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Domains

Domains are used to represent groupings of ChiContainers for logical organization. By default, the following domains are created:

  • chi::SubDomainId::kGlobalContainers: The set of all containers in the pool
  • chi::SubDomainId::kLocalContainers: The set of containers on this node

There is also a chi::SubDomainId::kPhysicalNode, which represents the address of an actual machine. When a runtime is launched on a node, it is assigned a unique ID between 1 and 2^32. This domain gets used for situations such as migrating ChiContainers across nodes.

Domain Query​

A Domain Query represents a subset of addresses. For example, a hashtable may route a task to a specific ChiContainer, which represents the bucket. Alternatively, a cache invalidation algorithm may want to broadcast a task across all ChiContainers to invalidate data caches.

Range Flags​

Range flags represent the scope of the query:

  • kLocal: Only addresses local to this node are used
  • kDirect: A single specific address is used
  • kGlobal: Can be a range of addresses across all nodes
  • kSchedule: Determine the addresses later through a scheduler

Selection Flags​

Selection flags indicate how the addresses are represented:

  • kId: The address is the exact address to be used
  • kHash: The address will be hashed against the size of the domain
  • kRange: The address will be a range of nodes

Iteration Algorithms​

Iteration flags indicate how a task will be dispersed among the domain

  • kBroadcast: Will broadcast the task across all nodes in the domain
  • kRepUntilSuccess: Will iterate over the domain until success

Domain Query: GetDirectHash​

static DomainQuery GetDirectHash(const SubDomainGroup &sub_id, u32 hash,
                                   u32 iter_flags = kBroadcast);

Hash the task to an offset in the subdomain vector. Good for things like hashtables.

Domain Query:: GetGlobal​

static DomainQuery GetGlobalBcast();

Broadcast the task to every ChiContainer in the ChiPool. Useful for things like flushing.