| <!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/census-0.4.1/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="../../census/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="../../census/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="doccomment">//! # Census |
| //! |
| //! Census' `Inventory` makes it possible to track a set of living items of a specific type. |
| //! Items are automatically removed from the `Inventory<T>` as the living item's are dropped. |
| //! |
| //! ```rust |
| //! use census::{Inventory, TrackedObject}; |
| //! |
| //! let inventory = Inventory::new(); |
| //! |
| //! // Each object tracked needs to be registered explicitely in the Inventory. |
| //! // A `TrackedObject<T>` wrapper is then returned. |
| //! let one = inventory.track("one".to_string()); |
| //! let two = inventory.track("two".to_string()); |
| //! |
| //! // A snapshot of the list of living instances can be obtained... |
| //! // (no guarantee on their order) |
| //! let living_instances: Vec<TrackedObject<String>> = inventory.list(); |
| //! assert_eq!(living_instances.len(), 2); |
| //! ``` |
| |
| </span><span class="kw">use </span>std::borrow::Borrow; |
| <span class="kw">use </span>std::fmt; |
| <span class="kw">use </span>std::ops::Deref; |
| |
| <span class="kw">use </span>std::sync::{Arc, Condvar, Mutex, MutexGuard, Weak}; |
| |
| <span class="kw">use </span>std::fmt::{Error, Formatter}; |
| |
| <span class="kw">struct </span>Items<T> { |
| alive_count: usize, |
| items: Vec<Weak<InnerTrackedObject<T>>>, |
| } |
| |
| <span class="kw">impl</span><T> Default <span class="kw">for </span>Items<T> { |
| <span class="kw">fn </span>default() -> <span class="self">Self </span>{ |
| Items { |
| alive_count: <span class="number">0</span>, |
| items: Vec::new(), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> Items<T> { |
| <span class="kw">fn </span>record_birth(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.alive_count += <span class="number">1</span>; |
| } |
| |
| <span class="kw">fn </span>record_death(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.alive_count -= <span class="number">1</span>; |
| } |
| |
| <span class="kw">fn </span>list_arc(<span class="kw-2">&mut </span><span class="self">self</span>) -> Vec<TrackedObject<T>> { |
| <span class="self">self</span>.items |
| .iter() |
| .flat_map(|weak| weak.upgrade()) |
| .map(|v| TrackedObject { inner: v }) |
| .collect() |
| } |
| |
| <span class="kw">fn </span>gc_if_needed(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="kw">if </span>!<span class="self">self</span>.should_gc() { |
| <span class="kw">return</span>; |
| } |
| <span class="kw">let </span><span class="kw-2">mut </span>i = <span class="number">0</span>; |
| <span class="kw">while </span>i < <span class="self">self</span>.items.len() { |
| <span class="kw">let </span>should_remove = <span class="self">self</span>.items[i].strong_count() == <span class="number">0</span>; |
| <span class="kw">if </span>should_remove { |
| <span class="self">self</span>.items.swap_remove(i); |
| } <span class="kw">else </span>{ |
| i += <span class="number">1</span>; |
| } |
| } |
| } |
| |
| <span class="kw">fn </span>alive_count(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.alive_count |
| } |
| |
| <span class="kw">fn </span>should_gc(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.alive_count * <span class="number">2 </span><= <span class="self">self</span>.items.len() |
| } |
| } |
| |
| <span class="kw">struct </span>InnerInventory<T> { |
| items: Mutex<Items<T>>, |
| condvar: Condvar, |
| } |
| |
| <span class="doccomment">/// The `Inventory` register and keeps track of all of the objects alive. |
| </span><span class="kw">pub struct </span>Inventory<T> { |
| inner: Arc<InnerInventory<T>>, |
| } |
| |
| <span class="kw">impl</span><T> Default <span class="kw">for </span>Inventory<T> { |
| <span class="kw">fn </span>default() -> <span class="self">Self </span>{ |
| Inventory { |
| inner: Arc::new(InnerInventory { |
| items: Mutex::new(Items::default()), |
| condvar: Condvar::new(), |
| }), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> Clone <span class="kw">for </span>Inventory<T> { |
| <span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{ |
| Inventory { |
| inner: <span class="self">self</span>.inner.clone(), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> Inventory<T> { |
| <span class="doccomment">/// Creates a new inventory. |
| </span><span class="kw">pub fn </span>new() -> Inventory<T> { |
