Implementing TCP timeout #3
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…execution Before this commit, the tcp_interface read method would constantly return a timeout error, even if data had been read properly. After this commit, the read method returns an OK status if the read was successful, or TIMEOUT or READ_FAILED depending on the failure type. In the Boost asio library, the io_service can be run continuously, or run once until an event hander has been dispatched. The return value of the run_one method was previously used as a while loop exit condition, but this resulted in the initial behavior describe above, as if the run_one method actually returned after several even handlers were dispatched, instead of just one. After removing the while loop and using the method alone, the desired behavior was achieved.
Before this commit, the timeout for the TCPInterface::read() method had a hard-coded timeout value of 5 ms. After this commit, the TCPInterface::read() function takes an optional parameter for the timeout, in milliseconds. This parameter defaults to 5 ms.
Before this commit, the read_exactly method used a blocking read call. After this commit, the read_exactly function has a configurable timeout in milliseconds, with a default of 5 ms.
joekale
approved these changes
Feb 28, 2018
…dler Before this commit, the result of a read or timeout was stored in a private variable, populated by the respective callback. After this commit, the conditional statements that proviously relied on the flags instead rely on the gloabl error message's value. Additionally, the timeout handler has added error checking to prevent it from executing fully when the timer.cancel() method is called after a successful read.
Before this commit, a timeout was used in every call TCPInterface::read or TCPInterface::read_exactly, with a default of 0 ms. After this commit, the default is set to 0 ms, and if the read or read_exactly methods receive a 0 timeout request, it will not set a deadline for the timeout, resulting in a blocking read. This allows for the TCPInterface to behave with a timeout, or else be used as it was previously.
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Adding the default timeout to be 0 and a 0 timeout meaning no timeout being used provides support for older drivers not equipped to deal with timeouts. With that addition the ESR Eth driver (on branch with parse corrections) functions as expected with no changes required. |
samrustan
approved these changes
Mar 1, 2018
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This PR contains the implementation of a timeout for the TCP interface read functions. The default timeout value is set to 5 milliseconds, but may be passed in as an optional argument to the TCPInterface::read and TCPInterface::read_exactly methods.
This PR is to resolve #2