MemoryManager (Jikes RVM API)

java.lang.Object
- org.jikesrvm.mm.mminterface.MemoryManager

```
public final class MemoryManager
extends Object
```
The interface that the MMTk memory manager presents to Jikes RVM

Field Summary

Fields
Modifier and Type	Field and Description
`private static boolean`	`booted` Has the interface been booted yet?
`private static boolean`	`CHECK_MEMORY_IS_ZEROED` `true` if checking of allocated memory to ensure it is zeroed is desired.
`private static boolean`	`collectionEnabled` Has garbage collection been enabled yet?
`private static boolean`	`traceAllocator`

Constructor Summary

Constructors
Modifier Constructor and Description

private MemoryManager()
Suppress default constructor to enforce noninstantiability.

Constructors
Modifier	Constructor and Description
`private`	`MemoryManager()` Suppress default constructor to enforce noninstantiability.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static void`	`addFinalizer(Object object)` Adds an object to the list of objects to have their `finalize` method called when they are reclaimed.
`static void`	`addPhantomReference(PhantomReference<?> obj, Object referent)` Add a phantom reference to the list of phantom references.
`static boolean`	`addressInVM(Address address)` Checks if an address refers to an in-use area of memory.
`static void`	`addSoftReference(SoftReference<?> obj, Object referent)` Add a soft reference to the list of soft references.
`static void`	`addWeakReference(WeakReference<?> obj, Object referent)` Add a weak reference to the list of weak references.
`static Offset`	`alignAllocation(Offset initialOffset, int align, int offset)` Align an allocation using some modulo arithmetic to guarantee the following property: `(region + offset) % alignment == 0`
`static Object`	`allocateArray(int numElements, int logElementSize, int headerSize, TIB tib, int allocator, int align, int offset, int site)` Allocate an array object.
`private static Object`	`allocateArrayInternal(int numElements, int size, TIB tib, int allocator, int align, int offset, int site)` Allocate an array object.
`static CodeArray`	`allocateCode(int numInstrs, boolean isHot)` Allocate a CodeArray into a code space.
`static Object`	`allocateScalar(int size, TIB tib, int allocator, int align, int offset, int site)` Allocate a scalar object.
`static Address`	`allocateSpace(CollectorContext context, int bytes, int align, int offset, int allocator, ObjectReference from)` Allocate space for GC-time copying of an object
`private static Address`	`allocateSpace(Selected.Mutator mutator, int bytes, int align, int offset, int allocator, int site)` Allocate space for runtime allocation of an object
`static void`	`boot(BootRecord theBootRecord)` Initialization that occurs at boot time (runtime initialization).
`static Word`	`bootTimeWriteBarrier(Word value)` Installs a reference into the boot image.
`static boolean`	`collectionEnabled()`
`static SpecializedMethod`	`createSpecializedMethod(int id)` Initialize a specified specialized method.
`static void`	`dumpRef(ObjectReference ref)` Logs information about a reference to the error output.
`static void`	`enableCollection()` Allow collection (assumes threads can be created).
`static void`	`flushMutatorContext()` Flush the mutator context.
`static Extent`	`freeMemory()` Returns the amount of free memory.
`static void`	`fullyBootedVM()` Notify the MM that the host VM is now fully booted.
`static void`	`gc()` External call to force a garbage collection.
`static boolean`	`gcInProgress()` Returns true if GC is in progress.
`static int`	`getAllocationSite(boolean compileTime)` Return an allocation site upon request.
`static Object`	`getFinalizedObject()` Gets an object from the list of objects that are to be reclaimed and need to have their `finalize` method called.
`static int`	`getMaxHeaps()` Returns the maximum number of heaps that can be managed.
`static Extent`	`getMaxHeapSize()` Return the max heap size in bytes (as set by -Xmx).
`static void`	`initializeHeader(BootImageInterface bootImage, Address ref, TIB tib, int size, boolean isScalar)` Override the boot-time initialization method here, so that the core MMTk code doesn't need to know about the BootImageInterface type.
`static boolean`	`isImmortal(Object obj)`
`private static boolean`	`isPrefix(String a, byte[] b)` Is string `a` a prefix of string `b`.
`static Extent`	`maxMemory()` Returns the maximum amount of memory VM will attempt to use.
`static boolean`	`mightBeFP(Address address)` Return true if address is in a space which may contain stacks
`static boolean`	`mightBeTIB(ObjectReference obj)` Check if object might be a TIB.
`static void`	`modifyCheck(Object object)` Checks that if a garbage collection is in progress then the given object is not movable.
`static int[]`	`newContiguousIntArray(int n)` Allocate a contiguous int array
`static IMT`	`newIMT()` Allocate a new interface method table (IMT).
`static ITable`	`newITable(int size)` Allocate a new ITable
`static ITableArray`	`newITableArray(int size)` Allocate a new ITableArray
`static double[]`	`newNonMovingDoubleArray(int size)` Allocates a non moving double array.
`static int[]`	`newNonMovingIntArray(int size)` Allocates a non moving int array.
`static short[]`	`newNonMovingShortArray(int size)` Allocates a non moving short array.
`static WordArray`	`newNonMovingWordArray(int size)` Allocates a non moving word array.
`static Object`	`newRuntimeTable(int size, RVMType type)` Allocates a new runtime table (at runtime).
`static byte[]`	`newStack(int bytes)` Allocate a stack
`static TIB`	`newTIB(int numVirtualMethods, int alignCode)` Allocates a new type information block (TIB).
`static void`	`notifyClassResolved(RVMType vmType)` A new type has been resolved by the VM.
`static int`	`numSpecializedMethods()`
`static boolean`	`objectInVM(ObjectReference object)` Checks if a reference refers to an object in an in-use area of memory.
`static int`	`pickAllocator(RVMType type)` Returns the appropriate allocation scheme/area for the given type.
`static int`	`pickAllocator(RVMType type, RVMMethod method)` Returns the appropriate allocation scheme/area for the given type and given method requesting the allocation.
`private static int`	`pickAllocatorForType(RVMType type)` Determine the default allocator to be used for a given type.
`static void`	`postBoot()` Perform postBoot operations such as dealing with command line options (this is called as soon as options have been parsed, which is necessarily after the basic allocator boot).
`static void`	`processCommandLineArg(String arg)`
`static void`	`startGCspyServer()` Start the GCspy server
`private static void`	`throwLargeArrayOutOfMemoryError()` Throw an out of memory error due to an array allocation request that is larger than the maximum allowed value.
`static Extent`	`totalMemory()` Returns the amount of total memory.
`static boolean`	`validRef(ObjectReference ref)` Checks if a reference is valid.
`static boolean`	`willNeverMove(Object obj)` Checks if the object can move.

