start: service config

Cargo.lock

@@ -524,6 +524,7 @@ dependencies = [
  "serde_cbor",
  "serde_json",
  "smallvec",
+ "stackalloc",
  "tokio",
  "uuid",
 ]
@@ -832,6 +833,16 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "stackalloc"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c790f3002980a878515d27f0f1b4d083f67f9103e9316205088cc4728277de51"
+dependencies = [
+ "cc",
+ "rustc_version",
+]
+
 [[package]]
 name = "subtle"
 version = "2.4.0"

Cargo.toml

@@ -23,6 +23,7 @@ serde = {version = "1.0.118", features=  ["derive"]}
 serde_cbor = "0.11.1"
 serde_json = "1.0.60"
 smallvec = "1.5.1"
+stackalloc = "1.1.0"
 tokio = {version = "0.2", features = ["full"]}
 uuid = {version = "0.8", features = ["v4", "serde"]}
 

src/ext/bytes.rs

@@ -62,3 +62,35 @@ pub fn explicit_clear(buffer : &mut[u8]) {
     }
     len
 }
+
+/// Max size of bytes we'll allocate to the stack at runtime before using a heap allocated buffer.
+pub const STACK_SIZE_LIMIT: usize = 4096;
+
+/// Allocate `size` bytes. Allocates on the stack if size is lower than `STACK_SIZE_LIMIT`, otherwise allocates on the heap.
+pub fn alloca_limit<F, T>(size: usize, f: F) -> T
+where F: FnOnce(&mut [u8]) -> T
+{
+    if size > STACK_SIZE_LIMIT {
+	thread_local! {
+	    static BUFFER: RefCell<Vec<u8>> = RefCell::new(vec![0u8; STACK_SIZE_LIMIT*2]);
+	}
+	BUFFER.with(move |buf| {
+	    // If the borrow fails then `f` has recursively called into this function, so for that we allocate a new buffer instead of reusing this static one.
+	    if let Ok(mut buf) = buf.try_borrow_mut() {
+		if buf.len() < size {
+		    buf.resize(size, 0);
+		}
+		let res = f(&mut buf[..size]);
+		bytes::clear(&mut buf[..size]);
+		res
+	    } else {
+		f(&mut vec![0u8; size])		
+	    }
+	})
+    } else {
+	stackalloc::alloca_zeroed(size, f)
+	    
+	// I don't think this is okay to do.
+	//stackalloc::alloca(size, move |buf| f(unsafe { stackalloc::helpers::slice_assume_init_mut(buf) }))
+    }
+}

src/ext/mod.rs

@@ -3,6 +3,9 @@ use std::collections::BTreeSet;
 use std::borrow::Borrow;
 use futures::prelude::*;
 
+use std::cell::RefCell;
+use std::ptr;
+
 mod iters;
 pub use iters::*;
 
@@ -26,8 +29,204 @@ pub use defer_drop::*;
 
 pub mod chunking;
 
+/// How many elements should `precollect` allocate on the stack before spilling to the heap.
 pub const PRECOLLECT_STACK_SIZE: usize = 64;
 
