[ruby-core:56213] [ruby-trunk - Feature #5138] Add nonblocking IO that does not use exceptions for EOF and EWOULDBLOCK

Issue #5138 has been updated by matz (Yukihiro Matsumoto).

Assignee changed from matz (Yukihiro Matsumoto) to tenderlovemaking (Aaron Patterson)

In the developers' meeting on 2007-07-27, we concluded we accepted the proposal from Aaron in https://dl.dropboxusercontent.com/u/582984/again_5138.pdf.

Matz.

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Feature #5138: Add nonblocking IO that does not use exceptions for EOF and EWOULDBLOCK
https://bugs.ruby-lang.org/issues/5138#change-40700

Author: wycats (Yehuda Katz)
Status: Assigned
Priority: Normal
Assignee: tenderlovemaking (Aaron Patterson)
Category: core
Target version: next minor


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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