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

- Field Detail
  - CHECK_MEMORY_IS_ZEROED
```
private static final boolean CHECK_MEMORY_IS_ZEROED
```
    true if checking of allocated memory to ensure it is zeroed is desired.
    
    See Also:
    
    Constant Field Values
  - traceAllocator
```
private static final boolean traceAllocator
```
    See Also:
    
    Constant Field Values
  - booted
```
private static boolean booted
```
    Has the interface been booted yet?
  - collectionEnabled
```
private static boolean collectionEnabled
```
    Has garbage collection been enabled yet?
- Constructor Detail
  - MemoryManager
```
private MemoryManager()
```
    Suppress default constructor to enforce noninstantiability.
- Method Detail
  - boot
```
public static void boot(BootRecord theBootRecord)
```
    Initialization that occurs at boot time (runtime initialization). This is only executed by one processor (the primordial thread).
    
    Parameters:
    
    theBootRecord - the boot record. Contains information about the heap size.
  - postBoot
```
public static void postBoot()
```
    Perform postBoot operations such as dealing with command line options (this is called as soon as options have been parsed, which is necessarily after the basic allocator boot).
  - enableCollection
```
public static void enableCollection()
```
    Allow collection (assumes threads can be created).
  - collectionEnabled
```
public static boolean collectionEnabled()
```
    Returns:
    
    whether collection is enabled
  - fullyBootedVM
```
public static void fullyBootedVM()
```
    Notify the MM that the host VM is now fully booted.
  - processCommandLineArg
```
public static void processCommandLineArg(String arg)
```
  - modifyCheck
```
public static void modifyCheck(Object object)
```
    Checks that if a garbage collection is in progress then the given object is not movable. If it is movable error messages are logged and the system exits.
    
