MemStore (Blazegraph Database Platform 2.1.5 API)

java.lang.Object
- com.bigdata.rawstore.AbstractRawStore
- - com.bigdata.rwstore.sector.MemStore

All Implemented Interfaces:

ICounterSetAccess, IAddressManager, IAllocationManagerStore, IRawStore, IStreamStore
```
public class MemStore
extends AbstractRawStore
implements IAllocationManagerStore
```
An IRawStore backed by an IMemoryManager.

Author:

thompsonbry

Field Summary
- Fields inherited from interface com.bigdata.rawstore.IAddressManager
  NULL

Constructor Summary

Constructors
Constructor and Description
`MemStore(DirectBufferPool pool)` Create a new instance.
`MemStore(DirectBufferPool pool, int bufferCapacity)` Create a new instance.
`MemStore(IMemoryManager mmgr)` Wrap an existing `IMemoryManager`.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`close()` Close the store immediately.
`MemStore`	`createAllocationContext()` Return a new view of the `MemStore` backed by a child `IMemoryManager`.
`void`	`delete(long addr)` The default implementation is a NOP.
`void`	`delete(long addr, IAllocationContext context)` Delete the data associated with the address within the allocation context.
`void`	`deleteResources()` Deletes the backing file(s) (if any).
`void`	`destroy()` Closes the store immediately (if open) and deletes its persistent resources.
`void`	`force(boolean metadata)` NOP since the `MemStore` is not backed by stable media.
`IAddressManager`	`getAddressManager()` Return the delegate object that provides the `IAddressManager` implementation for this `IRawStore`.
`int`	`getByteCount(long addr)` The length of the datum in bytes.
`CounterSet`	`getCounters()` Return performance counters.
`File`	`getFile()` This method always returns `null` since there is no backing file.
`InputStream`	`getInputStream(long addr)` Return an input stream from which a previously written stream may be read back.
`IMemoryManager`	`getMemoryManager()` Return the backing `IMemoryManager`.
`long`	`getOffset(long addr)` The offset on the store at which the datum is stored.
`IPSOutputStream`	`getOutputStream()` Return an output stream which can be used to write on the backing store.
`IPSOutputStream`	`getOutputStream(IAllocationContext context)` Return an output stream which can be used to write on the backing store within the given allocation context.
`long`	`getPhysicalAddress(long addr)` Determine the unencoded physical address
`IResourceMetadata`	`getResourceMetadata()` A description of this store in support of the scale-out architecture.
`MemStrategy`	`getStrategy()`
`UUID`	`getUUID()` Return the `UUID` which identifies this `IRawStore`.
`boolean`	`isFullyBuffered()` True iff the store is fully buffered (all reads are against memory).
`boolean`	`isOpen()` `true` iff the store is open.
`boolean`	`isReadOnly()` `true` iff the store does not allow writes.
`boolean`	`isStable()` True iff backed by stable storage.
`ByteBuffer`	`read(long addr)` Read the data (unisolated).
`long`	`size()` The #of application data bytes written on the store (does not count any headers or root blocks that may exist for the store).
`long`	`toAddr(int nbytes, long offset)` Converts a byte count and offset into a long integer.
`String`	`toString(long addr)` A human readable representation of the address.
`long`	`write(ByteBuffer data)` Write the data (unisolated).
`long`	`write(ByteBuffer data, IAllocationContext context)` Write the data within the allocation context.

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

- Constructor Detail
  - MemStore
```
public MemStore(DirectBufferPool pool)
```
    Create a new instance.
    
    Parameters:
    pool - The pool from which the backing direct ByteBuffers will be allocated.
  - MemStore
```
public MemStore(DirectBufferPool pool,
        int bufferCapacity)
```
    Create a new instance.
    
    Parameters:
    pool - The pool from which the backing direct ByteBuffers will be allocated.
    bufferCapacity - The maximum #of buffers which may be allocated by this MemStore from that pool. This may be Integer.MAX_VALUE for an effectively unlimited capacity.
  - MemStore
```
public MemStore(IMemoryManager mmgr)
```
    Wrap an existing IMemoryManager.
    
    Parameters:
    mmgr - The IMemoryManager.
- Method Detail
  - getStrategy
```
public MemStrategy getStrategy()
```
  - getMemoryManager
```
public IMemoryManager getMemoryManager()
```
    Return the backing IMemoryManager.
  - createAllocationContext
```
public MemStore createAllocationContext()
```
    Return a new view of the MemStore backed by a child IMemoryManager. Allocations against the MemStore may be released in bulk by close(). The life cycle of the returned MemStore is bounded by the life cycle of the MemStore from which it was allocated.
    
    See Also:
    IMemoryManager.createAllocationContext()
  - read
```
public ByteBuffer read(long addr)
```
    Description copied from interface: IRawStore
    
    Read the data (unisolated).
    
