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 <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/fail-0.5.1/src/lib.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lib.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../fail/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../fail/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span>
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 </pre><pre class="rust"><code><span class="comment">// Copyright 2019 TiKV Project Authors. Licensed under Apache-2.0.

 </span><span class="doccomment">//! A fail point implementation for Rust.
 //!
 //! Fail points are code instrumentations that allow errors and other behavior
 //! to be injected dynamically at runtime, primarily for testing purposes. Fail
 //! points are flexible and can be configured to exhibit a variety of behavior,
 //! including panics, early returns, and sleeping. They can be controlled both
 //! programmatically and via the environment, and can be triggered
 //! conditionally and probabilistically.
 //!
 //! This crate is inspired by FreeBSD&#39;s
 //! [failpoints](https://freebsd.org/cgi/man.cgi?query=fail).
 //!
 //! ## Usage
 //!
 //! First, add this to your `Cargo.toml`:
 //!
 //! ```toml
 //! [dependencies]
 //! fail = &quot;0.5&quot;
 //! ```
 //!
 //! Now you can import the `fail_point!` macro from the `fail` crate and use it
 //! to inject dynamic failures.
 //!
 //! As an example, here&#39;s a simple program that uses a fail point to simulate an
 //! I/O panic:
 //!
 //! ```rust
 //! use fail::{fail_point, FailScenario};
 //!
 //! fn do_fallible_work() {
 //!     fail_point!(&quot;read-dir&quot;);
 //!     let _dir: Vec&lt;_&gt; = std::fs::read_dir(&quot;.&quot;).unwrap().collect();
 //!     // ... do some work on the directory ...
 //! }
 //!
 //! let scenario = FailScenario::setup();
 //! do_fallible_work();
 //! scenario.teardown();
 //! println!(&quot;done&quot;);
 //! ```
 //!
 //! Here, the program calls `unwrap` on the result of `read_dir`, a function
 //! that returns a `Result`. In other words, this particular program expects
 //! this call to `read_dir` to always succeed. And in practice it almost always
 //! will, which makes the behavior of this program when `read_dir` fails
 //! difficult to test. By instrumenting the program with a fail point we can
 //! pretend that `read_dir` failed, causing the subsequent `unwrap` to panic,
 //! and allowing us to observe the program&#39;s behavior under failure conditions.
 //!
 //! When the program is run normally it just prints &quot;done&quot;:
 //!
 //! ```sh
 //! $ cargo run --features fail/failpoints
 //!     Finished dev [unoptimized + debuginfo] target(s) in 0.01s
 //!      Running `target/debug/failpointtest`
 //! done
 //! ```
 //!
 //! But now, by setting the `FAILPOINTS` variable we can see what happens if the
 //! `read_dir` fails:
 //!
 //! ```sh
 //! FAILPOINTS=read-dir=panic cargo run --features fail/failpoints
 //!     Finished dev [unoptimized + debuginfo] target(s) in 0.01s
 //!      Running `target/debug/failpointtest`
 //! thread &#39;main&#39; panicked at &#39;failpoint read-dir panic&#39;, /home/ubuntu/.cargo/registry/src/github.com-1ecc6299db9ec823/fail-0.2.0/src/lib.rs:286:25
 //! note: Run with `RUST_BACKTRACE=1` for a backtrace.
 //! ```
 //!
 //! ## Usage in tests
 //!
 //! The previous example triggers a fail point by modifying the `FAILPOINT`
 //! environment variable. In practice, you&#39;ll often want to trigger fail points
 //! programmatically, in unit tests.
 //! Fail points are global resources, and Rust tests run in parallel,
 //! so tests that exercise fail points generally need to hold a lock to
 //! avoid interfering with each other. This is accomplished by `FailScenario`.
 //!
 //! Here&#39;s a basic pattern for writing unit tests tests with fail points:
 //!
 //! ```rust
 //! use fail::{fail_point, FailScenario};
 //!
 //! fn do_fallible_work() {
 //!     fail_point!(&quot;read-dir&quot;);
 //!     let _dir: Vec&lt;_&gt; = std::fs::read_dir(&quot;.&quot;).unwrap().collect();
 //!     // ... do some work on the directory ...
 //! }
 //!
 //! #[test]
 //! #[should_panic]
 //! fn test_fallible_work() {
 //!     let scenario = FailScenario::setup();
 //!     fail::cfg(&quot;read-dir&quot;, &quot;panic&quot;).unwrap();
 //!
 //!     do_fallible_work();
 //!
 //!     scenario.teardown();
 //! }
 //! ```
 //!
 //! Even if a test does not itself turn on any fail points, code that it runs
 //! could trigger a fail point that was configured by another thread. Because of
 //! this it is a best practice to put all fail point unit tests into their own
 //! binary. Here&#39;s an example of a snippet from `Cargo.toml` that creates a
 //! fail-point-specific test binary:
 //!
 //! ```toml
 //! [[test]]
 //! name = &quot;failpoints&quot;
 //! path = &quot;tests/failpoints/mod.rs&quot;
 //! required-features = [&quot;fail/failpoints&quot;]
 //! ```
 //!
 //!
 //! ## Early return
 //!
 //! The previous examples illustrate injecting panics via fail points, but
 //! panics aren&#39;t the only &amp;mdash; or even the most common &amp;mdash; error pattern
 //! in Rust. The more common type of error is propagated by `Result` return
 //! values, and fail points can inject those as well with &quot;early returns&quot;. That
 //! is, when configuring a fail point as &quot;return&quot; (as opposed to &quot;panic&quot;), the
 //! fail point will immediately return from the function, optionally with a
 //! configurable value.
 //!
 //! The setup for early return requires a slightly diferent invocation of the
 //! `fail_point!` macro. To illustrate this, let&#39;s modify the `do_fallible_work`
 //! function we used earlier to return a `Result`:
 //!
 //! ```rust
 //! use fail::{fail_point, FailScenario};
 //! use std::io;
 //!
 //! fn do_fallible_work() -&gt; io::Result&lt;()&gt; {
 //!     fail_point!(&quot;read-dir&quot;);
 //!     let _dir: Vec&lt;_&gt; = std::fs::read_dir(&quot;.&quot;)?.collect();
 //!     // ... do some work on the directory ...
 //!     Ok(())
 //! }
 //!
 //! fn main() -&gt; io::Result&lt;()&gt; {
 //!     let scenario = FailScenario::setup();
 //!     do_fallible_work()?;
 //!     scenario.teardown();
 //!     println!(&quot;done&quot;);
 //!     Ok(())
 //! }
 //! ```
 //!
 //! This example has more proper Rust error handling, with no unwraps
 //! anywhere. Instead it uses `?` to propagate errors via the `Result` type
 //! return values. This is more realistic Rust code.
 //!
 //! The &quot;read-dir&quot; fail point though is not yet configured to support early
 //! return, so if we attempt to configure it to &quot;return&quot;, we&#39;ll see an error
 //! like
 //!
 //! ```sh
 //! $ FAILPOINTS=read-dir=return cargo run --features fail/failpoints
 //!     Finished dev [unoptimized + debuginfo] target(s) in 0.13s
 //!      Running `target/debug/failpointtest`
 //! thread &#39;main&#39; panicked at &#39;Return is not supported for the fail point &quot;read-dir&quot;&#39;, src/main.rs:7:5
 //! note: Run with `RUST_BACKTRACE=1` for a backtrace.
 //! ```
 //!
 //! This error tells us that the &quot;read-dir&quot; fail point is not defined correctly
 //! to support early return, and gives us the line number of that fail point.
 //! What we&#39;re missing in the fail point definition is code describring _how_ to
 //! return an error value, and the way we do this is by passing `fail_point!` a
 //! closure that returns the same type as the enclosing function.
 //!
 //! Here&#39;s a variation that does so:
 //!
 //! ```rust
 //! # use std::io;
 //! fn do_fallible_work() -&gt; io::Result&lt;()&gt; {
 //!     fail::fail_point!(&quot;read-dir&quot;, |_| {
 //!         Err(io::Error::new(io::ErrorKind::PermissionDenied, &quot;error&quot;))
 //!     });
 //!     let _dir: Vec&lt;_&gt; = std::fs::read_dir(&quot;.&quot;)?.collect();
 //!     // ... do some work on the directory ...
 //!     Ok(())
 //! }
 //! ```
 //!
 //! And now if the &quot;read-dir&quot; fail point is configured to &quot;return&quot; we get a
 //! different result:
 //!
 //! ```sh
 //! $ FAILPOINTS=read-dir=return cargo run --features fail/failpoints
 //!    Compiling failpointtest v0.1.0
 //!     Finished dev [unoptimized + debuginfo] target(s) in 2.38s
 //!      Running `target/debug/failpointtest`
 //! Error: Custom { kind: PermissionDenied, error: StringError(&quot;error&quot;) }
 //! ```
 //!
 //! This time, `do_fallible_work` returned the error defined in our closure,
 //! which propagated all the way up and out of main.
 //!
 //! ## Advanced usage
 //!
 //! That&#39;s the basics of fail points: defining them with `fail_point!`,
 //! configuring them with `FAILPOINTS` and `fail::cfg`, and configuring them to
 //! panic and return early. But that&#39;s not all they can do. To learn more see
 //! the documentation for [`cfg`](fn.cfg.html),
 //! [`cfg_callback`](fn.cfg_callback.html) and
 //! [`fail_point!`](macro.fail_point.html).
 //!
 //!
 //! ## Usage considerations
 //!
 //! For most effective fail point usage, keep in mind the following:
 //!
 //!  - Fail points are disabled by default and can be enabled via the `failpoints`
 //!    feature. When failpoints are disabled, no code is generated by the macro.
 //!  - Carefully consider complex, concurrent, non-deterministic combinations of
 //!    fail points. Put test cases exercising fail points into their own test
 //!    crate.
 //!  - Fail points might have the same name, in which case they take the
 //!    same actions. Be careful about duplicating fail point names, either within
 //!    a single crate, or across multiple crates.

