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2014-03-21fix sys:get_state/1,2 and sys:replace_state/2,3 when sys suspendedSteve Vinoski
Add two new system callbacks Module:system_get_state/1 and Module:system_replace_state/2 to allow sys:get_state/1,2 and sys:replace_state/2,3 to operate correctly even if a process is sys suspended. Modify gen_server, gen_fsm, and gen_event to support the new callbacks. If a callback module does not export these functions, then by default the Misc value (the same as that passed as the final argument to sys:handle_system_msg/6, and returned as part of the return value of sys:get_status/1,2) is treated as the callback module's state. The previous behaviour of intercepting the system message and passing a tuple of size 2 as the last argument to sys:handle_system_msg/6 is no longer supported. Add tests to verify the correctness of sys:get_state/1,2 and sys:replace_state/2,3 when processes are sys suspended. Add two tests for modules that implement special processes, one that exports system_get_state/1 and system_replace_state/2 and one that doesn't. Much of the credit for this patch goes to James Fish, who reported the initial problem and implemented much of the fix.
2013-04-19Convert XML files to UTF-8Hans Bolinder
2013-04-05Fixed broken links in sys.htmlFredrik Gustafsson
2013-04-02add sys:get_state/1,2 and sys:replace_state/2,3Steve Vinoski
At Erlang Factory 2013 there was discussion during one of the talks about the sys:get_status functions and how useful they were for debugging. Geoff Cant mentioned it would be very useful if the sys module also provided functions to use while debugging to get just the state of a process and also to be able to replace the state of a process, and many others in the audience appeared to agree. The sys:get_state/1,2 functions return the state of a gen_server, gen_fsm, or gen_event process. The return value varies depending on the process type: process state for a gen_server, state name and state data for a gen_fsm, and handler module, handler id, and handler state for each handler registered in a gen_event process. The sys:replace_state/2,3 functions allow the state of a gen_server, gen_fsm, or gen_event process to be replaced with a new state. These functions take a function argument that updates or replaces the process state; using a function to change the state eliminates the race condition of first reading the state via sys:get_state/1 or sys:get_state/2, using its return value to create a new state, and then replacing the old state with the new state, since during that time the process might have received other calls or messages that could have changed its state. * For a gen_server process, the state replacement function takes the process state as an argument and returns a new state. * For a gen_fsm process, the state replacement function gets a tuple of {StateName, StateData} and returns a similar tuple that specifies a new state name, new state data, or both. * For a gen_event process, the state replacement function is called for each registered event handler. It gets a tuple {Module, Id, HandlerState} and returns a similar tuple that specifies the same Module and Id values but may specify a different value for HandlerState. If the state replacement function crashes or results in an error, the original state of a gen_server or gen_fsm process is maintained; if such a crash occurs for a gen_event process, the original state of the event handler for which the state replacement function was called is maintained, but the states of other event handlers of the same gen_event process may still be updated if no errors or crashes occur while replacing their states. Add documentation for sys:get_state/1,2 and sys:replace_state/2,3. The documentation explicitly notes that the functions are intended for use during debugging. Add new tests for these functions to gen_server_SUITE, gen_fsm_SUITE, and gen_event_SUITE.
2013-03-29update sys:get_status/2,3 documentation for gen_eventSteve Vinoski
Modify the documentation for the sys:get_status/2,3 functions to reflect that they also work on gen_event processes, and add a cross reference for gen_event:format_status/2 to go along with the existing cross references for gen_server and gen_fsm.
2011-05-12rHans Bolinder
Use Erlang specs and types for documentation
2011-03-09Remove link_check warnings re httpc.xml,sys.xml and unicode.xmlPatrik Nyblom
2010-09-06Fix minor typos in the documentationCristian Greco
2009-12-04Merge branch 'sv/sys_get_status' into ccase/r13b04_devErlang/OTP
* sv/sys_get_status: Teach sys:get_status/1,2 to call Mod:format_status/2 gen_fsm: Fix format_status/2 to handle Pids OTP-8324 The ability for the gen_server and gen_fsm callback modules to format their own state for display under the sys:get_status/1,2 calls has been restored and documented. (Thanks to Steve Vinoski.)
2009-12-01Teach sys:get_status/1,2 to call Mod:format_status/2Steve Vinoski
Restore the ability for gen_server and gen_fsm callback modules to format their own state for display under the sys:get_status/1,2 calls. This ability is extremely useful for new behavior modules based on gen_server or gen_fsm, so that they can display their status in a more meaningful way than just dumping the state record. It is also generally useful for applications wanting to display their gen_server or gen_fsm callback module state in something other than the default manner. Also document the previously undocumented the gen_server:format_status/2 and gen_fsm:format_status/2 optional callback functions that, if exported by the callback module, are invoked when sys:get_status/1,2 are called. Add unit tests to ensure that format_status/2 functions exported from a gen_fsm callback module and a gen_server callback module are called when sys:get_status/1,2 are called.
2009-11-20The R13B03 release.OTP_R13B03Erlang/OTP