V4 Design: IocRecord
EPICS V4: IocRecord
August 30 2005
This document describes the V4 implementation of what was provided by the V3 dbCommon. It provides the Java version of code that implements the functionality.
For V4 dbCommon.dbd and IocRecord.dbd replace the V3 dbCommon.dbd. dbCommon.dbd define widely used definitions and IocRecord.dbd defines the fields that are common to all record types.
This document describes the following:
- Database Definition Files
- The database definition files for dbCommon.dbd and iocRecord.dbd. Together these are the replacement for the V3 dbCommon.
- Java code generated from the database definitions.
- The automatically generated code from dbCommon.dbd and iocRecord.dbd
- Java code that implements iocRecord.
- A proposed implementation of iocRecord.
This document requires that the reader be familiar with:
- V3 iocCore
- V4 Design: Record Processing
- V4 Design: dbdInterfaces
Unless the reader is familiar with all three, most of this document will be very difficult to understand.
Java is used as the example code for two reasons:
- For V4 iocCore it is intended that both C++ and Java implementations will be provided. Since V3 is only implemented in C and C++ the Java implemention of V4 is described first to make sure that the interfaces defined in dbdInterfaces will work for Java.
- Java provides facilities that make it easy to handle strings, arrays, and structures.
An implementaion of IocRecordInterface is presented for two reasons:
- It demonstrates how to implement code that uses or implements the interface described in "V4 Design: dbdInterfaces".
- It helps refine the interfaces described in "V4 Design: dbdInterfaces".
Database Definitions
dbCommon.dbd defines the following:
# menu definitions for dbRecordCommon fields
menu(menuPriority) {
choice(menuPriorityLow, "Low")
choice(menuPriorityMedium, "Medium")
choice(menuPriorityHigh, "High")
}
menu(menuScan) {
choice(menuScanPassive, "Passive")
choice(menuScanEvent, "Event")
choice(menuScanInterrupt, "Interrupt")
choice(menuScan10second, "10 second")
choice(menuScan5second, "5 second")
choice(menuScan2second, "2 second")
choice(menuScan1second, "1 second")
choice(menuScan_5second, ".5 second")
choice(menuScan_2second, ".2 second")
choice(menuScan_1second, ".1 second")
}
menu(menuAlarmSevr) {
choice(menuAlarmSevrNone, "None")
choice(menuAlarmSevrMinor, "Minor")
choice(menuAlarmSevrMajor, "Major")
choice(menuAlarmSevrInvalid, "Invalid")
}
menu(menuConvert) {
choice(menuConvertRaw, "Raw")
choice(menuConvertLinear, "Linear")
choice(menuConvertTable, "Table")
}
struct(Link) {
field(pvname,string) { link}
field(forceCA,bool)
field(parallel,bool)
field(process,bool)
field(wait,bool)
field(inheritSeverity,bool)
}
link(any,"StandardLinkSupport,Link);
#definitions for common properties
struct(TimeStamp) {
field(secPastEpoch,uint64)
field(nanoSeconds,uint32)
}
struct Scan {
field(scan,menu(menuScan)) {
special(yes)
}
field(phase,int16)
field(priority,menu(menuPriority)) {
special(yes)
}
}
THIS NEEDS NEW DEFINITIONS
// ???? Does IocRecord do anything for Event
struct Event {
field(eventNumber,int16) {
special(yes)
}
field(timeStampEvent,int16)
field(timeStampLink,link(in))
}
dbCommon.java
This file is automatically generated from dbCommon.dbd
class LinkData {
public String pvname;
public bool forceCA;
public bool parallel;
public bool process;
public bool wait;
public bool inheritSeverity;
}
public final class LinkAccess {
public static final void get(DbfStruct dbf, LinkData data);
public static final void put(DbfStruct dbf, LinkData data);
}
class TimeStampData {
public long secPastEpoch;
public int nanoSeconds;
}
public final class TimeStampAccess {
public static final void get(DbfStruct dbf, TimeStampData data);
public static final void put(DbfStruct dbf, TimeStampData data);
}
class ScanData {
public DbfMenu scan;
public short phase;
public DbfMenu priority;
}