 </span><span class="attribute">#![deny(missing_docs, missing_debug_implementations)]

 </span><span class="kw">use </span>std::collections::HashMap;
 <span class="kw">use </span>std::env::VarError;
 <span class="kw">use </span>std::fmt::Debug;
 <span class="kw">use </span>std::str::FromStr;
 <span class="kw">use </span>std::sync::atomic::{AtomicUsize, Ordering};
 <span class="kw">use </span>std::sync::{Arc, Condvar, Mutex, MutexGuard, RwLock, TryLockError};
 <span class="kw">use </span>std::time::{Duration, Instant};
 <span class="kw">use </span>std::{env, thread};

 <span class="attribute">#[derive(Clone)]
 </span><span class="kw">struct </span>SyncCallback(Arc&lt;<span class="kw">dyn </span>Fn() + Send + Sync&gt;);

 <span class="kw">impl </span>Debug <span class="kw">for </span>SyncCallback {
     <span class="kw">fn </span>fmt(<span class="kw-2">&amp;</span><span class="self">self</span>, f: <span class="kw-2">&amp;mut </span>std::fmt::Formatter&lt;<span class="lifetime">&#39;_</span>&gt;) -&gt; std::fmt::Result {
         f.write_str(<span class="string">&quot;SyncCallback()&quot;</span>)
     }
 }

 <span class="kw">impl </span>PartialEq <span class="kw">for </span>SyncCallback {
     <span class="attribute">#[allow(clippy::vtable_address_comparisons)]
     </span><span class="kw">fn </span>eq(<span class="kw-2">&amp;</span><span class="self">self</span>, other: <span class="kw-2">&amp;</span><span class="self">Self</span>) -&gt; bool {
         Arc::ptr_eq(<span class="kw-2">&amp;</span><span class="self">self</span>.<span class="number">0</span>, <span class="kw-2">&amp;</span>other.<span class="number">0</span>)
     }
 }

 <span class="kw">impl </span>SyncCallback {
     <span class="kw">fn </span>new(f: <span class="kw">impl </span>Fn() + Send + Sync + <span class="lifetime">&#39;static</span>) -&gt; SyncCallback {
         SyncCallback(Arc::new(f))
     }

     <span class="kw">fn </span>run(<span class="kw-2">&amp;</span><span class="self">self</span>) {
         <span class="kw">let </span>callback = <span class="kw-2">&amp;</span><span class="self">self</span>.<span class="number">0</span>;
         callback();
     }
 }

 <span class="doccomment">/// Supported tasks.
 </span><span class="attribute">#[derive(Clone, Debug, PartialEq)]
 </span><span class="kw">enum </span>Task {
     <span class="doccomment">/// Do nothing.
     </span>Off,
     <span class="doccomment">/// Return the value.
     </span>Return(<span class="prelude-ty">Option</span>&lt;String&gt;),
     <span class="doccomment">/// Sleep for some milliseconds.
     </span>Sleep(u64),
     <span class="doccomment">/// Panic with the message.
     </span>Panic(<span class="prelude-ty">Option</span>&lt;String&gt;),
     <span class="doccomment">/// Print the message.
     </span>Print(<span class="prelude-ty">Option</span>&lt;String&gt;),
     <span class="doccomment">/// Sleep until other action is set.
     </span>Pause,
     <span class="doccomment">/// Yield the CPU.
     </span>Yield,
     <span class="doccomment">/// Busy waiting for some milliseconds.
     </span>Delay(u64),
     <span class="doccomment">/// Call callback function.
     </span>Callback(SyncCallback),
 }

 <span class="attribute">#[derive(Debug)]
 </span><span class="kw">struct </span>Action {
     task: Task,
     freq: f32,
     count: <span class="prelude-ty">Option</span>&lt;AtomicUsize&gt;,
 }

 <span class="kw">impl </span>PartialEq <span class="kw">for </span>Action {
     <span class="kw">fn </span>eq(<span class="kw-2">&amp;</span><span class="self">self</span>, hs: <span class="kw-2">&amp;</span>Action) -&gt; bool {
         <span class="kw">if </span><span class="self">self</span>.task != hs.task || <span class="self">self</span>.freq != hs.freq {
             <span class="kw">return </span><span class="bool-val">false</span>;
         }
         <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="kw-2">ref </span>lhs) = <span class="self">self</span>.count {
             <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="kw-2">ref </span>rhs) = hs.count {
                 <span class="kw">return </span>lhs.load(Ordering::Relaxed) == rhs.load(Ordering::Relaxed);
             }
         } <span class="kw">else if </span>hs.count.is_none() {
             <span class="kw">return </span><span class="bool-val">true</span>;
         }
         <span class="bool-val">false
     </span>}
 }

 <span class="kw">impl </span>Action {
     <span class="kw">fn </span>new(task: Task, freq: f32, max_cnt: <span class="prelude-ty">Option</span>&lt;usize&gt;) -&gt; Action {
         Action {
             task,
             freq,
             count: max_cnt.map(AtomicUsize::new),
         }
     }

