Expand description
guacamole
Guacamole provides a linearly-seekable random number generator. It gives you a long continous stream of bytes (2**70
bytes worth) and the ability to seek to any 64-byte aligned offset within that stream in constant time. This is useful
for benchmarks and other trials that need pseudo-data as it recreates the same data over time, so long as the same index
and procedure are used.
The key example that guacamole is useful for is a large key-value-store workload. Imagine having 1e12 key-value pairs in a database. How would you keep track of that many keys to perform queries over the data in the workload without a second, large key-value store for them?
One answer is guacamole. Divide the 2**64 offsets into N contiguous ranges. Make them of equal size and it can be
done with division/modulus. Each of the N ranges generates a different sequence of 2**64/N bytes which should be used
as the sole basis of randomness for generating workload operations. Each time the same seed is used the same operation
results.
Use Cases
Please link yours here as appropriate.
key-value-store workload: As described above, the guacamole is partitioned into N different keys and each acts as an independent stream. Higher- level randomness can take control of which key gets generated when, picking numbers [0, N) using that other source of randomness and then acting like pseudo-fn(x: usize) -> [blargh; x]
distributed filesystem workload: Files can be carved out of the seed-space, and then generated in parallel, with a 1:1 correspondence between bytes of guacamole and bytes of the files written out.
Status
Maintenance track. The library is considered stable and will be put into maintenance mode if unchanged for one year.
Scope
This library provides the guacamole type and a tool for drawing from a Zipf distribution.
Warts
Documentation
The latest documentation is always available at docs.rs.
Modules
- This module includes a set of combinators that make it easy to construct complex types using simple statements.
Macros
- Run a block of code with the weight assigned to it. For example:
Structs
- Guacamole is a linearly-seekable random number generator. The linearly-seekable property comes from the fact that the seed for the random number generator preserves spacing in the input. Each one unit increase in the seed corresponds to a 64B movement in the output. This allows workloads that are partitionable or discrete with many members to predictably manipulate the output by the input.
- Zipf generator over [0, n). From:
Traits
- Generate Self from a reference to T and an instance of guacamole.