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Document login_grace_time and the shutdown phase properly

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Markus Armbruster 2012-03-28 18:29:04 +02:00
parent bc629096c0
commit 0b1218f164
1 changed files with 42 additions and 19 deletions
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61
doc/clients-howto
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@ -65,9 +65,10 @@ output until the server reads more input. That may never happen,
because the server may well block on output, which then deadlocks the
session.
An Empire session consists of two phases: login and playing.
empire-client is synchronous during the former and asynchronous during
the latter. Versions before 4.3.11 could deadlock as described above.
An Empire session consists of three phases: login, playing, and
shutdown. empire-client is synchronous in the login phase, and
asynchronous afterwards. Versions before 4.3.11 could deadlock as
described above.
Login phase
-----------
@ -76,7 +77,7 @@ In the login phase, the server prompts for login commands.
The server starts with a C_INIT prompt. The login phase ends when the
server sends another C_INIT prompt, which starts the playing phase, or
when it closes the connection.
when it enters the shutdown phase, as described below
The server replies to a login command with another prompt. Except as
noted below, the server replies C_BADCMD for syntax errors, C_CMDERR
@ -96,8 +97,9 @@ Login commands are:
* kill
If another connection is open for this country, forcibly close it,
else do nothing. Country must be authenticated.
If another connection for this country is in the playing phase,
force it into the shutdown phase, else do nothing. Country must be
authenticated.
Reply is C_EXIT regardless of success.
@ -151,8 +153,8 @@ Login commands are:
* quit
Terminate the session. The server replies with C_EXIT and closes
the connection.
Terminate the session. The server replies with C_EXIT and enters
the shutdown phase.
* sanc
@ -165,6 +167,9 @@ Login commands are:
Set the user name. This is optional and defaults to "".
If the login phase takes more than login_grace_time (default 120s),
the server enters the shutdown phase.
Playing phase
-------------
@ -183,9 +188,9 @@ The following ids occur:
* Command prompt C_PROMPT
The server consumes a line of input. On EOF, the server terminates
the session. Interrupt is ignored. Anything else is interpreted as
Empire command.
The server consumes a line of input. On EOF, the server enters the
shutdown phase. Interrupt is ignored. Anything else is interpreted
as Empire command.
Text is minutes used, space, BTUs left. Both numbers are in
decimal. Clients shall ignore additional text separated by another
@ -202,7 +207,7 @@ The following ids occur:
The server aborts the command on interrupt and EOF. Any argument
prompts it may send before the next command prompt do not consume
input. On EOF, the server then terminates the session (but see
input. On EOF, the server then enters the shutdown phase (but see
C_EXECUTE for an exception).
If an update runs while the server waits for the line of input to
@ -273,13 +278,6 @@ The following ids occur:
Clients are not required to support C_EXECUTE. Clients are
encouraged to offer alternative means for scripting.
* Control C_EXIT
End of session. The server is about to close the connection. Text
is a human-readable farewell.
empire-client prints this text prepended with "Exit: ".
* Control C_FLASH
Asynchronous message. The client should display the text
@ -361,6 +359,31 @@ The following ids occur:
4.3.11 prepend "Aborted\n" to C_ABORT lines, and "Error; " to
C_CMDERR and C_BADCMD lines for historical reasons.
Shutdown phase
--------------
In the shutdown phase, the server first sends a C_EXIT message. Its
text is a human-readable farewell.
empire-client prints this text prepended with "Exit: ".
The server then waits for the output queue to drain, then shuts down
the output direction of the connection. This makes the client detect
an end-of-file condition after it received all output. The client
should then close its end of the connection. The server continues to
read and ignore input until it detects an end-of-file condition. It
then closes its end of the connection, and the session terminates.
If the server closed its end of the connection without waiting for the
client to close the other end first, asynchronous clients could lose
output: an attempt to send input after the server closed its end would
fail with a connection reset error even when some output is still in
flight. Versions before 4.3.30 could misbehave like that in certain
circumstances.
If the shutdown phase doesn't complete within login_grace_time
(default 120s), the server closes the connection immediately. Output
may be lost.
Session Options
===============