Struct StorageTierMigrator 

pub struct StorageTierMigrator {
    pub config: MigratorConfig,
    pub blocks: HashMap<String, BlockMeta>,
    pub migration_log: VecDeque<MigrationAction>,
    pub total_migrations: u64,
    pub total_bytes_migrated: u64,
}

Production-grade intelligent block migration engine.

Tracks blocks across four storage tiers (Hot, Warm, Cold, Archive) and demotes them according to configurable TierPolicy rules based on age, access frequency, and size constraints.

Lifecycle

1. Configure via MigratorConfig and create with StorageTierMigrator::new.
2. Register blocks with register_block.
3. Record access events with record_access.
4. Trigger a migration cycle with run_migration_cycle.
5. Inspect results via migration_log or migrator_stats.

Fields

config: MigratorConfig

Migrator configuration (policies, dry-run flag, batch/max sizes).

blocks: HashMap<String, BlockMeta>

Map from CID → block metadata. Central registry.

migration_log: VecDeque<MigrationAction>

Bounded ring-buffer of recently executed (or dry-run planned) migrations.

total_migrations: u64

All-time migration execution count.

total_bytes_migrated: u64

All-time total bytes migrated.

Implementations

impl StorageTierMigrator

pub fn new(config: MigratorConfig) -> Self

Create a new migrator from the given configuration.

pub fn register_block(&mut self, meta: BlockMeta)

Register a new block or overwrite an existing entry with updated metadata.

pub fn unregister_block(&mut self, cid: &str) -> bool

Remove a block from the registry. Returns true if the block existed.

pub fn record_access(&mut self, cid: &str, now_ms: u64) -> bool

Record an access event for a block, incrementing its counter and updating last_accessed_ms. Returns true if the block was found.

pub fn evaluate_block( &self, meta: &BlockMeta, now_ms: u64, ) -> Option<MigrationAction>

Evaluate whether a single block needs to be migrated, given the current timestamp now_ms.

Policies are checked in descending tier priority order. If a block’s current tier matches a policy and any demotion condition is satisfied, a MigrationAction targeting the next-colder tier is returned. Returns None if no migration is required.

pub fn plan_migrations(&self, now_ms: u64) -> Vec<MigrationAction>

Evaluate every tracked block and return the list of MigrationActions that should be executed.

Actions are sorted by from_tier.priority() descending (hottest blocks first) and capped at MigratorConfig::max_migrations_per_run.

pub fn execute_migrations( &mut self, actions: Vec<MigrationAction>, now_ms: u64, ) -> MigrationResult

Execute a pre-planned list of migration actions.

In dry-run mode: populates actions_planned but leaves block metadata untouched. In live mode: blocks are processed in batches of MigratorConfig::batch_size. CIDs that no longer exist in the registry are recorded in failed_cids.

pub fn run_migration_cycle(&mut self, now_ms: u64) -> MigrationResult

Convenience method: plan migrations for now_ms, then execute them in one atomic call. Returns a combined MigrationResult.

pub fn blocks_in_tier(&self, tier: &StorageTier) -> Vec<&BlockMeta>

Returns all blocks currently residing in tier, sorted by access_count descending (most-accessed first).

pub fn migration_log(&self) -> &VecDeque<MigrationAction>

Immutable reference to the internal migration log ring-buffer.

pub fn migrator_stats(&self) -> MigratorStats

Snapshot of current migrator statistics.