    Specified by:
    
    read in interface IRawStore
    
    Parameters:
    addr - A long integer that encodes both the offset from which the data will be read and the #of bytes to be read. See IAddressManager.toAddr(int, long).
    
    Returns:
    The data read. The buffer will be flipped to prepare for reading (the position will be zero and the limit will be the #of bytes read).
  - write
```
public long write(ByteBuffer data)
```
    Description copied from interface: IRawStore
    
    Write the data (unisolated).
    
    Specified by:
    
    write in interface IRawStore
    
    Parameters:
    data - The data. The bytes from the current Buffer.position() to the Buffer.limit() will be written and the Buffer.position() will be advanced to the Buffer.limit() . The caller may subsequently modify the contents of the buffer without changing the state of the store (i.e., the data are copied into the store).
    
    Returns:
    A long integer formed that encodes both the offset from which the data may be read and the #of bytes to be read. See IAddressManager.
  - write
```
public long write(ByteBuffer data,
         IAllocationContext context)
```
    Description copied from interface: IAllocationManagerStore
    
    Write the data within the allocation context. The write is not visible outside of the allocation until the allocation context has been merged into the parent allocation context.
    
    Specified by:
    
    write in interface IAllocationManagerStore
    
    Parameters:
    data - The data.
    context - The allocation context.
    
    Returns:
    The address at which the data was written.
  - delete
```
public void delete(long addr)
```
    Description copied from class: AbstractRawStore
    
    The default implementation is a NOP.
    
    Specified by:
    
    delete in interface IRawStore
    
    Overrides:
    
    delete in class AbstractRawStore
    
    Parameters:
    addr - A long integer formed using Addr that encodes both the offset at which the data was written and the #of bytes that were written.
  - delete
```
public void delete(long addr,
          IAllocationContext context)
```
    Description copied from interface: IAllocationManagerStore
    
    Delete the data associated with the address within the allocation context. The delete is not visible outside of the allocation until the allocation context has been merged into the parent allocation context.
    
    Specified by:
    
    delete in interface IAllocationManagerStore
    
    Parameters:
    addr - The address whose allocation is to be deleted.
    context - The allocation context.
  - getCounters
```
public CounterSet getCounters()
```
    Description copied from interface: ICounterSetAccess
    
    Return performance counters.
    
    Specified by:
    
    getCounters in interface ICounterSetAccess
  - isOpen
```
public boolean isOpen()
```
    Description copied from interface: IRawStore
    
    true iff the store is open.
    
    Specified by:
    
    isOpen in interface IRawStore
    
    Returns:
    true iff the store is open.
  - close
```
public void close()
```
    Description copied from interface: IRawStore
    
    Close the store immediately.
    
    Specified by:
    
    close in interface IRawStore
  - deleteResources
```
public void deleteResources()
```
    Description copied from interface: IRawStore
    
    Deletes the backing file(s) (if any).
    
    Specified by:
    
    deleteResources in interface IRawStore
  - destroy
```
public void destroy()
```
    Description copied from interface: IRawStore
    
    Closes the store immediately (if open) and deletes its persistent resources. Does NOT throw an IllegalStateException if the store is already closed, but still deletes the backing resources.
    
    Specified by:
    
    destroy in interface IRawStore
    
    See Also:
    IRawStore.deleteResources()
  - force
```
public void force(boolean metadata)
```
    NOP since the MemStore is not backed by stable media.
    Force the data to stable storage. While this is NOT sufficient to guarantee an atomic commit, the data must be forced to disk as part of an atomic commit protocol.
    
    Specified by:
    
    force in interface IRawStore
    
    Parameters:
    metadata - If true, then force both the file contents and the file metadata to disk.
  - getFile
```
public File getFile()
```
    This method always returns null since there is no backing file.
    The backing file -or- null if there is no backing file for the store.
    
    Specified by:
    
    getFile in interface IRawStore
  - getResourceMetadata
```
public IResourceMetadata getResourceMetadata()
```
    Description copied from interface: IRawStore
    
    A description of this store in support of the scale-out architecture.
    
    Specified by:
    
    getResourceMetadata in interface IRawStore
  - getUUID
```
public UUID getUUID()
```
    Description copied from interface: IRawStore
    
    Return the UUID which identifies this IRawStore. This supports IRawStore.getResourceMetadata().
    
    Specified by:
    
    getUUID in interface IRawStore
  - isFullyBuffered
```
public boolean isFullyBuffered()
```
    Description copied from interface: IRawStore
    
    True iff the store is fully buffered (all reads are against memory). Implementations MAY change the value returned by this method over the life cycle of the store, e.g., to conserve memory a store may drop or decrease its buffer if it is backed by disk.
    Note: This does not guarantee that the OS will not swap the buffer onto disk.
    
    Specified by:
    
    isFullyBuffered in interface IRawStore
  - isReadOnly
```
public boolean isReadOnly()
```
    Description copied from interface: IRawStore
    
    true iff the store does not allow writes.
    
