bounded senders

diff --git a/Cargo.lock b/Cargo.lock
index e8164938790d0a00b632f60de2d792adf657289a..41ce6c3db2d942f52108558401a8dbcbad660e59 100644 (file)
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -20,6 +20,18 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
+[[package]]
+name = "bytes"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4872d67bab6358e59559027aa3b9157c53d9358c51423c17554809a8858e0f8"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "darling"
 version = "0.14.1"
@@ -94,10 +106,110 @@ name = "foo"
 version = "0.1.0"
 dependencies = [
  "derive_builder",
+ "futures",
  "ron",
  "serde",
  "serde-value",
  "serde_json",
+ "tokio",
+]
+
+[[package]]
+name = "futures"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f73fe65f54d1e12b726f517d3e2135ca3125a437b6d998caf1962961f7172d9e"
+dependencies = [
+ "futures-channel",
+ "futures-core",
+ "futures-executor",
+ "futures-io",
+ "futures-sink",
+ "futures-task",
+ "futures-util",
+]
+
+[[package]]
+name = "futures-channel"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3083ce4b914124575708913bca19bfe887522d6e2e6d0952943f5eac4a74010"
+dependencies = [
+ "futures-core",
+ "futures-sink",
+]
+
+[[package]]
+name = "futures-core"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c09fd04b7e4073ac7156a9539b57a484a8ea920f79c7c675d05d289ab6110d3"
+
+[[package]]
+name = "futures-executor"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9420b90cfa29e327d0429f19be13e7ddb68fa1cccb09d65e5706b8c7a749b8a6"
+dependencies = [
+ "futures-core",
+ "futures-task",
+ "futures-util",
+]
+
+[[package]]
+name = "futures-io"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc4045962a5a5e935ee2fdedaa4e08284547402885ab326734432bed5d12966b"
+
+[[package]]
+name = "futures-macro"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "33c1e13800337f4d4d7a316bf45a567dbcb6ffe087f16424852d97e97a91f512"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "futures-sink"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "21163e139fa306126e6eedaf49ecdb4588f939600f0b1e770f4205ee4b7fa868"
+
+[[package]]
+name = "futures-task"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57c66a976bf5909d801bbef33416c41372779507e7a6b3a5e25e4749c58f776a"
+
+[[package]]
+name = "futures-util"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8b7abd5d659d9b90c8cba917f6ec750a74e2dc23902ef9cd4cc8c8b22e6036a"
+dependencies = [
+ "futures-channel",
+ "futures-core",
+ "futures-io",
+ "futures-macro",
+ "futures-sink",
+ "futures-task",
+ "memchr",
+ "pin-project-lite",
+ "pin-utils",
+ "slab",
+]
+
+[[package]]
+name = "hermit-abi"
+version = "0.1.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "62b467343b94ba476dcb2500d242dadbb39557df889310ac77c5d99100aaac33"
+dependencies = [
+ "libc",
 ]
 
 [[package]]
@@ -112,6 +224,49 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1aab8fc367588b89dcee83ab0fd66b72b50b72fa1904d7095045ace2b0c81c35"
 
+[[package]]
+name = "libc"
+version = "0.2.126"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "349d5a591cd28b49e1d1037471617a32ddcda5731b99419008085f72d5a53836"
+
+[[package]]
+name = "lock_api"
+version = "0.4.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "327fa5b6a6940e4699ec49a9beae1ea4845c6bab9314e4f84ac68742139d8c53"
+dependencies = [
+ "autocfg",
+ "scopeguard",
+]
+
+[[package]]
+name = "log"
+version = "0.4.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "abb12e687cfb44aa40f41fc3978ef76448f9b6038cad6aef4259d3c095a2382e"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "memchr"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
+
+[[package]]
+name = "mio"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "713d550d9b44d89174e066b7a6217ae06234c10cb47819a88290d2b353c31799"
+dependencies = [
+ "libc",
+ "log",
+ "wasi",
+ "windows-sys",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.14"
@@ -121,6 +276,22 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "num_cpus"
+version = "1.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "19e64526ebdee182341572e50e9ad03965aa510cd94427a4549448f285e957a1"
+dependencies = [
+ "hermit-abi",
+ "libc",
+]
+
+[[package]]
+name = "once_cell"
+version = "1.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7709cef83f0c1f58f666e746a08b21e0085f7440fa6a29cc194d68aac97a4225"
+
 [[package]]
 name = "ordered-float"
 version = "2.10.0"
@@ -130,6 +301,41 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "parking_lot"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3742b2c103b9f06bc9fff0a37ff4912935851bee6d36f3c02bcc755bcfec228f"
+dependencies = [
+ "lock_api",
+ "parking_lot_core",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09a279cbf25cb0757810394fbc1e359949b59e348145c643a939a525692e6929"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "redox_syscall",
+ "smallvec",
+ "windows-sys",
+]
+
+[[package]]
+name = "pin-project-lite"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e0a7ae3ac2f1173085d398531c705756c94a4c56843785df85a60c1a0afac116"
+
+[[package]]
+name = "pin-utils"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.37"
@@ -148,6 +354,15 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.2.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "62f25bc4c7e55e0b0b7a1d43fb893f4fa1361d0abe38b9ce4f323c2adfe6ef42"
+dependencies = [
+ "bitflags",
+]
+
 [[package]]
 name = "ron"
 version = "0.7.0"
@@ -165,6 +380,12 @@ version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "73b4b750c782965c211b42f022f59af1fbceabdd026623714f104152f1ec149f"
 
