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method

read_nonblock

Importance_2
read_nonblock(maxlen, buf=nil) public

Reads at most maxlen bytes in the non-blocking manner.

When no data can be read without blocking, It raises OpenSSL::SSL::SSLError extended by IO::WaitReadable or IO::WaitWritable.

IO::WaitReadable means SSL needs to read internally. So read_nonblock should be called again after underlying IO is readable.

IO::WaitWritable means SSL needs to write internally. So read_nonblock should be called again after underlying IO is writable.

So OpenSSL::Buffering#read_nonblock needs two rescue clause as follows.

# emulates blocking read (readpartial). begin

result = ssl.read_nonblock(maxlen)

rescue IO::WaitReadable

IO.select([io])
retry

rescue IO::WaitWritable

IO.select(nil, [io])
retry

end

Note that one reason that read_nonblock write to a underlying IO is the peer requests a new TLS/SSL handshake. See openssl FAQ for more details. http://www.openssl.org/support/faq.html

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