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Feature #11484

closed

add output offset for readpartial/read_nonblock/etc

Feature #11484: add output offset for readpartial/read_nonblock/etc

Added by normalperson (Eric Wong) about 10 years ago. Updated about 8 years ago.

Status:
Feedback
Target version:
-
[ruby-core:<unknown>]

Description

Specifying a destination offset will allow allocating less garbage strings to improve performance when reading partial data off a pipe or socket. For example: tmp = "".b buf = "".b case rv = io.read_nonblock(8192, tmp, exception: false) when String buf << tmp break if parsing_done?(buf) else return rv end while true Can be written as: buf = "".b case rv = io.read_nonblock(8192, buf, exception: false, off_out: buf.size) when String break if parsing_done?(buf) else return rv end while true For reference, here is the relevant part from "perldoc -f sysread" sysread FILEHANDLE,SCALAR,LENGTH,OFFSET sysread FILEHANDLE,SCALAR,LENGTH	-snip- An OFFSET may be specified to place the read data at some place in the string other than the beginning. A negative OFFSET specifies placement at that many characters counting backwards from the end of the string. A positive OFFSET greater than the length of SCALAR results in the string being padded to the required size with "\0" bytes before the result of the read is appended.	-snip- Maybe we can shortcut by allowing "off_out: :end" to avoid redundant words and potentially using the wrong variable: io.read_nonblock(8192, buf, exception: false, off_out: :end) I'm not sure when I'll have time to work on this feature. Lately I've been working in Perl again and rediscovered this API subtlety. 
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