autosave v4.7

Autosave automatically saves the values of EPICS process variables (PVs) to files on a server, and restores those values when the IOC is rebooted. The original author is Bob Dalesio; I made some improvements; Frank Lenkszus made some more improvements, which I folded into the version I've been maintaining. A bunch of people contributed to getting the software running on PPC hardware, including Ron Sluiter, Andrew Johnson, and Pete Jemian (APS), Markus Janousch and David Maden (SLS), and I'm not sure who else.

Autosave is a two-part operation: run-time save, and boot-time restore. The run-time part (save_restore.c) is started by commands in the IOC startup file, and persists while the IOC is running. Its primary job is to save PV values to files on a server, but it also supports manual restore and other management operations. The boot-time part (dbrestore.c) is invoked during iocInit, via an EPICS initHook. It restores PV values from files written by the run-time part, and does not persist after iocInit() returns.

In addition to the autosave software, the autosave module contains a client program, asVerify, to compare written autosave files with current PV values. This program can also write an autosave file from which PV values can be restored.

Important nuances

Autosave uses dbStaticLib to write parameters at boot time, just like dbLoadRecords(). Thus, boot-time restore does not cause record processing to occur, and it does not make a record's value defined (doesn't set UDF to 0). Exception: arrays cannot be written by dbStaticLib, so autosave writes arrays using database access. This still doesn't cause processing to occur, though it should cause the record's UDF field to be set to 0.
At run time (after boot-time restore), autosave reads and writes using channel-access. Thus, restoring at run time will in general produce a different result than restoring at boot time. Exception: arrays are read and written using database access.
Boot-time restore can occur at either or both of two times: before record initialization ("pass 0"); and after record initialization ("pass 1"). (Record initialization includes device initialization.) For most PV's, you don't need to think about this; just tell autosave to restore at both times, and autosave will do whatever is required to get the value written. You cannot make this restore-time choice on a PV-by-PV basis; you can only specify when an entire file of parameters should be restored.
If you want the restored value available for use by device support during its initialization, you must cause the value to be restored during pass 0. (Note that arrays cannot be restored at this time.) If you want the restored value to overwrite the value written by record/device initialization, you must cause the value to be restored dusing pass 1.
Motor-record positions (VAL or DVAL) should be restored only before record initialization, because this is the assumption under which motor-record device support was written.
In the lore that has built up around autosave, PV's that should be restored only before record initialization have been termed "positions". All other PV's have been termed "settings". Thus, you might run across a file called 'auto_positions.req', and now you'll know that the parameters in this file are intended to be restored only during autosave's pass-0.
You can save parameters without also restoring them, and restore parameters without also saving them, but you can't make these choices for individual parameters, only for entire files of parameters.

Module contents

asApp/src

save_restore.c: saves PV values in files on a file server according to preset rules.
dbrestore.c: restore PV values at boot time, using dbStaticLib
initHooks.c: call restore routines at the correct time during boot.
fGetDateStr.c: Frank Lenkszus' date-string routines
save_restore.h, fGetDateStr.h: headers
asVerify.c: Client-side tool to compare autosaved file with current PV values. Can also write an autosave file.

asApp/Db

auto_settings.req, auto_positions.req: Sample request files
save_restoreStatus.db: database containing records save_restore uses to report status.
infoExample.db: database containing a record with info nodes specifying fields to be autosaved.
SR_test.db: Test database for autosave and asVerify.

asApp/op/adl

save_restoreStatus*.adl, save_restoreStatusLegend.adl, save_restoreStatus_more.adl, save_restoreStatus_tiny.adl, SR_X_Status.adl: MEDM displays of save_restore status.

