Add crate for the transaction-chaining Scheduler

.github/workflows/tests.yml

@@ -42,6 +42,7 @@ jobs:
             -p serai-processor-key-gen \
             -p serai-processor-frost-attempt-manager \
             -p serai-processor-primitives \
+            -p serai-processor-transaction-chaining-scheduler \
             -p serai-processor-scanner \
             -p serai-processor \
             -p tendermint-machine \

Cargo.toml

@@ -74,6 +74,7 @@ members = [
   "processor/frost-attempt-manager",
 
   "processor/primitives",
+  "processor/scheduler/transaction-chaining",
   "processor/scanner",
   "processor",
 

deny.toml

@@ -48,6 +48,9 @@ exceptions = [
   { allow = ["AGPL-3.0"], name = "serai-processor-messages" },
   { allow = ["AGPL-3.0"], name = "serai-processor-key-gen" },
   { allow = ["AGPL-3.0"], name = "serai-processor-frost-attempt-manager" },
+
+  { allow = ["AGPL-3.0"], name = "serai-processor-transaction-chaining-scheduler" },
+  { allow = ["AGPL-3.0"], name = "serai-processor-scanner" },
   { allow = ["AGPL-3.0"], name = "serai-processor" },
 
   { allow = ["AGPL-3.0"], name = "tributary-chain" },

processor/scheduler/transaction-chaining/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "serai-processor-transaction-chaining-scheduler"
+version = "0.1.0"
+description = "Scheduler for networks with transaction chaining for the Serai processor"
+license = "AGPL-3.0-only"
+repository = "https://github.com/serai-dex/serai/tree/develop/processor/scheduler/transaction-chaining"
+authors = ["Luke Parker <lukeparker5132@gmail.com>"]
+keywords = []
+edition = "2021"
+publish = false
+
+[package.metadata.docs.rs]
+all-features = true
+rustdoc-args = ["--cfg", "docsrs"]
+
+[package.metadata.cargo-machete]
+ignored = ["scale"]
+
+[lints]
+workspace = true
+
+[dependencies]

processor/scheduler/transaction-chaining/LICENSE

@@ -0,0 +1,15 @@
+AGPL-3.0-only license
+
+Copyright (c) 2022-2024 Luke Parker
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License Version 3 as
+published by the Free Software Foundation.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.

processor/scheduler/transaction-chaining/README.md

@@ -0,0 +1,19 @@
+# Transaction Chaining Scheduler
+
+A scheduler of transactions for networks premised on the UTXO model which
+support transaction chaining. Transaction chaining refers to the ability to
+obtain an identifier for an output within a transaction not yet signed usable
+to build and sign a transaction spending it.
+
+### Design
+
+The scheduler is designed to achieve fulfillment of all expected payments with
+an `O(1)` delay (regardless of prior scheduler state), `O(log n)` time, and
+`O(n)` computational complexity.
+
+Due to the ability to chain transactions, we can immediately plan/sign dependent
+transactions. For the time/computational complexity, we use a tree to fulfill
+payments. This quickly gives us the ability to make as many outputs as necessary
+(regardless of per-transaction output limits) and only has the latency of
+including a chain of `O(log n)` transactions on-chain. The only computational
+overhead is in creating the transactions which are branches in the tree.

processor/scheduler/transaction-chaining/src/lib.rs

@@ -0,0 +1,3 @@
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![doc = include_str!("../README.md")]
+#![deny(missing_docs)]