Interface exported by classes which support aggregation of
Summary of duration tracking statistics as extracted from an IOStatistics instance.
Utility operations convert IO Statistics sources/instances to strings, especially for robustly logging.
Snapshot of statistics from a different source.
Support for working with IOStatistics.
A mean statistic represented as the sum and the sample count; the mean is calculated on demand.
Common statistic names for object store operations..
These are common statistic names.
This package defines two interfaces:
a source of statistic data, which can be retrieved
through a call to
IOStatistics the statistics retrieved
from a statistics source.
The retrieved statistics may be an immutable snapshot -in which case to get
updated statistics another call to
must be made. Or they may be dynamic -in which case every time a specific
statistic is retrieved, the latest version is returned. Callers should assume
that if a statistics instance is dynamic, there is no atomicity when querying
multiple statistics. If the statistics source was a closeable object (e.g. a
stream), the statistics MUST remain valid after the stream is closed.
An application probes an object (filesystem, stream etc) to see if it
IOStatisticsSource, and, if it is,
getIOStatistics() to get its statistics.
If this is non-null, the client has statistics on the current
state of the statistics.
The expectation is that a statistics source is dynamic: when a value is looked up the most recent values are returned. When iterating through the set, the values of the iterator SHOULD be frozen at the time the iterator was requested.
These statistics can be used to: log operations, profile applications, and make assertions about the state of the output.
The names of statistics are a matter of choice of the specific source.
set of names recommended for object store operations.
recommended names for statistics provided for
input and output streams.
IOStatisticsSupport. General support, including the ability to take a serializable snapshot of the current state of an IOStatistics instance.
IOStatisticsLogging. Methods for robust/on-demand string conversion, designed for use in logging statements and
IOStatisticsSnapshot. A static snaphot of statistics which can be marshalled via java serialization or as JSON via jackson. It supports aggregation, so can be used to generate aggregate statistics.
IOStatisticsSource. (i.e. not shared the way StorageStatistics are)
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