Search code examples
javanetwork-programmingconnection

What is the functionality of setSoTimeout and how it works?

I'm trying to learn Socket and I'm confused by following text from Oracle's website:

setSoTimeout

public void setSoTimeout(int timeout) throws SocketException

Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a non-zero timeout, a read() call on the InputStream associated with this Socket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the Socket is still valid. The option must be enabled prior to entering the blocking operation to have effect. The timeout must be > 0. A timeout of zero is interpreted as an infinite timeout.

My questions:

  1. What is SO_TIMEOUT?

  2. Socket is the endpoint of a connection. If I say

    mySocket.setSoTimeout(2000);

    Does it mean that I'm blocking reading any input from the Server/Client for this socket for 2000 millisecond and after this time the socket is ready to read data?

  3. What does it mean timeout expire?

  4. What is the option which must be enabled prior to blocking operation?

  5. Infinite Timeout means that the socket doesn't read anymore?

Solution

  • The JavaDoc explains it very well:

    With this option set to a non-zero timeout, a read() call on the InputStream associated with this Socket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the Socket is still valid. The option must be enabled prior to entering the blocking operation to have effect. The timeout must be > 0. A timeout of zero is interpreted as an infinite timeout.

    SO_TIMEOUT is the timeout that a read() call will block. If the timeout is reached, a java.net.SocketTimeoutException will be thrown. If you want to block forever put this option to zero (the default value), then the read() call will block until at least 1 byte could be read.