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* tdef: Fix license: GPLv2+ instead of AGPLv3+Harald Welte2019-05-271-4/+4
| | | | | | | | | | | | libosmo{core,gsm,vty} code is GPLv2+. The tdef code originated in osmo-msc.git and was moved here without changing the license. That was a mistake, it always was meant to be under GPLv2-or-later after moving to libosmocore.git. Copyright is with sysmocom, so I as the managing director can approve the license change. Change-Id: Ie483ff6f6ea0a56c477649677b4b163c49df11d7
* fsm: add osmo_fsm_inst_state_chg_keep_or_start_timer()Neels Hofmeyr2019-03-071-7/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | During FSM design for osmo-msc, I noticed that the current behavior that keep_timer=true doesn't guarantee a running timer can make FSM design a bit complex, especially when using osmo_tdef for timeout definitions. A desirable keep_timer=true behavior is one that keeps the previous timer running, but starts a timer if no timer is running yet. The simplest example is: a given state repeatedly transitions back to itself, but wants to set a timeout only on first entering, avoiding to restart the timeout on re-entering. Another example is a repeated transition between two or more states, where the first time we enter this group a timeout should start, but it should not restart from scratch on every transition. When using osmo_tdef timeout definitions for this, so far separate meaningless states have to be introduced that merely set a fixed timeout. To simplify, add osmo_fsm_inst_state_chg_keep_or_start_timer(), and use this in osmo_tdef_fsm_inst_state_chg() when both keep_timer == true *and* T != 0. In tdef_test.ok, the changes show that on first entering state L, the previous T=1 is now kept with a large remaining timeout. When entering state L from O, where no timer was running, this time L's T123 is started. Change-Id: Id647511a4b18e0c4de0e66fb1f35dc9adb9177db
* add osmo_tdef API, originally adopted from osmo-bsc T_defNeels Hofmeyr2019-02-041-0/+282
Move T_def from osmo-bsc to libosmocore as osmo_tdef. Adjust naming to be more consistent. Upgrade to first class API: - add timer grouping - add generic vty support - add mising API doc - add C test - add VTY transcript tests, also as examples for using the API From osmo_fsm_inst_state_chg() API doc, cross reference to osmo_tdef API. The root reason for moving to libosmocore is that I want to use the mgw_endpoint_fsm in osmo-msc for inter-MSC handover, and hence want to move the FSM to libosmo-mgcp-client. This FSM uses the T_def from osmo-bsc. Though the mgw_endpoint_fsm's use of T_def is minimal, I intend to use the osmo_tdef API in osmo-msc (and probably elsewhere) as well. libosmocore is the most sensible place for this. osmo_tdef provides: - a list of Tnnnn (GSM) timers with description, unit and default value. - vty UI to allow users to configure non-default timeouts. - API to tie T timers to osmo_fsm states and set them on state transitions. - a few standard units (minute, second, millisecond) as well as a custom unit (which relies on the timer's human readable description to indicate the meaning of the value). - conversion for standard units: for example, some GSM timers are defined in minutes, while our FSM definitions need timeouts in seconds. Conversion is for convenience only and can be easily avoided via the custom unit. By keeping separate osmo_tdef arrays, several groups of timers can be kept separately. The VTY tests in tests/tdef/ showcase different schemes: - tests/vty/tdef_vty_test_config_root.c: Keep several timer definitions in separately named groups: showcase the osmo_tdef_vty_groups*() API. Each timer group exists exactly once. - tests/vty/tdef_vty_test_config_subnode.c: Keep a single list of timers without separate grouping. Put this list on a specific subnode below the CONFIG_NODE. There could be several separate subnodes with timers like this, i.e. continuing from this example, sets timers could be separated by placing timers in specific config subnodes instead of using the global group name. - tests/vty/tdef_vty_test_dynamic.c: Dynamically allocate timer definitions per each new created object. Thus there can be an arbitrary number of independent timer definitions, one per allocated object. T_def was introduced during the recent osmo-bsc refactoring for inter-BSC handover, and has proven useful: - without osmo_tdef, each invocation of osmo_fsm_inst_state_chg() needs to be programmed with the right timeout value, for all code paths that invoke this state change. It is a likely source of errors to get one of them wrong. By defining a T timer exactly for an FSM state, the caller can merely invoke the state change and trust on the original state definition to apply the correct timeout. - it is helpful to have a standardized config file UI to provide user configurable timeouts, instead of inventing new VTY commands for each separate application of T timer numbers. Change-Id: Ibd6b1ed7f1bd6e1f2e0fde53352055a4468f23e5