    Parameters:
    
    object - the object to check
  - freeMemory
```
public static Extent freeMemory()
```
    Returns the amount of free memory.
    
    Returns:
    
    The amount of free memory.
  - totalMemory
```
public static Extent totalMemory()
```
    Returns the amount of total memory.
    
    Returns:
    
    The amount of total memory.
  - maxMemory
```
public static Extent maxMemory()
```
    Returns the maximum amount of memory VM will attempt to use.
    
    Returns:
    
    The maximum amount of memory VM will attempt to use.
  - gc
```
public static void gc()
```
    External call to force a garbage collection.
  - dumpRef
```
public static void dumpRef(ObjectReference ref)
```
    Logs information about a reference to the error output.
    
    Parameters:
    
    ref - the address to log information about
  - validRef
```
public static boolean validRef(ObjectReference ref)
```
    Checks if a reference is valid.
    
    Parameters:
    
    ref - the address to be checked
    
    Returns:
    
    true if the reference is valid
  - addressInVM
```
public static boolean addressInVM(Address address)
```
    Checks if an address refers to an in-use area of memory.
    
    Parameters:
    
    address - the address to be checked
    
    Returns:
    
    true if the address refers to an in use area
  - objectInVM
```
public static boolean objectInVM(ObjectReference object)
```
    Checks if a reference refers to an object in an in-use area of memory.
    References may be addresses just outside the memory region allocated to the object.
    
    Parameters:
    
    object - the reference to be checked
    
    Returns:
    
    true if the object refered to is in an in-use area
  - mightBeFP
```
public static boolean mightBeFP(Address address)
```
    Return true if address is in a space which may contain stacks
    
    Parameters:
    
    address - The address to be checked
    
    Returns:
    
    true if the address is within a space which may contain stacks
  - getAllocationSite
```
public static int getAllocationSite(boolean compileTime)
```
    Return an allocation site upon request. The request may be made in the context of compilation.
    
    Parameters:
    
    compileTime - true if this request is being made in the context of a compilation.
    
    Returns:
    
    an allocation site
  - pickAllocator
```
public static int pickAllocator(RVMType type)
```
    Returns the appropriate allocation scheme/area for the given type. This form is deprecated. Without the RVMMethod argument, it is possible that the wrong allocator is chosen which may affect correctness. The prototypical example is that JMTk meta-data must generally be in immortal or at least non-moving space.
    
    Parameters:
    
    type - the type of the object to be allocated
    
    Returns:
    
    the identifier of the appropriate allocator
  - isPrefix
```
private static boolean isPrefix(String a,
                                byte[] b)
```
    Is string a a prefix of string b. String b is encoded as an ASCII byte array.
    
    Parameters:
    
    a - prefix string
    
    b - string which may contain prefix, encoded as an ASCII byte array.
    
    Returns:
    
    true if a is a prefix of b
  - pickAllocator
```
public static int pickAllocator(RVMType type,
                                RVMMethod method)
```
    Returns the appropriate allocation scheme/area for the given type and given method requesting the allocation.
    
    Parameters:
    
    type - the type of the object to be allocated
    
    method - the method requesting the allocation
    
    Returns:
    
    the identifier of the appropriate allocator
  - pickAllocatorForType
```
private static int pickAllocatorForType(RVMType type)
```
    Determine the default allocator to be used for a given type.
    
    Parameters:
    
    type - The type in question
    
    Returns:
    
    The allocator to use for allocating instances of type type.
  - allocateScalar
```
public static Object allocateScalar(int size,
                                    TIB tib,
                                    int allocator,
                                    int align,
                                    int offset,
                                    int site)
```
    Allocate a scalar object.
    
