Counters-based backend for CounterEx using Erlang's :counters module.

This backend uses Erlang's :counters for write-optimized atomic counter operations:

• Fixed capacity: Pre-allocated array of atomic counters
• Write-optimized: Optimized for heavy concurrent writes
• No GC pressure: Counters live outside the process heap
• Key mapping: Uses ETS to map keys to array indices

Characteristics

• Performance: Optimized for write-heavy workloads
• Memory: Fixed at initialization
• Limitations: Fixed number of counters per namespace (default: 1000)

Configuration

Options:

• :capacity - Max counters per namespace (default: 1000)
• :write_concurrency - Enable write concurrency optimization (default: true)

When to Use

Use this backend when:

• You have write-heavy workloads with many concurrent writers
• You have a bounded, known set of counters
• You can pre-allocate capacity
• You need predictable memory usage

Atomics vs Counters

• Atomics: Better for read-heavy or mixed workloads
• Counters: Better for write-heavy workloads with many concurrent writers

Limitations

• Cannot create more counters than the configured capacity
• Deleting a counter doesn't free its slot (reusable after explicit delete)
• Each namespace requires separate counter array
• Counters do not support compare-and-swap natively (emulated with get+put)

Example

# Initialize with capacity for 5,000 counters
{:ok, state} = CounterEx.Backend.Counters.init(capacity: 5_000)
{:ok, 1} = CounterEx.Backend.Counters.inc(state, :default, :requests, 1, 0)
{:ok, 1} = CounterEx.Backend.Counters.get(state, :default, :requests)