IWriteCacheServiceCounters (Blazegraph Database Platform 2.1.5 API)

All Known Implementing Classes:

WriteCacheServiceCounters
```
public interface IWriteCacheServiceCounters
```
Interface declaring the counters exposed by the WriteCacheService .

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`AVERAGE_BUFFER_EVICTED_TO_CHANNEL_NANOS` The average latency (nanoseconds) to evict a write cache buffer onto the backing channel, which is `NBUFFER_EVICTED_TO_CHANNEL` / `ELAPSED_BUFFER_EVICTED_TO_CHANNEL_NANOS`.
`static String`	`AVERAGE_CACHE_WRITE_NANOS` The average latency (nanoseconds) to write a record onto the write cache, which is `NCACHE_WRITES` / `ELAPSED_CACHE_WRITES_NANOS`.
`static String`	`AVERAGE_RANDOM_WRITES_PER_SECOND` A variant of "averageRecordEvictedToChannelNanos" that is expressed directly in terms of random write IO / second.
`static String`	`AVERAGE_RECORD_EVICTED_TO_CHANNEL_NANOS` The average latency per record written onto the backing channel, which is `NRECORDS_EVICTED_TO_CHANNEL` / `ELAPSED_BUFFER_EVICTED_TO_CHANNEL_NANOS`
`static String`	`COMPACTING_THRESHOLD` The threshold of reclaimable space at which we will attempt to coalesce records in cache buffers.
`static String`	`DIRTY_LIST_THRESHOLD` The configured dirty list threshold before evicting to disk (immutable).
`static String`	`ELAPSED_BUFFER_EVICTED_TO_CHANNEL_NANOS` The cumulative number of nanoseconds latency when writing into the write cache.
`static String`	`ELAPSED_CACHE_WRITES_NANOS` The cumulative number of nanoseconds latency when writing into the write cache.
`static String`	`MAX_DIRTY` The maximum #of dirty buffers observed by the `WriteCacheService.WriteTask` (its maximum observed backlog).
`static String`	`MB_PER_SEC` The #of megabytes per second written onto the backing channel.
`static String`	`MEMO_CACHE_SIZE` The current size of the `Memoizer`'s internal cache that is used to serialize reads against a given byte offset on the backing file.
`static String`	`NBUFFER_EVICTED_TO_CHANNEL` The #of `WriteCache` buffers evicted to the backing channel.
`static String`	`NBUFFERS` The configured number of `WriteCache` buffers.
`static String`	`NCACHE_WRITES` The #of record-level writes made onto the `WriteCacheService`.
`static String`	`NCLEAN` The #of `WriteCache` buffers on the clean list at the moment in time when the measurement was taken.
`static String`	`NCLEAR_ADDR_CLEARED` The #of addresses actually found and cleared from the cache by the `WriteCacheService`.
`static String`	`NCLEAR_ADDR_REQUESTS` The requests to clear an address from the cache.
`static String`	`NCOMPACT` The #of `WriteCache` buffers that have been compacted.
`static String`	`NDIRTY` #of dirty buffers (instantaneous).
`static String`	`NREAD_NOT_INSTALLED` The #of read requests that were a miss in the cache and resulted in a read through to the disk where the record was NOT installed into the read cache (either because there is no read cache, because the record is too large for the read cache, or because the thread could not obtain a `WriteCache.ReadCache` block to install the read).
`static String`	`NRECORDS_EVICTED_TO_CHANNEL` The cumulative number of records written onto the backing channel.
`static String`	`NRESET` #of times the `WriteCacheService` was reset (typically to handle an error condition).
`static String`	`NSEND` The #of `WriteCache` blocks sent by the leader to the first downstream follower.

- Field Detail
  - NBUFFERS
```
static final String NBUFFERS
```
    The configured number of WriteCache buffers.
    