| Inventory::default() |
| } |
| |
| <span class="kw">fn </span>lock_items(<span class="kw-2">&</span><span class="self">self</span>) -> MutexGuard<Items<T>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>guard = <span class="self">self</span>.inner.items.lock().unwrap(); |
| guard.gc_if_needed(); |
| guard |
| } |
| |
| <span class="doccomment">/// Takes a snapshot of the list of tracked object. |
| /// |
| /// Note that the list is a simple `Vec` of tracked object. |
| /// As a result, it is a consistent snapshot of the |
| /// list of living instance at the time of the call, |
| /// |
| /// Obviously, instances may have been created after the call. |
| /// They will obviously not appear in the snapshot. |
| /// |
| /// ```rust |
| /// use census::{Inventory, TrackedObject}; |
| /// |
| /// let inventory = Inventory::new(); |
| /// |
| /// let one = inventory.track("one".to_string()); |
| /// let living_instances: Vec<TrackedObject<String>> = inventory.list(); |
| /// let two = inventory.track("two".to_string()); |
| /// |
| /// // our snapshot is a bit old. |
| /// assert_eq!(living_instances.len(), 1); |
| /// |
| /// // a fresher snapshot would contain our new element. |
| /// assert_eq!(inventory.list().len(), 2); |
| /// ``` |
| /// |
| /// Also, the instance in the snapshot itself |
| /// are considered "living". |
| /// |
| /// As a result, as long as a snapshot is not dropped, |
| /// all of its instances will be part of the inventory. |
| /// |
| /// ```rust |
| /// # use census::{Inventory, TrackedObject}; |
| /// |
| /// let inventory = Inventory::new(); |
| /// |
| /// let one = inventory.track("one".to_string()); |
| /// let living_instances: Vec<TrackedObject<String>> = inventory.list(); |
| /// |
| /// // let's drop one here |
| /// drop(one); |
| /// |
| /// // The instance is technically still in the inventory |
| /// // as our previous snapshot is extending its life... |
| /// assert_eq!(inventory.list().len(), 1); |
| /// |
| /// // If we drop our previous snapshot however... |
| /// drop(living_instances); |
| /// |
| /// // `one` is really untracked. |
| /// assert!(inventory.list().is_empty()); |
| /// ``` |
| /// |
| </span><span class="kw">pub fn </span>list(<span class="kw-2">&</span><span class="self">self</span>) -> Vec<TrackedObject<T>> { |
| <span class="self">self</span>.lock_items().list_arc() |
| } |
| |
| <span class="doccomment">/// This function blocks until there are no more items in the inventory. |
| /// |
| /// It is a helper calling |
| /// ```ignore |
| /// self.wait_until_predicate(|count| count == 0) |
| /// ``` |
| /// |
| /// Note it is very easy to misuse this function and create a deadlock. |
| /// For instance, if any living TrackedObject is on the stack at the moment of the call, |
| /// it will not get dropped, and the inventory cannot become empty. |
| </span><span class="kw">pub fn </span>wait_until_empty(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="self">self</span>.wait_until_predicate(|count| count == <span class="number">0</span>) |
| } |
| |
| <span class="doccomment">/// This function blocks until the number of items in the repository matches a specific |
| /// predicate. |
| /// |
| /// See also `wait_until_empty`. |
| /// |
| /// Note it is very easy to misuse this function and create a deadlock. |
| /// For instance, if any living TrackedObject is on the stack at the moment of the call, |
| /// it will not get dropped, and the inventory cannot become empty. |
| </span><span class="kw">pub fn </span>wait_until_predicate<F: Fn(usize) -> bool>(<span class="kw-2">&</span><span class="self">self</span>, predicate_on_count: F) { |
| <span class="kw">let </span><span class="kw-2">mut </span>count = <span class="self">self</span>.lock_items(); |
| <span class="kw">while </span>!predicate_on_count(count.alive_count()) { |
| count = <span class="self">self</span>.inner.condvar.wait(count).unwrap(); |
| } |
| } |
| |
| <span class="doccomment">/// Starts tracking a given `T` object. |
| </span><span class="kw">pub fn </span>track(<span class="kw-2">&</span><span class="self">self</span>, item: T) -> TrackedObject<T> { |
| <span class="kw">let </span>item_arc = Arc::new(InnerTrackedObject { |
| census: <span class="self">self</span>.clone(), |
| item, |
| }); |
| <span class="kw">let </span>item_weak = Arc::downgrade(<span class="kw-2">&</span>item_arc); |
| <span class="kw">let </span><span class="kw-2">mut </span>items_lock = <span class="self">self</span>.lock_items(); |
| items_lock.items.push(item_weak); |