class ScanAccess {
public static final void get(DbfStruct dbf, ScanData data);
public static final void put(DbfStruct dbf, ScanData data);
}
// also definition for EventData and EventAccess
IocRecord.dbd must be part of every record, and defines the following:
struct Disable {
field(disableValue,int16) {
default("1")
}
field(disableInput,int16)
field(disableLink,link(in))
field(disableAlarmSeverity,menu(menuAlarmSevr))
}
record(IocRecord) {
field(description,string)
field(scan,struct(Scan))
field(accessSecurityGroup,string)
field(pini,bool)
field(disablePutField,bool)
field(alarmAckSeverity,menu(menuAlarmSevr)) {
design(no)
readonly(yes)
}
field(alarmAckTransient,bool) {
readonly(yes)
default("YES")
}
field(udf,bool) {
dynamic(yes)
default("1")
}
field(time,struct(timeStamp)) {
design(no)
dynamic(yes)
readonly(yes)
}
field(disable,struct(Disable)) {
special(yes)
}
field(alarmStatus,string) {
default("UDF")
}
field(alarmSeverity,menu(menuAlarmSevr)) {
readonly(yes)
default("Invalid")
}
field(processLink,array([] struct(Link))) {
special(yes)
}
}
Although it has many fewer fields, iocRecord.dbd is a complete replacement for the V3 dbCommon. The following V3 fields are no longer needed:
- private fields - Private fields will truly be privaye to the implementation
- previous value fields - All puts to database fields will be posted. The layer above will decide if clients should be notified of changes.
iocRecord.java
This file is automatically generated from iocRecord.dbd
class Disable {
public DbfInt16 disableValue;
public DbfInt16 disableInput;
public DbfLink disableLink;
public DbfMenu disableAlarmSeverity;
public static final int16 disableValueIndex = 1;
public static final int16 disableInputIndex = 2;
public static final int16 disableLinkIndex = 3
public static final int16 disableAlarmSeverityIndex = 4;
public static final int16 lastIndex = disableAlarmSeverityIndex
}
class DisableData {
public short disableValue;
public short disableInput;
public short disableLink;
public DbfLink disableLink;
public DbfMenu disableAlarmSeverity;
}
class DisableAccess {
public static final get(Dbf dbf, DisableData data);
public static final put(Dbf dbf, DisableData data);
}
class IocRecord {
public DbfString description;
public DbfStruct scan;
public DbfString accessSecurityGroup;
public DbfBool pini;
public DbfBool disablePutField;
public DbfMenu alarmAckSeverity;
public DbfBool alarmAckTransient;
public DbfBool udf;
public DbfStruct time;
public DbfStruct disable;
public DbfString alarmStatus;
public DbfMenu alarmSeverity;
public DbfArray processLink;
public static final int16 description = 1;
...
public static final int16 processLinkIndex = 13;
public static final int16 lastIndex = processLinkIndex;
};
interface Common
In addition to implementing code that handles the fields in iocRecord.dbd, iocRecord implements the following interface:
interface Common {
bool setSeverity(AlarmSeverity severity, string status);
}
iocRecordInterface.java
Overview
This section describes the java implementation of iocRecord functionality. This code handles processing of the following fields of IocRecord:
- disable
- Decides if the record is disabled.
- alarmStatus and alarmSeverity
- The only way to change alarmStatus and alarmSeverity is via interface Common, which is implemented by IocRecordInterface.
- processLink
- This is an array of process links, which replace the V3 FLNK
Beginning of class definition
enum Mode {modeNone,modeInput,modeOutput};
public class IocRecordInterface extends RecordSupport, Callback, Common {
private RecordInstance instance;
private Mode mode;
private Input input;
private Output output;
private Alarm alarm;
private bool requestProcess;
// Constructor
public IocRecordInterface(RecordInstance instance) {
this.instance = instance;
}
IocRecordInterface implements the following interfaces:
- RecordSupport
- Record support for the fields in IocRecord.
