Format (starrocks-bdb-je 18.3.17 API)

java.lang.Object
- com.sleepycat.persist.impl.Format

All Implemented Interfaces:

RawType, Serializable

Direct Known Subclasses:

ComplexFormat, CompositeKeyFormat, EnumFormat, ObjectArrayFormat, PrimitiveArrayFormat, ProxiedFormat, SimpleFormat
```
public abstract class Format
extends Object
implements RawType, Serializable
```
The base class for all object formats. Formats are used to define the stored layout for all persistent classes, including simple types. The design documentation below describes the storage format for entities and its relationship to information stored per format in the catalog. Requirements ------------ + Provides EntityBinding for objects and EntryBinding for keys. + Provides SecondaryKeyCreator, SecondaryMultiKeyCreator and SecondaryMultiKeyNullifier (SecondaryKeyNullifier is redundant). + Works with reflection and bytecode enhancement. + For reflection only, works with any entity model not just annotations. + Bindings are usable independently of the persist API. + Performance is almost equivalent to hand coded tuple bindings. + Small performance penalty for compatible class changes (new fields, widening). + Secondary key create/nullify do not have to deserialize the entire record; in other words, store secondary keys at the start of the data. Class Format ------------ Every distinct class format is given a unique format ID. Class IDs are not equivalent to class version numbers (as in the version property of @Entity and @Persistent) because the format can change when the version number does not. Changes that cause a unique format ID to be assigned are: + Add field. + Widen field type. + Change primitive type to primitive wrapper class. + Add or drop secondary key. + Any incompatible class change. The last item, incompatible class changes, also correspond to a class version change. For each distinct class format the following information is conceptually stored in the catalog, keyed by format ID. - Class name - Class version number - Superclass format - Kind: simple, enum, complex, array - For kind == simple: - Primitive class - For kind == enum: - Array of constant names, sorted by name. - For kind == complex: - Primary key fieldInfo, or null if no primary key is declared - Array of secondary key fieldInfo, sorted by field name - Array of other fieldInfo, sorted by field name - For kind == array: - Component class format - Number of array dimensions - Other metadata for RawType Where fieldInfo is: - Field name - Field class - Other metadata for RawField Data Layout ----------- For each entity instance the data layout is as follows: instanceData: formatId keyFields... nonKeyFields... keyFields: fieldValue... nonKeyFields: fieldValue... The formatId is the (positive non-zero) ID of a class format, defined above. This is ID of the most derived class of the instance. It is stored as a packed integer. Following the format ID, zero or more sets of secondary key field values appear, followed by zero or more sets of other class field values. The keyFields are the sets of secondary key fields for each class in order of the highest superclass first. Within a class, fields are ordered by field name. The nonKeyFields are the sets of other non-key fields for each class in order of the highest superclass first. Within a class, fields are ordered by field name. A field value is: fieldValue: primitiveValue | nullId | instanceRef | instanceData | simpleValue | enumValue | arrayValue For a primitive type, a primitive value is used as defined for tuple bindings. For float and double, sorted float and sorted double tuple values are used. For a non-primitive type with a null value, a nullId is used that has a zero (illegal formatId) value. This includes String and other simple reference types. The formatId is stored as a packed integer, meaning that it is stored as a single zero byte. For a non-primitive type, an instanceRef is used for a non-null instance that appears earlier in the data byte array. An instanceRef is the negation of the byte offset of the instanceData that appears earlier. It is stored as a packed integer. The remaining rules apply only to reference types with non-null values that do not appear earlier in the data array. For an array type, an array formatId is used that identifies the component type and the number of array dimensions. This is followed by an array length (stored as a packed integer) and zero or more fieldValue elements. For an array with N+1 dimensions where N is greater than zero, the leftmost dimension is enumerated such that each fieldValue element is itself an array of N dimensions or null. arrayValue: formatId length fieldValue... For an enum type, an enumValue is used, consisting of a formatId that identifies the enum class and an enumIndex (stored as a packed integer) that identifies the constant name in the enum constant array of the enum class format: enumValue: formatId enumIndex For a simple type, a simpleValue is used. This consists of the formatId that identifies the class followed by the simple type value. For a primitive wrapper type the simple type value is the corresponding primitive, for a Date it is the milliseconds as a long primitive, and for BigInteger or BigDecimal it is a byte array as defined for tuple bindings of these types. simpleValue: formatId value For all other complex types, an instanceData is used, which is defined above. Secondary Keys -------------- For secondary key support we must account for writing and nullifying specific keys. Rather than instantiating the entity and then performing the secondary key operation, we strive to perform the secondary key operation directly on the byte format. To create a secondary key we skip over other fields and then copy the bytes of the embedded key. This approach is very efficient because a) the entity is not instantiated, and b) the secondary keys are stored at the beginning of the byte format and can be quickly read. To nullify we currently instantiate the raw entity, set the key field to null (or remove it from the array/collection), and convert the raw entity back to bytes. Although the performance of this approach is not ideal because it requires serialization, it avoids the complexity of modifying the packed serialized format directly, adjusting references to key objects, etc. Plus, when we nullify a key we are going to write the record, so the serialization overhead may not be significant. For the record, I tried implementing nullification of the bytes directly and found it was much too complex. Lifecycle --------- Format are managed by a Catalog class. Simple formats are managed by SimpleCatalog, and are copied from the SimpleCatalog by PersistCatalog. Other formats are managed by PersistCatalog. The lifecycle of a format instance is: - Constructed by the catalog when a format is requested for a Class that currently has no associated format. - The catalog calls setId() and adds the format to its format list (indexed by format id) and map (keyed by class name). - The catalog calls collectRelatedFormats(), where a format can create additional formats that it needs, or that should also be persistent. - The catalog calls initializeIfNeeded(), which calls the initialize() method of the format class. - initialize() should initialize any transient fields in the format. initialize() can assume that all related formats are available in the catalog. It may call initializeIfNeeded() for those related formats, if it needs to interact with an initialized related format; this does not cause a cycle, because initializeIfNeeded() does nothing for an already initialized format. - The catalog creates a group of related formats at one time, and then writes its entire list of formats to the catalog DB as a single record. This grouping reduces the number of writes. - When a catalog is opened and the list of existing formats is read. After a format is deserialized, its initializeIfNeeded() method is called. setId() and collectRelatedFormats() are not called, since the ID and related formats are stored in serialized fields. - There are two modes for opening an existing catalog: raw mode and normal mode. In raw mode, the old format is used regardless of whether it matches the current class definition; in fact the class is not accessed and does not need to be present. - In normal mode, for each existing format that is initialized, a new format is also created based on the current class and metadata definition. If the two formats are equal, the new format is discarded. If they are unequal, the new format becomes the current format and the old format's evolve() method is called. evolve() is responsible for adjusting the old format for class evolution. Any number of non-current formats may exist for a given class, and are setup to evolve the single current format for the class.

