BTreeCounters (Blazegraph Database Platform 2.1.5 API)

java.lang.Object
- com.bigdata.btree.BTreeCounters

All Implemented Interfaces:

ICounterSetAccess, Cloneable
```
public final class BTreeCounters
extends Object
implements Cloneable, ICounterSetAccess
```
A helper class that collects statistics on an AbstractBTree.
Note: This class DOES NOT have a hard reference to the AbstractBTree. Holding an instance of this class WILL NOT force the AbstractBTree to remain strongly reachable.
Note: Counters for mutation are plain fields. Counters for read-only operations are AtomicLong or AtomicInteger objects since read operations may involve high concurrently and could otherwise lead to lost counter updates.

Author:

Bryan Thompson

Field Summary

Fields
Modifier and Type	Field and Description
`AtomicLong`	`bytesOnStore_nodesAndLeaves` The #of bytes in node and leaf) records on the backing store for the unisolated view of the index.
`AtomicLong`	`bytesOnStore_rawRecords` The #of bytes in the unisolated view of the index which are being used to store raw records.
`CAT`	`bytesRead`
`CAT`	`bytesReleased`
`CAT`	`bytesWritten`
`CAT`	`cacheMisses` #of misses when testing the BTree cache (getChild()).
`CAT`	`cacheTests` #of tests of the BTree cache (getChild()).
`CAT`	`deserializeNanos` De-serialization time for nodes and leaves.
`int`	`headSplit`
`int`	`leavesCopyOnWrite`
`int`	`leavesJoined`
`CAT`	`leavesRead` #of leaf read operations.
`int`	`leavesSplit`
`CAT`	`leavesWritten`
`CAT`	`ngetKey`
`CAT`	`ngetValue`
`CAT`	`nindexOf`
`AtomicLong`	`ninserts` #of keys looked up in the tree by contains/lookup(key) (does not count those rejected by the bloom filter before they are tested against the B+Tree).
`int`	`nodesCopyOnWrite`
`int`	`nodesJoined`
`CAT`	`nodesRead` #of node read operations.
`int`	`nodesSplit`
`CAT`	`nodesWritten`
`CAT`	`nrangeCount`
`CAT`	`nrangeIterator`
`AtomicLong`	`nremoves`
`long`	`ntupleInsertDelete` #of deleted tuples that were inserted into the B+Tree (rather than deleting the value for an existing tuple).
`long`	`ntupleInsertValue` #of non-deleted tuples that were inserted into the B+Tree (rather than updating the value for an existing tuple).
`long`	`ntupleRemove` #of pre-existing tuples that were removed from the B+Tree (only non-zero when the B+Tree does not support delete markers).
`long`	`ntupleUpdateDelete` #of pre-existing un-deleted tuples whose delete marker was set (we don't count re-deletes of an already deleted tuple).
`long`	`ntupleUpdateValue` #of pre-existing tuples whose value was updated to a non-deleted value (includes update of a deleted tuple to a non-deleted tuple by overwrite of the tuple).
`CAT`	`rawRecordsBytesRead` Total bytes read for raw records.
`CAT`	`rawRecordsBytesWritten`
`CAT`	`rawRecordsRead` The #of raw record read operations.
`CAT`	`rawRecordsWritten`
`CAT`	`readNanos` Read time for nodes and leaves (but not raw records).
`int`	`rootsJoined`
`int`	`rootsSplit`
`CAT`	`serializeNanos`
`int`	`tailSplit`
`CAT`	`writeNanos`

Constructor Summary

Constructors
Constructor and Description

BTreeCounters()

BTreeCounters(BTreeCounters c)
Copy constructor.

Constructors
Constructor and Description
`BTreeCounters()`
`BTreeCounters(BTreeCounters c)` Copy constructor.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`add(BTreeCounters o)` Adds the values from another `BTreeCounters` object to this one.
`BTreeCounters`	`clone()`
`double`	`computeRawReadScore()` Return a score whose increasing value is correlated with the amount of read activity on an index as reflected in these `BTreeCounters`.
`double`	`computeRawReadWriteScore()` Return a score whose increasing value is correlated with the amount of read/write activity on an index as reflected in these `BTreeCounters`.
`double`	`computeRawWriteScore()` Return a score whose increasing value is correlated with the amount of write activity on an index as reflected in these `BTreeCounters`.
`boolean`	`equals(Object o)` Equal iff they are the same instance.
`long`	`getBytesRead()` The number of bytes read from the backing store.
`long`	`getBytesReleased()` The number of bytes released from the backing store.
`long`	`getBytesWritten()` The number of bytes written onto the backing store.
`CounterSet`	`getCounters()` Return a `CounterSet` reporting on the various counters tracked in the instance fields of this class.
`long`	`getLeavesWritten()` The #of leaves written on the backing store.
`long`	`getNodesWritten()` The #of nodes written on the backing store.
`static double`	`normalize(double rawScore, double totalRawScore)` Normalizes a raw score in the context of totals for some data service.
`BTreeCounters`	`subtract(BTreeCounters o)` Subtracts the given counters from the current counters, returning a new counter object containing their difference.
`String`	`toString()`

