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Diffstat (limited to 'lib/stdlib/doc/src/gen_server.xml')
| -rw-r--r-- | lib/stdlib/doc/src/gen_server.xml | 55 |
1 files changed, 40 insertions, 15 deletions
diff --git a/lib/stdlib/doc/src/gen_server.xml b/lib/stdlib/doc/src/gen_server.xml index 30c04d1d52..7a4aff4b11 100644 --- a/lib/stdlib/doc/src/gen_server.xml +++ b/lib/stdlib/doc/src/gen_server.xml @@ -599,32 +599,57 @@ gen_server:abcast -----> Module:handle_cast/2 </desc> </func> <func> - <name>Module:format_status(normal, [PDict, State]) -> Status</name> + <name>Module:format_status(Opt, [PDict, State]) -> Status</name> <fsummary>Optional function for providing a term describing the current gen_server status.</fsummary> <type> + <v>Opt = normal | terminate</v> <v>PDict = [{Key, Value}]</v> <v>State = term()</v> - <v>Status = [term()]</v> + <v>Status = term()</v> </type> <desc> - <p><em>This callback is optional, so callback modules need not - export it. The gen_server module provides a default - implementation of this function that returns the callback - module state.</em></p> - <p>This function is called by a gen_server process when one + <note> + <p>This callback is optional, so callback modules need not + export it. The gen_server module provides a default + implementation of this function that returns the callback + module state.</p> + </note> + <p>This function is called by a gen_server process when:</p> + <list typed="bulleted"> + <item>One of <seealso marker="sys#get_status/1">sys:get_status/1,2</seealso> - is invoked to get the gen_server status. A callback module - wishing to customise the <c>sys:get_status/1,2</c> return - value exports an instance of <c>format_status/2</c> that - returns a term describing the current status of the - gen_server.</p> + is invoked to get the gen_server status. <c>Opt</c> is set + to the atom <c>normal</c> for this case.</item> + <item>The gen_server terminates abnormally and logs an + error. <c>Opt</c> is set to the atom <c>terminate</c> for this + case.</item> + </list> + <p>This function is useful for customising the form and + appearance of the gen_server status for these cases. A + callback module wishing to customise + the <c>sys:get_status/1,2</c> return value as well as how + its status appears in termination error logs exports an + instance of <c>format_status/2</c> that returns a term + describing the current status of the gen_server.</p> <p><c>PDict</c> is the current value of the gen_server's process dictionary.</p> <p><c>State</c> is the internal state of the gen_server.</p> - <p>The function should return <c>Status</c>, a list of one or - more terms that customise the details of the current state - and status of the gen_server.</p> + <p>The function should return <c>Status</c>, a term that + customises the details of the current state and status of + the gen_server. There are no restrictions on the + form <c>Status</c> can take, but for + the <c>sys:get_status/1,2</c> case (when <c>Opt</c> + is <c>normal</c>), the recommended form for + the <c>Status</c> value is <c>[{data, [{"State", + Term}]}]</c> where <c>Term</c> provides relevant details of + the gen_server state. Following this recommendation isn't + required, but doing so will make the callback module status + consistent with the rest of the <c>sys:get_status/1,2</c> + return value.</p> + <p>One use for this function is to return compact alternative + state representations to avoid having large state terms + printed in logfiles.</p> </desc> </func> </funcs> |