fd935ce4c9
The three-way hand-off has a problem: there's no way to arrange for the state of the migration to be unambiguous in case of failure. If the final "disconnect" message is lost (as in, the destination never receives it whether it is sent by the sender or not), the destination has no option but to quit with an error status and let a human sort it out. However, at that point we can either arrange to have a .INCOMPLETE file still on disc or not - and it doesn't matter which we choose, we can still end up with dataloss by picking a specific calamity to have befallen the sender. Given this, it makes sense to fall back to a simpler protocol: just send all the data, then send a "disconnect" message. This has the same downside that we need a human to sort out specific failure cases, but combined with --unlink before sending "disconnect" (see next patch) it will always be possible for a human to disambiguate, whether the destination quit with an error status or not.
42 lines
1.1 KiB
C
42 lines
1.1 KiB
C
#ifndef CLIENT_H
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#define CLIENT_H
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/** CLIENT_MAX_WAIT_SECS
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* This is the length of time an inbound migration will wait for a fresh
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* write before assuming the source has Gone Away. Note: it is *not*
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* the time from one write to the next, it is the gap between the end of
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* one write and the start of the next.
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*/
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#define CLIENT_MAX_WAIT_SECS 5
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struct client {
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/* When we call pthread_join, if the thread is already dead
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* we can get an ESRCH. Since we have no other way to tell
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* if that ESRCH is from a dead thread or a thread that never
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* existed, we use a `stopped` flag to indicate a thread which
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* did exist, but went away. Only check this after a
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* pthread_join call.
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*/
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int stopped;
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int socket;
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int fileno;
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char* mapped;
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struct self_pipe * stop_signal;
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struct server* serve; /* FIXME: remove above duplication */
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/* Have we seen a REQUEST_DISCONNECT message? */
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int disconnect;
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};
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void* client_serve(void* client_uncast);
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struct client * client_create( struct server * serve, int socket );
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void client_destroy( struct client * client );
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void client_signal_stop( struct client * client );
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#endif
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