How to use autosave

This software can be used in many different ways. I'll describe what you have to do to use it as it's commonly used at APS beamlines to save PV values periodically, and restore them on reboot. A complete example of how autosave is used at APS can be found in the synApps xxx module. The relevant files in that module are the following:

xxx/configure/RELEASE: look for "AUTOSAVE"
xxx/xxxApp/src/Makefile: look for "autosave"
xxx/xxxApp/src/xxxCommonInclude.dbd: look for "asSupport.dbd"
xxx/iocBoot/iocvxWorks/save_restore.cmd: the whole file
xxx/iocBoot/iocvxWorks/auto_positions.req: the whole file
xxx/iocBoot/iocvxWorks/auto_settings.req: the whole file
xxx/iocBoot/iocvxWorks/st.cmd: look for "save_restore.cmd" before the call to iocInit, and "create_monitor_set" after the call to iocInit.
xxx/iocBoot/iocvxWorks/autosave: a directory to hold autosave .sav files

Here's a step-by-step program for deploying autosave. Some of the steps are optional:

1. Build (required)

Build the module and include the resulting library, libautosave.a, and database-definition file, asSupport.dbd, in an IOC's build. For example, add

	AUTOSAVE=<path to the autosave module>

to xxx/configure/RELEASE, add

	xxx_LIBS += autosave

to xxxApp/src/Makefile, and add

	include "asSupport.dbd"

to iocxxxInclude.dbd.

2. Write request files (optional, though this is the most common use)

Create "request" files (e.g., auto_settings.req, auto_positions.req) specifying the PVs whose values you want to save and restore. The save files corresponding to these request files will have the ".req" suffix replaced by ".sav". Request files can include other request files (nested includes are allowed) and macro substitution can be performed on the included files (using William Lupton's macro library), with the following syntax:

	file <request_file> <macro-substitution_string>

e.g.,

	file motor_settings.req P=xxx:,M=m1

I've tried to defend against forseeable variations in syntax, so that include lines with embedded whitespace and/or quotes, macro strings without commas, empty macro strings, and lines with trailing comments will be parsed as one would want. Generally, quotes are ignored, whitespace implies a comma but otherwise is ignored, and everything after the second sequence of non-whitespace characters (i.e., after the file name) and before the (optional) comment character '#' is taken as the macro-substitution string. Macro substitution is performed on the entire line, so it's possible to parameterize names of included files, as well as PV names. It is also possible to define a macro that replaces its target with nothing.

Most synApps modules contain autosave-request files that are intended to be included in an ioc's autosave-request file(s). For example, calc/calcApp/Db/scalcout_settings.req contains a list of the fields one might want to autosave for a single scalcout record. This file is included in calc/calcApp/Db/userStringCalcs10_settings.req, which, in turn, is included in xxx/iocBoot/iocvxWorks/auto_settings.req.

Beginning with version 4.3, autosave can generate request files from info nodes contained in an EPICS database. See the function makeAutosaveFiles(), below, for more information on this topic.

Note: Beginning with synApps version 5.2.1, synApps contains software to generate autosave-request files from information contained in command and database files. See synApps/support/utils/makeAutosaveFiles.py.

3. Set request-file path (optional, recommended)

Specify one or more directories to be searched for request files, using one or more invocations of the function

	set_requestfile_path()

4. Set NFS host (optional, only available on vxWorks)

Specify the NFS host from which save files will be read at restore time, and to which they will be written at save time, by calling the function

	save_restoreSet_NFSHost()

When autosave manages its own NFS mount, as this command directs it to do, it can fix a stale file handle by dismounting and remounting the file system.

5. Use NFS (required on vxWorks)

Use NFS, preferably as described above, or by including an nfsMount() command in your startup script. Save_restore is only tested with NFS, and probably will not work with vxWorks' netDrv .

When autosave runs under operating systems other than vxWorks, it simply uses whatever mount the operating system, or a system administrator, has provided.

6. Set save-file path (optional, recommended)

Specify the directory in which you want save files to be written, by calling the function

	set_savefile_path()

in your startup script, before the create_xxx_set() commands, to specify the path to the directory. If you are using NFS (strongly recommended), ensure that the path does not contain symbolic links. In my experience, VxWorks cannot write through a symbolic link. (I don't understand all the ins and outs of this limitation. It may be that symbolic links are OK if they contain absolute path names.)