Author:

Mark Hayes

See Also:

Serialized Form

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`allowEvolveFromProxy()` Currently, only FBigDec will return true.
`com.sleepycat.persist.impl.Accessor`	`getAccessor(boolean rawAccess)`
`ClassMetadata`	`getClassMetadata()` Returns the original model class metadata used to create this class, or null if this is not a model class.
`String`	`getClassName()` Returns the class name for this type in the format specified by `Class.getName()`.
`Format`	`getComponentType()` Returns the array component type, or null if this is not an array type.
`int`	`getDimensions()` Returns the number of array dimensions, or zero if this is not an array type.
`EntityMetadata`	`getEntityMetadata()` Returns the original model entity metadata used to create this class, or null if this is not an entity class.
`List<String>`	`getEnumConstants()` Returns an unmodifiable list of the names of the enum instances, or null if this is not an enum type.
`Map<String,RawField>`	`getFields()` Returns a map of field name to raw field for each non-static non-transient field declared in this class, or null if this is not a complex type (in other words, this is a simple type or an array type).
`int`	`getId()` Returns the format ID.
`String`	`getOldKeyName(String keyName)` For an entity class or subclass, returns the old key name for the given key name that has been renamed, or returns the given key name if it has not been renamed.
`Format`	`getPreviousVersion()` Returns the previous version of this format in the linked list of versions, or null if this is the only version.
`Format`	`getSuperType()` Returns the type of the superclass, or null if the superclass is Object or this is not a complex type (in other words, this is a simple type or an array type).
`int`	`getVersion()` Returns the class version for this type.
`void`	`initializeReader(com.sleepycat.persist.impl.Catalog catalog, EntityModel model, int initVersion, Format oldFormat)` Called to initialize a separate Reader implementation.
`boolean`	`isArray()` Returns whether this is an array type.
`boolean`	`isDeleted()` Returns whether the class for this format was deleted.
`boolean`	`isEnum()` Returns whether this is an enum type.
`boolean`	`isPrimitive()` Returns whether this type is a Java primitive: char, byte, short, int, long, float or double.
`boolean`	`isSimple()` Returns whether this is a simple type: primitive, primitive wrapper, BigInteger, BigDecimal, String or Date.
`abstract Object`	`newInstance(EntityInput input, boolean rawAccess)` Creates a new instance of the target class using its default constructor.
`abstract Object`	`readObject(Object o, EntityInput input, boolean rawAccess)` Called after newInstance() to read the rest of the data bytes and fill in the object contents.
`void`	`readPriKey(Object o, EntityInput input, boolean rawAccess)` Reads the primary key from the given input bytes and sets the primary key field in the given object.
`String`	`toString()` Returns an XML representation of the raw type.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Method Detail
  - getId
```
public final int getId()
```
    Returns the format ID.
    
