moonbridge
view reference.txt @ 233:8593a1f2c15d
Proper documentation of error handling of moonbridge_io.exec(...) function
| author | jbe |
|---|---|
| date | Sat Jan 16 01:18:21 2016 +0100 (2016-01-16) |
| parents | 828e2bca2e16 |
| children | e8084e64aa91 |
line source
2 Moonbridge reference
3 ====================
7 Global function listen{...}
8 ---------------------------
10 This function initializes the Moonbridge Network Server. It may be called
11 multiple times. However, it is not allowed to register additional listeners by
12 calling listen(...) from a "prepare", "connect", or "finish" handler.
14 See file "example.lua" for parametrization of the listen(...) function.
16 Warning: Moonbridge will fork the Lua environment to handle parallel requests.
17 Functions provided as "prepare", "connect", and "finish" handlers may access
18 global variables, but for every child process these global variables will not
19 be shared! If you require a global state, a DBMS, cache server, or similar is
20 necessary.
24 Global function timeout(...)
25 ----------------------------
27 Calling this function with a positive number (time in seconds) sets a timer
28 that kills the current process after the selected time runs out. The remaining
29 time can be queried by calling this function without arguments.
31 Calling this function with a single argument that is the number zero will
32 disable the timeout.
34 Another mode of operation is selected by passing two arguments: a time (in
35 seconds) as first argument and a function as second argument. In this case, a
36 sub-timer will be used to limit the execution time of the function. In case of
37 timeout, the process will be killed (and the timeout function does not return).
38 If the time for the sub-timer is longer than a previously set timeout (using
39 the timeout(...) function with one argument), the shorter timeout (of the
40 previous call of timeout(...)) will have precedence.
42 Timers are also automatically reset (disabled) when a handler (prepare handler
43 or connect handler) returns. To shutdown processes after a certain time waiting
44 for a new request, use the idle_time parameter of the listen function.
48 Socket object passed to "connect" handler
49 -----------------------------------------
51 For every incoming connection, the registered "connect" handler is called with
52 a single socket object as argument, which is described below:
55 ### socket:close()
57 Closes the socket connection (input and output stream) by flushing all data and
58 sending a TCP FIN packet.
60 Returns true on success, or nil plus error message in case of an I/O error.
61 Using this method on sockets that have already been closed (or reset) will
62 throw an error.
64 Warning: Pending data on the input stream may cause connection aborts (TCP RST)
65 when network connections are used. All pending input data should have been read
66 (or drained) before calling socket:close(). Use socket:finish() to send a
67 TCP FIN packet to the peer before waiting for EOF from the peer.
69 A socket passed to the "connect" handler will be closed automatically if it was
70 not closed by the "connect" handler and if the "connect" handler returns
71 normally (i.e. without throwing an error). If the "connect" handler throws an
72 error, then the socket will be reset. See socket:reset().
75 ### socket:drain(maxlen, terminator)
77 Same as socket:read(maxlen, terminator), but discards the input and returns the
78 number of discarded bytes (as first return value) and the status code ("term",
79 "maxlen", "eof" as second return value).
81 In case of an I/O error, nil (as first return value) plus an error message (as
82 second return value) are returned.
85 ### socket:drain_call(waitfunc, maxlen, terminator)
87 Same as socket:drain(maxlen, terminator), but calls waitfunc(socket, "r") (in
88 an infinite loop) as long as the reading is blocked.
91 ### socket:drain_nb(maxlen, terminator)
93 Same as socket:drain(maxlen, terminator), but non-blocking. The status code
94 (which is returned as second return value) may therefore be "term", "maxlen",
95 "eof", or "block".
97 In case of an I/O error, nil (as first return value) plus an error message (as
98 second return value) are returned.
101 ### socket:drain_yield(maxlen, terminator)
103 Alias for socket:drain_call(coroutine.yield, maxlen, terminator)
106 ### socket:finish()
108 Sends a TCP FIN packet to indicate EOF on write stream. Subsequent reads are
109 still possible. When there is no more input data to be read, the connection
110 should finally be closed with socket:close().
