blocks.summary — mvxcvi/blocks 1.2.0

A 'summary' represents a collection of blocks, including certain statistics and an imprecise membership test in the form of a bloom filter. These are useful for returning from certain operations to represent the set of blocks acted upon.

bucket->range clj

(bucket->range n)

Returns a vector with the boundaries which a given size bucket covers.

init clj

(init)

(init expected-population false-positive-rate)

Return a new, empty summary. An optional expected population and error frequency may be passed in for more control. The following fields are present in a summary:

• :count is the total number of blocks added to the summary
• :size is the total size of blocks added to the summary, in bytes
• :sizes gives a map from bucket exponent to a count of the blocks in that bucket (see size->bucket and bucket->range)
• :membership a bloom filter holding the statistical membership set of block ids

merge clj

(merge a b)

Merge two storage summaries together.

probably-contains? clj

(probably-contains? summary id)

Uses a summary map to check whether the the store (probably) contains the given block identifier. False positives may be possible, but false negatives are not.

size->bucket clj

(size->bucket size)

Assigns a block size to an exponential histogram bucket. Given a size s, returns n such that 2^n <= s < 2^(n+1).

update clj

(update summary block)

Update the storage summary with the stats from the given block.