Add no_std feature and hashbrown dependency

Add no_std feature as an initial step to supporting embedded platforms.

Use hashbrown for HashMap, HashSet, and hash_map replacements for their
std::collections counterparts.

Author: GeneFerneau

ci/check-compiles.sh

@@ -4,3 +4,4 @@ set -x
 echo Testing $(git log -1 --oneline)
 cargo check
 cd fuzz && cargo check --features=stdin_fuzz
+cd ../lightning && cargo check --features=no_std

lightning/Cargo.toml

@@ -21,6 +21,7 @@ max_level_error = []
 max_level_warn = []
 max_level_info = []
 max_level_debug = []
+no_std = ["hashbrown"]
 # Allow signing of local transactions that may have been revoked or will be revoked, for functional testing (e.g. justice tx handling).
 # This is unsafe to use in production because it may result in the counterparty publishing taking our funds.
 unsafe_revoked_tx_signing = []
@@ -29,6 +30,7 @@ unstable = []
 [dependencies]
 bitcoin = "0.26"
 
+hashbrown = { version = "0.9", optional = true }
 hex = { version = "0.3", optional = true }
 regex = { version = "0.1.80", optional = true }
 

lightning/src/chain/chainmonitor.rs

@@ -42,7 +42,10 @@ use util::logger::Logger;
 use util::events;
 use util::events::Event;
 
+#[cfg(not(feature = "no_std"))]
 use std::collections::{HashMap, hash_map};
+#[cfg(feature = "no_std")]
+use hashbrown::{HashMap, hash_map};
 use std::sync::RwLock;
 use std::ops::Deref;
 

lightning/src/chain/channelmonitor.rs

@@ -51,10 +51,15 @@ use util::ser::{Readable, ReadableArgs, MaybeReadable, Writer, Writeable, U48};
 use util::byte_utils;
 use util::events::Event;
 
+#[cfg(not(feature = "no_std"))]
 use std::collections::{HashMap, HashSet, hash_map};
-use std::{cmp, mem};
+#[cfg(feature = "no_std")]
+use hashbrown::{HashMap, HashSet, hash_map};
+#[cfg(not(feature = "no_std"))]
+use std::{cmp, mem, ops::Deref};
+#[cfg(feature = "no_std")]
+use core::{cmp, mem, ops::Deref};
 use std::io::Error;
-use std::ops::Deref;
 use std::sync::Mutex;
 
 /// An update generated by the underlying Channel itself which contains some new information the

lightning/src/chain/keysinterface.rs

@@ -36,8 +36,14 @@ use ln::chan_utils;
 use ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction};
 use ln::msgs::UnsignedChannelAnnouncement;
 
+#[cfg(not(feature = "no_std"))]
 use std::collections::HashSet;
+#[cfg(feature = "no_std")]
+use hashbrown::HashSet;
+#[cfg(not(feature = "no_std"))]
 use std::sync::atomic::{AtomicUsize, Ordering};
+#[cfg(feature = "no_std")]
+use core::sync::atomic::{AtomicUsize, Ordering};
 use std::io::Error;
 use ln::msgs::{DecodeError, MAX_VALUE_MSAT};
 

lightning/src/lib.rs

@@ -34,6 +34,9 @@ extern crate bitcoin;
 #[cfg(any(test, feature = "_test_utils"))] extern crate hex;
 #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))] extern crate regex;
 
+#[cfg(feature = "no_std")] extern crate core;
+#[cfg(feature = "no_std")] extern crate hashbrown;
+
 #[macro_use]
 pub mod util;
 pub mod chain;

lightning/src/ln/chan_utils.rs

@@ -31,12 +31,14 @@ use bitcoin::secp256k1::{Secp256k1, Signature, Message};
 use bitcoin::secp256k1::Error as SecpError;
 use bitcoin::secp256k1;
 
-use std::cmp;
+#[cfg(not(feature = "no_std"))]
+use std::{cmp, ops::Deref};
+#[cfg(feature = "no_std")]
+use core::{cmp, ops::Deref};
 use ln::chan_utils;
 use util::transaction_utils::sort_outputs;
 use ln::channel::INITIAL_COMMITMENT_NUMBER;
 use std::io::Read;
-use std::ops::Deref;
 use chain;
 
 const HTLC_OUTPUT_IN_COMMITMENT_SIZE: usize = 1 + 8 + 4 + 32 + 5;

lightning/src/ln/channel.rs

@@ -38,9 +38,10 @@ use util::logger::Logger;
 use util::errors::APIError;
 use util::config::{UserConfig,ChannelConfig};
 
-use std;
-use std::{cmp,mem,fmt};
-use std::ops::Deref;
+#[cfg(not(feature = "no_std"))]
+use std::{cmp, mem, fmt, ops::Deref};
+#[cfg(feature = "no_std")]
+use core::{cmp, mem, fmt, ops::Deref};
 #[cfg(any(test, feature = "fuzztarget"))]
 use std::sync::Mutex;
 use bitcoin::hashes::hex::ToHex;

lightning/src/ln/channelmanager.rs

@@ -55,16 +55,32 @@ use util::chacha20::{ChaCha20, ChaChaReader};
 use util::logger::Logger;
 use util::errors::APIError;
 
-use std::{cmp, mem};
+#[cfg(not(feature = "no_std"))]
+use std::{
+    cmp,
+    mem,
+    marker::{Sync, Send},
+    ops::Deref,
+    sync::atomic::{AtomicUsize, Ordering},
+    time::Duration,
+};
+#[cfg(feature = "no_std")]
+use core::{
+    cmp,
+    mem,
+    marker::{Sync, Send},
+    ops::Deref,
+    sync::atomic::{AtomicUsize, Ordering},
+    time::Duration,
+};
+#[cfg(not(feature = "no_std"))]
 use std::collections::{HashMap, hash_map, HashSet};
+#[cfg(feature = "no_std")]
+use hashbrown::{HashMap, HashSet, hash_map};
 use std::io::{Cursor, Read};
 use std::sync::{Arc, Condvar, Mutex, MutexGuard, RwLock, RwLockReadGuard};
-use std::sync::atomic::{AtomicUsize, Ordering};
-use std::time::Duration;
 #[cfg(any(test, feature = "allow_wallclock_use"))]
 use std::time::Instant;
-use std::marker::{Sync, Send};
-use std::ops::Deref;
 use bitcoin::hashes::hex::ToHex;
 
 // We hold various information about HTLC relay in the HTLC objects in Channel itself:
@@ -4306,7 +4322,10 @@ impl<'a, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
 mod tests {
 	use ln::channelmanager::PersistenceNotifier;
 	use std::sync::Arc;
+	#[cfg(not(feature = "no_std"))]
 	use std::sync::atomic::{AtomicBool, Ordering};
+	#[cfg(feature = "no_std")]
+	use core::sync::atomic::{AtomicBool, Ordering};
 	use std::thread;
 	use std::time::Duration;
 

lightning/src/ln/features.rs

@@ -25,8 +25,10 @@
 //! [`Features`]: struct.Features.html
 //! [`Context`]: sealed/trait.Context.html
 
-use std::{cmp, fmt};
-use std::marker::PhantomData;
+#[cfg(not(feature = "no_std"))]
+use std::{cmp, fmt, marker::PhantomData};
+#[cfg(feature = "no_std")]
+use core::{cmp, fmt, marker::PhantomData};
 
 use ln::msgs::DecodeError;
 use util::ser::{Readable, Writeable, Writer};