    Parameters:
    
    size - Size in bytes of the object, including any headers that need space.
    
    tib - Type of the object (pointer to TIB).
    
    allocator - Specify which allocation scheme/area JMTk should allocate the memory from.
    
    align - the alignment requested; must be a power of 2.
    
    offset - the offset at which the alignment is desired.
    
    site - allocation site.
    
    Returns:
    
    the initialized Object
  - allocateArray
```
public static Object allocateArray(int numElements,
                                   int logElementSize,
                                   int headerSize,
                                   TIB tib,
                                   int allocator,
                                   int align,
                                   int offset,
                                   int site)
```
    Allocate an array object. This is the interruptible component, including throwing an OutOfMemoryError for arrays that are too large.
    
    Parameters:
    
    numElements - number of array elements
    
    logElementSize - size in bytes of an array element, log base 2.
    
    headerSize - size in bytes of array header
    
    tib - type information block for array object
    
    allocator - int that encodes which allocator should be used
    
    align - the alignment requested; must be a power of 2.
    
    offset - the offset at which the alignment is desired.
    
    site - allocation site.
    
    Returns:
    
    array object with header installed and all elements set to zero/null See also: bytecode 0xbc ("newarray") and 0xbd ("anewarray")
  - throwLargeArrayOutOfMemoryError
```
private static void throwLargeArrayOutOfMemoryError()
```
    Throw an out of memory error due to an array allocation request that is larger than the maximum allowed value. This is in a separate method so it can be forced out of line.
  - allocateArrayInternal
```
private static Object allocateArrayInternal(int numElements,
                                            int size,
                                            TIB tib,
                                            int allocator,
                                            int align,
                                            int offset,
                                            int site)
```
    Allocate an array object.
    
    Parameters:
    
    numElements - The number of element bytes
    
    size - size in bytes of array header
    
    tib - type information block for array object
    
    allocator - int that encodes which allocator should be used
    
    align - the alignment requested; must be a power of 2.
    
    offset - the offset at which the alignment is desired.
    
    site - allocation site.
    
    Returns:
    
    array object with header installed and all elements set to zero/null See also: bytecode 0xbc ("newarray") and 0xbd ("anewarray")
  - allocateSpace
```
private static Address allocateSpace(Selected.Mutator mutator,
                                     int bytes,
                                     int align,
                                     int offset,
                                     int allocator,
                                     int site)
```
    Allocate space for runtime allocation of an object
    
    Parameters:
    
    mutator - The mutator instance to be used for this allocation
    
    bytes - The size of the allocation in bytes
    
    align - The alignment requested; must be a power of 2.
    
    offset - The offset at which the alignment is desired.
    
    allocator - The MMTk allocator to be used (if allocating)
    
    site - Allocation site.
    
    Returns:
    
    The first byte of a suitably sized and aligned region of memory.
  - allocateSpace
```
public static Address allocateSpace(CollectorContext context,
                                    int bytes,
                                    int align,
                                    int offset,
                                    int allocator,
                                    ObjectReference from)
```
    Allocate space for GC-time copying of an object
    
    Parameters:
    
    context - The collector context to be used for this allocation
    
    bytes - The size of the allocation in bytes
    
    allocator - the allocator associated with this request
    
    align - The alignment requested; must be a power of 2.
    
    offset - The offset at which the alignment is desired.
    
    from - The source object from which this is to be copied
    
    Returns:
    
    The first byte of a suitably sized and aligned region of memory.
  - alignAllocation
```
public static Offset alignAllocation(Offset initialOffset,
                                     int align,
                                     int offset)
```
    Align an allocation using some modulo arithmetic to guarantee the following property:
    (region + offset) % alignment == 0
    
    Parameters:
    
    initialOffset - The initial (unaligned) start value of the allocated region of memory.
    
    align - The alignment requested, must be a power of two
    
    offset - The offset at which the alignment is desired
    
    Returns:
    
    initialOffset plus some delta (possibly 0) such that the return value is aligned according to the above constraints.
  - allocateCode
```
public static CodeArray allocateCode(int numInstrs,
                                     boolean isHot)
```
    Allocate a CodeArray into a code space. Currently the interface is fairly primitive; just the number of instructions in the code array and a boolean to indicate hot or cold code.
    