Beginning with autosave v4.3, you can also specify the path and/or filename, to which an autosave .sav file is to be written, with an EPICS PV. See the documentation of create_xxx_set() for details.

7. Give the ioc write permission to the autosave directory (required)

Give the IOC write permission to the directory in which the save files are to be written. If you forget this step, save_restore may be able to write save files, but the files will be corrupted because save_restore will not be permitted to change their lengths. Save_restore attempts to detect this condition, but cannot work around it if the file length must increase.

8. Specify restore files (optional, recommended)

Specify which save files are to be restored before record initialization (pass 0) and which are to be restored after record initialization (pass 1), using the commands

	set_pass0_restoreFile()
	set_pass1_restoreFile()

Place these commands in the startup file before iocInit. In versions earlier than 4.4, autosave would attempt to restore "auto_positions.sav" and "auto_settings.sav", if no restore files had been specified. Beginning with version 4.5, only files specified in calls to set_passn_restoreFile() are restored.

To disable boot-time restore completely, delete or comment out all set_passn_restoreFile() calls.

Notes on restore passes:

Link fields cannot be restored (by dbStatic calls) after record initialization. If you want save/restore to work for link fields you must specify them in a pass-0 file.
Device support code for the motor record uses the value of the field DVAL, restored during pass 0, only if the value read from the hardware is zero. If the value from hardware is nonzero, it is used instead of the restored value.
Arrays cannot be restored during pass 0.
Scalar PV's which have type DBF_NOACCESS in the .dbd file, and are set to some other DBF type during record initialization, cannot be restored during pass 0.
It is not an error to attempt to restore PV's during the wrong pass. The default strategy, implemented with auto_settings.req and auto_positions.req, is to use both passes for everything except PV's that shouldn't be restored in pass 1. (Motor positions aren't restored in pass 1 because doing so would overwrite any values read from the hardware.)

9. Load initHook routine (required)

Load a copy of initHooks that calls reboot_restore() to restore saved parameter values. The copy of initHooks included in this distribution is recommended. This will happen automatically if the ioc's executable is built as described above.

You can disable boot-time restore by refraining from loading the initHook routine, but this is not always practical. Another way to disable boot-time restore is described in step 8. Specify restore files, above.

10. Select save-file options (optional, recommended)

Tell save_restore to writed dated backup files. At boot time, the restore software writes a backup copy of the ".sav" file from which it restored PV's. This file can either be named xxx.sav.bu, and be rewritten every reboot, or named xxx.sav_YYMMDD-HHMMSS, where "YY..." is a date. Dated backups are not overwritten. If you want dated backup files, put the following line in your st.cmd file before the call toiocInit():
```
	save_restoreSet_DatedBackupFiles(1)
```
Note: If a save file is restored in both pass 0 and pass 1, the boot-backup file will be written only during pass 0.
Tell save_restore to save sequence files. The commands:
```
	save_restoreSet_NumSeqFiles(3)
	save_restoreSet_SeqPeriodInSeconds(600)
```
will cause save_restore to maintain three copies of each .sav file, at ten-minute intervals. Note: if autosave fails to write the .sav file, it will stop making sequence copies until it again succeeds.
Specify the time delay between a failed .sav-file write and the retry of that write. The default delay is 60 seconds. If list-PV's change during the delay, the new values will be written.
```
	save_restoreSet_RetrySeconds(60)
```

11. Start the save task (required)

Invoke the "save" part of this software as part of the EPICS startup sequence, by calling create_XXX_set() -- e.g., adding lines of the form

	create_monitor_set("auto_positions.req", 5, "P=xxx:")
	create_monitor_set("auto_settings.req", 30, "P=xxx:")

to your EPICS startup file after iocInit. You can call the files anything you want, but note that the file names "auto_positions" and "auto_settings" receive special treatment: they are default restore-file names specified by asInitHooks() if set_passN_restoreFile() were never called. The third argument to create_monitor_set() is a macro-substitution string, as described above in the discussion of request files (step 2). If supplied, this macro-substitution string supplements any macro strings supplied in include-file directives of request files read for this save set.