112 In case of local sockets (Unix Domain Sockets), socket:finish() simply closes
113 the underlying socket and emulates EOF on subsequent reads. Also in this case,
114 the connection should be finally closed with socket:close().
117 ### socket:flush(...)
119 Same as socket:write(...) but additionally flushes the socket (i.e. all pending
120 data is passed to the operating system).
122 In case of an I/O error, nil (as first return value) plus an error message (as
123 second return value) are returned. On success, the socket userdata object is
124 returned.
127 ### socket:flush_call(waitfunc, ...)
129 Same as socket:flush(...), but calls waitfunc() (in an infinite loop) as long
130 as the writing is blocked.
133 ### socket:flush_nb(...)
135 Same as socket:write_nb(...) but additionally flushes the socket (i.e. all
136 pending data is passed to the operating system). The total number of bytes that
137 could not be passed yet to the operating system is returned. Zero is returned
138 if all data could be flushed out.
140 In case of an I/O error, nil (as first return value) plus an error message (as
141 second return value) are returned.
144 ### socket:flush_yield(...)
146 Alias for socket:flush_call(coroutine.yield, ...)
149 ### socket.interval
151 Set to the name of an interval timer if the "connect" handler was called due to
152 an elapsed interval timer. Otherwise nil.
155 ### socket.local_ip4
157 Local IPv4 address used for the connection. Encoded as 4 raw bytes in form of a
158 string.
161 ### socket.local_ip6
163 Local IPv6 address used for the connection. Encoded as 16 raw bytes in form of
164 a string.
167 ### socket.local_tcpport
169 Local TCP port used for the connection.
172 ### socket:read(maxlen, terminator)
174 Reads up to maxlen bytes or until an optional termination character is
175 encountered (which is included in the result). The maxlen value may be nil, in
176 which case there is no limit on the number of bytes read.
178 In case of an I/O error, nil (as first return value) plus an error message (as
179 second return value) are returned.
181 In all other cases (including EOF), the following two values are returned:
183 - a string containing the bytes read (first return value, may be empty string)
184 - a status code equal to "term", "maxlen", or "eof" (second return value)
186 If an EOF is encountered before all data could be read, then "eof" is returned
187 as second return value. If maxlen bytes have been read and no termination
188 character has been read, then "maxlen" is returned as second return value. If
189 the termination character is the last character of the read string, the second
190 return value will be "term".
193 ### socket:read_call(waitfunc, maxlen, terminator)
195 Same as socket:read(maxlen, terminator), but calls waitfunc() (in an infinite
196 loop) as long as the reading is blocked.
199 ### socket:read_nb(maxlen, terminator)
201 Same as socket:read(maxlen, terminator), but does not block.
203 In case of an I/O error, nil (as first return value) plus an error message (as
204 second return value) are returned.
206 In all other cases (including EOF), the following two values are returned:
208 - a string containing the bytes read (first return value, may be empty string)
209 - a status code equal to "term", "maxlen", "eof", "block" (second return value)
211 The status code "block" as second return value is used if the function returned
212 prematurely because it would block otherwise. In this case, the first return
213 value is a string that contains the bytes that could be read without blocking.
216 ### socket:read_yield(maxlen, terminator)
218 Alias for socket:read_call(coroutine.yield, maxlen, terminator)
221 ### socket.remote_ip4
223 Remote IPv4 address used for the connection. Encoded as 4 raw bytes in form of
224 a string.
227 ### socket.remote_ip6
229 Remote IPv6 address used for the connection. Encoded as 16 raw bytes in form of
230 a string.
233 ### socket.remote_tcpport
235 Remote TCP port used for the connection.
238 ### socket:reset()
240 Alias for socket:close(). Closes the socket connection by sending a TCP RST
241 packet if possible to indicate error condition. This is the default operation
242 when a socket handle gets garbage collected or the process is terminated
243 abnormally.