    Parameters:
    
    numInstrs - number of instructions
    
    isHot - is this a request for hot code space allocation?
    
    Returns:
    
    The array
  - newStack
```
public static byte[] newStack(int bytes)
```
    Allocate a stack
    
    Parameters:
    
    bytes - The number of bytes to allocate
    
    Returns:
    
    The stack
  - newNonMovingWordArray
```
public static WordArray newNonMovingWordArray(int size)
```
    Allocates a non moving word array.
    
    Parameters:
    
    size - The size of the array
    
    Returns:
    
    the new non moving word array
  - newNonMovingDoubleArray
```
public static double[] newNonMovingDoubleArray(int size)
```
    Allocates a non moving double array.
    
    Parameters:
    
    size - The size of the array
    
    Returns:
    
    the new non moving double array
  - newNonMovingIntArray
```
public static int[] newNonMovingIntArray(int size)
```
    Allocates a non moving int array.
    
    Parameters:
    
    size - The size of the array
    
    Returns:
    
    the new non moving int array
  - newNonMovingShortArray
```
public static short[] newNonMovingShortArray(int size)
```
    Allocates a non moving short array.
    
    Parameters:
    
    size - The size of the array
    
    Returns:
    
    the new non moving short array
  - newTIB
```
public static TIB newTIB(int numVirtualMethods,
                         int alignCode)
```
    Allocates a new type information block (TIB).
    
    Parameters:
    
    numVirtualMethods - the number of virtual method slots in the TIB
    
    alignCode - alignment encoding for the TIB
    
    Returns:
    
    the new TIB
    
    See Also:
    
    AlignmentEncoding
  - newIMT
```
public static IMT newIMT()
```
    Allocate a new interface method table (IMT).
    
    Returns:
    
    the new IMT
  - newITable
```
public static ITable newITable(int size)
```
    Allocate a new ITable
    
    Parameters:
    
    size - the number of slots in the ITable
    
    Returns:
    
    the new ITable
  - newITableArray
```
public static ITableArray newITableArray(int size)
```
    Allocate a new ITableArray
    
    Parameters:
    
    size - the number of slots in the ITableArray
    
    Returns:
    
    the new ITableArray
  - newRuntimeTable
```
public static Object newRuntimeTable(int size,
                                     RVMType type)
```
    Allocates a new runtime table (at runtime).
    
    Parameters:
    
    size - The size of the table
    
    type - the type for the table
    
    Returns:
    
    the newly allocated table
  - willNeverMove
```
public static boolean willNeverMove(Object obj)
```
    Checks if the object can move. This information is useful to optimize some JNI calls.
    
    Parameters:
    
    obj - the object in question
    
    Returns:
    
    true if this object can never move, false if it can move.
  - isImmortal
```
public static boolean isImmortal(Object obj)
```
    Parameters:
    
    obj - the object in question
    
    Returns:
    
    whether the object is immortal
  - addFinalizer
```
public static void addFinalizer(Object object)
```
    Adds an object to the list of objects to have their finalize method called when they are reclaimed.
    
    Parameters:
    
    object - the object to be added to the finalizer's list
  - getFinalizedObject
```
public static Object getFinalizedObject()
```
    Gets an object from the list of objects that are to be reclaimed and need to have their finalize method called.
    
    Returns:
    
    the object needing to be finialized
  - addSoftReference
```
public static void addSoftReference(SoftReference<?> obj,
                                    Object referent)
```
    Add a soft reference to the list of soft references.
    
    Parameters:
    
    obj - the soft reference to be added to the list
    
    referent - the object that the reference points to
  - addWeakReference
```
public static void addWeakReference(WeakReference<?> obj,
                                    Object referent)
```
    Add a weak reference to the list of weak references.
    
    Parameters:
    
    obj - the weak reference to be added to the list
    
    referent - the object that the reference points to
  - addPhantomReference
```
public static void addPhantomReference(PhantomReference<?> obj,
                                       Object referent)
```
    Add a phantom reference to the list of phantom references.
    
