zacheryasc
f4f26c9f41
Improve the runtime, increase test coverage, add new actor types for monitoring and supervision to an `std` crate.
76 lines
2.8 KiB
Rust
76 lines
2.8 KiB
Rust
/// Backoff policy for worker threads when idle.
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///
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/// Workers spin → yield → sleep with increasing delay when no work is available.
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pub struct BackoffPolicy {
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/// Number of idle ticks before switching from spin to yield.
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pub spin_threshold: u32,
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/// Number of idle ticks before switching from yield to sleep.
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pub yield_threshold: u32,
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/// Microseconds added per tick beyond the yield threshold.
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pub sleep_increment_us: u64,
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/// Maximum sleep duration in microseconds.
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pub sleep_max_us: u64,
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}
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impl Default for BackoffPolicy {
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fn default() -> Self {
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Self {
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spin_threshold: 64,
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yield_threshold: 256,
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sleep_increment_us: 50,
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sleep_max_us: 1000,
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}
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}
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}
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/// What to do when a bounded mailbox is full.
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub enum MailboxOverflow {
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/// Drop the incoming message (newest). The message is silently discarded.
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DropNewest,
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/// Drop the oldest message in the queue to make room for the new one.
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DropOldest,
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}
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/// The tunable settings for the runtime.
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pub struct RuntimeConfig {
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pub max_actors: usize,
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pub channel_buffer_size: usize,
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pub num_threads: usize,
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pub backoff_policy: BackoffPolicy,
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/// Maximum messages processed per actor per tick.
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/// Prevents a single actor with a large mailbox from starving others.
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/// `0` means unlimited (drain entire mailbox).
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pub actor_message_budget: usize,
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/// Default per-actor mailbox capacity. `0` means unbounded (no limit).
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/// When non-zero, `mailbox_overflow` controls what happens when the mailbox is full.
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pub default_mailbox_capacity: usize,
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/// Overflow policy for bounded mailboxes. Ignored when `default_mailbox_capacity` is 0.
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pub mailbox_overflow: MailboxOverflow,
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}
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/// 8kB for the `Box<..>` before counting the rest of the memory
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const DEFAULT_MAX_ACTORS: usize = 1_000;
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/// Pre-allocated ring buffer capacity for each channel (transfer, spawn, inbox).
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/// When the ring is full, messages overflow into an unbounded backup queue.
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const DEFAULT_CHANNEL_BUFFER_SIZE: usize = 1_000;
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/// Default per-actor message budget per tick.
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/// Inspired by BEAM's reduction budget (4000) and tokio's cooperative budget (128).
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/// 64 is a good default: high enough for throughput, low enough for fairness.
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const DEFAULT_ACTOR_MESSAGE_BUDGET: usize = 64;
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impl Default for RuntimeConfig {
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fn default() -> Self {
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Self {
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max_actors: DEFAULT_MAX_ACTORS,
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channel_buffer_size: DEFAULT_CHANNEL_BUFFER_SIZE,
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num_threads: 1,
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backoff_policy: BackoffPolicy::default(),
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actor_message_budget: DEFAULT_ACTOR_MESSAGE_BUDGET,
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default_mailbox_capacity: 0,
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mailbox_overflow: MailboxOverflow::DropNewest,
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}
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}
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}
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