    Specified by:
    
    getId in interface RawType
    
    Returns:
    
    the ID.
  - getPreviousVersion
```
public final Format getPreviousVersion()
```
    Returns the previous version of this format in the linked list of versions, or null if this is the only version.
  - isDeleted
```
public final boolean isDeleted()
```
    Returns whether the class for this format was deleted.
    
    Specified by:
    
    isDeleted in interface RawType
    
    Returns:
    
    whether this type has been deleted.
  - initializeReader
```
public void initializeReader(com.sleepycat.persist.impl.Catalog catalog,
                             EntityModel model,
                             int initVersion,
                             Format oldFormat)
```
    Called to initialize a separate Reader implementation. This method is called when no separate Reader exists, and does nothing.
  - getClassName
```
public String getClassName()
```
    Description copied from interface: RawType
    
    Returns the class name for this type in the format specified by Class.getName().
    If this class currently exists (has not been removed or renamed) then the class name may be passed to Class.forName(java.lang.String) to get the current Class object. However, if this raw type is not the current version of the class, this type information may differ from that of the current Class.
    
    Specified by:
    
    getClassName in interface RawType
    
    Returns:
    
    the class name.
  - getVersion
```
public int getVersion()
```
    Description copied from interface: RawType
    
    Returns the class version for this type. For simple types, zero is always returned.
    
    Specified by:
    
    getVersion in interface RawType
    
    Returns:
    
    the version.
    
    See Also:
    
    Entity.version(), Persistent.version()
  - getSuperType
```
public Format getSuperType()
```
    Description copied from interface: RawType
    
    Returns the type of the superclass, or null if the superclass is Object or this is not a complex type (in other words, this is a simple type or an array type).
    
    Specified by:
    
    getSuperType in interface RawType
    
    Returns:
    
    the type of the superclass, or null.
  - isSimple
```
public boolean isSimple()
```
    Description copied from interface: RawType
    
    Returns whether this is a simple type: primitive, primitive wrapper, BigInteger, BigDecimal, String or Date.
    If true is returned, RawType.isPrimitive() can be called for more information, and a raw value of this type is represented as a simple type object (not as a RawObject).
    
    If false is returned, this is a complex type, an array type (see RawType.isArray()), or an enum type, and a raw value of this type is represented as a RawObject.
    
    Specified by:
    
    isSimple in interface RawType
    
    Returns:
    
    whether this is a simple type.
  - isPrimitive
```
public boolean isPrimitive()
```
    Description copied from interface: RawType
    
    Returns whether this type is a Java primitive: char, byte, short, int, long, float or double.
    If true is returned, this is also a simple type. In other words, primitive types are a subset of simple types.
    
    If true is returned, a raw value of this type is represented as a non-null instance of the primitive type's wrapper class. For example, an int raw value is represented as an Integer.
    
    Specified by:
    
    isPrimitive in interface RawType
    
    Returns:
    
    whether this is a Java primitive.
  - isEnum
```
public boolean isEnum()
```
    Description copied from interface: RawType
    
    Returns whether this is an enum type.
    If true is returned, a value of this type is a RawObject and the enum constant String is available via RawObject.getEnum().
    
    If false is returned, then this is a complex type, an array type (see RawType.isArray()), or a simple type (see RawType.isSimple()).
    
    Specified by:
    
    isEnum in interface RawType
    
    Returns:
    
    whether this is a enum type.
  - getEnumConstants
```
public List<String> getEnumConstants()
```
    Description copied from interface: RawType
    
    Returns an unmodifiable list of the names of the enum instances, or null if this is not an enum type.
    
    Specified by:
    
    getEnumConstants in interface RawType
    
    Returns:
    
    the list of enum names.
  - isArray
```
public boolean isArray()
```
    Description copied from interface: RawType
    
    Returns whether this is an array type. Raw value arrays are represented as RawObject instances.
    If true is returned, the array component type is returned by RawType.getComponentType() and the number of array dimensions is returned by RawType.getDimensions().
    
    If false is returned, then this is a complex type, an enum type (see RawType.isEnum()), or a simple type (see RawType.isSimple()).
    