245 Returns true on success, or nil (as first return value) plus error message (as
246 second return value) in case of an I/O error. Using this method on sockets that
247 have already been closed (or reset) will throw an error.
249 Warning: Previously sent (and flushed) data may be lost during transmission.
252 ### socket:write(...)
254 Takes a variable number of strings and sends them to the peer. The operation is
255 buffered, so to actually send out the data, it is necessary to eventually call
256 socket:flush(), socket:finish(), or socket:close().
258 In case of an I/O error, nil (as first return value) plus an error message (as
259 second return value) are returned. On success, the socket userdata object is
260 returned.
263 ### socket:write_call(waitfunc, ...)
265 Same as socket:write(...), but calls waitfunc() (in an infinite loop) as long
266 as the writing is blocked.
269 ### socket:write_nb(...)
271 Takes a variable number of strings and sends them to the peer. The operation is
272 buffered, so to actually send out the data, it is necessary to eventually call
273 socket:flush_nb(), socket:flush(), socket:finish(), or socket:close().
275 This function always returns immediately (i.e. it does not block). If all data
276 (but a small buffered portion) could be sent out, then zero is returned.
277 Otherwise, all arguments that could not be sent are stored in a buffer of
278 unlimited size (up to memory capabilities) and an integer is returned that
279 indicates the number of bytes currently in the buffer.
281 In case of an I/O error, nil (as first return value) plus an error message (as
282 second return value) are returned.
285 ### socket:write_yield(...)
287 Alias for socket:write_call(coroutine.yield, ...)
291 I/O library
292 -----------
294 The Moonbridge Network Server for Lua Applications comes with its own I/O
295 library to support blocking as well as nonblocking I/O operations.
297 All methods on an I/O handle (e.g. socket) are described in the previous
298 section regarding the "socket" object. All other functions of the library are
299 listed below.
302 ### moonbridge_io.exec(command, arg1, arg2, ...)
304 Executes the given command and returns a handle with three sockets named
305 "stdin", "stdout", and "stderr" as well as the following methods:
307 - :kill(signal)
308 - :wait()
309 - :wait_nb()
310 - :wait_call(waitfunc)
311 - :wait_yield()
313 Use :kill(signal) to terminate the process with the given signal (defaults to
314 15 for SIGTERM).
316 The :wait() method will wait for the process to terminate and return its exit
317 code. If the process was terminated by a signal, a negative integer is returned
318 which corresponds to the respective positive signal number.
320 The method :wait_nb() is the same as :wait(), except that it does not block but
321 returns false (plus a notice as second return value) if the child process has
322 not terminated yet.
324 The method :wait_call() is the same as :wait() but calls waitfunc() (in an
325 infinite loop) as long as the process is still running.
327 The method :wait_yield() is an alias for :wait_call(coroutine.yield).
329 moonbridge_io.exec(...) returns nil (as first return value) plus an error
330 message (as second return value) in case of error.
333 ### moonbridge_io.localconnect(path)
335 Tries to connect to a local socket (also known as Unix Domain Socket). Returns
336 a socket object on success, or nil (as first return value) plus an error
337 message (as second return value) in case of error.
340 ### moonbridge_io.localconnect_nb(path)
342 Tries to connect to a local socket (also known as Unix Domain Socket). Returns
343 a socket object on success, or nil (as first return value) plus an error
344 message (as second return value) in case of error.
346 Same as moonbridge_io.localconnect(path), except that this function does not
347 block and immediately returns a socket object.
349 In case of an I/O error, nil (as first return value) plus an error message (as
350 second return value) may be returned. However, connection errors may also be
351 reported on first read or write on the socket.
354 ### moonbridge_io.locallisten(path)
356 Attempts to create a local socket (also known as Unix Domain Socket) to accept
357 incoming connections. If the file does already exist and is a socket, then it
358 is deleted automatically before being re-created.
360 In case of an I/O error, nil (as first return value) plus an error message (as
361 second return value) may be returned. On success, a listener object is returned
362 which supports the methods :accept(), :accept_nb(), and :close().