If you want to start the save task without also creating a save set, you can make the call create_monitor_set("", 0, "").

The macro string can also be used to override the default path and name to which the .sav file will be written. If the macro SAVEPATHPV=<pv-name> is included, autosave will write the .sav file to the path read from the EPICS PV <pv-name>, instead of writing to the path specified in set_savefile_path(). If the macro SAVENAMEPV=<pv-name> is included, autosave will write the .sav file to the filename read from the EPICS PV <pv-name>. (By default, the .sav file name is the request-file name, with .req replaced by .sav.)

NOTE: If either SAVEPATHPV or SAVENAMEPV occurs in the macro string, autosave will not attempt to save backup or sequence files for the save set.

For each create_monitor_set(<name>.req, <time>, <macro>) command, the save_restore process will write the files <name>.sav and <name>.savB every <time> seconds, if any of the PVs named in the file <name>.req have changed value since the last write. Other create_xxx_set() commands do the same thing, but with different conditions triggering the save operation.

Note that in versions prior to 2.7, create_monitor_set() used an argument of type double to specify the period (in seconds). This doesn't work on PowerPC processors, under vWorks, so the arguments for this and similar functions were changed to int.

If your IOC takes a really long time to boot, it's possible the PVs you want to save will not have the correct values when the save_restore task first looks at them. (If you are restoring lots of long arrays, this is even more likely.) Under vxWorks, you can avoid this by putting a

	taskDelay(<number_of_60_Hz_clock_ticks>)

before create_monitor_set().

12. Maintain save files

Autosave is not completely bulletproof. Most APS beamlines have at least one autosave related problem every year. If autosave fails, you might be able to detect it, or work around it, using asVerify. This client-side program reads an autosave .sav file and independently verifies that the values it contains agree with current PV values. The program can also be used to write a .sav file, given a list of PVs. The list of PVs is normally an autosave .sav file, but a file containing nothing but PV names, one per line, would also work. Here's asVerify's command line:

usage: asVerify [-vrd] <autosave_file>
         -v (verbose) causes all PV's to be printed out
             Otherwise, only PV's whose values differ are printed.
         -r (restore_file) causes a restore file named
            '<autosave_file>.asVerify' to be written.
         -d (debug) increment debug level by one.
         -rv (or -vr) does both
examples:
    asVerify auto_settings.sav
        (reports only PVs whose values differ from saved values)
    asVerify -v auto_settings.sav
        (reports all PVs, marking differences with '***'.)
    asVerify -vr auto_settings.sav
        (reports all PVs, and writes a restore file.)
    asVerify auto_settings.sav
    caput <myStatusPV> $?
        (writes number of differences found to a PV.)

NOTE: For the purpose of writing a restore file, you can specify a .req
file (or any file that contains PV names, one per line) instead of a
.sav file.  However, this program will misunderstand any 'file' commands
that occur in a .req file.  (It will look for a PV named 'file'.)

Note that asVerify cannot read an autosave request file; it will understand any PV names contained in the file, but it cannot parse the "file" command, perform macro substitutions, or include other request files.

About save files

PV values in a save file have been converted to strings, in most cases simply by having been read as strings -- e.g., ca_get(DBR_STRING,...). Most data types are read using channel access and written using dbStaticLib calls. Four data types get special attention:

double: read as double, converted to string with the format "%.14g". (Otherwise, the record's .PREC field would limit the precision.)
float: Same as double, but the format is "%.7g".
menu and enum: Menu and enum are integer data types with values restricted to the set (0,1,...N), where 'N' depends on the PV, but is usually 15 or smaller. EPICS associates a string with each number in the set, and permits clients to use either the number or the string. For menu PV's, the strings are specified in a .dbd file; for enum PV's, the strings can be specified in a database file, and they can be modified at run time.
Channel access does not distinguish these types, so neither does autosave. Autosave cannot write enums as strings, because enum strings may not have been defined at the time they must be restored.
arrays of any kind: Arrays are read and written using database access. Channel access cannot read only the defined portion of an array, dbStaticLib cannot write an array. (However, asVerify uses channel access to read arrays.)