     <span class="kw">fn </span>from_callback(f: <span class="kw">impl </span>Fn() + Send + Sync + <span class="lifetime">&#39;static</span>) -&gt; Action {
         <span class="kw">let </span>task = Task::Callback(SyncCallback::new(f));
         Action {
             task,
             freq: <span class="number">1.0</span>,
             count: <span class="prelude-val">None</span>,
         }
     }

     <span class="kw">fn </span>get_task(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="prelude-ty">Option</span>&lt;Task&gt; {
         <span class="kw">use </span>rand::Rng;

         <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="kw-2">ref </span>cnt) = <span class="self">self</span>.count {
             <span class="kw">let </span>c = cnt.load(Ordering::Acquire);
             <span class="kw">if </span>c == <span class="number">0 </span>{
                 <span class="kw">return </span><span class="prelude-val">None</span>;
             }
         }
         <span class="kw">if </span><span class="self">self</span>.freq &lt; <span class="number">1f32 </span>&amp;&amp; !rand::thread_rng().gen_bool(f64::from(<span class="self">self</span>.freq)) {
             <span class="kw">return </span><span class="prelude-val">None</span>;
         }
         <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="kw-2">ref </span>ref_cnt) = <span class="self">self</span>.count {
             <span class="kw">let </span><span class="kw-2">mut </span>cnt = ref_cnt.load(Ordering::Acquire);
             <span class="kw">loop </span>{
                 <span class="kw">if </span>cnt == <span class="number">0 </span>{
                     <span class="kw">return </span><span class="prelude-val">None</span>;
                 }
                 <span class="kw">let </span>new_cnt = cnt - <span class="number">1</span>;
                 <span class="kw">match </span>ref_cnt.compare_exchange_weak(
                     cnt,
                     new_cnt,
                     Ordering::AcqRel,
                     Ordering::Acquire,
                 ) {
                     <span class="prelude-val">Ok</span>(<span class="kw">_</span>) =&gt; <span class="kw">break</span>,
                     <span class="prelude-val">Err</span>(c) =&gt; cnt = c,
                 }
             }
         }
         <span class="prelude-val">Some</span>(<span class="self">self</span>.task.clone())
     }
 }

 <span class="kw">fn </span>partition(s: <span class="kw-2">&amp;</span>str, pattern: char) -&gt; (<span class="kw-2">&amp;</span>str, <span class="prelude-ty">Option</span>&lt;<span class="kw-2">&amp;</span>str&gt;) {
     <span class="kw">let </span><span class="kw-2">mut </span>splits = s.splitn(<span class="number">2</span>, pattern);
     (splits.next().unwrap(), splits.next())
 }

 <span class="kw">impl </span>FromStr <span class="kw">for </span>Action {
     <span class="kw">type </span><span class="prelude-val">Err </span>= String;

     <span class="doccomment">/// Parse an action.
     ///
     /// `s` should be in the format `[p%][cnt*]task[(args)]`, `p%` is the frequency,
     /// `cnt` is the max times the action can be triggered.
     </span><span class="kw">fn </span>from_str(s: <span class="kw-2">&amp;</span>str) -&gt; <span class="prelude-ty">Result</span>&lt;Action, String&gt; {
         <span class="kw">let </span><span class="kw-2">mut </span>remain = s.trim();
         <span class="kw">let </span><span class="kw-2">mut </span>args = <span class="prelude-val">None</span>;
         <span class="comment">// in case there is &#39;%&#39; in args, we need to parse it first.
         </span><span class="kw">let </span>(first, second) = partition(remain, <span class="string">&#39;(&#39;</span>);
         <span class="kw">if let </span><span class="prelude-val">Some</span>(second) = second {
             remain = first;
             <span class="kw">if </span>!second.ends_with(<span class="string">&#39;)&#39;</span>) {
                 <span class="kw">return </span><span class="prelude-val">Err</span>(<span class="string">&quot;parentheses do not match&quot;</span>.to_owned());
             }
             args = <span class="prelude-val">Some</span>(<span class="kw-2">&amp;</span>second[..second.len() - <span class="number">1</span>]);
         }

         <span class="kw">let </span><span class="kw-2">mut </span>frequency = <span class="number">1f32</span>;
         <span class="kw">let </span>(first, second) = partition(remain, <span class="string">&#39;%&#39;</span>);
         <span class="kw">if let </span><span class="prelude-val">Some</span>(second) = second {
             remain = second;
             <span class="kw">match </span>first.parse::&lt;f32&gt;() {
                 <span class="prelude-val">Err</span>(e) =&gt; <span class="kw">return </span><span class="prelude-val">Err</span>(<span class="macro">format!</span>(<span class="string">&quot;failed to parse frequency: {}&quot;</span>, e)),
                 <span class="prelude-val">Ok</span>(freq) =&gt; frequency = freq / <span class="number">100.0</span>,
             }
         }

         <span class="kw">let </span><span class="kw-2">mut </span>max_cnt = <span class="prelude-val">None</span>;
         <span class="kw">let </span>(first, second) = partition(remain, <span class="string">&#39;*&#39;</span>);
         <span class="kw">if let </span><span class="prelude-val">Some</span>(second) = second {
             remain = second;
             <span class="kw">match </span>first.parse() {
                 <span class="prelude-val">Err</span>(e) =&gt; <span class="kw">return </span><span class="prelude-val">Err</span>(<span class="macro">format!</span>(<span class="string">&quot;failed to parse count: {}&quot;</span>, e)),
                 <span class="prelude-val">Ok</span>(cnt) =&gt; max_cnt = <span class="prelude-val">Some</span>(cnt),
             }
         }

         <span class="kw">let </span>parse_timeout = || <span class="kw">match </span>args {
             <span class="prelude-val">None </span>=&gt; <span class="prelude-val">Err</span>(<span class="string">&quot;sleep require timeout&quot;</span>.to_owned()),
             <span class="prelude-val">Some</span>(timeout_str) =&gt; <span class="kw">match </span>timeout_str.parse() {
                 <span class="prelude-val">Err</span>(e) =&gt; <span class="prelude-val">Err</span>(<span class="macro">format!</span>(<span class="string">&quot;failed to parse timeout: {}&quot;</span>, e)),
                 <span class="prelude-val">Ok</span>(timeout) =&gt; <span class="prelude-val">Ok</span>(timeout),
             },
         };

         <span class="kw">let </span>task = <span class="kw">match </span>remain {
             <span class="string">&quot;off&quot; </span>=&gt; Task::Off,
             <span class="string">&quot;return&quot; </span>=&gt; Task::Return(args.map(str::to_owned)),
             <span class="string">&quot;sleep&quot; </span>=&gt; Task::Sleep(parse_timeout()<span class="question-mark">?</span>),
             <span class="string">&quot;panic&quot; </span>=&gt; Task::Panic(args.map(str::to_owned)),
             <span class="string">&quot;print&quot; </span>=&gt; Task::Print(args.map(str::to_owned)),
             <span class="string">&quot;pause&quot; </span>=&gt; Task::Pause,
             <span class="string">&quot;yield&quot; </span>=&gt; Task::Yield,
             <span class="string">&quot;delay&quot; </span>=&gt; Task::Delay(parse_timeout()<span class="question-mark">?</span>),
             <span class="kw">_ </span>=&gt; <span class="kw">return </span><span class="prelude-val">Err</span>(<span class="macro">format!</span>(<span class="string">&quot;unrecognized command {:?}&quot;</span>, remain)),
         };