364 The method :accept() blocks until a new incoming connection is available, in
365 which case a socket object is returned.
367 The method :accept_nb() works like :accept(), except that the call is
368 nonblocking and returns false (plus a notice as second return value) in case no
369 incoming connection is available. It is possible to wait for an incoming
370 connection by including the listener object in the input_set of the
371 moonbridge_io.poll(...) call.
373 The method :close() will close the listening socket. In case of local sockets
374 (Unix Domain Sockets), the socket will not be unlinked in the file system.
376 I/O errors by the methods of the listener object are also reported by returning
377 nil (as first return value) plus an error message (as second return value).
380 ### moonbridge_io.poll(input_set, output_set, timeout)
382 This function waits for at least one of the given file descriptors and/or
383 I/O handles to be ready for input or output. The two sets of file descriptors
384 and/or handles must contain the file descriptor or handle as a key, and a value
385 which does evaluate to true, e.g. input_set = {[socketA] = true}. If a set is
386 nil, it is treated as being empty.
388 Returns true when at least one file descriptor or handle is ready for reading
389 or writing respectively. Returns false (plus a notice as second return value)
390 in case of timeout. Returns nil (plus a notice as second return value) if a
391 signal was received during waiting.
394 ### moonbridge_io.tcpconnect(hostname, port)
396 Tries to open a TCP connection with the given host and TCP port number. Returns
397 a socket object on success, or nil (as first return value) plus an error
398 message (as second return value) in case of error.
401 ### moonbridge_io.tcpconnect_nb(hostname, port)
403 Same as moonbridge_io.tcpconnect(hostname, port), except that this function
404 does not block and immediately returns a socket object.
406 Note: The current implementation still blocks during the DNS lookup. Use a
407 numeric IP address as hostname to be truly nonblocking.
409 In case of an I/O error, nil (as first return value) plus an error message (as
410 second return value) may be returned. However, connection errors may also be
411 reported on first read or write on the socket.
414 ### moonbridge_io.tcplisten(hostname, port)
416 Attempts to open a TCP port for listening. To listen on the loopback interface,
417 use "::1" as hostname if IPv6 shall be used, or use "127.0.0.1" as hostname if
418 IPv4 shall be used. To listen on all available interfaces, use "::" (IPv6) or
419 "0.0.0.0" (IPv4) respectively.
421 In case of an I/O error, nil (as first return value) plus an error message (as
422 second return value) may be returned. On success, a listener object is returned
423 which supports the methods :accept(), :accept_nb(), and :close(). See reference
424 for moonbridge.io_locallisten(...).
428 HTTP module
429 -----------
431 The HTTP module exports the function moonbridge_http.generate_handler(callback)
432 that converts an HTTP handler to a "connect" handler. See file "helloworld.lua"
433 for a simple example or "example_application.lua" for a more complex example of
434 invocation. A table with options may be passed either as a second argument, or
435 as a first argument preceeding the callback function (whichever is more
436 convenient).
438 The following options are supported:
440 - request_body_size_limit: maximum size of payload of HTTP request body
441 (transfer encoding is allowed to add a limited amount of extra data)
442 - chunk_size: optional default value for maximum_input_chunk_size and
443 minimum_output_chunk_size
444 - request_header_size_limit: maximum size of HTTP request headers
445 - maximum_input_chunk_size: maximum chunk size when streaming a request body or
446 certain POST fields (bigger chunks will be fragmented automatically)
447 - minimum_output_chunk_size: minimum size for a chunk when sending a response
448 body (smaller chunks will be buffered and concatenated with future data;
449 ignored when request:flush() is called)
450 - static_headers: a set of headers to be included in every HTTP response
451 (may be a string, a table or strings, or a table of key-value pairs)
453 The callback function receives a single request object as argument, which is
454 described below.
457 ### request.body
459 The request body (without headers) as a string. Accessing this value makes
460 further access to request.post_params and request.post_params_list, or
461 invocation of request:stream_request_body(...) impossible.
