V4 Design: IocRecord

EPICS V4: IocRecord

September 15 2005

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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:

1. V3 iocCore
2. V4 Design: Record Processing
3. V4 Design: dbdInterfaces
4. V4 Design: Runtime interfaces

Unless the reader is familiar with these most of this document will be very difficult to understand.

Java is used as the example code for two reasons:

1. 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.
2. Java provides facilities that make it easy to handle strings, arrays, and structures.

An implementaion of IocRecordSupport is presented for two reasons:

1. It demonstrates how to implement code that uses or implements the interface described in "V4 Design: dbdInterfaces" and "V4 Design: Runtime interfaces".
2. It helps refine the interfaces described in them

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Database Definitions

dbCommon.dbd defines the following:

    # menu definitions for IocRecord 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(MonitorLink) {
        field(pvname,string) { link}
        field(process,bool) // process this record when monitor occurs
        field(inheritSeverity,bool) 
    }
    struct(InputLink) {
        field(pvname,string) { link}
        field(parallel,bool)
        field(process,bool)
        field(wait,bool)
        field(inheritSeverity,bool)
    }
    struct(OutputLink) {
        field(pvname,string) { link}
        field(parallel,bool)
        field(process,bool)
        field(wait,bool)
        field(inheritSeverity,bool)
    }
    struct(ProcessLink) {
        field(pvname,string) { link}
        field(parallel,bool)
        field(wait,bool)
    }

    link(in,"MonitorLink",MonitorLink);
    link(in,"InputLink",InputLink);
    link(out,"OutputLink",OutputLink);
    link(process,"ProcessLink",ProcessLink);

    #definitions for common properties
    struct(TimeStamp) {
        field(secondsPastEpoch,int64)
        field(nanoSeconds,int32)
    }

    struct Scan {
        field(scan,menu(menuScan)) {
            special(yes)
        }
        field(phase,int16)
        field(priority,menu(menuPriority)) {
            special(yes)
        }
    }

Event NEEDS NEW DEFINITIONS

    struct Event {
        field(eventNumber,int16) {
            special(yes)
        }
        field(timeStampEvent,int16)
        field(timeStampLink,link(in))
    }

---

dbCommon.java

Link support must register for each of the link definitions.

From dbCommon.dbd the following class implementations are generated:

• For the link structures:
  • MonitorLink and MonitorLinkData, and MonitorLinkSupport
  • InputLink, InputLinkData, and InputLinkSupport
  • OutputLink, OutputLinkData, and OutputLinkSupport
  • ProcessLink, ProcessLinkData, and ProcessLinkSupport
• For TimeStamp
  • TimeStamp, TimeStampData, and TimeStampSupport
• For Scan
  • Scan, ScanData, and ScanSupport

See "V4 Design: Runtime interfaces" for an example of how these classes are defined.

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iocRecord.dbd

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.

Implementations of Disable, DisableData, and DisableDataSupport are automatically generated.

An implementations of IocRecord is also generated. See "V4 Design: Runtime interfaces" for an example of the generated classes.

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iocRecordSupport.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 IocRecordSupport.

processLink

This is an array of process links, which replace the V3 FLNK

The following subsection contains the complete code for IocRecordSupport.java. The remaining subsections discuss each part of the code.

IocCommon.java

This defines

    interface Common {
        bool setSeverity(AlarmSeverity severity, string status);
    }

IocRecordSupport.java

    enum Mode {modeNone,modeInput,modeOutput};
    
    public class IocRecordSupport extends RecordSupport
    implements Callback, Common  {
        private RecordInstance instance;
        private Mode           mode;
        private Input          input;
        private Output         output;
        private Alarm          alarm;
        private bool           requestProcess;
    
        // Constructor
        public IocRecordSupport(RecordInstance instance) {
            this.instance = instance;
        }
    
        // Beginning of RecordSupport
        public initialize(int pass) {
            if(pass==0) return;
            input.init(instance);
            output.init(instance);
            alarm.init(instance);
        }
        public destroy() {} // destroy not needed for Java

        public processState process(processState state) {
            switch(state) {
            case processCancel: mode = modeNone; return processDone;
            case processStart: {
                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;
            }
        }

        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: {
                    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");
            }
        }

        // Start of Callback methods
        public void done() {
            lock(instance);
            switch(mode) {
            case modeNone:
                 unlock(instance)
                 throw java.lang.IllegalStateException;
            case modeInput:
                if(requestProcess) {
                    requestProcess = false;
                    DbAccess.process(instance);
                }
                break;
            case modeOutput:
                output.numberLinksActive--;
                if(output.numberLinksActive==0 && requestProcess) {
                    requestProcess = false;
                    DbAccess.process(instance); 
                }
                if(output.numberLinksActive==0 && requestProcess)
                break;
            }
            unlock(instance)
        }
        public void failure() { done(); }

        // 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;
        }
    }
    
    // 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;
            }
        }
    }

    // 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);
            }
        }
    }

    // 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");
        }
    }

Beginning of class definition

    enum Mode {modeNone,modeInput,modeOutput};
    
    public class IocRecordSupport extends RecordSupport
    implements Callback, Common  {
        private RecordInstance instance;
        private Mode           mode;
        private Input          input;
        private Output         output;
        private Alarm          alarm;
        private bool           requestProcess;
    
        // Constructor
        public IocRecordSupport(RecordInstance instance) {
            this.instance = instance;
        }

IocRecordSupport 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. IocRecordSupport 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 IocRecordSupport.
• Each makes fields available to IocRecordSupport.
• 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 IocRecordSupport.

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.

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 processDone;
            case processStart: {
                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: {
                    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() {
            lock(instance);
            switch(mode) {
            case modeNone:
                unlock(instance);
                throw java.lang.IllegalStateException;
            case modeInput:
                if(requestProcess) {
                    requestProcess = false;
                    DbAccess.process(instance);
                }
                break;
            case modeOutput:
                output.numberLinksActive--;
                if(output.numberLinksActive==0 && requestProcess) {
                    requestProcess = false;
                    DbAccess.process(instance); 
                }
                return;
            }
            unlock(instance);
        }
        public void failure() { 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 IocRecordSupport. 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 IocRecordSupport. 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 IocRecordSupport. 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");
        }
    }
    

IocRecordSupportFactory

This is the factory for creating an IocRecordSupport. It is called by dbLoadRecords.

    public class IocRecordSupportFactory implements RecordSupportFactory{
        RecordSupport create(RecordInstance instance) {
            return new IocRecordSupport(instance);
        }
        void destroy(RecordSupport support) {
            IocRecordSupport iocRecordSupport = support;
            iocRecordSupport.destroy();
        }
    }

    public final class IocRecordSupportFactoryRegister {
        static public createAndRegister() {
            IocRecordSupportFactory factory = new IocRecordSupportFactory;
            RegisterSupport.record(factory,"IocRecord");
        }
    }

Question Who calls IocRecordSupportFactoryRegister.createAndRegister?