         <span class="prelude-val">Ok</span>(Action::new(task, frequency, max_cnt))
     }
 }

 <span class="attribute">#[cfg_attr(feature = <span class="string">&quot;cargo-clippy&quot;</span>, allow(clippy::mutex_atomic))]
 #[derive(Debug)]
 </span><span class="kw">struct </span>FailPoint {
     pause: Mutex&lt;bool&gt;,
     pause_notifier: Condvar,
     actions: RwLock&lt;Vec&lt;Action&gt;&gt;,
     actions_str: RwLock&lt;String&gt;,
 }

 <span class="attribute">#[cfg_attr(feature = <span class="string">&quot;cargo-clippy&quot;</span>, allow(clippy::mutex_atomic))]
 </span><span class="kw">impl </span>FailPoint {
     <span class="kw">fn </span>new() -&gt; FailPoint {
         FailPoint {
             pause: Mutex::new(<span class="bool-val">false</span>),
             pause_notifier: Condvar::new(),
             actions: RwLock::default(),
             actions_str: RwLock::default(),
         }
     }

     <span class="kw">fn </span>set_actions(<span class="kw-2">&amp;</span><span class="self">self</span>, actions_str: <span class="kw-2">&amp;</span>str, actions: Vec&lt;Action&gt;) {
         <span class="kw">loop </span>{
             <span class="comment">// TODO: maybe busy waiting here.
             </span><span class="kw">match </span><span class="self">self</span>.actions.try_write() {
                 <span class="prelude-val">Err</span>(TryLockError::WouldBlock) =&gt; {}
                 <span class="prelude-val">Ok</span>(<span class="kw-2">mut </span>guard) =&gt; {
                     <span class="kw-2">*</span>guard = actions;
                     <span class="kw-2">*</span><span class="self">self</span>.actions_str.write().unwrap() = actions_str.to_string();
                     <span class="kw">return</span>;
                 }
                 <span class="prelude-val">Err</span>(e) =&gt; <span class="macro">panic!</span>(<span class="string">&quot;unexpected poison: {:?}&quot;</span>, e),
             }
             <span class="kw">let </span><span class="kw-2">mut </span>guard = <span class="self">self</span>.pause.lock().unwrap();
             <span class="kw-2">*</span>guard = <span class="bool-val">false</span>;
             <span class="self">self</span>.pause_notifier.notify_all();
         }
     }

     <span class="attribute">#[cfg_attr(feature = <span class="string">&quot;cargo-clippy&quot;</span>, allow(clippy::option_option))]
     </span><span class="kw">fn </span>eval(<span class="kw-2">&amp;</span><span class="self">self</span>, name: <span class="kw-2">&amp;</span>str) -&gt; <span class="prelude-ty">Option</span>&lt;<span class="prelude-ty">Option</span>&lt;String&gt;&gt; {
         <span class="kw">let </span>task = {
             <span class="kw">let </span>actions = <span class="self">self</span>.actions.read().unwrap();
             <span class="kw">match </span>actions.iter().filter_map(Action::get_task).next() {
                 <span class="prelude-val">Some</span>(Task::Pause) =&gt; {
                     <span class="kw">let </span><span class="kw-2">mut </span>guard = <span class="self">self</span>.pause.lock().unwrap();
                     <span class="kw-2">*</span>guard = <span class="bool-val">true</span>;
                     <span class="kw">loop </span>{
                         guard = <span class="self">self</span>.pause_notifier.wait(guard).unwrap();
                         <span class="kw">if </span>!<span class="kw-2">*</span>guard {
                             <span class="kw">break</span>;
                         }
                     }
                     <span class="kw">return </span><span class="prelude-val">None</span>;
                 }
                 <span class="prelude-val">Some</span>(t) =&gt; t,
                 <span class="prelude-val">None </span>=&gt; <span class="kw">return </span><span class="prelude-val">None</span>,
             }
         };

         <span class="kw">match </span>task {
             Task::Off =&gt; {}
             Task::Return(s) =&gt; <span class="kw">return </span><span class="prelude-val">Some</span>(s),
             Task::Sleep(t) =&gt; thread::sleep(Duration::from_millis(t)),
             Task::Panic(msg) =&gt; <span class="kw">match </span>msg {
                 <span class="prelude-val">Some</span>(<span class="kw-2">ref </span>msg) =&gt; <span class="macro">panic!</span>(<span class="string">&quot;{}&quot;</span>, msg),
                 <span class="prelude-val">None </span>=&gt; <span class="macro">panic!</span>(<span class="string">&quot;failpoint {} panic&quot;</span>, name),
             },
             Task::Print(msg) =&gt; <span class="kw">match </span>msg {
                 <span class="prelude-val">Some</span>(<span class="kw-2">ref </span>msg) =&gt; <span class="macro">log::info!</span>(<span class="string">&quot;{}&quot;</span>, msg),
                 <span class="prelude-val">None </span>=&gt; <span class="macro">log::info!</span>(<span class="string">&quot;failpoint {} executed.&quot;</span>, name),
             },
             Task::Pause =&gt; <span class="macro">unreachable!</span>(),
             Task::Yield =&gt; thread::yield_now(),
             Task::Delay(t) =&gt; {
                 <span class="kw">let </span>timer = Instant::now();
                 <span class="kw">let </span>timeout = Duration::from_millis(t);
                 <span class="kw">while </span>timer.elapsed() &lt; timeout {}
             }
             Task::Callback(f) =&gt; {
                 f.run();
             }
         }
         <span class="prelude-val">None
     </span>}
 }

 <span class="doccomment">/// Registry with failpoints configuration.
 </span><span class="kw">type </span>Registry = HashMap&lt;String, Arc&lt;FailPoint&gt;&gt;;

 <span class="attribute">#[derive(Debug, Default)]
 </span><span class="kw">struct </span>FailPointRegistry {
     <span class="comment">// TODO: remove rwlock or store *mut FailPoint
     </span>registry: RwLock&lt;Registry&gt;,
 }

 <span class="kw">use </span>once_cell::sync::Lazy;

 <span class="kw">static </span>REGISTRY: Lazy&lt;FailPointRegistry&gt; = Lazy::new(FailPointRegistry::default);
 <span class="kw">static </span>SCENARIO: Lazy&lt;Mutex&lt;<span class="kw-2">&amp;</span><span class="lifetime">&#39;static </span>FailPointRegistry&gt;&gt; = Lazy::new(|| Mutex::new(<span class="kw-2">&amp;</span>REGISTRY));

 <span class="doccomment">/// Test scenario with configured fail points.
 </span><span class="attribute">#[derive(Debug)]
 </span><span class="kw">pub struct </span>FailScenario&lt;<span class="lifetime">&#39;a</span>&gt; {
     scenario_guard: MutexGuard&lt;<span class="lifetime">&#39;a</span>, <span class="kw-2">&amp;</span><span class="lifetime">&#39;static </span>FailPointRegistry&gt;,
 }

