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
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146

// Copyright 2018 MaidSafe.net limited.
//
// This SAFE Network Software is licensed to you under the MIT license <LICENSE-MIT
// http://opensource.org/licenses/MIT> or the Modified BSD license <LICENSE-BSD
// https://opensource.org/licenses/BSD-3-Clause>, at your option. This file may not be copied,
// modified, or distributed except according to those terms. Please review the Licences for the
// specific language governing permissions and limitations relating to use of the SAFE Network
// Software.

//! # sn_fake_clock
//!
//! A crate providing a virtual clock mimicking `std::time::Instant`'s interface, enabling full
//! control over the flow of time during testing.

#![doc(
    html_logo_url = "https://raw.githubusercontent.com/maidsafe/QA/master/Images/maidsafe_logo.png",
    html_favicon_url = "https://maidsafe.net/img/favicon.ico",
    test(attr(forbid(warnings)))
)]
// For explanation of lint checks, run `rustc -W help` or see
// https://github.com/maidsafe/QA/blob/master/Documentation/Rust%20Lint%20Checks.md
#![forbid(
    bad_style,
    arithmetic_overflow,
    mutable_transmutes,
    no_mangle_const_items,
    unknown_crate_types,
    warnings
)]
#![deny(
    deprecated,
    improper_ctypes,
    missing_docs,
    non_shorthand_field_patterns,
    overflowing_literals,
    stable_features,
    unconditional_recursion,
    unknown_lints,
    unsafe_code,
    unused,
    unused_allocation,
    unused_attributes,
    unused_comparisons,
    unused_features,
    unused_parens,
    while_true
)]
#![warn(
    trivial_casts,
    trivial_numeric_casts,
    unused_extern_crates,
    unused_import_braces,
    unused_qualifications,
    unused_results
)]
#![allow(
    box_pointers,
    missing_copy_implementations,
    missing_debug_implementations,
    variant_size_differences
)]

use std::cell::RefCell;
use std::fmt;
use std::ops::{Add, Sub};
use std::time::Duration;

/// Struct representing a fake instant
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct FakeClock {
    time_created: u64,
}

thread_local! {
    static LOCAL_TIME: RefCell<u64> = RefCell::new(0);
}

impl FakeClock {
    /// Sets the thread-local fake time to the given value
    pub fn set_time(time: u64) {
        LOCAL_TIME.with(|t| {
            *t.borrow_mut() = time;
        });
    }

    /// Advances the thread-local fake time by the given amount of milliseconds
    pub fn advance_time(millis: u64) {
        LOCAL_TIME.with(|t| {
            *t.borrow_mut() += millis;
        });
    }

    /// Returns the current thread-local fake time
    pub fn time() -> u64 {
        LOCAL_TIME.with(|t| *t.borrow())
    }

    /// Returns a `FakeClock` instance representing the current instant.
    pub fn now() -> Self {
        let time = Self::time();
        FakeClock { time_created: time }
    }

    /// Returns the duration that passed between `self` and `earlier`.
    pub fn duration_since(self, earlier: Self) -> Duration {
        Duration::from_millis(self.time_created - earlier.time_created)
    }

    /// Returns how much fake time has elapsed since the creation of `self`.
    pub fn elapsed(self) -> Duration {
        Duration::from_millis(Self::time() - self.time_created)
    }
}

impl fmt::Debug for FakeClock {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(
            formatter,
            "FakeClock {{ time_created: {} }}",
            self.time_created
        )
    }
}

impl Add<Duration> for FakeClock {
    type Output = FakeClock;
    fn add(mut self, other: Duration) -> FakeClock {
        self.time_created += other.as_secs() * 1000 + u64::from(other.subsec_nanos()) / 1_000_000;
        self
    }
}

impl Sub<Duration> for FakeClock {
    type Output = FakeClock;
    fn sub(mut self, other: Duration) -> FakeClock {
        self.time_created -= other.as_secs() * 1000 + u64::from(other.subsec_nanos()) / 1_000_000;
        self
    }
}

impl Sub<FakeClock> for FakeClock {
    type Output = Duration;
    fn sub(self, other: FakeClock) -> Duration {
        Duration::from_millis(self.time_created - other.time_created)
    }
}