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
 [[package]]
 name = "serde"
 version = "1.0.136"
@@ -206,6 +427,37 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "signal-hook-registry"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e51e73328dc4ac0c7ccbda3a494dfa03df1de2f46018127f60c693f2648455b0"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "slab"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb703cfe953bccee95685111adeedb76fabe4e97549a58d16f03ea7b9367bb32"
+
+[[package]]
+name = "smallvec"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2dd574626839106c320a323308629dcb1acfc96e32a8cba364ddc61ac23ee83"
+
+[[package]]
+name = "socket2"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "66d72b759436ae32898a2af0a14218dbf55efde3feeb170eb623637db85ee1e0"
+dependencies = [
+ "libc",
+ "winapi",
+]
+
 [[package]]
 name = "strsim"
 version = "0.10.0"
@@ -223,8 +475,110 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "tokio"
+version = "1.19.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c51a52ed6686dd62c320f9b89299e9dfb46f730c7a48e635c19f21d116cb1439"
+dependencies = [
+ "bytes",
+ "libc",
+ "memchr",
+ "mio",
+ "num_cpus",
+ "once_cell",
+ "parking_lot",
+ "pin-project-lite",
+ "signal-hook-registry",
+ "socket2",
+ "tokio-macros",
+ "winapi",
+]
+
+[[package]]
+name = "tokio-macros"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9724f9a975fb987ef7a3cd9be0350edcbe130698af5b8f7a631e23d42d052484"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+
+[[package]]
+name = "windows-sys"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea04155a16a59f9eab786fe12a4a450e75cdb175f9e0d80da1e17db09f55b8d2"
+dependencies = [
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9bb8c3fd39ade2d67e9874ac4f3db21f0d710bee00fe7cab16949ec184eeaa47"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "180e6ccf01daf4c426b846dfc66db1fc518f074baa793aa7d9b9aaeffad6a3b6"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2e7917148b2812d1eeafaeb22a97e4813dfa60a3f8f78ebe204bcc88f12f024"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4dcd171b8776c41b97521e5da127a2d86ad280114807d0b2ab1e462bc764d9e1"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c811ca4a8c853ef420abd8592ba53ddbbac90410fab6903b3e79972a631f7680"

diff --git a/Cargo.toml b/Cargo.toml
index 3b562afde5bb6cf45779b54a4fa4944c5d50f9cb..0a62d73c407d649078e082fba8ac3d56bb3b6eac 100644 (file)
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,3 +12,5 @@ serde = { version="1", features=["derive"] }
 ron = "*"
 serde_json = "*"
 derive_builder = { version = "0.11.2", git = "https://github.com/ijackson/rust-derive-builder", rev = "ba0c1a5311bd9f93ddf5f5b8ec2a5f6f03b22fbe" }
+tokio = { version="1", features=["full"] }
+futures = "0.3"

diff --git a/src/main.rs b/src/main.rs
index d5e0cbd2513432f33ee390410f10ffb216fe3216..d9fd48504fbf816b2f3def16e6a8b3303c01bbe1 100644 (file)
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,80 +5,70 @@
 use std::mem;
 use std::mem::MaybeUninit;
 
-type S = &'static str;
+#[tokio::main]
+async fn main(){
+    let (mut tx, mut rx) = futures::channel::mpsc::channel(0);
+    let () = tx.try_send(0).unwrap();
 
+    for i in 1..=3 {
+        let mut tx2 = tx.clone();
+        let () = tx2.try_send(i).unwrap();
+        assert!{ tx2.try_send(i+10).unwrap_err().is_full() }
+        assert!{ tx.try_send(i+20).unwrap_err().is_full() }
+        eprintln!("S {:?}", i);
+    }
 