 <span class="kw">impl</span>&lt;<span class="lifetime">&#39;a</span>&gt; FailScenario&lt;<span class="lifetime">&#39;a</span>&gt; {
     <span class="doccomment">/// Set up the system for a fail points scenario.
     ///
     /// Configures all fail points specified in the `FAILPOINTS` environment variable.
     /// It does not otherwise change any existing fail point configuration.
     ///
     /// The format of `FAILPOINTS` is `failpoint=actions;...`, where
     /// `failpoint` is the name of the fail point. For more information
     /// about fail point actions see the [`cfg`](fn.cfg.html) function and
     /// the [`fail_point`](macro.fail_point.html) macro.
     ///
     /// `FAILPOINTS` may configure fail points that are not actually defined. In
     /// this case the configuration has no effect.
     ///
     /// This function should generally be called prior to running a test with fail
     /// points, and afterward paired with [`teardown`](#method.teardown).
     ///
     /// # Panics
     ///
     /// Panics if an action is not formatted correctly.
     </span><span class="kw">pub fn </span>setup() -&gt; <span class="self">Self </span>{
         <span class="comment">// Cleanup first, in case of previous failed/panic&#39;ed test scenarios.
         </span><span class="kw">let </span>scenario_guard = SCENARIO.lock().unwrap_or_else(|e| e.into_inner());
         <span class="kw">let </span><span class="kw-2">mut </span>registry = scenario_guard.registry.write().unwrap();
         <span class="self">Self</span>::cleanup(<span class="kw-2">&amp;mut </span>registry);

         <span class="kw">let </span>failpoints = <span class="kw">match </span>env::var(<span class="string">&quot;FAILPOINTS&quot;</span>) {
             <span class="prelude-val">Ok</span>(s) =&gt; s,
             <span class="prelude-val">Err</span>(VarError::NotPresent) =&gt; <span class="kw">return </span><span class="self">Self </span>{ scenario_guard },
             <span class="prelude-val">Err</span>(e) =&gt; <span class="macro">panic!</span>(<span class="string">&quot;invalid failpoints: {:?}&quot;</span>, e),
         };
         <span class="kw">for </span><span class="kw-2">mut </span>cfg <span class="kw">in </span>failpoints.trim().split(<span class="string">&#39;;&#39;</span>) {
             cfg = cfg.trim();
             <span class="kw">if </span>cfg.is_empty() {
                 <span class="kw">continue</span>;
             }
             <span class="kw">let </span>(name, order) = partition(cfg, <span class="string">&#39;=&#39;</span>);
             <span class="kw">match </span>order {
                 <span class="prelude-val">None </span>=&gt; <span class="macro">panic!</span>(<span class="string">&quot;invalid failpoint: {:?}&quot;</span>, cfg),
                 <span class="prelude-val">Some</span>(order) =&gt; {
                     <span class="kw">if let </span><span class="prelude-val">Err</span>(e) = set(<span class="kw-2">&amp;mut </span>registry, name.to_owned(), order) {
                         <span class="macro">panic!</span>(<span class="string">&quot;unable to configure failpoint \&quot;{}\&quot;: {}&quot;</span>, name, e);
                     }
                 }
             }
         }
         <span class="self">Self </span>{ scenario_guard }
     }

     <span class="doccomment">/// Tear down the fail point system.
     ///
     /// Clears the configuration of all fail points. Any paused fail
     /// points will be notified before they are deactivated.
     ///
     /// This function should generally be called after running a test with fail points.
     /// Calling `teardown` without previously calling `setup` results in a no-op.
     </span><span class="kw">pub fn </span>teardown(<span class="self">self</span>) {
         drop(<span class="self">self</span>)
     }

     <span class="doccomment">/// Clean all registered fail points.
     </span><span class="kw">fn </span>cleanup(registry: <span class="kw-2">&amp;mut </span>std::sync::RwLockWriteGuard&lt;<span class="lifetime">&#39;a</span>, Registry&gt;) {
         <span class="kw">for </span>p <span class="kw">in </span>registry.values() {
             <span class="comment">// wake up all pause failpoint.
             </span>p.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[]);
         }
         registry.clear();
     }
 }

 <span class="kw">impl</span>&lt;<span class="lifetime">&#39;a</span>&gt; Drop <span class="kw">for </span>FailScenario&lt;<span class="lifetime">&#39;a</span>&gt; {
     <span class="kw">fn </span>drop(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
         <span class="kw">let </span><span class="kw-2">mut </span>registry = <span class="self">self</span>.scenario_guard.registry.write().unwrap();
         <span class="self">Self</span>::cleanup(<span class="kw-2">&amp;mut </span>registry)
     }
 }

 <span class="doccomment">/// Returns whether code generation for failpoints is enabled.
 ///
 /// This function allows consumers to check (at runtime) whether the library
 /// was compiled with the (buildtime) `failpoints` feature, which enables
 /// code generation for failpoints.
 </span><span class="kw">pub const fn </span>has_failpoints() -&gt; bool {
     <span class="macro">cfg!</span>(feature = <span class="string">&quot;failpoints&quot;</span>)
 }

 <span class="doccomment">/// Get all registered fail points.
 ///
 /// Return a vector of `(name, actions)` pairs.
 </span><span class="kw">pub fn </span>list() -&gt; Vec&lt;(String, String)&gt; {
     <span class="kw">let </span>registry = REGISTRY.registry.read().unwrap();
     registry
         .iter()
         .map(|(name, fp)| (name.to_string(), fp.actions_str.read().unwrap().clone()))
         .collect()
 }

 <span class="attribute">#[doc(hidden)]
 </span><span class="kw">pub fn </span>eval&lt;R, F: FnOnce(<span class="prelude-ty">Option</span>&lt;String&gt;) -&gt; R&gt;(name: <span class="kw-2">&amp;</span>str, f: F) -&gt; <span class="prelude-ty">Option</span>&lt;R&gt; {
     <span class="kw">let </span>p = {
         <span class="kw">let </span>registry = REGISTRY.registry.read().unwrap();
         <span class="kw">match </span>registry.get(name) {
             <span class="prelude-val">None </span>=&gt; <span class="kw">return </span><span class="prelude-val">None</span>,
             <span class="prelude-val">Some</span>(p) =&gt; p.clone(),
         }
     };
     p.eval(name).map(f)
 }

 <span class="doccomment">/// Configure the actions for a fail point at runtime.
 ///
 /// Each fail point can be configured with a series of actions, specified by the
 /// `actions` argument. The format of `actions` is `action[-&gt;action...]`. When
 /// multiple actions are specified, an action will be checked only when its
 /// former action is not triggered.
 ///
 /// The format of a single action is `[p%][cnt*]task[(arg)]`. `p%` is the
 /// expected probability that the action is triggered, and `cnt*` is the max
 /// times the action can be triggered. The supported values of `task` are:
 ///
 /// - `off`, the fail point will do nothing.
 /// - `return(arg)`, return early when the fail point is triggered. `arg` is passed to `$e` (
 /// defined via the `fail_point!` macro) as a string.
 /// - `sleep(milliseconds)`, sleep for the specified time.
 /// - `panic(msg)`, panic with the message.
 /// - `print(msg)`, log the message, using the `log` crate, at the `info` level.
 /// - `pause`, sleep until other action is set to the fail point.
 /// - `yield`, yield the CPU.
 /// - `delay(milliseconds)`, busy waiting for the specified time.
 ///
 /// For example, `20%3*print(still alive!)-&gt;panic` means the fail point has 20% chance to print a
 /// message &quot;still alive!&quot; and 80% chance to panic. And the message will be printed at most 3
 /// times.
 ///
 /// The `FAILPOINTS` environment variable accepts this same syntax for its fail
 /// point actions.
 ///
 /// A call to `cfg` with a particular fail point name overwrites any existing actions for
 /// that fail point, including those set via the `FAILPOINTS` environment variable.
 </span><span class="kw">pub fn </span>cfg&lt;S: Into&lt;String&gt;&gt;(name: S, actions: <span class="kw-2">&amp;</span>str) -&gt; <span class="prelude-ty">Result</span>&lt;(), String&gt; {
     <span class="kw">let </span><span class="kw-2">mut </span>registry = REGISTRY.registry.write().unwrap();
     set(<span class="kw-2">&amp;mut </span>registry, name.into(), actions)
 }

