Description:
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Problem Description:
I have an issue with a functionality in the function _rollback_transactions defined in ext/pgsql/pgsql.c. This function is responsible to rollback all transaction that are currently open in persistent database connections, so those transactions do not leak over to following scripts.

Before it sends any commands over the connection, it does the following:

if (PQ_SETNONBLOCKING(link, 0)) {
    php_error_docref("ref.pgsql" TSRMLS_CC, E_NOTICE, "Cannot set connection to blocking mode");
    return -1;
}

When this "Cannot set connection to blocking mode" error is raised, then in almost all cases it is because the connection to the database server is broken, maybe because the PostgreSQL server was restarted, or the network connection to it broke.

The problem is not the error message, because if something is wrong with the database connection, it is correct to print an error (or to call the error handler).

The problem is that in this special case this error message is not displayed in the script that opened the database connection, but rather in the first script this is run after the persistent connection broke. This can be a script that is executed sometime afterwards - maybe a long time afterwards, maybe in a script that never opened a database connection. Basically it could occur in scripts that would normally not cause an error at all. My point is that cause and effect of the error are disconnected.

Real-Life example:
The company i work for has this problem currently in one of our applications. We use persistent connections to a PostgreSQL database over an unreliable internet connection, that breaks every now and then. Normally, this is not a big deal, because we have local database caches which is used as a failsafe solution, and all scripts are programmed in a way to watch out for database errors and automatically re-connect to this failsafe database without the user noticing a thing. All fine until now.

But every time the internet connection - and therefore the connection to the remote database - breaks, all other PHP applications that are hosted on the same server, which do use different databases or do not use a database at all, suddenly print the message "Notice: (null)(): Cannot set connection to blocking mode in Unknown on line 0" at the end of the output.

Suggested Resolution:
Remove the line that calls php_error_docref to raise the error. The database link is removed anyway from the list of persistent connections, due to the "return -1;" directly afterwards.

I am aware that there are other solutions, like adjusting "error_reporting" not to include E_NOTICE, or to turn off "display_errors". Or to install a custom error handler that silently ignores this error.

However, after carefully considering all options, IMHO i think that removing the line in the PHP sources that raises the error is the cleanest solution, with the main argument for it being that cause and effect of the problem do not directly relate. That means the script that prints the error and/or handles the error in its custom error handler may have nothing to do with the broken database connection.


Actual result:
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Notice: (null)(): Cannot set connection to blocking mode in Unknown on line 0