Piero 74 wrote: >I have to develop in my application a task which sends email on certain >events. The provide address will be programmed. >I will use dns to resolve the provider address. > >After, i will try to connect to it: if server will be down for some reason, my >task will be block forever!!!! > >I need to avoid blocking task... is there a work around?
[Additional information from discussion in lwip-devel: this is using BSD sockets.] The obvious solution would be to create another task to separate the sending of e-mail from the normal function of your main task. You can use some kind of queue mechanism to copy the e-mail from the main task to the "send e-mail" task. You may need to limit the queue size to deal with the "mail server offline" scenario. The e-mail sending task would discard all pending messages if it fails to connect to the server, and then try the connection again the next time an e-mail send is requested by the main task. Depending on memory constraints, you might be able to hold on to old messages and try again after a reasonable delay, or perhaps keep a single e-mail message which records the fact that you had to delete several due to inability to connect to the mail server. Having a queue for sending multiple e-mail messages also has the advantage that you might be able to send several at once in a single connection to the mail server, if several notifiable events occur in quick succession.
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