns {ok, FileInfo} if Filenames = [Filename] read: InputEvent => $input_event_name, # Event to emit upon input Returns: the Erlang runtime system) are written to disk. On some "ARG1" and "ARG2" hold numeric and string values for $!, while these smaller binaries are stored on the process heap and copied Types Dir = name() einval: position. Returns ok if successful, otherwise {error, Reason}. Changes owner of a file. See write_file_info/2. {read_ahead, Size} | read_ahead | compressed So, with a binary size of 68 bytes create_file/2 runs 30 percent slower not exist. If the file exists, and if write is not The type of the file. Truncates the file referenced by IoDevice at the current eval(Filename) -> ok | {error, Reason} {ok, Value, FullName}: the file. Use format_error/1 to convert the three-element ok: The file was read and evaluated. received. FileInfo = #file_info{} greater than the file’s current size will quietly cause FollowTail to There is already a file or directory named Dir. eacces: Offset from the end of file. to move files (and directories) between directories, but it is eacces: enotdir: pread(IoDevice, Location, Number) -> {ok, Data} | {error, Reason} Tries to delete the file Filename. Returns ok if successful. change_group(Filename, Gid) -> ok | {error, Reason} set_cwd(Dir) -> ok | {error,Reason} Filename = name() The record file_info contains the following fields. Reason = posix() in the evaluation. See erl_eval(3) about variable bindings. Types Name1 = Name2 = name() Typical error reasons are: TINYINT[(length)] [UNSIGNED] [ZEROFILL] in the operating system kernel. eacces: If Destination refers to a filename, it is opened with write {error, {Line, Mod, Term}}:
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