Statistics are accumulated from the time a cache is created. They can be reset
to zero using clear.
There are no defined consistency semantics for statistics. Refer to the implementation for precise semantics.
Each cache's statistics object must be registered with an ObjectName that is unique and has the following type and attributes:
Type:
javax.cache:type=CacheStatistics
Required Attributes:
| Modifier and Type | Method and Description |
|---|---|
| public void | |
| public float | |
| public float | |
| public float | |
| public long | |
| public long | |
| public float | Returns: the percentage of successful hits, as a decimal e.g 75.This is a measure of cache efficiency. |
| public long | Returns: the number of hitsThe number of get requests that were satisfied by the cache. |
| public long | |
| public float | Returns: the percentage of accesses that failed to find anythingReturns the percentage of cache accesses that did not find a requested entry in the cache. |
| public long | |
| public long |
| clear | back to summary |
|---|---|
| public void clear() Clears the statistics counters to 0 for the associated Cache. | |
| getAverageGetTime | back to summary |
|---|---|
| public float getAverageGetTime() The mean time to execute gets. In a read-through cache the time taken to load an entry on miss is not included in get time.
| |
| getAveragePutTime | back to summary |
|---|---|
| public float getAveragePutTime() The mean time to execute puts.
| |
| getAverageRemoveTime | back to summary |
|---|---|
| public float getAverageRemoveTime() The mean time to execute removes.
| |
| getCacheEvictions | back to summary |
|---|---|
| public long getCacheEvictions() The total number of evictions from the cache. An eviction is a removal initiated by the cache itself to free up space. An eviction is not treated as a removal and does not appear in the removal counts.
| |
| getCacheGets | back to summary |
|---|---|
| public long getCacheGets() The total number of requests to the cache. This will be equal to the sum of the hits and misses. A "get" is an operation that returns the current or previous value. It does not include checking for the existence of a key. In a caches with multiple tiered storage, a gets may be implemented as a get to the cache or to the first tier.
| |
| getCacheHitPercentage | back to summary |
|---|---|
| public float getCacheHitPercentage() This is a measure of cache efficiency.
It is calculated as:
| |
| getCacheHits | back to summary |
|---|---|
| public long getCacheHits() The number of get requests that were satisfied by the cache.
In a caches with multiple tiered storage, a hit may be implemented as a hit to the cache or to the first tier.
For an
| |
| getCacheMisses | back to summary |
|---|---|
| public long getCacheMisses() A miss is a get request that is not satisfied. In a simple cache a miss occurs when the cache does not satisfy the request.
For an In a caches with multiple tiered storage, a miss may be implemented as a miss to the cache or to the first tier. In a read-through cache a miss is an absence of the key in the cache that will trigger a call to a CacheLoader. So it is still a miss even though the cache will load and return the value. Refer to the implementation for precise semantics.
| |
| getCacheMissPercentage | back to summary |
|---|---|
| public float getCacheMissPercentage() Returns the percentage of cache accesses that did not find a requested entry in the cache.
This is calculated as
| |
| getCachePuts | back to summary |
|---|---|
| public long getCachePuts() The total number of puts to the cache. A put is counted even if it is immediately evicted. Replaces, where a put occurs which overrides an existing mapping is counted as a put.
| |
| getCacheRemovals | back to summary |
|---|---|
| public long getCacheRemovals() The total number of removals from the cache. This does not include evictions, where the cache itself initiates the removal to make space.
| |