    See Also:
    Constant Field Values
  - DIRTY_LIST_THRESHOLD
```
static final String DIRTY_LIST_THRESHOLD
```
    The configured dirty list threshold before evicting to disk (immutable).
    
    See Also:
    Constant Field Values
  - COMPACTING_THRESHOLD
```
static final String COMPACTING_THRESHOLD
```
    The threshold of reclaimable space at which we will attempt to coalesce records in cache buffers.
    
    See Also:
    Constant Field Values
  - NDIRTY
```
static final String NDIRTY
```
    #of dirty buffers (instantaneous).
    Note: This is set by the WriteCacheService.WriteTask thread and by WriteCacheService.reset(). It is volatile so it is visible from a thread which looks at the counters and for correct publication from reset().
    
    See Also:
    Constant Field Values
  - MAX_DIRTY
```
static final String MAX_DIRTY
```
    The maximum #of dirty buffers observed by the WriteCacheService.WriteTask (its maximum observed backlog). This is only set by the WriteCacheService.WriteTask thread, but it is volatile so it is visible from a thread which looks at the counters.
    
    See Also:
    Constant Field Values
  - NCLEAN
```
static final String NCLEAN
```
    The #of WriteCache buffers on the clean list at the moment in time when the measurement was taken.
    
    See Also:
    Constant Field Values
  - NRESET
```
static final String NRESET
```
    #of times the WriteCacheService was reset (typically to handle an error condition).
    Note: This is set by WriteCacheService.reset(). It is volatile so it is visible from a thread which looks at the counters and for correct publication from reset().
    
    See Also:
    Constant Field Values
  - NSEND
```
static final String NSEND
```
    The #of WriteCache blocks sent by the leader to the first downstream follower.
    
    See Also:
    Constant Field Values
  - NBUFFER_EVICTED_TO_CHANNEL
```
static final String NBUFFER_EVICTED_TO_CHANNEL
```
    The #of WriteCache buffers evicted to the backing channel.
    Note: This always reports buffers written to the channel, not records written on the channel, even if there are many records in the buffer and we are using gathered writes on the channel.
    
    See Also:
    Constant Field Values
  - ELAPSED_BUFFER_EVICTED_TO_CHANNEL_NANOS
```
static final String ELAPSED_BUFFER_EVICTED_TO_CHANNEL_NANOS
```
    The cumulative number of nanoseconds latency when writing into the write cache.
    
    See Also:
    (new latency-oriented counters), Constant Field Values
  - AVERAGE_BUFFER_EVICTED_TO_CHANNEL_NANOS
```
static final String AVERAGE_BUFFER_EVICTED_TO_CHANNEL_NANOS
```
    The average latency (nanoseconds) to evict a write cache buffer onto the backing channel, which is NBUFFER_EVICTED_TO_CHANNEL / ELAPSED_BUFFER_EVICTED_TO_CHANNEL_NANOS.
    
    See Also:
    (new latency-oriented counters), Constant Field Values
  - NRECORDS_EVICTED_TO_CHANNEL
```
static final String NRECORDS_EVICTED_TO_CHANNEL
```
    The cumulative number of records written onto the backing channel. This may be used to track the number of induced write operators per second. However, note that the RWStore will pad out writes to their slot size in order to offer the underlying file system and disk controller an opportunity to meld together multiple writes into a single IO. This is particularly effective in combination with the small slots optimization.
    
    See Also:
    (new latency-oriented counters), Constant Field Values
  - AVERAGE_RECORD_EVICTED_TO_CHANNEL_NANOS
```
static final String AVERAGE_RECORD_EVICTED_TO_CHANNEL_NANOS
```
    The average latency per record written onto the backing channel, which is NRECORDS_EVICTED_TO_CHANNEL / ELAPSED_BUFFER_EVICTED_TO_CHANNEL_NANOS
    Note: records are evicted a buffer at a time. Therefore we use the same divisor here as we do for the AVERAGE_BUFFER_EVICTED_TO_CHANNEL_NANOS.
    This number is fairly misleading as writes are normally transferred to the disk write queue without blocking. Latency only begins to appear when the disk write channel is full.
    