- Callback
- The callbacks called by link support
- Common
- For now this just has the method setSeverity
It has the following private fields:
- instance - The record instance to which it is attached. IocRecordInterface has a single constructor which is passed the RecordInstance to which it is attached.
- mode - This keeps the state for record processing:
- modeNone - The record is not being processed.
- modeInput - The disable link is active but not complete.
- modeOutput - The processLinks are active but not complete.
- input - Input is a private class that provides access to the fields of disable.
- output - Output is a private class that provides access to processLink.
- alarm - Alarm is a private class that provides access to fields alarmSeverity and alarmStatus.
- requestProcess - This is used by callback to decide if a request should be made to process the record.
Notes about Input, Output, and Alarm. Each of these is a private class to IocRecordInterface. Each makes fields available to IocRecordInterface. Each has "introspection" code that gets the values of the private fields from IocRecord fields during record initialization of if the an IocRecord fields is changed via a call to Dbf.put. The implementations of each of these private classes is given after the implementaion of IocRecordInterface.
RecordSupport
initialize
// Beginning of RecordSupport
public initialize(int pass) {
if(pass==0) return;
input.init(instance);
output.init(instance);
alarm.init(instance);
}
During the first pass of initialization, nothing needs to be done. Before initialize is called on pass 1, iocInit has already called link support so that it connects. Initialize just calls its private class init methods. They get the current values of their private fields.
destroy
public destroy() {} // destroy not needed for Java
Since Java does garbage collection destroy is not needed. Note that iocCore will call all the link support destroy methods.
process
process is called by dbProcess at the beginning of record processing and after the record specific record support completes. During the beginning of record processing process takes care of field disable During the end of record processing process takes care of field processLink<./b>.
A few features of process are:
- implements a state machine that handles the links.
- interacts with Callback, which is called by link support when links complete.
- interacts with special, which is called when fields in IocRecord are modified.
public processState process(processState state) {
switch(state) {
case processCancel: mode = modeNone; return;
case processIdle: {
mode = modeInput;
requestProcess = false;
LinkWaitResult result = input.disableSupport.getWait(
input.disableInput,0.0,this);
if(result==linkNoop || result==linkDone) return processDone;
requestProcess = true;
}
// fall through to processInputActive
case processInputActive: {
if(requestProcess) return processInputActive;
if(input.disable.disableValue == disable.disableInput)
return processDone;
return processActive;
}
case processDone: {
mode = modeOutput;
output.nextLink = 0;
output.numberLinksActive = 0;
}
// fall through to processOutputActive
case processOutputActive:
LinkWaitResult result = linkWaitParallel;
requestProcess = false;
while(output.nextLink< output.link.length) {
if(result==linkWaitSequential) break;
result = output.link[nextLink].support.processWait(0.0,this);
if(result==linkWaitSequential || result==linkWaitParallel)
output.numberLinksActive++
output.nextLink++;
}
if(output.numberLinksActive==0) {
mode = modeNone;
return processDone;
}
requestProcess = true;
return processOutputActive;
default: throw java.lang.IllegalStateException;
}
}
special
special is called when any of the fields in disable, alarmStatus, alarmSeverity, or processLink are changed.
public bool special(bool after,Dbf[] field) {
int nlevels = field.length;
assert(nlevels>0);
if(index==alarmStatusIndex || index==alarmSeverityIndex) {
if(!alarm.modifyingAlarm) return false;
return true;
}
if(!after) return;
switch(index) {
case disableIndex : input.init(instance); break;
case disableIndex: {
if(nlevels==1) {
input.init(instance);
} else {
input.special(instance,Dbf[1]);
}
break;
}
case processLinkIndex : output.init(instance); break;
default: printf("Why is special being called?\n");
}
}
Callback methods
These are the callback methods that are called by link support.
