Module counter 

Counter management for promotional code generation.

Supports multiple counter storage modes:

• File: Separate .counter file with OS locking
• InBin: Counter stored in the .bin mutable section
• External: Consumer-managed counter (e.g., database column, PostgreSQL)

Structs

CounterManager

Counter manager for different storage modes.

Enums

CounterMode

Counter storage mode.

Functions

counter_from_bytes

Deserialize counter value from bytes.

counter_to_bytes

Serialize counter value to bytes (for in-bin storage).

increment_counter_file

Increment counter by a specific amount.

read_counter_file

Read counter value from a file.

reserve_counter_file

Atomically reserve a range of counter values.

write_counter_file

Write counter value to a file.