| items_lock.record_birth(); |
| <span class="self">self</span>.inner.condvar.notify_all(); |
| TrackedObject { inner: item_arc } |
| } |
| } |
| |
| <span class="doccomment">/// Your tracked object. |
| /// |
| /// A tracked object contains reference counting logic and an |
| /// `Arc` to your object. It is cloneable but calling clone will |
| /// not clone your internal object. |
| /// |
| /// Your object cannot be mutated. You can borrow it using |
| /// the `Deref` interface. |
| </span><span class="attribute">#[derive(Clone)] |
| </span><span class="kw">pub struct </span>TrackedObject<T> { |
| inner: Arc<InnerTrackedObject<T>>, |
| } |
| |
| <span class="kw">struct </span>InnerTrackedObject<T> { |
| census: Inventory<T>, |
| item: T, |
| } |
| |
| <span class="kw">impl</span><T: fmt::Debug> fmt::Debug <span class="kw">for </span>TrackedObject<T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>Formatter<<span class="lifetime">'_</span>>) -> <span class="prelude-ty">Result</span><(), Error> { |
| <span class="macro">write!</span>(f, <span class="string">"Tracked({:?})"</span>, <span class="self">self</span>.inner.item) |
| } |
| } |
| |
| <span class="kw">impl</span><T> TrackedObject<T> { |
| <span class="doccomment">/// Creates a new object from an existing one. |
| /// |
| /// The new object will be registered |
| /// in your original object's inventory. |
| /// |
| /// ```rust |
| /// use census::{Inventory, TrackedObject}; |
| /// |
| /// let inventory = Inventory::new(); |
| /// |
| /// let seven = inventory.track(7); |
| /// let fourteen = seven.map(|i| i * 2); |
| /// assert_eq!(*fourteen, 14); |
| /// |
| /// let living_instances = inventory.list(); |
| /// assert_eq!(living_instances.len(), 2); |
| /// ``` |
| </span><span class="kw">pub fn </span>map<F>(<span class="kw-2">&</span><span class="self">self</span>, f: F) -> TrackedObject<T> |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&</span>T) -> T, |
| { |
| <span class="kw">let </span>t = f(<span class="kw-2">&</span><span class="self">self</span>); |
| <span class="self">self</span>.inner.census.track(t) |
| } |
| } |
| |
| <span class="kw">impl</span><T> Drop <span class="kw">for </span>InnerTrackedObject<T> { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="kw">let </span><span class="kw-2">mut </span>lock = <span class="self">self</span>.census.lock_items(); |
| lock.record_death(); |
| <span class="self">self</span>.census.inner.condvar.notify_all(); |
| } |
| } |
| |
| <span class="kw">impl</span><T> Deref <span class="kw">for </span>TrackedObject<T> { |
| <span class="kw">type </span>Target = T; |
| |
| <span class="kw">fn </span>deref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>T { |
| <span class="kw-2">&</span><span class="self">self</span>.inner.item |
| } |
| } |
| |
| <span class="kw">impl</span><T> AsRef<T> <span class="kw">for </span>TrackedObject<T> { |
| <span class="kw">fn </span>as_ref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>T { |
| <span class="kw-2">&</span><span class="self">self</span>.inner.item |
| } |
| } |
| |
| <span class="kw">impl</span><T> Borrow<T> <span class="kw">for </span>TrackedObject<T> { |
| <span class="kw">fn </span>borrow(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>T { |
| <span class="kw-2">&</span><span class="self">self</span>.inner.item |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| |
| <span class="kw">use </span><span class="kw">super</span>::Inventory; |
| <span class="kw">use </span>std::sync::mpsc::channel; |
| <span class="kw">use </span>std::sync::{Arc, Barrier}; |
| <span class="kw">use </span>std::thread; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_census_map() { |
| <span class="kw">let </span>census = Inventory::new(); |
| <span class="kw">let </span>a = census.track(<span class="number">1</span>); |
| <span class="kw">let </span>_b = a.map(|v| v * <span class="number">7</span>); |
| <span class="macro">assert_eq!</span>( |
| census.list().into_iter().map(|m| <span class="kw-2">*</span>m).collect::<Vec<<span class="kw">_</span>>>(), |
| <span class="macro">vec!</span>[<span class="number">1</span>, <span class="number">7</span>] |
| ); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_census() { |
| <span class="kw">let </span>census = Inventory::new(); |
| <span class="kw">let </span>_a = census.track(<span class="number">1</span>); |
| <span class="kw">let </span>_b = census.track(<span class="number">3</span>); |
| <span class="macro">assert_eq!</span>( |