Here is a sample save file. Characters in blue are documentation comments, and are not part of the file:

# save/restore V4.9	Automatically generated - DO NOT MODIFY - 060720-154526
! 1 channel(s) not connected - or not all gets were successful
xxx:SR_ao.DISP 0 (uchar)
xxx:SR_ao.PREC 1 (short)
xxx:SR_bo.IVOV 2 (ushort)
xxx:SR_ao.SCAN 3 (enum - saved/restored as a short)
xxx:SR_ao.VAL 4.1234567890123 (double, printed with format "%.14g")
xxx:SR_scaler.RATE 1.234568 (float, printed with format "%.7g")
xxx:SR_ao.DESC description (string)
xxx:SR_ao.OUT xxx:SR_bo.VAL NPP NMS (link)
xxx:SR_ao.RVAL 4 (long)
xxx:SR_bi.SVAL 2 (ulong)
#i_dont_exist.VAL Search Issued (no such PV)
xxx:SR_char_array @array@ { "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" }
xxx:SR_double_array @array@ { "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" }
xxx:SR_float_array @array@ { "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" }
xxx:SR_long_array @array@ { "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" }
xxx:SR_short_array @array@ { "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" }
xxx:SR_string_array @array@ { "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" }
xxx:SR_uchar_array @array@ { "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" }
xxx:SR_ulong_array @array@ { "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" }
xxx:SR_ushort_array @array@ { "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" }
<END>

Save files are not intended to be edited manually. If you, nevertheless, do edit a save file, you must end it with the text

<END>

followed by one or two arbitrary characters (normally '\n' or '\r\n'). If the file does not end with this text, reboot_restore() will assume the crate crashed while the file was being written, or that some other bad thing happened, and will not use the file. Once a save file has been created successfully, save_restore will not overwrite the file unless a good ".savB" backup file exists. Similarly, it will not overwrite the ".savB" file unless the save file was successfully written.

You can comment out lines in a .sav file by beginning them with '#'.

User-callable functions

int manual_save(char *request_file)

If a manual save set for the request file request_file was created with create_manual_set(), this command will cause current PV values to be saved.

int set_savefile_name(char *request_file, char *save_file)

If a save set has already been created for the request file, this function will change the save file name.

int create_periodic_set(char *request_file, int period, char *macrostring)

Create a save set for the request file. The save file will be written every period seconds.

See "Start the save task", above for information about the macro string.

This function can be called at any time after iocInit.

int create_triggered_set(char *request_file, char *trigger_channel, char *macrostring)

Create a save set for the request file. The save file will be written whenever the PV specified by trigger_channel is posted. Normally this occurs when the PV's value changes.

See "Start the save task", above for information about the macro string.

This function can be called at any time after iocInit.

int create_monitor_set(char *request_file, int period, char *macrostring)

Create a save set for the request file. The save file will be written every period seconds, if any PV in the save set was posted (changed value) since the last write.

See "Start the save task", above for information about the macro string.

This function can be called at any time after iocInit.

int create_manual_set(char *request_file, char *macrostring)

Create a save set for the request file. The save file will be written when the function manual_save() is called with the same request-file name.

See "Start the save task", above for information about the macro string.

This function can be called at any time after iocInit.

int fdbrestore(char *save_file)

If save_file refers to a save set that exists in memory, then PV's in the save set will be restored from values in memory. Otherwise, this functions restores the PV's in <saveRestorePath>/<save_file> and creates a new backup file "<saveRestorePath>/<save_file>.bu". The effect probably will not be the same as a boot-time restore, because caput() calls are used instead of static database access dbPutX() calls. Record processing will result from caput()'s to inherently process- passive fields.