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

- Field Detail
  - ninserts
```
public final AtomicLong ninserts
```
    #of keys looked up in the tree by contains/lookup(key) (does not count those rejected by the bloom filter before they are tested against the B+Tree).
  - nremoves
```
public final AtomicLong nremoves
```
  - nindexOf
```
public final CAT nindexOf
```
  - ngetKey
```
public final CAT ngetKey
```
  - ngetValue
```
public final CAT ngetValue
```
  - nrangeCount
```
public final CAT nrangeCount
```
  - nrangeIterator
```
public final CAT nrangeIterator
```
  - rootsSplit
```
public int rootsSplit
```
  - rootsJoined
```
public int rootsJoined
```
  - nodesSplit
```
public int nodesSplit
```
  - nodesJoined
```
public int nodesJoined
```
  - leavesSplit
```
public int leavesSplit
```
  - leavesJoined
```
public int leavesJoined
```
  - tailSplit
```
public int tailSplit
```
  - headSplit
```
public int headSplit
```
  - nodesCopyOnWrite
```
public int nodesCopyOnWrite
```
  - leavesCopyOnWrite
```
public int leavesCopyOnWrite
```
  - ntupleInsertValue
```
public long ntupleInsertValue
```
    #of non-deleted tuples that were inserted into the B+Tree (rather than updating the value for an existing tuple).
  - ntupleInsertDelete
```
public long ntupleInsertDelete
```
    #of deleted tuples that were inserted into the B+Tree (rather than deleting the value for an existing tuple). Note that delete markers MAY be written into a B+Tree when there is no tuple for that key in the BTree. Those cases arise when the B+Tree is used to isolate a transaction's write set and are counted here.
  - ntupleUpdateValue
```
public long ntupleUpdateValue
```
    #of pre-existing tuples whose value was updated to a non-deleted value (includes update of a deleted tuple to a non-deleted tuple by overwrite of the tuple).
  - ntupleUpdateDelete
```
public long ntupleUpdateDelete
```
    #of pre-existing un-deleted tuples whose delete marker was set (we don't count re-deletes of an already deleted tuple).
  - ntupleRemove
```
public long ntupleRemove
```
    #of pre-existing tuples that were removed from the B+Tree (only non-zero when the B+Tree does not support delete markers).
  - cacheTests
```
public final CAT cacheTests
```
    #of tests of the BTree cache (getChild()). See BLZG-1657. Should correlate to #of getChild() calls.
  - cacheMisses
```
public final CAT cacheMisses
```
    #of misses when testing the BTree cache (getChild()). See BLZG-1657. Should correlate to nodesRead+leavesRead.
  - nodesRead
```
public final CAT nodesRead
```
    #of node read operations.
  - leavesRead
```
public final CAT leavesRead
```
    #of leaf read operations.
  - bytesRead
```
public final CAT bytesRead
```
  - readNanos
```
public final CAT readNanos
```
    Read time for nodes and leaves (but not raw records).
  - deserializeNanos
```
public final CAT deserializeNanos
```
    De-serialization time for nodes and leaves.
  - rawRecordsRead
```
public final CAT rawRecordsRead
```
    The #of raw record read operations.
  - rawRecordsBytesRead
```
public final CAT rawRecordsBytesRead
```
    Total bytes read for raw records.
  - nodesWritten
```
public CAT nodesWritten
```
  - leavesWritten
```
public CAT leavesWritten
```
  - bytesWritten
```
public CAT bytesWritten
```
  - bytesReleased
```
public CAT bytesReleased
```
  - writeNanos
```
public CAT writeNanos
```
  - serializeNanos
```
public CAT serializeNanos
```
  - rawRecordsWritten
```
public CAT rawRecordsWritten
```
  - rawRecordsBytesWritten
```
public CAT rawRecordsBytesWritten
```
  - bytesOnStore_rawRecords
```
public final AtomicLong bytesOnStore_rawRecords
```
    The #of bytes in the unisolated view of the index which are being used to store raw records.
  - bytesOnStore_nodesAndLeaves
```
public final AtomicLong bytesOnStore_nodesAndLeaves
```
    The #of bytes in node and leaf) records on the backing store for the unisolated view of the index. This value grows and shrinks as nodes (leaves) are added to and removed from the index. The actual space occupied by the index on the backing store depends on whether and when persistence store reclaims the storage associated with deleted nodes and leaves.
- Constructor Detail
  - BTreeCounters
```
public BTreeCounters()
```
  - BTreeCounters
```
public BTreeCounters(BTreeCounters c)
```
    Copy constructor.
    
