1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101

// Copyright 2023-2024 Paradigm.xyz
// This file is part of reth.
// Reth is a modular, contributor-friendly and blazing-fast implementation of
// the Ethereum protocol

// Permission is hereby granted, free of charge, to any
// person obtaining a copy of this software and associated
// documentation files (the "Software"), to deal in the
// Software without restriction, including without
// limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following
// conditions:

// The above copyright notice and this permission notice
// shall be included in all copies or substantial portions
// of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//! Helper type for `EthPubSubApiServer` implementation.
//!
//! Generates IDs for tracking subscriptions.

use std::fmt::Write;

use jsonrpsee_types::SubscriptionId;

/// An [`IdProvider`](jsonrpsee_core::traits::IdProvider) for ethereum
/// subscription ids.
///
/// Returns new hex-string [QUANTITY](https://ethereum.org/en/developers/docs/apis/json-rpc/#quantities-encoding) ids
#[derive(Debug, Clone, Copy, Default)]
#[non_exhaustive]
pub struct EthSubscriptionIdProvider;

impl jsonrpsee_core::traits::IdProvider for EthSubscriptionIdProvider {
    fn next_id(&self) -> SubscriptionId<'static> {
        to_quantity(rand::random::<u128>())
    }
}

/// Returns a hex quantity string for the given value
///
/// Strips all leading zeros, `0` is returned as `0x0`
#[inline(always)]
fn to_quantity(val: u128) -> SubscriptionId<'static> {
    let bytes = val.to_be_bytes();
    let b = bytes.as_slice();
    let non_zero = b.iter().take_while(|b| **b == 0).count();
    let b = &b[non_zero..];
    if b.is_empty() {
        return SubscriptionId::Str("0x0".into());
    }

    let mut id = String::with_capacity(2 * b.len() + 2);
    id.push_str("0x");
    let first_byte = b[0];
    write!(id, "{first_byte:x}").unwrap();

    for byte in &b[1..] {
        write!(id, "{byte:02x}").unwrap();
    }
    id.into()
}

#[cfg(test)]
mod tests {
    use super::*;
    use alloy_primitives::U128;

    #[test]
    fn test_id_provider_quantity() {
        let id = to_quantity(0);
        assert_eq!(id, SubscriptionId::Str("0x0".into()));
        let id = to_quantity(1);
        assert_eq!(id, SubscriptionId::Str("0x1".into()));

        for _ in 0..1000 {
            let val = rand::random::<u128>();
            let id = to_quantity(val);
            match id {
                SubscriptionId::Str(id) => {
                    let from_hex: U128 = id.parse().unwrap();
                    assert_eq!(from_hex, U128::from(val));
                }
                SubscriptionId::Num(_) => {
                    unreachable!()
                }
            }
        }
    }
}