Struct StorageTierBalancer 

pub struct StorageTierBalancer {
    pub tiers: HashMap<TierKind, TierStatus>,
    pub pending_tasks: Vec<MoveTask>,
    pub next_task_id: u64,
    pub total_completed_tasks: u64,
}

Balances data across storage tiers by monitoring utilization and generating rebalancing plans.

Rebalancing proceeds tier-by-tier: for each over-target tier the balancer selects candidate blocks (in the order supplied by the caller) until the estimated excess is covered, creating a MoveTask for each block. The destination is always the under-target tier with the most free bytes.

Fields

tiers: HashMap<TierKind, TierStatus>

Registered tiers indexed by TierKind.

pending_tasks: Vec<MoveTask>

Outstanding move tasks, sorted by priority descending (highest first).

next_task_id: u64

Monotonically increasing counter used to generate unique task IDs.

total_completed_tasks: u64

Total number of tasks that have been completed via Self::complete_task.

Implementations

impl StorageTierBalancer

pub fn new() -> Self

Creates a new, empty balancer.

pub fn add_tier(&mut self, status: TierStatus)

Registers a tier with the balancer. Overwrites any existing entry for the same TierKind.

pub fn update_usage(&mut self, kind: TierKind, used_bytes: u64)

Updates the used_bytes counter for an existing tier.

If the tier has not been registered the call is a no-op.

pub fn plan_rebalance( &mut self, candidates: Vec<(String, u64, TierKind)>, ) -> Vec<&MoveTask>

Plans a rebalancing run given a list of candidate blocks.

Parameters

• candidates — (cid, size_bytes, current_tier) tuples describing blocks eligible for migration.

Returns

Shared references to the newly created MoveTasks in their sorted (priority-descending) order within Self::pending_tasks.

pub fn complete_task(&mut self, task_id: u64) -> bool

Marks a task as completed and removes it from the pending queue.

Returns true when the task was found and removed, false otherwise.

pub fn tier_status(&self, kind: TierKind) -> Option<&TierStatus>

Returns a reference to the TierStatus for the given kind, if any.

pub fn stats(&self) -> BalancerStats

Returns aggregate statistics about the balancer’s current state.

Trait Implementations

impl Default for StorageTierBalancer

fn default() -> Self

Returns the “default value” for a type.