| census.list().into_iter().map(|m| <span class="kw-2">*</span>m).collect::<Vec<<span class="kw">_</span>>>(), |
| <span class="macro">vec!</span>[<span class="number">1</span>, <span class="number">3</span>] |
| ); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_census_2() { |
| <span class="kw">let </span>census = Inventory::new(); |
| { |
| <span class="kw">let </span>_a = census.track(<span class="number">1</span>); |
| <span class="kw">let </span>_b = census.track(<span class="number">3</span>); |
| <span class="comment">// dropping both here |
| </span>} |
| <span class="macro">assert!</span>(census.list().is_empty()); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_census_3() { |
| <span class="kw">let </span>census = Inventory::new(); |
| <span class="kw">let </span>a = census.track(<span class="number">1</span>); |
| <span class="kw">let </span>_a2 = a.clone(); |
| drop(a); |
| <span class="macro">assert_eq!</span>( |
| census.list().into_iter().map(|m| <span class="kw-2">*</span>m).collect::<Vec<<span class="kw">_</span>>>(), |
| <span class="macro">vec!</span>[<span class="number">1</span>] |
| ); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_census_list_extends_life() { |
| <span class="kw">let </span>census = Inventory::new(); |
| <span class="kw">let </span>a = census.track(<span class="number">1</span>); |
| <span class="kw">let </span>living = census.list(); |
| <span class="macro">assert_eq!</span>(living.len(), <span class="number">1</span>); |
| drop(a); |
| <span class="kw">let </span>living_2 = census.list(); |
| <span class="macro">assert_eq!</span>(living_2.len(), <span class="number">1</span>); |
| drop(living_2); |
| drop(living); |
| <span class="macro">assert!</span>(census.list().is_empty()); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_census_race_condition() { |
| <span class="kw">let </span>census = Inventory::new(); |
| <span class="kw">let </span>census_clone = census.clone(); |
| thread::spawn(<span class="kw">move </span>|| { |
| <span class="kw">for _ in </span><span class="number">0</span>..<span class="number">1_000 </span>{ |
| <span class="kw">let </span>_a = census_clone.track(<span class="number">1</span>); |
| } |
| }); |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..<span class="number">10_000 </span>{ |
| <span class="macro">println!</span>(<span class="string">"i {}"</span>, i); |
| census.list(); |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_census_concurrent_drop() { |
| <span class="kw">let </span>census = Inventory::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>senders = Vec::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>handles = Vec::new(); |
| <span class="kw">let </span>barrier = Arc::new(Barrier::new(<span class="number">2</span>)); |
| <span class="kw">for _ in </span><span class="number">0</span>..<span class="number">2 </span>{ |
| <span class="kw">let </span>(send, recv) = channel(); |
| <span class="kw">let </span>barrier = barrier.clone(); |
| handles.push(thread::spawn(<span class="kw">move </span>|| { |
| <span class="kw">for </span>obj <span class="kw">in </span>recv { |
| barrier.wait(); |
| drop(obj); |
| } |
| })); |
| senders.push(send); |
| } |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..<span class="number">50_000 </span>{ |
| <span class="kw">let </span>tracked = census.track(i); |
| <span class="kw">for </span>send <span class="kw">in </span><span class="kw-2">&</span>senders { |
| send.send(tracked.clone()).unwrap(); |
| } |
| } |
| drop(senders); |
| <span class="kw">for </span>handle <span class="kw">in </span>handles { |
| handle.join().unwrap(); |
| } |
| |
| <span class="macro">assert_eq!</span>(census.lock_items().alive_count(), <span class="number">0</span>); |
| } |
| |
| <span class="kw">fn </span>test_census_changes_iter_util(el: usize) { |
| <span class="kw">let </span>census = Inventory::new(); |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..el { |
| <span class="kw">let </span>tracked = census.track(i); |
| thread::spawn(<span class="kw">move </span>|| { |
| <span class="kw">let </span>_tracked = tracked; |
| }); |
| } |
| census.wait_until_empty(); |
| <span class="macro">assert!</span>(census.list().is_empty()); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_census_changes_iter_many() { |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">1</span>..<span class="number">200 </span>{ |
| test_census_changes_iter_util(i); |
| } |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="census" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
