java.lang.Object
- org.bitcoinj.store.SPVBlockStore

All Implemented Interfaces:

BlockStore
```
public class SPVBlockStore
extends java.lang.Object
implements BlockStore
```
An SPVBlockStore holds a limited number of block headers in a memory mapped ring buffer. With such a store, you may not be able to process very deep re-orgs and could be disconnected from the chain (requiring a replay), but as they are virtually unheard of this is not a significant risk.

Field Summary

Fields
Modifier and Type	Field	Description
`protected java.util.LinkedHashMap<Sha256Hash,StoredBlock>`	`blockCache`
`protected java.nio.MappedByteBuffer`	`buffer`
`static int`	`DEFAULT_CAPACITY`	The default number of headers that will be stored in the ring buffer.
`protected static int`	`FILE_PROLOGUE_BYTES`
`protected java.nio.channels.FileLock`	`fileLock`
`static java.lang.String`	`HEADER_MAGIC`
`protected StoredBlock`	`lastChainHead`
`protected java.util.concurrent.locks.ReentrantLock`	`lock`
`protected java.util.LinkedHashMap<Sha256Hash,java.lang.Object>`	`notFoundCache`
`protected NetworkParameters`	`params`
`protected java.io.RandomAccessFile`	`randomAccessFile`
`protected static int`	`RECORD_SIZE`

Constructor Summary

Constructors
Constructor	Description
`SPVBlockStore(NetworkParameters params, java.io.File file)`	Creates and initializes an SPV block store that can hold `DEFAULT_CAPACITY` block headers.
`SPVBlockStore(NetworkParameters params, java.io.File file, int capacity, boolean grow)`	Creates and initializes an SPV block store that can hold a given amount of blocks.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`clear()`
`void`	`close()`	Closes the store.
`StoredBlock`	`get(Sha256Hash hash)`	Returns the StoredBlock given a hash.
`StoredBlock`	`getChainHead()`	Returns the `StoredBlock` that represents the top of the chain of greatest total work.
`static int`	`getFileSize(int capacity)`	Returns the size in bytes of the file that is used to store the chain with the current parameters.
`NetworkParameters`	`getParams()`	Get the `NetworkParameters` of this store.
`void`	`put(StoredBlock block)`	Saves the given block header+extra data.
`void`	`setChainHead(StoredBlock chainHead)`	Sets the `StoredBlock` that represents the top of the chain of greatest total work.

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

- Field Detail
  - lock
```
protected final java.util.concurrent.locks.ReentrantLock lock
```
  - DEFAULT_CAPACITY
```
public static final int DEFAULT_CAPACITY
```
    The default number of headers that will be stored in the ring buffer.
    
    See Also:
    
    Constant Field Values
  - HEADER_MAGIC
```
public static final java.lang.String HEADER_MAGIC
```
    See Also:
    
    Constant Field Values
  - buffer
```
protected volatile java.nio.MappedByteBuffer buffer
```
  - params
```
protected final NetworkParameters params
```
  - blockCache
```
protected java.util.LinkedHashMap<Sha256Hash,StoredBlock> blockCache
```
  - notFoundCache
```
protected java.util.LinkedHashMap<Sha256Hash,java.lang.Object> notFoundCache
```
  - fileLock
```
protected java.nio.channels.FileLock fileLock
```
  - randomAccessFile
```
protected java.io.RandomAccessFile randomAccessFile
```
  - lastChainHead
```
protected StoredBlock lastChainHead
```
  - RECORD_SIZE
```
protected static final int RECORD_SIZE
```
    See Also:
    
    Constant Field Values
  - FILE_PROLOGUE_BYTES
```
protected static final int FILE_PROLOGUE_BYTES
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - SPVBlockStore
```
public SPVBlockStore(NetworkParameters params,
                     java.io.File file)
              throws BlockStoreException
```
    Creates and initializes an SPV block store that can hold DEFAULT_CAPACITY block headers. Will create the given file if it's missing. This operation will block on disk.
    
    Parameters:
    
    file - file to use for the block store
    
    Throws:
    
    BlockStoreException - if something goes wrong
  - SPVBlockStore
```
public SPVBlockStore(NetworkParameters params,
                     java.io.File file,
                     int capacity,
                     boolean grow)
              throws BlockStoreException
```
    Creates and initializes an SPV block store that can hold a given amount of blocks. Will create the given file if it's missing. This operation will block on disk.
    
    Parameters:
    
    file - file to use for the block store
    
    capacity - custom capacity in number of block headers
    
    grow - wether or not to migrate an existing block store of different capacity
    
    Throws:
    
    BlockStoreException - if something goes wrong
- Method Detail
  - getFileSize
```
public static final int getFileSize(int capacity)
```
    Returns the size in bytes of the file that is used to store the chain with the current parameters.
  - put
```
public void put(StoredBlock block)
         throws BlockStoreException
```
    Description copied from interface: BlockStore
    
    Saves the given block header+extra data. The key isn't specified explicitly as it can be calculated from the StoredBlock directly. Can throw if there is a problem with the underlying storage layer such as running out of disk space.
    
    Specified by:
    
    put in interface BlockStore
    
    Throws:
    
    BlockStoreException
  - get
```
@Nullable
public StoredBlock get(Sha256Hash hash)
                throws BlockStoreException
```
    Description copied from interface: BlockStore
    
    Returns the StoredBlock given a hash. The returned values block.getHash() method will be equal to the parameter. If no such block is found, returns null.
    
    Specified by:
    
    get in interface BlockStore
    
    Throws:
    
    BlockStoreException
  - getChainHead
```
public StoredBlock getChainHead()
                         throws BlockStoreException
```
    Description copied from interface: BlockStore
    
    Returns the StoredBlock that represents the top of the chain of greatest total work. Note that this can be arbitrarily expensive, you probably should use AbstractBlockChain.getChainHead() or perhaps AbstractBlockChain.getBestChainHeight() which will run in constant time and not take any heavyweight locks.
    
    Specified by:
    
    getChainHead in interface BlockStore
    
    Throws:
    
    BlockStoreException
  - setChainHead
```
public void setChainHead(StoredBlock chainHead)
                  throws BlockStoreException
```
    Description copied from interface: BlockStore
    
    Sets the StoredBlock that represents the top of the chain of greatest total work.
    
    Specified by:
    
    setChainHead in interface BlockStore
    
    Throws:
    
    BlockStoreException
  - close
```
public void close()
           throws BlockStoreException
```
    Description copied from interface: BlockStore
    
    Closes the store.
    
    Specified by:
    
    close in interface BlockStore
    
    Throws:
    
    BlockStoreException
  - getParams
```
public NetworkParameters getParams()
```
    Description copied from interface: BlockStore
    
    Get the NetworkParameters of this store.
    
    Specified by:
    
    getParams in interface BlockStore
    
    Returns:
    
    The network params.
  - clear
```
public void clear()
           throws java.lang.Exception
```
    Throws:
    
    java.lang.Exception

Class SPVBlockStore

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

lock

DEFAULT_CAPACITY

HEADER_MAGIC

buffer

params

blockCache

notFoundCache

fileLock

randomAccessFile

lastChainHead

RECORD_SIZE

FILE_PROLOGUE_BYTES

Constructor Detail

SPVBlockStore

SPVBlockStore

Method Detail

getFileSize

put

get

getChainHead

setChainHead

close

getParams

clear