// Start of Callback methods
public void done() {
switch(mode) {
case modeNone: throw java.lang.IllegalStateException;
case modeInput:
if(requestProcess) DbAccess.process(instance);
requestProcess = false;
return;
case modeOutput:
output.numberLinksActive--;
if(output.numberLinksActive==0 && requestProcess)
DbAccess.process(instance);
return;
}
}
public void timedout() { done(); }
Common methods
For now the only method is setSeverity, The only way code can change severity and status is to call this method.
// Start of Common methods
bool setSeverity(AlarmSeverity severity, string status) {
Alarm alarm = this.alarm;
if(severity<= alarm.severity) return false;
alarm.severity = severity;
alarm.status = status;
alarm.modifyingAlarm = true;
alarm.alarmSeverity.putIndex(severity);
alarm.alarmStatus.put(status);
alarm.modifyingAlarm = false;
}
}
Input
This is a private class for IocRecordInterface. It directly accesses the fields in this class. The init and special methods are called to get values for the private fields.
// Definitions for modeInput
class Input {
DisableData disable;
LinkSupport disableSupport;
DbfInt16 disableInput;
DbfInt16 disableValue;
DbfInt16 alarmSeverity;
void init(RecordInstance instance) {
RecordAccess recordAccess = instance.getIocRecordAccess();
DbfLink link = recordAccess.getField("disable.disableLink");
disableSupport = link.getSupport();
DisplayLimitAccess.get(
recordAccess.getField("disable"),disable);
recordAccess.getField("disable.disableInput",disableInput);
}
void special(RecordInstance instance,Dbf field) {
int16 index = Dbf.getIndex();
switch(index) {
case disableValueIndex:
disableValue = ((DbfInt16)Dbf).get(); break;
case disableInputIndex:
disableInput = ((DbfInt16)Dbf).get(); break;
case disableAlarmSeverityIndex:
alarmSeverity = ((dbfMenu)Dbf).getIndex(); break;
case disableLinkIndex:
init(instance); break;
default:
throw java.lang.IllegalStateException;
}
}
}
OutputLink and Output
Output is a private class for IocRecordInterface. It directly accesses the fields in this class. The init method is called to get values for the private fields. OutputLink is used by Output.
// Definitions for modeOutput
class OutputLink {
Link link;
LinkSupport support;
void init(RecordInstance instance,String linkFieldName) {
RecordAccess recordAccess = instance.getIocRecordAccess();
DbfLink link = recordAccess.getField(linkFieldName);
support = link.getSupport();
}
};
class Output {
int nextLink;
int numberLinksActive;
OutputLink[] link;
void init(RecordInstance instance) {
RecordAccess recordAccess = instance.getIocRecordAccess();
DbfArray array = recordAccess.getField("processLink");
int n = array.getNelements();
link = new OutputLink[n];
for(i=0; i< n; i++) {
String field = "processLink[" + "i" + "]";
link[i].init(instance,field);
}
}
}
Alarm
This is a private class for IocRecordInterface. It directly accesses the fields in this class. The init method is called to get values for the private fields.
// Definitions for alarm handling
class Alarm {
short severity;
String status;
DbfMenu alarmSeverity;
DbfString alarmStatus;
bool modifyingAlarm;
void init(RecordInstance instance) {
RecordAccess recordAccess = instance.getIocRecordAccess();
alarmSeverity = recordAccess.getField("alarmSeverity");
alarmStatus = recordAccess.getField("alarmStatus");
}
}
IocRecordFactory
This is the factory for creating an IocRecordInterface. It is called by dbLoadRecords.
public final class IocRecordFactory implements RecordFactor {
RecordSupport create(RecordInstance instance) {
return new IocRecordInterface(instance);
}
void destroy(RecordSupport support) {
IocRecordInterface iocRecordInterface = support;
iocRecordInterface.destroy();
}
}
Question: How does IocRecordFactory get registered?