    Parameters:
    c -
- Method Detail
  - equals
```
public boolean equals(Object o)
```
    Equal iff they are the same instance.
    
    Overrides:
    
    equals in class Object
  - clone
```
public BTreeCounters clone()
```
    Overrides:
    
    clone in class Object
  - add
```
public void add(BTreeCounters o)
```
    Adds the values from another BTreeCounters object to this one.
    
    Parameters:
    o -
  - subtract
```
public BTreeCounters subtract(BTreeCounters o)
```
    Subtracts the given counters from the current counters, returning a new counter object containing their difference.
    
    Parameters:
    o -
  - computeRawReadWriteScore
```
public double computeRawReadWriteScore()
```
    Return a score whose increasing value is correlated with the amount of read/write activity on an index as reflected in these BTreeCounters.
    The score is the serialization / deserialization time plus the read / write time. Time was chosen since it is a common unit and since it reflects the combination of CPU time, memory time (for allocations and garbage collection - the latter can be quite significant), and the disk wait time. The other main component of time is key search, but that is not instrumented right now.
    Serialization and deserialization are basically a CPU activity and drive memory to the extent that allocations are made, especially during deserialization.
    The read/write time is strongly dominated by actual DISK IO and by garbage collection time (garbage collection can cause threads to be suspended at any time). For deep B+Trees, DISK READ time dominates DISK WRITE time since increasing numbers of random reads are required to materialize any given leaf.
    The total read-write cost (in seconds) for a BTree is one of the factors that is considered when choosing which index partition to move. Comparing the total read/write cost for BTrees across a database can help to reveal which index partitions have the heaviest load. If only a few index partitions for a given scale-out index have a heavy load, then those index partitions are hotspots for that index.
    
    Returns:
    The computed score.
  - computeRawReadScore
```
public double computeRawReadScore()
```
    Return a score whose increasing value is correlated with the amount of read activity on an index as reflected in these BTreeCounters. The score is deserializeNanos + readNanos.
    
    See Also:
    computeRawReadWriteScore()
  - computeRawWriteScore
```
public double computeRawWriteScore()
```
    Return a score whose increasing value is correlated with the amount of write activity on an index as reflected in these BTreeCounters. The score is serializeNanos plus writeNanos.
    
    See Also:
    computeRawReadWriteScore()
  - normalize
```
public static double normalize(double rawScore,
               double totalRawScore)
```
    Normalizes a raw score in the context of totals for some data service.
    
    Parameters:
    rawScore - The raw score.
    totalRawScore - The raw score computed from the totals.
    
    Returns:
    The normalized score.
  - getNodesWritten
```
public final long getNodesWritten()
```
    The #of nodes written on the backing store.
  - getLeavesWritten
```
public final long getLeavesWritten()
```
    The #of leaves written on the backing store.
  - getBytesRead
```
public final long getBytesRead()
```
    The number of bytes read from the backing store.
  - getBytesWritten
```
public final long getBytesWritten()
```
    The number of bytes written onto the backing store.
  - getBytesReleased
```
public final long getBytesReleased()
```
    The number of bytes released from the backing store.
  - getCounters
```
public CounterSet getCounters()
```
    Return a CounterSet reporting on the various counters tracked in the instance fields of this class.
    
    Specified by:
    
    getCounters in interface ICounterSetAccess
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class BTreeCounters

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

ninserts

nremoves

nindexOf

ngetKey

ngetValue

nrangeCount

nrangeIterator

rootsSplit

rootsJoined

nodesSplit

nodesJoined

leavesSplit

leavesJoined

tailSplit

headSplit

nodesCopyOnWrite

leavesCopyOnWrite

ntupleInsertValue

ntupleInsertDelete

ntupleUpdateValue

ntupleUpdateDelete

ntupleRemove

cacheTests

cacheMisses

nodesRead

leavesRead

bytesRead

readNanos

deserializeNanos

rawRecordsRead

rawRecordsBytesRead

nodesWritten

leavesWritten

bytesWritten

bytesReleased

writeNanos

serializeNanos

rawRecordsWritten

rawRecordsBytesWritten

bytesOnStore_rawRecords

bytesOnStore_nodesAndLeaves

Constructor Detail

BTreeCounters

BTreeCounters

Method Detail

equals

clone

add

subtract

computeRawReadWriteScore

computeRawReadScore

computeRawWriteScore

normalize

getNodesWritten

getLeavesWritten

getBytesRead

getBytesWritten

getBytesReleased

getCounters

toString