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https://issues.apache.org/jira/browse/PROTON-708?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rafael H. Schloming resolved PROTON-708.
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Resolution: Fixed
Fix Version/s: 0.8
> C proton driver needs a getter function to access the pn_error so it can be
> cleared
> -----------------------------------------------------------------------------------
>
> Key: PROTON-708
> URL: https://issues.apache.org/jira/browse/PROTON-708
> Project: Qpid Proton
> Issue Type: Bug
> Components: proton-c
> Affects Versions: 0.7
> Reporter: Jesse Fugitt
> Assignee: Rafael H. Schloming
> Fix For: 0.8
>
>
> Our team is currently using Proton 0.7 and ran into an issue on Windows while
> testing where we could not successfully reconnect to a broker once it was
> taken down and brought back up (we are using a pn_driver_t in C). It appears
> that having the ability to clear the pn_error_t stored in the driver struct
> would have solved the issue for us. I'll include some of the details below
> that were also sent to the mailing list but the solution is probably a pretty
> easy fix that just involves adding a function to the driver that simply
> returns its pn_error_t field.
> Details
> The Proton library's Driver Module (both Posix and Windows) does not supply a
> mechanism to clear an error that was detected. In contrast, other modules
> such as Connection supply a method to obtain the pn_error_t structure (see
> pn_connection_error()). This method can be used in combination with
> pn_error_clear() to clear an error.
> It was observed that when establishing a connection from Windows to a
> potential broker on Linux that a WSAECONNREFUSED can be returned from the
> connect() call if the broker is not running. This results in a call to
> select() with a -1 file descriptor. The select() returns a socket error which
> is recorded in the Error Module. The error number can be obtained using the
> pn_driver_errno() call. Deleting the Connection and therefore removing the
> erroneous -1 file description results in subsequent successful select()
> calls. However, querying the Driver module for an error will perpetually
> return the last error. There is no mechanism to clear that error.
> A small patch to the driver.c below is working for us currently but we wanted
> input on what the best or more general solution to the problem should be:
> < return d ? pn_error_code(d->error) : PN_ARG_ERR;
> ---
> > int rtn = PN_ARG_ERR;
> > if (d) {
> > rtn = pn_error_code(d->error);
> > pn_error_clear(d->error);
> > }
> > return rtn;
> On the mailing list, Rafael said his preference would be to expose the
> driver's pn_error_t as the other modules do so it can be cleared rather than
> auto-clearing it as we do in the sample patch above. However, the
> pn_driver_error function already exists so either we need to break convention
> with the other modules in terms of the function name or break compatibility.
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