revm_state/
account_extension.rs

1//! Shared chain-specific account payloads.
2
3use core::{cmp::Ordering, ops::Deref};
4use primitives::Bytes;
5use std::vec::Vec;
6use triomphe::ThinArc;
7
8/// Raw, unencoded account bytes with a one-pointer inline representation.
9///
10/// Empty payloads allocate nothing. Nonempty payloads store their length and bytes
11/// in one reference-counted allocation; cloning shares that allocation.
12///
13/// Accounts omit empty extensions in Serde. Their binary representation requires
14/// struct boundaries, as in MessagePack; bincode and Postcard are not supported.
15#[derive(Clone, Debug, Default)]
16pub struct AccountExtension(Option<ThinArc<(), u8>>);
17
18impl AccountExtension {
19    /// Takes ownership of a shared payload without copying its bytes.
20    pub fn from_shared(payload: Option<ThinArc<(), u8>>) -> Self {
21        Self(payload.filter(|arc| !arc.slice.is_empty()))
22    }
23
24    /// Transfers the shared allocation without copying its bytes.
25    pub fn into_shared(self) -> Option<ThinArc<(), u8>> {
26        self.0
27    }
28
29    /// Creates an empty payload without allocating.
30    pub const fn new() -> Self {
31        Self(None)
32    }
33
34    /// Copies bytes into a single shared allocation.
35    pub fn copy_from_slice(bytes: &[u8]) -> Self {
36        Self((!bytes.is_empty()).then(|| ThinArc::from_header_and_slice((), bytes)))
37    }
38
39    /// Allocates a zero-filled payload and initializes it in place.
40    ///
41    /// Encoders can write directly into the final allocation, avoiding an intermediate Vec.
42    pub fn new_with(len: usize, write: impl FnOnce(&mut [u8])) -> Self {
43        if len == 0 {
44            write(&mut []);
45            return Self::new();
46        }
47        let mut arc = ThinArc::from_header_and_iter((), core::iter::repeat_n(0, len));
48        arc.with_arc_mut(|arc| {
49            let unique = triomphe::Arc::get_mut(arc).expect("new allocation is unique");
50            write(unique.slice_mut());
51        });
52        Self(Some(arc))
53    }
54
55    /// Returns whether the payload is empty.
56    pub const fn is_empty(&self) -> bool {
57        self.0.is_none()
58    }
59}
60
61impl AsRef<[u8]> for AccountExtension {
62    fn as_ref(&self) -> &[u8] {
63        self.0.as_ref().map_or(&[], |arc| &arc.slice)
64    }
65}
66
67impl Deref for AccountExtension {
68    type Target = [u8];
69    fn deref(&self) -> &[u8] {
70        self.as_ref()
71    }
72}
73
74impl From<Bytes> for AccountExtension {
75    fn from(bytes: Bytes) -> Self {
76        Self::copy_from_slice(&bytes)
77    }
78}
79
80impl From<Vec<u8>> for AccountExtension {
81    fn from(bytes: Vec<u8>) -> Self {
82        Self::copy_from_slice(&bytes)
83    }
84}
85
86impl PartialEq for AccountExtension {
87    fn eq(&self, other: &Self) -> bool {
88        self.0 == other.0
89    }
90}
91impl Eq for AccountExtension {}
92
93impl core::hash::Hash for AccountExtension {
94    fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
95        core::hash::Hash::hash(self.as_ref(), state);
96    }
97}
98
99impl PartialOrd for AccountExtension {
100    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
101        Some(self.cmp(other))
102    }
103}
104
105impl Ord for AccountExtension {
106    fn cmp(&self, other: &Self) -> Ordering {
107        // Order payload bytes, not ThinArc's length header.
108        self.as_ref().cmp(other.as_ref())
109    }
110}
111
112#[cfg(feature = "serde")]
113impl serde::Serialize for AccountExtension {
114    fn serialize<S: serde::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
115        if serializer.is_human_readable() {
116            primitives::hex::serialize(self.as_ref(), serializer)
117        } else {
118            serializer.serialize_bytes(self.as_ref())
119        }
120    }
121}
122
123#[cfg(feature = "serde")]
124impl<'de> serde::Deserialize<'de> for AccountExtension {
125    fn deserialize<D: serde::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
126        Bytes::deserialize(deserializer).map(Self::from)
127    }
128}
129
130#[cfg(test)]
131mod tests {
132    use super::*;
133
134    #[test]
135    fn shared_payload_and_in_place_encoding() {
136        assert_eq!(size_of::<AccountExtension>(), size_of::<usize>());
137        let payload = AccountExtension::new_with(32, |out| out.fill(42));
138        let cloned = payload.clone();
139        assert_eq!(payload.as_ref(), &[42; 32]);
140        assert_eq!(payload.as_ptr(), cloned.as_ptr());
141        assert_eq!(payload, AccountExtension::copy_from_slice(&[42; 32]));
142        assert!(AccountExtension::new_with(0, |out| assert!(out.is_empty())).is_empty());
143        assert!(
144            AccountExtension::copy_from_slice(&[0, 255]) < AccountExtension::copy_from_slice(&[1])
145        );
146    }
147
148    #[test]
149    #[cfg(feature = "serde")]
150    fn byte_wire_format() {
151        for payload in [&[][..], &[0x82, 0xaa][..], &[42; 256][..]] {
152            let bytes = Bytes::copy_from_slice(payload);
153            let extension = AccountExtension::from(bytes.clone());
154            let json = serde_json::to_vec(&bytes).unwrap();
155            assert_eq!(serde_json::to_vec(&extension).unwrap(), json);
156            assert_eq!(
157                serde_json::from_slice::<AccountExtension>(&json).unwrap(),
158                extension
159            );
160            let binary = postcard::to_allocvec(&bytes).unwrap();
161            assert_eq!(postcard::to_allocvec(&extension).unwrap(), binary);
162            assert_eq!(
163                postcard::from_bytes::<AccountExtension>(&binary).unwrap(),
164                extension
165            );
166            let pair = (extension.clone(), 42u8);
167            let encoded = postcard::to_allocvec(&pair).unwrap();
168            assert_eq!(
169                postcard::from_bytes::<(AccountExtension, u8)>(&encoded).unwrap(),
170                pair
171            );
172            if !payload.is_empty() {
173                assert!(
174                    postcard::from_bytes::<AccountExtension>(&binary[..binary.len() - 1]).is_err()
175                );
176            }
177        }
178    }
179}
revm_state/account_extension.rs

revm_state/
account_extension.rs
