Class StringRegistry

• Defined in File string_registry.h

Class Documentation

class StringRegistry

Global singleton registry for StringId string storage and lifetime management.

StringRegistry maintains a permanent mapping of 64-bit hashes to their associated strings. When a StringId is constructed with a runtime string (via the constructor taking both hash and string), the string is stored in this registry and persists for the application’s entire lifetime.

Architecture: The registry uses Meyer’s singleton pattern (static local in get_entries()) and employs std::pmr (polymorphic memory resources) for efficient string storage:

• monotonic_buffer_resource (64KB) for fast bulk allocation

• unsynchronized_pool_resource on top for variable-sized string allocations

• Strings are never deallocated (monotonic buffer only grows)

This design is optimal for StringId usage patterns: strings are typically registered once at startup or load time, then referenced many times. The monotonic buffer avoids allocation fragmentation and deallocation overhead.

Thread Safety: NOT thread-safe. String registration (store()) and lookup (find()) are not protected by locks. However, this is typically acceptable because:

• Most string registration happens during initialization (single-threaded)

• Compile-time STRING_ID() macros don’t use the registry at all

• Runtime StringId construction is usually at load time, not hot paths

If concurrent access is required, external synchronization must be used.

Usage: You rarely call StringRegistry methods directly - StringId constructors handle it automatically. The registry is an implementation detail of the StringId system.

See also

StringId for the main string identifier interface

Public Static Functions

static std::string_view store(uint64_t id, std::string_view string)

Stores a string in the registry, associating it with a hash.

If the hash already exists in the registry, returns the existing stored string view (deduplication). If new, allocates a std::pmr::string using the registry’s memory resources and stores it permanently.

The returned string_view points into the registry’s storage and remains valid for the application’s lifetime.

Parameters:

• id – The 64-bit hash of the string (typically from hash::rapidhash)

• string – The string to store

Returns:

string_view pointing to the registry’s copy of the string

static std::string_view find(uint64_t id)

Looks up a string by its hash in the registry.

Returns the stored string if found, or INVALID_STRING_VIEW if the hash is not in the registry. Used by StringId’s hash-only constructor during deserialization.

Parameters:

id – The 64-bit hash to look up

Returns:

string_view to the stored string, or INVALID_STRING_VIEW if not found