    Specified by:
    
    isReadOnly in interface IRawStore
  - isStable
```
public boolean isStable()
```
    Description copied from interface: IRawStore
    
    True iff backed by stable storage.
    
    Specified by:
    
    isStable in interface IRawStore
  - size
```
public long size()
```
    The #of application data bytes written on the store (does not count any headers or root blocks that may exist for the store).
    Overridden to return the #of bytes in the allocation slots rather than the user bytes. This is because the MemoryManager, like the RWStore, does not know the #of bytes of user data in each allocation slot. Therefore it is not able to keep accurate track of the user bytes as allocation slots are cycled.
    
    Specified by:
    
    size in interface IRawStore
    
    See Also:
    (Records must store the as-written length for HA failover reads to be successful.)
  - getAddressManager
```
public IAddressManager getAddressManager()
```
    Description copied from class: AbstractRawStore
    
    Return the delegate object that provides the IAddressManager implementation for this IRawStore.
    Note: LRUNexus depends on the delegation model to retain references to the IAddressManager without causing the IRawStore to be retained. It uses the IAddressManager to decode the address in order to track the bytesOnDisk for the buffered records.
    
    Specified by:
    
    getAddressManager in class AbstractRawStore
  - getByteCount
```
public int getByteCount(long addr)
```
    Description copied from interface: IAddressManager
    
    The length of the datum in bytes. This must be the actual length of the record on the disk, not the length of the caller's byte[]. This is necessary in order to support transparent checksums and/or compression for records in the IRawStore.
    
    Specified by:
    
    getByteCount in interface IAddressManager
    
    Parameters:
    addr - The opaque identifier that is the within store locator for some datum.
    
    Returns:
    The offset of that datum.
  - getOffset
```
public long getOffset(long addr)
```
    Description copied from interface: IAddressManager
    
    The offset on the store at which the datum is stored. While this is often the offset of a byte into a file on disk, implementations MAY assign offsets using other strategies.
    
    Specified by:
    
    getOffset in interface IAddressManager
    
    Parameters:
    addr - The opaque identifier that is the within store locator for some datum.
    
    Returns:
    The offset of that datum.
  - getPhysicalAddress
```
public long getPhysicalAddress(long addr)
```
    Description copied from interface: IAddressManager
    
    Determine the unencoded physical address
    
    Specified by:
    
    getPhysicalAddress in interface IAddressManager
    
    Parameters:
    addr - The encoded address
    
    Returns:
    an unencoded address offset
  - toAddr
```
public long toAddr(int nbytes,
          long offset)
```
    Description copied from interface: IAddressManager
    
    Converts a byte count and offset into a long integer.
    
    Specified by:
    
    toAddr in interface IAddressManager
    
    Parameters:
    nbytes - The byte count.
    offset - The byte offset.
    
    Returns:
    The long integer.
  - toString
```
public String toString(long addr)
```
    Description copied from interface: IAddressManager
    
    A human readable representation of the address.
    
    Specified by:
    
    toString in interface IAddressManager
    
    Parameters:
    addr - The opaque identifier that is the within store locator for some datum.
    
    Returns:
    A human readable representation.
  - getOutputStream
```
public IPSOutputStream getOutputStream()
```
    Description copied from interface: IStreamStore
    
    Return an output stream which can be used to write on the backing store. You can recover the address used to read back the data from the IPSOutputStream.
    
    Specified by:
    
    getOutputStream in interface IStreamStore
    
    Overrides:
    
    getOutputStream in class AbstractRawStore
    
    Returns:
    The output stream.
  - getOutputStream
```
public IPSOutputStream getOutputStream(IAllocationContext context)
```
    Return an output stream which can be used to write on the backing store within the given allocation context. You can recover the address used to read back the data from the IPSOutputStream.
    
    Specified by:
    
    getOutputStream in interface IAllocationManagerStore
    
    Parameters:
    context - The context within which any allocations are made by the returned IPSOutputStream.
    
    Returns:
    an output stream to stream data to and to retrieve an address to later stream the data back.
  - getInputStream
```
public InputStream getInputStream(long addr)
```
    Return an input stream from which a previously written stream may be read back.
    
    Specified by:
    
    getInputStream in interface IStreamStore
    
    Overrides:
    
    getInputStream in class AbstractRawStore
    
    Parameters:
    addr - The address at which the stream was written.
    
    Returns:
    an input stream for the data for provided address

Class MemStore

Field Summary

Fields inherited from interface com.bigdata.rawstore.IAddressManager

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

MemStore

MemStore

MemStore

Method Detail

getStrategy

getMemoryManager

createAllocationContext

read

write

write

delete

delete

getCounters

isOpen

close

deleteResources

destroy

force

getFile

getResourceMetadata

getUUID

isFullyBuffered

isReadOnly

isStable

size

getAddressManager

getByteCount

getOffset

getPhysicalAddress

toAddr

toString

getOutputStream

getOutputStream

getInputStream