+/// Create a duration with time suffix `h`, `m`, `s`, `ms` or `ns`.
+///
+/// # Combination
+/// These can also be combined.
+/// ```
+/// # use flan_utils::duration;
+/// duration!(1 h, 20 m, 30 s);
+/// ```
+#[macro_export] macro_rules! duration
+{
+    (0 $($_any:tt)?) => (::core::time::Duration::from_secs(0));
+    ($dur:literal ms) => (::core::time::Duration::from_millis($dur));
+    ($dur:literal ns) => (::core::time::Duration::from_nanos($dur));
+    ($dur:literal s) => (::core::time::Duration::from_secs($dur));
+    ($dur:literal m) => (::core::time::Duration::from_secs($dur * 60));
+    ($dur:literal h) => (::core::time::Duration::from_secs($dur * 60 * 60));
+    
+    ( $($dur:literal $unit:tt),*)=> {
+        duration!(0 s) $(
+            + duration!($dur $unit)
+        )*
+    };
+}
+
+
+/// Create a basic, C-like enum
+#[macro_export] macro_rules! basic_enum {
+    ($(#[$meta:meta])* $vis:vis $name:ident $(; $tcomment:literal)?: $($var:ident $(=> $comment:literal)?),+ $(,)?) => {
+        $(#[$meta])*
+	    #[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Copy)]
+	$(#[doc = $tcomment])?
+	    $vis enum $name {
+		$(
+		    $(#[doc = $comment])?
+			$var
+		),+
+	    }
+    }
+}
+
+
+/// Create a `Yes` or `No` enum.
+#[macro_export] macro_rules! bool_type {
+    ($vis:vis $name:ident $(; $comment:literal)? => $yes:ident, $no:ident) => {
+	basic_enum!(#[repr(u8)] $vis $name $(; $comment)?: $yes => "# First variant\n\nYes/true", $no => "# Second variant\n\nNo/false");
+
+	impl From<bool> for $name
+	{
+	    #[inline] fn from(from: bool) -> Self
+	    {
+		if from {
+		    Self::$yes
+		} else {
+		    Self::$no
+		}
+	    }
+	}
+
+	impl From<$name> for bool
+	{
+	    #[inline] fn from(from: $name) -> Self
+	    {
+		match from {
+		    $name::$yes => true,
+		    $name::$no => false,
+		}
+	    }
+	}
+
+	impl $name
+	{
+	    /// Create from a bool value.
+	    #[inline] pub const fn new(from: bool) -> Self
+	    {
+		if from {
+		    Self::$yes
+		} else {
+		    Self::$no
+		}
+	    }
+
+	    /// Is this false?
+	    #[inline] pub const fn is_no(self) -> bool
+	    {
+		!self.is_yes()
+	    }
+	    /// Is this true?
+	    #[inline] pub const fn is_yes(self) -> bool
+	    {
+		match self {
+		    Self::$yes => true,
+		    Self::$no => false,
+		}	
+	    }
+
+	    /// Return Some(T) if self is true.
+	    #[inline] pub fn some<T>(self, value: T) -> Option<T>
+	    {
+		self.and_then(move || value)
+	    }
+	    
+	    /// Map this value
+	    #[inline] pub fn map<F, T>(self, f: F) -> T
+	    where F: FnOnce(bool) -> T
+	    {
+		f(self.is_yes())
+	    }
+
+	    /// Run this closure if value is false
+	    #[inline] pub fn or_else<F, T>(self, f: F) -> Option<T>
+	    where F: FnOnce() -> T
+	    {
+		if let Self::$no = self {
+		    Some(f())
+		} else {
+		    None
+		}
+	    }
+	    /// Run this closure if value is true
+	    #[inline] pub fn and_then<F, T>(self, f: F) -> Option<T>
+	    where F: FnOnce() -> T
+	    {
+		if let Self::$yes = self {
+		    Some(f())
+		} else {
+		    None
+		}
+	    }
+
+	    /// Return `yes` if true and `no` if false
+	    #[inline] pub fn either<T>(self, yes: T, no: T) -> T
+	    {
+		self.and_either(move || yes, move || no)
+	    }
+	    /// Run closure `yes` if value is true, `no` if value is false.
+	    #[inline] pub fn and_either<F, G, T>(self, yes: F, no: G) -> T
+	    where F: FnOnce() -> T,
+	    G: FnOnce() -> T,
+	    {
+		match self {
+		    Self::$yes => yes(),
+		    Self::$no => no(),
+		}
+	    }
+	}
+    };
+    ($vis:vis $name:ident $(; $comment:literal)?) => {
+		  $crate::bool_type!($vis $name $(; $comment)? => Yes, No);
+    }
+}
+
+
+/// Create an accessor method. for a field in a structure.
+///
+/// The supported accessor types are: `ref`, `mut`, and `move`.
+#[macro_export] macro_rules! accessor {
+    ($vis:vis ref $name:ident -> $ty:ty => $internal:ident $(; $comment:literal)?) => {
+	$(#[doc=$comment])?
+	    #[inline] $vis fn $name(&self) -> &$ty {
+		&self.$internal
+	    }
+    };
+    ($vis:vis ref $name:ident -> $ty:ty => $internal:tt $(; $comment:literal)?) => {
+	$(#[doc=$comment])?
+	    #[inline] $vis fn $name(&self) -> &$ty {
+		&self.$internal
+	    }
+    };
+    ($vis:vis mut $name:ident -> $ty:ty => $internal:ident $(; $comment:literal)?) => {
+	$(#[doc=$comment])?
+	    #[inline] $vis fn $name(&self) -> &mut $ty {
+		&mut self.$internal
+	    }
+    };
+    ($vis:vis mut $name:ident -> $ty:ty => $internal:tt $(; $comment:literal)?) => {
+	$(#[doc=$comment])?
+	    #[inline] $vis fn $name(&self) -> &mut $ty {
+		&mut self.$internal
+	    }
+    };
+    ($vis:vis move $name:ident -> $ty:ty => $internal:ident $(; $comment:literal)?) => {
+	$(#[doc=$comment])?
+	    #[inline] $vis fn $name(&self) -> $ty {
+		self.$internal
+	    }
+    };
+    ($vis:vis move $name:ident -> $ty:ty => $internal:tt $(; $comment:literal)?) => {
+	$(#[doc=$comment])?
+	    #[inline] $vis fn $name(&self) -> $ty {
+		self.$internal
+	    }
+    };
+}
+
+
 /// Collect an iterator's output and then drop it to detach the iterator from any references or resources it might have.
 #[macro_export] macro_rules! precollect {
     ($iter:expr, $num:literal) => {