 <span class="doccomment">/// Configure the actions for a fail point at runtime.
 ///
 /// Each fail point can be configured by a callback. Process will call this callback function
 /// when it meet this fail-point.
 </span><span class="kw">pub fn </span>cfg_callback&lt;S, F&gt;(name: S, f: F) -&gt; <span class="prelude-ty">Result</span>&lt;(), String&gt;
 <span class="kw">where
     </span>S: Into&lt;String&gt;,
     F: Fn() + Send + Sync + <span class="lifetime">&#39;static</span>,
 {
     <span class="kw">let </span><span class="kw-2">mut </span>registry = REGISTRY.registry.write().unwrap();
     <span class="kw">let </span>p = registry
         .entry(name.into())
         .or_insert_with(|| Arc::new(FailPoint::new()));
     <span class="kw">let </span>action = Action::from_callback(f);
     <span class="kw">let </span>actions = <span class="macro">vec!</span>[action];
     p.set_actions(<span class="string">&quot;callback&quot;</span>, actions);
     <span class="prelude-val">Ok</span>(())
 }

 <span class="doccomment">/// Remove a fail point.
 ///
 /// If the fail point doesn&#39;t exist, nothing will happen.
 </span><span class="kw">pub fn </span>remove&lt;S: AsRef&lt;str&gt;&gt;(name: S) {
     <span class="kw">let </span><span class="kw-2">mut </span>registry = REGISTRY.registry.write().unwrap();
     <span class="kw">if let </span><span class="prelude-val">Some</span>(p) = registry.remove(name.as_ref()) {
         <span class="comment">// wake up all pause failpoint.
         </span>p.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[]);
     }
 }

 <span class="doccomment">/// Configure fail point in RAII style.
 </span><span class="attribute">#[derive(Debug)]
 </span><span class="kw">pub struct </span>FailGuard(String);

 <span class="kw">impl </span>Drop <span class="kw">for </span>FailGuard {
     <span class="kw">fn </span>drop(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
         remove(<span class="kw-2">&amp;</span><span class="self">self</span>.<span class="number">0</span>);
     }
 }

 <span class="kw">impl </span>FailGuard {
     <span class="doccomment">/// Configure the actions for a fail point during the lifetime of the returning `FailGuard`.
     ///
     /// Read documentation of [`cfg`] for more details.
     </span><span class="kw">pub fn </span>new&lt;S: Into&lt;String&gt;&gt;(name: S, actions: <span class="kw-2">&amp;</span>str) -&gt; <span class="prelude-ty">Result</span>&lt;FailGuard, String&gt; {
         <span class="kw">let </span>name = name.into();
         cfg(<span class="kw-2">&amp;</span>name, actions)<span class="question-mark">?</span>;
         <span class="prelude-val">Ok</span>(FailGuard(name))
     }

     <span class="doccomment">/// Configure the actions for a fail point during the lifetime of the returning `FailGuard`.
     ///
     /// Read documentation of [`cfg_callback`] for more details.
     </span><span class="kw">pub fn </span>with_callback&lt;S, F&gt;(name: S, f: F) -&gt; <span class="prelude-ty">Result</span>&lt;FailGuard, String&gt;
     <span class="kw">where
         </span>S: Into&lt;String&gt;,
         F: Fn() + Send + Sync + <span class="lifetime">&#39;static</span>,
     {
         <span class="kw">let </span>name = name.into();
         cfg_callback(<span class="kw-2">&amp;</span>name, f)<span class="question-mark">?</span>;
         <span class="prelude-val">Ok</span>(FailGuard(name))
     }
 }

 <span class="kw">fn </span>set(
     registry: <span class="kw-2">&amp;mut </span>HashMap&lt;String, Arc&lt;FailPoint&gt;&gt;,
     name: String,
     actions: <span class="kw-2">&amp;</span>str,
 ) -&gt; <span class="prelude-ty">Result</span>&lt;(), String&gt; {
     <span class="kw">let </span>actions_str = actions;
     <span class="comment">// `actions` are in the format of `failpoint[-&gt;failpoint...]`.
     </span><span class="kw">let </span>actions = actions
         .split(<span class="string">&quot;-&gt;&quot;</span>)
         .map(Action::from_str)
         .collect::&lt;<span class="prelude-ty">Result</span>&lt;<span class="kw">_</span>, <span class="kw">_</span>&gt;&gt;()<span class="question-mark">?</span>;
     <span class="comment">// Please note that we can&#39;t figure out whether there is a failpoint named `name`,
     // so we may insert a failpoint that doesn&#39;t exist at all.
     </span><span class="kw">let </span>p = registry
         .entry(name)
         .or_insert_with(|| Arc::new(FailPoint::new()));
     p.set_actions(actions_str, actions);
     <span class="prelude-val">Ok</span>(())
 }

 <span class="doccomment">/// Define a fail point (requires `failpoints` feature).
 ///
 /// The `fail_point!` macro has three forms, and they all take a name as the
 /// first argument. The simplest form takes only a name and is suitable for
 /// executing most fail point behavior, including panicking, but not for early
 /// return or conditional execution based on a local flag.
 ///
 /// The three forms of fail points look as follows.
 ///
 /// 1. A basic fail point:
 ///
 /// ```rust
 /// # #[macro_use] extern crate fail;
 /// fn function_return_unit() {
 ///     fail_point!(&quot;fail-point-1&quot;);
 /// }
 /// ```
 ///
 /// This form of fail point can be configured to panic, print, sleep, pause, etc., but
 /// not to return from the function early.
 ///
 /// 2. A fail point that may return early:
 ///
 /// ```rust
 /// # #[macro_use] extern crate fail;
 /// fn function_return_value() -&gt; u64 {
 ///     fail_point!(&quot;fail-point-2&quot;, |r| r.map_or(2, |e| e.parse().unwrap()));
 ///     0
 /// }
 /// ```
 ///
 /// This form of fail point can additionally be configured to return early from
 /// the enclosing function. It accepts a closure, which itself accepts an
 /// `Option&lt;String&gt;`, and is expected to transform that argument into the early
 /// return value. The argument string is sourced from the fail point
 /// configuration string. For example configuring this &quot;fail-point-2&quot; as
 /// &quot;return(100)&quot; will execute the fail point closure, passing it a `Some` value
 /// containing a `String` equal to &quot;100&quot;; the closure then parses it into the
 /// return value.
 ///
 /// 3. A fail point with conditional execution:
 ///
 /// ```rust
 /// # #[macro_use] extern crate fail;
 /// fn function_conditional(enable: bool) {
 ///     fail_point!(&quot;fail-point-3&quot;, enable, |_| {});
 /// }
 /// ```
 ///
 /// In this final form, the second argument is a local boolean expression that
 /// must evaluate to `true` before the fail point is evaluated. The third
 /// argument is again an early-return closure.
 ///
 /// The three macro arguments (or &quot;designators&quot;) are called `$name`, `$cond`,
 /// and `$e`. `$name` must be `&amp;str`, `$cond` must be a boolean expression,
 /// and`$e` must be a function or closure that accepts an `Option&lt;String&gt;` and
 /// returns the same type as the enclosing function.
 ///
 /// For more examples see the [crate documentation](index.html). For more
 /// information about controlling fail points see the [`cfg`](fn.cfg.html)
 /// function.
 </span><span class="attribute">#[macro_export]
 #[cfg(feature = <span class="string">&quot;failpoints&quot;</span>)]
 </span><span class="macro">macro_rules! </span>fail_point {
     (<span class="macro-nonterminal">$name</span>:expr) =&gt; {{
         <span class="macro-nonterminal">$crate::eval</span>(<span class="macro-nonterminal">$name</span>, |<span class="kw">_</span>| {
             <span class="macro">panic!</span>(<span class="string">&quot;Return is not supported for the fail point \&quot;{}\&quot;&quot;</span>, <span class="macro-nonterminal">$name</span>);
         });
     }};
     (<span class="macro-nonterminal">$name</span>:expr, <span class="macro-nonterminal">$e</span>:expr) =&gt; {{
         <span class="kw">if let </span><span class="prelude-val">Some</span>(res) = <span class="macro-nonterminal">$crate::eval</span>(<span class="macro-nonterminal">$name</span>, <span class="macro-nonterminal">$e</span>) {
             <span class="kw">return </span>res;
         }
     }};
     (<span class="macro-nonterminal">$name</span>:expr, <span class="macro-nonterminal">$cond</span>:expr, <span class="macro-nonterminal">$e</span>:expr) =&gt; {{
         <span class="kw">if </span><span class="macro-nonterminal">$cond </span>{
             <span class="macro-nonterminal">$</span><span class="macro">crate::fail_point!</span>(<span class="macro-nonterminal">$name</span>, <span class="macro-nonterminal">$e</span>);
         }
     }};
 }

