rhmap - a robin-hood hashmap in golang

In other words: map[[]byte][]byte or map[[]byte]SomeOtherType

Example

    var size = 97 // Ideally, some prime number.

    m := rhmap.New(size)

    wasNew, err := m.Set([]byte("hi"), []byte("world"))
    // wasNew == true

    v, ok := m.Get([]byte("hi"))
    // ok == true
    // v == []byte("world")

    previous, existed := m.Del([]byte("hi"))
    // existed == true
    // previous == []byte("world")

Some features

• Key and Val types are []byte
• Get(), Set(), and Del() methods.
• Visit() method with key-val callback.
• CopyTo(anotherRHMap) method.
• Overridable hash function -- see the HashFunc field.
• Overridable growth multiplier function -- see the Growth field.
• Overridable grow function -- see the Grow field.
• Automatic growth when linear probe distances become larger than a configured maximum distance -- see the MaxDistance field.
• All fields are public for advanced user tweaking.
• An RHMap is not concurrent safe -- please use your own favorite outside sync approaches.
• Makefile shows how to codegen maps of different types using sed.
• Reset() method allows an RHMap to be efficiently cleared, and the underlying, already allocated memory will be recycled for reuse, which can reduce garbage memory pressure for some applications.
• The store subpackage provides map and heap implementations that can optionally spill out to files when memory usage grows too large.

Motivations

The RHMap was intended for a use case where many application data objects needed to be processed, where the processing of a single data object needed its own temporary hashmap instance. The standard golang hashmap did not support []byte keys, so conversions from []byte to-and-from strings (i.e., we were using map[string][]byte) was creating garbage. Instead, we needed a (mythical) map[[]byte][]byte.

License

Apache 2.0