    Parameters:
    
    obj - the phantom reference to be added to the list
    
    referent - the object that the reference points to
  - getMaxHeapSize
```
public static Extent getMaxHeapSize()
```
    Return the max heap size in bytes (as set by -Xmx).
    
    Returns:
    
    The max heap size in bytes (as set by -Xmx).
  - notifyClassResolved
```
public static void notifyClassResolved(RVMType vmType)
```
    A new type has been resolved by the VM. Create a new MM type to reflect the VM type, and associate the MM type with the VM type.
    
    Parameters:
    
    vmType - The newly resolved type
  - mightBeTIB
```
public static boolean mightBeTIB(ObjectReference obj)
```
    Check if object might be a TIB.
    
    Parameters:
    
    obj - address of object to check
    
    Returns:
    
    false if the object is in the wrong allocation scheme/area for a TIB, true otherwise
  - gcInProgress
```
public static boolean gcInProgress()
```
    Returns true if GC is in progress.
    
    Returns:
    
    True if GC is in progress.
  - startGCspyServer
```
public static void startGCspyServer()
```
    Start the GCspy server
  - flushMutatorContext
```
public static void flushMutatorContext()
```
    Flush the mutator context.
  - numSpecializedMethods
```
public static int numSpecializedMethods()
```
    Returns:
    
    the number of specialized methods.
  - createSpecializedMethod
```
public static SpecializedMethod createSpecializedMethod(int id)
```
    Initialize a specified specialized method.
    
    Parameters:
    
    id - the specializedMethod
    
    Returns:
    
    the created specialized scan method
  - initializeHeader
```
public static void initializeHeader(BootImageInterface bootImage,
                                    Address ref,
                                    TIB tib,
                                    int size,
                                    boolean isScalar)
```
    Override the boot-time initialization method here, so that the core MMTk code doesn't need to know about the BootImageInterface type.
    
    Parameters:
    
    bootImage - the bootimage instance
    
    ref - the object's address
    
    tib - the object's TIB
    
    size - the number of bytes allocated by the GC system for the object
    
    isScalar - whether the header belongs to a scalar or an array
  - bootTimeWriteBarrier
```
public static Word bootTimeWriteBarrier(Word value)
```
    Installs a reference into the boot image.
    
    Parameters:
    
    value - the reference to install
    
    Returns:
    
    the installed reference
  - getMaxHeaps
```
public static int getMaxHeaps()
```
    Returns the maximum number of heaps that can be managed.
    
    Returns:
    
    the maximum number of heaps
  - newContiguousIntArray
```
public static int[] newContiguousIntArray(int n)
```
    Allocate a contiguous int array
    
    Parameters:
    
    n - The number of ints
    
    Returns:
    
    The contiguous int array

Class MemoryManager

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

CHECK_MEMORY_IS_ZEROED

traceAllocator

booted

collectionEnabled

Constructor Detail

MemoryManager

Method Detail

boot

postBoot

enableCollection

collectionEnabled

fullyBootedVM

processCommandLineArg

modifyCheck

freeMemory

totalMemory

maxMemory

gc

dumpRef

validRef

addressInVM

objectInVM

mightBeFP

getAllocationSite

pickAllocator

isPrefix

pickAllocator

pickAllocatorForType

allocateScalar

allocateArray

throwLargeArrayOutOfMemoryError

allocateArrayInternal

allocateSpace

allocateSpace

alignAllocation

allocateCode

newStack

newNonMovingWordArray

newNonMovingDoubleArray

newNonMovingIntArray

newNonMovingShortArray

newTIB

newIMT

newITable

newITableArray

newRuntimeTable

willNeverMove

isImmortal

addFinalizer

getFinalizedObject

addSoftReference

addWeakReference

addPhantomReference

getMaxHeapSize

notifyClassResolved

mightBeTIB

gcInProgress

startGCspyServer

flushMutatorContext

numSpecializedMethods

createSpecializedMethod

initializeHeader

bootTimeWriteBarrier

getMaxHeaps

newContiguousIntArray