 <span class="doccomment">/// Define a fail point (disabled, see `failpoints` feature).
 </span><span class="attribute">#[macro_export]
 #[cfg(not(feature = <span class="string">&quot;failpoints&quot;</span>))]
 </span><span class="macro">macro_rules! </span>fail_point {
     (<span class="macro-nonterminal">$name</span>:expr, <span class="macro-nonterminal">$e</span>:expr) =&gt; {{}};
     (<span class="macro-nonterminal">$name</span>:expr) =&gt; {{}};
     (<span class="macro-nonterminal">$name</span>:expr, <span class="macro-nonterminal">$cond</span>:expr, <span class="macro-nonterminal">$e</span>:expr) =&gt; {{}};
 }

 <span class="attribute">#[cfg(test)]
 </span><span class="kw">mod </span>tests {
     <span class="kw">use super</span>::<span class="kw-2">*</span>;

     <span class="kw">use </span>std::sync::<span class="kw-2">*</span>;

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_has_failpoints() {
         <span class="macro">assert_eq!</span>(<span class="macro">cfg!</span>(feature = <span class="string">&quot;failpoints&quot;</span>), has_failpoints());
     }

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_off() {
         <span class="kw">let </span>point = FailPoint::new();
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Off, <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         <span class="macro">assert!</span>(point.eval(<span class="string">&quot;test_fail_point_off&quot;</span>).is_none());
     }

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_return() {
         <span class="kw">let </span>point = FailPoint::new();
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Return(<span class="prelude-val">None</span>), <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         <span class="kw">let </span>res = point.eval(<span class="string">&quot;test_fail_point_return&quot;</span>);
         <span class="macro">assert_eq!</span>(res, <span class="prelude-val">Some</span>(<span class="prelude-val">None</span>));

         <span class="kw">let </span>ret = <span class="prelude-val">Some</span>(<span class="string">&quot;test&quot;</span>.to_owned());
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Return(ret.clone()), <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         <span class="kw">let </span>res = point.eval(<span class="string">&quot;test_fail_point_return&quot;</span>);
         <span class="macro">assert_eq!</span>(res, <span class="prelude-val">Some</span>(ret));
     }

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_sleep() {
         <span class="kw">let </span>point = FailPoint::new();
         <span class="kw">let </span>timer = Instant::now();
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Sleep(<span class="number">1000</span>), <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         <span class="macro">assert!</span>(point.eval(<span class="string">&quot;test_fail_point_sleep&quot;</span>).is_none());
         <span class="macro">assert!</span>(timer.elapsed() &gt; Duration::from_millis(<span class="number">1000</span>));
     }

     <span class="attribute">#[should_panic]
     #[test]
     </span><span class="kw">fn </span>test_panic() {
         <span class="kw">let </span>point = FailPoint::new();
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Panic(<span class="prelude-val">None</span>), <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         point.eval(<span class="string">&quot;test_fail_point_panic&quot;</span>);
     }

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_print() {
         <span class="kw">struct </span>LogCollector(Arc&lt;Mutex&lt;Vec&lt;String&gt;&gt;&gt;);
         <span class="kw">impl </span>log::Log <span class="kw">for </span>LogCollector {
             <span class="kw">fn </span>enabled(<span class="kw-2">&amp;</span><span class="self">self</span>, <span class="kw">_</span>: <span class="kw-2">&amp;</span>log::Metadata) -&gt; bool {
                 <span class="bool-val">true
             </span>}
             <span class="kw">fn </span>log(<span class="kw-2">&amp;</span><span class="self">self</span>, record: <span class="kw-2">&amp;</span>log::Record) {
                 <span class="kw">let </span><span class="kw-2">mut </span>buf = <span class="self">self</span>.<span class="number">0</span>.lock().unwrap();
                 buf.push(<span class="macro">format!</span>(<span class="string">&quot;{}&quot;</span>, record.args()));
             }
             <span class="kw">fn </span>flush(<span class="kw-2">&amp;</span><span class="self">self</span>) {}
         }

         <span class="kw">let </span>buffer = Arc::new(Mutex::new(<span class="macro">vec!</span>[]));
         <span class="kw">let </span>collector = LogCollector(buffer.clone());
         log::set_max_level(log::LevelFilter::Info);
         log::set_boxed_logger(Box::new(collector)).unwrap();

         <span class="kw">let </span>point = FailPoint::new();
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Print(<span class="prelude-val">None</span>), <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         <span class="macro">assert!</span>(point.eval(<span class="string">&quot;test_fail_point_print&quot;</span>).is_none());
         <span class="kw">let </span>msg = buffer.lock().unwrap().pop().unwrap();
         <span class="macro">assert_eq!</span>(msg, <span class="string">&quot;failpoint test_fail_point_print executed.&quot;</span>);
     }

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_pause() {
         <span class="kw">let </span>point = Arc::new(FailPoint::new());
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Pause, <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         <span class="kw">let </span>p = point.clone();
         <span class="kw">let </span>(tx, rx) = mpsc::channel();
         thread::spawn(<span class="kw">move </span>|| {
             <span class="macro">assert_eq!</span>(p.eval(<span class="string">&quot;test_fail_point_pause&quot;</span>), <span class="prelude-val">None</span>);
             tx.send(()).unwrap();
         });
         <span class="macro">assert!</span>(rx.recv_timeout(Duration::from_secs(<span class="number">1</span>)).is_err());
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Off, <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         rx.recv_timeout(Duration::from_secs(<span class="number">1</span>)).unwrap();
     }

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_yield() {
         <span class="kw">let </span>point = FailPoint::new();
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Yield, <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         <span class="macro">assert!</span>(point.eval(<span class="string">&quot;test_fail_point_yield&quot;</span>).is_none());
     }

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_delay() {
         <span class="kw">let </span>point = FailPoint::new();
         <span class="kw">let </span>timer = Instant::now();
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Delay(<span class="number">1000</span>), <span class="number">1.0</span>, <span class="prelude-val">None</span>)]);
         <span class="macro">assert!</span>(point.eval(<span class="string">&quot;test_fail_point_delay&quot;</span>).is_none());
         <span class="macro">assert!</span>(timer.elapsed() &gt; Duration::from_millis(<span class="number">1000</span>));
     }