    See Also:
    (new latency-oriented counters), Constant Field Values
  - AVERAGE_RANDOM_WRITES_PER_SECOND
```
static final String AVERAGE_RANDOM_WRITES_PER_SECOND
```
    A variant of "averageRecordEvictedToChannelNanos" that is expressed directly in terms of random write IO / second.
    
    See Also:
    Constant Field Values
  - NCOMPACT
```
static final String NCOMPACT
```
    The #of WriteCache buffers that have been compacted.
    
    See Also:
    Constant Field Values
  - NCACHE_WRITES
```
static final String NCACHE_WRITES
```
    The #of record-level writes made onto the WriteCacheService.
    
    See Also:
    Constant Field Values
  - ELAPSED_CACHE_WRITES_NANOS
```
static final String ELAPSED_CACHE_WRITES_NANOS
```
    The cumulative number of nanoseconds latency when writing into the write cache. See BLZG-1589 (new latency-oriented counters)
    
    See Also:
    Constant Field Values
  - AVERAGE_CACHE_WRITE_NANOS
```
static final String AVERAGE_CACHE_WRITE_NANOS
```
    The average latency (nanoseconds) to write a record onto the write cache, which is NCACHE_WRITES / ELAPSED_CACHE_WRITES_NANOS. See BLZG-1589 (new latency-oriented counters)
    
    See Also:
    Constant Field Values
  - NCLEAR_ADDR_REQUESTS
```
static final String NCLEAR_ADDR_REQUESTS
```
    The requests to clear an address from the cache.
    
    See Also:
    WriteCacheService.clearWrite(long, int), Constant Field Values
  - NCLEAR_ADDR_CLEARED
```
static final String NCLEAR_ADDR_CLEARED
```
    The #of addresses actually found and cleared from the cache by the WriteCacheService.
    
    See Also:
    WriteCacheService.clearWrite(long, int), Constant Field Values
  - MB_PER_SEC
```
static final String MB_PER_SEC
```
    The #of megabytes per second written onto the backing channel.
    
    See Also:
    Constant Field Values
  - NREAD_NOT_INSTALLED
```
static final String NREAD_NOT_INSTALLED
```
    The #of read requests that were a miss in the cache and resulted in a read through to the disk where the record was NOT installed into the read cache (either because there is no read cache, because the record is too large for the read cache, or because the thread could not obtain a WriteCache.ReadCache block to install the read).
    
    See Also:
    Constant Field Values
  - MEMO_CACHE_SIZE
```
static final String MEMO_CACHE_SIZE
```
    The current size of the Memoizer's internal cache that is used to serialize reads against a given byte offset on the backing file.
    
    See Also:
    Constant Field Values

Interface IWriteCacheServiceCounters

Field Summary

Field Detail

NBUFFERS

DIRTY_LIST_THRESHOLD

COMPACTING_THRESHOLD

NDIRTY

MAX_DIRTY

NCLEAN

NRESET

NSEND

NBUFFER_EVICTED_TO_CHANNEL

ELAPSED_BUFFER_EVICTED_TO_CHANNEL_NANOS

AVERAGE_BUFFER_EVICTED_TO_CHANNEL_NANOS

NRECORDS_EVICTED_TO_CHANNEL

AVERAGE_RECORD_EVICTED_TO_CHANNEL_NANOS

AVERAGE_RANDOM_WRITES_PER_SECOND

NCOMPACT

NCACHE_WRITES

ELAPSED_CACHE_WRITES_NANOS

AVERAGE_CACHE_WRITE_NANOS

NCLEAR_ADDR_REQUESTS

NCLEAR_ADDR_CLEARED

MB_PER_SEC

NREAD_NOT_INSTALLED

MEMO_CACHE_SIZE