    Specified by:
    
    isArray in interface RawType
    
    Returns:
    
    whether this is an array type.
  - getDimensions
```
public int getDimensions()
```
    Description copied from interface: RawType
    
    Returns the number of array dimensions, or zero if this is not an array type.
    
    Specified by:
    
    getDimensions in interface RawType
    
    Returns:
    
    the number of array dimensions, or zero if this is not an array type.
  - getComponentType
```
public Format getComponentType()
```
    Description copied from interface: RawType
    
    Returns the array component type, or null if this is not an array type.
    
    Specified by:
    
    getComponentType in interface RawType
    
    Returns:
    
    the array component type, or null if this is not an array type.
  - getFields
```
public Map<String,RawField> getFields()
```
    Description copied from interface: RawType
    
    Returns a map of field name to raw field for each non-static non-transient field declared in this class, or null if this is not a complex type (in other words, this is a simple type or an array type).
    
    Specified by:
    
    getFields in interface RawType
    
    Returns:
    
    a map of field name to raw field, or null.
  - getClassMetadata
```
public ClassMetadata getClassMetadata()
```
    Description copied from interface: RawType
    
    Returns the original model class metadata used to create this class, or null if this is not a model class.
    
    Specified by:
    
    getClassMetadata in interface RawType
    
    Returns:
    
    the model class metadata, or null.
  - getEntityMetadata
```
public EntityMetadata getEntityMetadata()
```
    Description copied from interface: RawType
    
    Returns the original model entity metadata used to create this class, or null if this is not an entity class.
    
    Specified by:
    
    getEntityMetadata in interface RawType
    
    Returns:
    
    the model entity metadata, or null.
  - newInstance
```
public abstract Object newInstance(EntityInput input,
                                   boolean rawAccess)
                            throws RefreshException
```
    Creates a new instance of the target class using its default constructor. Normally this creates an empty object, and readObject() is called next to fill in the contents. This is done in two steps to allow the instance to be registered by EntityInput before reading the contents. This allows the fields in an object or a nested object to refer to the parent object in a graph. Alternatively, this method may read all or the first portion of the data, rather than that being done by readObject(). This is required for simple types and enums, where the object cannot be created without reading the data. In these cases, there is no possibility that the parent object will be referenced by the child object in the graph. It should not be done in other cases, or the graph references may not be maintained faithfully. Is public only in order to implement the Reader interface. Note that this method should only be called directly in raw conversion mode or during conversion of an old format. Normally it should be called via the getReader method and the Reader interface.
    
    Throws:
    
    RefreshException
  - readObject
```
public abstract Object readObject(Object o,
                                  EntityInput input,
                                  boolean rawAccess)
                           throws RefreshException
```
    Called after newInstance() to read the rest of the data bytes and fill in the object contents. If the object was read completely by newInstance(), this method does nothing. Is public only in order to implement the Reader interface. Note that this method should only be called directly in raw conversion mode or during conversion of an old format. Normally it should be called via the getReader method and the Reader interface.
    
    Throws:
    
    RefreshException
  - readPriKey
```
public void readPriKey(Object o,
                       EntityInput input,
                       boolean rawAccess)
                throws RefreshException
```
    Reads the primary key from the given input bytes and sets the primary key field in the given object. This is complement of writePriKey(). Is public only in order to implement the Reader interface. Note that this method should only be called directly in raw conversion mode or during conversion of an old format. Normally it should be called via the getReader method and the Reader interface.
    
    Throws:
    
    RefreshException
  - getOldKeyName
```
public String getOldKeyName(String keyName)
```
    For an entity class or subclass, returns the old key name for the given key name that has been renamed, or returns the given key name if it has not been renamed.
  - allowEvolveFromProxy
```
public boolean allowEvolveFromProxy()
```
    Currently, only FBigDec will return true. It is a workaround for reading the BigDecimal data stored by BigDecimal proxy before je4.1.
  - getAccessor
```
public com.sleepycat.persist.impl.Accessor getAccessor(boolean rawAccess)
```
  - toString
```
public String toString()
```
    Description copied from interface: RawType
    
    Returns an XML representation of the raw type.
    
    Specified by:
    
    toString in interface RawType
    
    Overrides:
    
    toString in class Object

Class Format

Method Summary

Methods inherited from class java.lang.Object

Method Detail

getId

getPreviousVersion

isDeleted

initializeReader

getClassName

getVersion

getSuperType

isSimple

isPrimitive

isEnum

getEnumConstants

isArray

getDimensions

getComponentType

getFields

getClassMetadata

getEntityMetadata

newInstance

readObject

readPriKey

getOldKeyName

allowEvolveFromProxy

getAccessor

toString