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_frequency_and_count() {
         <span class="kw">let </span>point = FailPoint::new();
         point.set_actions(<span class="string">&quot;&quot;</span>, <span class="macro">vec!</span>[Action::new(Task::Return(<span class="prelude-val">None</span>), <span class="number">0.8</span>, <span class="prelude-val">Some</span>(<span class="number">100</span>))]);
         <span class="kw">let </span><span class="kw-2">mut </span>count = <span class="number">0</span>;
         <span class="kw">let </span><span class="kw-2">mut </span>times = <span class="number">0f64</span>;
         <span class="kw">while </span>count &lt; <span class="number">100 </span>{
             <span class="kw">if </span>point.eval(<span class="string">&quot;test_fail_point_frequency&quot;</span>).is_some() {
                 count += <span class="number">1</span>;
             }
             times += <span class="number">1f64</span>;
         }
         <span class="macro">assert!</span>(<span class="number">100.0 </span>/ <span class="number">0.9 </span>&lt; times &amp;&amp; times &lt; <span class="number">100.0 </span>/ <span class="number">0.7</span>, <span class="string">&quot;{}&quot;</span>, times);
         <span class="kw">for _ in </span><span class="number">0</span>..times <span class="kw">as </span>u64 {
             <span class="macro">assert!</span>(point.eval(<span class="string">&quot;test_fail_point_frequency&quot;</span>).is_none());
         }
     }

     <span class="attribute">#[test]
     </span><span class="kw">fn </span>test_parse() {
         <span class="kw">let </span>cases = <span class="macro">vec!</span>[
             (<span class="string">&quot;return&quot;</span>, Action::new(Task::Return(<span class="prelude-val">None</span>), <span class="number">1.0</span>, <span class="prelude-val">None</span>)),
             (
                 <span class="string">&quot;return(64)&quot;</span>,
                 Action::new(Task::Return(<span class="prelude-val">Some</span>(<span class="string">&quot;64&quot;</span>.to_owned())), <span class="number">1.0</span>, <span class="prelude-val">None</span>),
             ),
             (<span class="string">&quot;5*return&quot;</span>, Action::new(Task::Return(<span class="prelude-val">None</span>), <span class="number">1.0</span>, <span class="prelude-val">Some</span>(<span class="number">5</span>))),
             (<span class="string">&quot;25%return&quot;</span>, Action::new(Task::Return(<span class="prelude-val">None</span>), <span class="number">0.25</span>, <span class="prelude-val">None</span>)),
             (
                 <span class="string">&quot;125%2*return&quot;</span>,
                 Action::new(Task::Return(<span class="prelude-val">None</span>), <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>)),
             ),
             (
                 <span class="string">&quot;return(2%5)&quot;</span>,
                 Action::new(Task::Return(<span class="prelude-val">Some</span>(<span class="string">&quot;2%5&quot;</span>.to_owned())), <span class="number">1.0</span>, <span class="prelude-val">None</span>),
             ),
             (<span class="string">&quot;125%2*off&quot;</span>, Action::new(Task::Off, <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>))),
             (
                 <span class="string">&quot;125%2*sleep(100)&quot;</span>,
                 Action::new(Task::Sleep(<span class="number">100</span>), <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>)),
             ),
             (<span class="string">&quot; 125%2*off &quot;</span>, Action::new(Task::Off, <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>))),
             (<span class="string">&quot;125%2*panic&quot;</span>, Action::new(Task::Panic(<span class="prelude-val">None</span>), <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>))),
             (
                 <span class="string">&quot;125%2*panic(msg)&quot;</span>,
                 Action::new(Task::Panic(<span class="prelude-val">Some</span>(<span class="string">&quot;msg&quot;</span>.to_owned())), <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>)),
             ),
             (<span class="string">&quot;125%2*print&quot;</span>, Action::new(Task::Print(<span class="prelude-val">None</span>), <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>))),
             (
                 <span class="string">&quot;125%2*print(msg)&quot;</span>,
                 Action::new(Task::Print(<span class="prelude-val">Some</span>(<span class="string">&quot;msg&quot;</span>.to_owned())), <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>)),
             ),
             (<span class="string">&quot;125%2*pause&quot;</span>, Action::new(Task::Pause, <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>))),
             (<span class="string">&quot;125%2*yield&quot;</span>, Action::new(Task::Yield, <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>))),
             (<span class="string">&quot;125%2*delay(2)&quot;</span>, Action::new(Task::Delay(<span class="number">2</span>), <span class="number">1.25</span>, <span class="prelude-val">Some</span>(<span class="number">2</span>))),
         ];
         <span class="kw">for </span>(expr, exp) <span class="kw">in </span>cases {
             <span class="kw">let </span>res: Action = expr.parse().unwrap();
             <span class="macro">assert_eq!</span>(res, exp);
         }

         <span class="kw">let </span>fail_cases = <span class="macro">vec!</span>[
             <span class="string">&quot;delay&quot;</span>,
             <span class="string">&quot;sleep&quot;</span>,
             <span class="string">&quot;Return&quot;</span>,
             <span class="string">&quot;ab%return&quot;</span>,
             <span class="string">&quot;ab*return&quot;</span>,
             <span class="string">&quot;return(msg&quot;</span>,
             <span class="string">&quot;unknown&quot;</span>,
         ];
         <span class="kw">for </span>case <span class="kw">in </span>fail_cases {
             <span class="macro">assert!</span>(case.parse::&lt;Action&gt;().is_err());
         }
     }

     <span class="comment">// This case should be tested as integration case, but when calling `teardown` other cases
     // like `test_pause` maybe also affected, so it&#39;s better keep it here.
     </span><span class="attribute">#[test]
     #[cfg_attr(not(feature = <span class="string">&quot;failpoints&quot;</span>), ignore)]
     </span><span class="kw">fn </span>test_setup_and_teardown() {
         <span class="kw">let </span>f1 = || {
             <span class="macro">fail_point!</span>(<span class="string">&quot;setup_and_teardown1&quot;</span>, |<span class="kw">_</span>| <span class="number">1</span>);
             <span class="number">0
         </span>};
         <span class="kw">let </span>f2 = || {
             <span class="macro">fail_point!</span>(<span class="string">&quot;setup_and_teardown2&quot;</span>, |<span class="kw">_</span>| <span class="number">2</span>);
             <span class="number">0
         </span>};
         env::set_var(
             <span class="string">&quot;FAILPOINTS&quot;</span>,
             <span class="string">&quot;setup_and_teardown1=return;setup_and_teardown2=pause;&quot;</span>,
         );
         <span class="kw">let </span>scenario = FailScenario::setup();
         <span class="macro">assert_eq!</span>(f1(), <span class="number">1</span>);

         <span class="kw">let </span>(tx, rx) = mpsc::channel();
         thread::spawn(<span class="kw">move </span>|| {
             tx.send(f2()).unwrap();
         });
         <span class="macro">assert!</span>(rx.recv_timeout(Duration::from_millis(<span class="number">500</span>)).is_err());

         scenario.teardown();
         <span class="macro">assert_eq!</span>(rx.recv_timeout(Duration::from_millis(<span class="number">500</span>)).unwrap(), <span class="number">0</span>);
         <span class="macro">assert_eq!</span>(f1(), <span class="number">0</span>);
     }
 }
 </code></pre></div>
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