464 ### request:close_after_finish()
466 Closes the connection after answering the request.
468 This method can only be called before the HTTP response header section has been
469 finished (i.e. before request:finish_headers(), request:send_data(...), or
470 request:finish() were called), but it may be called before a status code has
471 been sent using request:send_status(...).
473 A corresponding "Connection: close" header is automatically sent.
475 See also request:monologue().
478 ### request:consume_input()
480 Starts processing the request body (if existent) to set the values
481 request.post_params, request.post_params_list, request.post_metadata, and
482 and request.post_metadata_list and/or to call POST field stream handlers that
483 have been previously registered with request:stream_post_param(...) or
484 request:stream_post_params(...), or to call a previously registered request
485 body stream handler that was set with request:set_request_body_streamer().
487 This method gets invoked automatically when the POST param tables
488 (request.post_params, etc.) are accessed or if request.body is accessed.
491 ### request.cookies
493 A table with all cookies sent by the client.
496 ### request.faulty
498 Normally set to false. In case of a write error on the client connection or
499 certain other unexpected errors, this value is set to true before a Lua error
500 is raised.
502 A faulty request handle must not be used, or another Lua error will be raised.
505 ### request:finish()
507 Finishes and flushes a HTTP response. An HTTP status, all headers, and the
508 response body (if applicable) must have been previously sent. May be called
509 multiple times (performs no operation if called on a finished request handle).
510 Gets automatically invoked when the callback handler returns. After calling
511 this method explicitly, no further data may be written.
514 ### request:finish_headers()
516 Finishes and flushes the HTTP response header section. May be called multiple
517 times, as long as the request is not finished completely. This method is
518 automatically invoked if the application is beginning to send a response body.
519 After calling this method, no further headers may be sent.
522 ### request:flush()
524 Flushes any pending output data. Note: In order to mark the end of a response
525 body, it is required to call request:finish().
528 ### request.fresh
530 Set to false whenever the request object has been used (e.g. data has been read
531 or sent out, or a stream handler was installed); true otherwise.
534 ### request.get_params
536 A table that maps field names to their corresponding GET value. If there are
537 several GET values with the given field name, then the first value is used.
539 Note: May be implemented through metamethods, but does support iteration
540 through pairs(...).
543 ### request.get_params_list
545 A table that maps field names to a sequence of their corresponding GET values.
547 Note: May be implemented through metamethods, but does support iteration
548 through pairs(...).
551 ### request.headers
553 A table that maps (case-insensitively) a HTTP header field name to a sequence
554 of values. For each occurrence of the respective header line, a string entry is
555 created in that sequence. Non-existent headers are mapped to an empty table.
558 ### request.headers_csv_string
560 A table that maps (case-insensitively) a HTTP header field name to a comma
561 separated string. Multiple occurrences of the header with the given field name
562 are automatically merged into the comma separated string.
565 ### request.headers_csv_table
567 A table that maps (case-insensitively) a HTTP header field name to a sequence
568 of values. One entry is created in that sequence for every comma separated
569 value of each header with the given field name.
572 ### request.headers_flags
574 A table that maps (case-insensitively) a HTTP header field name to another
575 table which (again case-insensitively) maps a string to a boolean, depending on
576 whether this string occurred in the list of comma separated values of one
577 header line with the given field name that was the key in the first table.
580 ### request.headers_value
582 A table that maps (case-insensitively) a HTTP header field name to a value. If
583 multiple header lines with the given field name have been received, false is
584 used as value.
587 ### request.method
589 The HTTP request method, e.g. "HEAD", "GET", or "POST".
592 ### request:monologue()
594 Same as request:close_after_finish() but additionally discards all input data
595 immediately.
598 ### request.path
600 The requested path without a leading slash and without the query part (e.g.
601 "index.html" if "/index.html?a=b&c=d" has been requested). For the query part,
602 see request.query.
604 This value will be nil if (and only if) the request method is "OPTIONS" with a
605 request target equal to "*" (see also asterisk-form of request-target in
606 section 5.3.4 in RFC 7230).