This function can be called at any time after one of the create_*_set() functions have been called. If you want to call this function before creating any save sets, you can call create_*_set() with an empty request-file name. Autosave will complain about this, but it won't think you're a bad person.

int fdbrestoreX(char *save_file)

This function restores from the file <saveRestorePath>/<save_file>, which can look just like a save file, but which needn't end in <END>?. No backup file will be written. The effect probably will not be the same as a boot-time restore, because caput() calls are used instead of static database access dbPutX() calls. Record processing will result from caput()'s to inherently process-passive fields.

This function can be called at any time after one of the create_*_set() functions have been called. If you want to call this function before creating any save sets, you can call create_*_set() with an empty request-file name. Autosave will not hate you for doing this, though it will complain.

void save_restoreSet_FilePermissions(int permissions)

Specify the file permissions used to create new .sav files. This integer value will be supplied, exactly as given, to the system call, open(). Typically, file permissions are set with an octal number, such as 0640, and save_restoreSet_FilePermissions() will confirm any number given to it by echoing it to the console as an octal number.

This function can be called at any time after iocInit.

void save_restoreShow(int verbose)

List all the save sets currently being managed by the save_restore task. If (verbose != 0), lists the PV's as well.

This function can be called at any time after iocInit.

int set_requestfile_path(char *path, char *pathsub)

Called before create_xxx_set(), this function specifies the path to be prepended to request-file names. pathsub, if present, will be appended to path, if present, with a separating '/', whether or not path ends or pathsub begins with '/'. If the result does not end in '/', one will be appended to it.

You can specify several directories to be searched for request files by calling this routine several times. Directories will be searched in the order in which the set_requestfile_path() calls were made. If you never call the routine, the crate's current working directory will be searched. If you ever call it, the current directory ("./") will be searched only if you've asked for it explicitly.

int set_savefile_path(char *path, char *pathsub)

Called before iocInit(), this function specifies the path to be prepended to save-file and restore-file names. pathsub, if present, will be appended to path, if present, with a separating '/', whether or not path ends or pathsub begins with '/'. If the result does not end in '/', one will be appended to it.

If save_restore is managing its own NFS mount, this function specifies the mount point, and calling it will result in an NFS mount if all other requirements have already been met. If a valid NFS mount already exists, the file system will be dismounted and then mounted with the new path name. This function can be called at any time.

int set_saveTask_priority(int priority)

Set the priority of the save_restore task.

int remove_data_set(char *request_file)

If a save set has been created for request_file, this function will delete it.

int reload_periodic_set(char *request_file, int period, char *macrostring)

This function allows you to change the PV's and the period associated with a save set created by create_periodic_set().

int reload_triggered_set(char *request_file, char *trigger_channel, char *macrostring)

This function allows you to change the PV's and the trigger channel associated with a save set created by create_triggered_set().

int reload_monitor_set(char * request_file, int period, char *macrostring)

This function allows you to change the PV's and the period associated with a save set created by create_monitor_set().

int reload_manual_set(char * request_file, char *macrostring)

This function allows you to change the PV's associated with a save set created by create_manual_set().

Note: Don't get too ambitious with the remove/reload functions. You have to wait for one to finish completely (the save_restore task must get through its service loop) before executing another. If you call one before the previous function is completely finished, I don't know what will happen.

int reboot_restore(char *save_file, initHookState init_state)

This should only be called from initHooks because it can only function correctly if called at particular times during iocInit.

int set_pass0_restoreFile(char *save_file)

This function specifies a save file to be restored during iocInit, before record initialization. Up to eight files can be specified using calls to this function.

int set_pass1_restoreFile(char *save_file)

This function specifies a save file to be restored during iocInit, after record initialization. Up to eight files can be specified using calls to this function.

void save_restoreSet_Debug(int debug_level)

Sets the value (int) save_restoreDebug (initially 0). Increase to get more informational messages printed to the console.