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name: patterns/arena-allocator description: Arena Allocator Pattern (C-Specific) pattern for C development

Arena Allocator Pattern (C-Specific)

Allocate many objects from single memory region, free all at once. No individual frees. Hierarchical arenas enable nested lifetimes.

ikigai Application

talloc: ikigai uses talloc for hierarchical arenas:

CopyTALLOC_CTX *request_ctx = talloc_new(parent);
// All allocations are children
char *str = talloc_strdup(request_ctx, "hello");
ik_msg_t *msg = talloc(request_ctx, ik_msg_t);
// Single free cleans everything
talloc_free(request_ctx);

Ownership hierarchy:

Copyroot_ctx
  └─> repl_ctx
       └─> scrollback (freed with repl)
       └─> messages[] (freed with repl)

Benefits: No memory leaks by design. No use-after-free. Clear ownership. Fast bulk deallocation.

See: project/memory.md for talloc patterns.