609 ### request.post_metadata
611 Only set for multipart/form-data POST requests. A table that maps field names
612 to their corresponding POST metadata table which contains two entries:
613 "file_name" and "content_type". If there are several POST values with the given
614 field name, then the first value/file is used.
616 Note: May be implemented through metamethods, but does support iteration
617 through pairs(...).
620 ### request.post_metadata_list
622 Only set for multipart/form-data POST requests. A table that maps field names
623 to a sequence with their corresponding POST metadata tables. Needed if multiple
624 files are uploaded with the same field name.
626 Note: May be implemented through metamethods, but does support iteration
627 through pairs(...).
630 ### request.post_params
632 A table that maps field names to their corresponding POST value. If there are
633 several POST values with the given field name, then the first value is used.
635 Note: May be implemented through metamethods, but does support iteration
636 through pairs(...).
639 ### request.post_params_list
641 A table that maps field names to a sequence of their corresponding POST values.
643 Note: May be implemented through metamethods, but does support iteration
644 through pairs(...).
647 ### request.query
649 Query part of the request target including the leading question mark, e.g.
650 "?a=b&c=d" if the requested target is "/index.html?a=b&c=d". The data is
651 automatically parsed and made available through request.get_params and
652 request.get_params_list.
654 If there is no query part given in the request target, then this string is
655 the empty string. This value will be nil if (and only if) the request method
656 is "OPTIONS" with a request target equal to "*" (see also asterisk-form of
657 request-target in section 5.3.4 in RFC 7230).
660 ### request:send_data(...)
662 Sends data as response body. All arguments are converted via tostring(...) and
663 concatenated. May be called multiple times until the request has been finished
664 by calling request:finish().
666 If the request method (see request.method) is "HEAD", then calls to
667 request:send_data(...) are automatically ignored.
670 ### request:send_header(key, value)
672 Sends a HTTP response header that consists of the given key and the given
673 value. Note: Key and value must be provided as separate arguments. Before any
674 headers can be sent, a HTTP status must have been set with
675 request:send_status(status_string).
678 ### request:send_status(status_string)
680 Sends a HTTP response status that is given as a string consisting of a 3-digit
681 number and an explanatory string, e.g. "200 OK" or "404 Not Found". This
682 function must be called once before any headers or response body data may be
683 sent.
686 ### request.socket
688 The underlaying socket. Can be used to force a TCP RST, etc.
691 ### request:stream_post_param(field_name, callback)
693 Registers a stream handler for the given POST parameter. The callback function
694 will be called in the following manner:
696 - For the initial chunk, the first chunk gets passed as first argument while a
697 table with metadata ("field_name" and "content_type") gets passed as second
698 argument. In case of an immediate EOF (i.e. an empty file), the passed
699 chunk is the empty string. In all other cases the chunk has a length greater
700 than zero.
701 - For any remaining chunks, the respective chunk gets passed as first and only
702 argument (no metadata). Here, the chunk has always a length greater than
703 zero.
704 - To indicate the end of the stream, the callback function is called without
705 arguments. This also happens in case of an immediate EOF (see above).
707 In case of an immediate EOF (i.e. an empty file), the callback function is thus
708 called as follows:
710 - The first time with an empty string as first argument, and with the metadata
711 as second argument.
712 - The second time without any arguments.
714 Note that request:consume_input() needs to be called to enforce streaming to
715 finish.
718 ### request:stream_post_params(pattern, callback)
720 Same as request:stream_post_param(...) but providing a string pattern to match
721 multiple field names (e.g. "^file_[0-9]+$").
724 ### request:stream_request_body(callback)
726 Registeres a stream handler for the whole request body. For each chunk of the
727 request body, the callback function is called with the corresponding chunk. End
728 of data is indicated by passing a nil value to the callback functuion.
730 Note that request:consume_input() needs to be called to enforce streaming to
731 finish.
734 ### request:stream_request_body_now(callback)
736 Start streaming of request body immediately. On EOF the function returns and
737 the callback function is *not* called with nil as argument.