-#[repr(C)]
-struct Concat<const A: usize, const B: usize>(
-    [S; A], 
-    [S; B],
-);
-
-trait Ish {
-    const N: usize;
-}
-
-trait Has<const N: usize> {
-    const F: [S; N];
-}
-
-struct Inner { i: usize, }
-
-impl Ish for Inner {
-    const N: usize = 1;
-}
-impl Has<1> for Inner {
-    const F: [S; 1] = ["i"];
-}
-
-struct Outer { o: usize, p: usize }
-
-impl Ish for Outer {
-    const N: usize = Inner::N + 2;
-}
-impl Has<{ Inner::N + 2 }> for Outer {
-    const F: [S; Inner::N + 2] = {
-        const TUPLE: Concat<
-                2,
-                { Inner::N },
-            > = Concat(
-                ["o", "p"],
-                Inner::F,
-            );
-        unsafe { mem::transmute(TUPLE) }
+    let m = loop {
+        let m = rx.try_next();
+        let m = if let Ok(Some(m)) = m { m } else { break m };
+        eprintln!("Y {:?}", m);
     };
+    eprintln!("N {:?}", m);
 }
 
-/*
-const fn plus<const N: usize>
-(x: &'static [S],
- b: &'static [S],
- ary: &mut [MaybeUninit<S>],
-)
- -> &'static [S]
-{
-//    unsafe {
-        
-//    }
-    panic!()
-}
-
-struct Outer { o: usize, }
-impl Ish for Outer {
-    const N: usize = Inner::N + 1;
-    const F: &'static [S] = {
-        static mut ARY: [MaybeUninit<S>; Inner::N + 1] = [MaybeUninit::uninit(); Inner::N + 1];
-
-        plus::<{Inner::N + 1}>(
-            Inner::F,
-            &["o"],
-            &mut ARY[..],
-        )
-    };
-}
-*/
-
-fn main(){
-    eprintln!("IF {:?}", Inner::F);
-    eprintln!("OF {:?}", Outer::F);
-}
+14:58 <+Diziet> TIL that if you have a sender for a bounded 
+                futures::channel::mpsc::channel, you can always cheat and 
+                squeeze an extra message in: clone your sender (giving you a 
+                free slot); try_send is guaranteed to succeed because you have 
+                a reserved slot; then drop your cloned sender and now your 
+                message lives on the heap somewhere
+14:58 <+nickm> that's evil 
+14:58 <+nickm> let's not do it in arti?
+14:59 <+Diziet> I have a use for it
+14:59 <+nickm> not in arti I hope? 
+14:59 <+Diziet> We want to send channel padding negotiation cells
+15:00 <+Diziet> We only want to wake up to send such a cell when the output is 
+                writeable, so it wants to be in the inner select where we read 
+                the input
+15:00 <+Diziet> This trick lets us put the renegotiation message into the input 
+                without adding *any* code to the hot path in the reactor
+15:01 <+Diziet> The reactor code for handling the control message can do this 
+                even though it doesn't know (and can't know) the output is 
+                unblocked.
+15:02 <+nickm> Hm. I still think this might be a bad idea, but I'm less 
+               certain.  One request: Please define a new wrapper for 
+               mpsc::channel that explicitly has these semantics; maybe some 
+               kind of "semibounded" channel?
+15:02 <+Diziet> Well, the semantics we need don't actually include that the 
+                message gets delivered.
+15:02 <+nickm> Ah.  Then that's okay.
+15:02 <+Diziet> We can keep the cloned sender around until the *next* channel 
+                renegotiation message.
+15:02 <+nickm> try_send is correct if we don't care if it gets delivered 
+15:03 <+Diziet> We care that *this* message will get delivered *eventually*, 
+                *unless* some other superseding message arises.
+15:03 <+Diziet> So we need try_send to succeed but we don't care if dropping 
+                the sender drops the message it was queueing
+15:04 <+nickm> Hrrm.  Then I think a wrapper might be right.  Unless this is 
+               docmented behavior?
+15:04 <+Diziet> That every channel comes with a sending slot *is* documented
+15:04 <+Diziet> That the sending slot is reserved *for that channel* is not 
+                documented but is implied by the semantics of Sink
+15:05 <+Diziet> What happens if you drop the sender after using the slot is 
+                *not* documented but that is the part we don't care about (so 
+                long as it's not some crazy malfunction or panic)
+15:05 <+Diziet> So I think the right answer is to c&p my ad-hoc experiment into 
+                a test case :-)
+15:05 <+nickm> also add careful comments :)
+15:05 <+Diziet> Absolutely!
+15:05 <+nickm> eta: You may have thoughts on the above too