Issue #5138 has been reported by Yehuda Katz.

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Bug #5138: Add nonblocking IO that does not use exceptions for EOF and EWOULDBLOCK
http://redmine.ruby-lang.org/issues/5138

Author: Yehuda Katz
Status: Open
Priority: Normal
Assignee: Yukihiro Matsumoto
Category: core
Target version: 1.9.4
ruby -v: ruby 1.9.4dev (2011-07-31 trunk 32788) [x86_64-darwin11.0.0]


The current Ruby I/O classes have non-blocking methods (read_nonblock and write_nonblock). These methods will never block, and if they would block, they raise an exception instead (IO::WaitReadable or IO::WaitWritable). In addition, if the IO is at EOF, they raise an EOFError.

These exceptions are raised repeatedly in virtually every use of the non-blocking methods. This patch adds a pair of methods (try_read_nonblock and try_write_nonblock) that have the same semantics as the existing methods, but they return Symbols instead of raising exceptions for these routine cases:

* :read_would_block
* :write_would_block
* :eof

The patch contains updates for IO, StringIO, and OpenSSL. The updates are fully documented and tested.


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