src/service/builder.rs

@@ -0,0 +1,11 @@
+use super::*;
+use config::*;
+
+/// Builder for a service
+#[derive(Debug, Clone)]
+pub struct ServiceBuilder
+{
+    /// Settings for the service to use
+    // Boxed because this is a large structure
+    settings: Box<ServiceSettings>,
+}

src/service/config.rs

@@ -0,0 +1,56 @@
+//! Configuration for services
+use super::*;
+use std::time::Duration;
+use std::num::NonZeroUsize;
+
+/// How long to wait before resetting the restart counter for `StopDirective::Restart`.
+pub const SUPERVISOR_RESTART_TIME_LIMIT: Option<Duration> = Some(Duration::from_secs(5));
+
+/// What the supervisor task should do when its background service unexpectedly exits
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Copy, Serialize, Deserialize)]
+pub enum StopDirective
+{
+    /// Ignore it, allow the service to exit
+    Ignore,
+    /// Restart the service, either infinitely, or up to this many times before exiting.
+    ///
+    /// If the restart limit is exceeded, exit with error.
+    /// The limit is reset every `SUPERVISOR_RESTART_TIME_LIMIT` seconds (or never, if it is `None`.)
+    Restart(Option<NonZeroUsize>),
+    /// Panic the supervisor
+    Panic,
+    /// Exit with error
+    Error,
+}
+
+impl Default for StopDirective
+{
+    #[inline]
+    fn default() -> Self
+    {
+	Self::Error
+    }
+}
+
+/// Settings for how a background service runs
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Copy, Serialize, Deserialize)]
+pub struct ServiceSettings
+{
+    // Supervisor controls
+
+    /// What to do when the supervisor's child task exits unexpectedly
+    pub supervisor_stop_directive: StopDirective,
+    
+    // Request dispatching options
+    
+    /// How many requests to batch together
+    pub req_dispatch_hold: usize,
+    /// How long to wait before forcefully processing an unfilled batch of requests
+    pub req_dispatch_force_timeout: Option<Duration>,
+    /// How long to wait before processing batches of requests
+    pub req_dispatch_delay: Option<Duration>,
+    /// Random delay between request batch processing
+    pub req_dispatch_jitter: Option<(Duration, Duration)>,
+}
+
+//TODO: impl Default for ServiceSettings

src/service/mod.rs

@@ -1,12 +1,15 @@
 //! The actual running service
 use super::*;
 use std::sync::Arc;
-use tokio::sync::{
-    RwLock,
-    Mutex,
+use tokio::{
+    task::JoinHandle,
+    sync::{
+	RwLock,
+	Mutex,
 	
-    mpsc,
-    oneshot,
+	mpsc,
+	oneshot,
+    }
 };
 
 pub mod command;
@@ -15,17 +18,27 @@ use command::{
     CommandID,
 };
 
+pub mod config;
+
+mod builder;
+pub use builder::*;
+
 /// Handle to a running service. Can be used to join it or create `Channel`s.
 #[derive(Debug)]
 pub struct Handle
 {
+    task: JoinHandle<()>,
     
+    channel: Channel,
 }
 
+/// Inner portion of a `Channel`. Also held through `Arc` by the background service and its supervisor.
 #[derive(Debug)]
 struct ChannelInner
 {
-
+    /// The settings for the service
+    // Boxed because this is a large structure.
+    opt: Box<config::ServiceSettings>,
 }
 
 
@@ -46,7 +59,7 @@ struct Request
 
 /// Communicates with a running service
 #[derive(Debug, Clone)]
-pub struct Channel{
+pub struct Channel {
     inner: Arc<ChannelInner>,
 
     
@@ -60,3 +73,9 @@ impl PartialEq for Channel {
 	Arc::ptr_eq(&self.inner, &other.inner)
     }
 }
+
+/// Create a new service
+pub fn create() -> ServiceBuilder
+{
+    todo!()
+}