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#![forbid(missing_docs)] #![cfg_attr(not(feature = "std"), no_std)] //! A utility for recursively measuring the size of an object //! //! This contains the [`DeepSizeOf`](DeepSizeOf) trait, and re-exports //! the `DeepSizeOf` derive macro from [`deepsize_derive`](https://docs.rs/deepsize_derive) //! //! ```rust //! use deepsize::DeepSizeOf; //! //! #[derive(DeepSizeOf)] //! struct Test { //! a: u32, //! b: Box<u8>, //! } //! //! let object = Test { //! a: 15, //! b: Box::new(255), //! }; //! //! // The stack size of the struct: //! // The size of a u32 (4) //! // 4 bytes padding (64 bit only) //! // The stack size of the Box (a usize pointer, 32 or 64 bits: 4 or 8 bytes) //! // + the size of a u8 (1), the Box's heap storage //! #[cfg(target_pointer_width = "64")] //! assert_eq!(object.deep_size_of(), 17); //! #[cfg(target_pointer_width = "32")] //! assert_eq!(object.deep_size_of(), 9); //! ``` //! extern crate alloc; extern crate core; #[cfg(feature = "derive")] extern crate self as deepsize; #[cfg(feature = "derive")] pub use deepsize_derive::*; use core::mem::{size_of, size_of_val}; #[cfg(test)] mod test; mod default_impls; mod external_impls; /// A trait for measuring the size of an object and its children /// /// In many cases this is just `std::mem::size_of::<T>()`, but if /// the struct contains a `Vec`, `String`, `Box`, or other allocated object or /// reference, then it is the size of the struct, plus the size of the contents /// of the object. pub trait DeepSizeOf { /// Returns an estimation of a total size of memory owned by the /// object, including heap-managed storage. /// /// This is an estimation and not a precise result because it /// doesn't account for allocator's overhead. /// /// ```rust /// use deepsize::DeepSizeOf; /// /// let mut map: Vec<(Box<u32>, String)> = Vec::new(); /// /// map.push((Box::new(42u32), String::from("Hello World"))); /// map.push((Box::new(20u32), String::from("Something"))); /// map.push((Box::new(0u32), String::from("A string"))); /// map.push((Box::new(255u32), String::from("Dynamically Allocated!"))); /// /// assert_eq!(map.deep_size_of(), /// std::mem::size_of::<Vec<(Box<u32>, String)>>() + /// 4 * std::mem::size_of::<(Box<u32>, String)>() + /// 4 * std::mem::size_of::<u32>() + /// 11 + 9 + 8 + 22 /// ); /// ``` fn deep_size_of(&self) -> usize { size_of_val(self) + self.deep_size_of_children(&mut Context::new()) } /// Returns an estimation of the heap-managed storage of this object. /// This does not include the size of the object itself. /// /// This is an estimation and not a precise result, because it /// doesn't account for allocator's overhead. /// /// This is an internal function (this shouldn't be called directly), /// and requires a [`Context`](Context) to track visited references. /// Implementations of this function should only call `deep_size_of_children`, /// and not `deep_size_of` so that they reference tracking is not reset. /// /// In all other cases, `deep_size_of` should be called instead of this function. /// /// If a struct and all of its children do not allocate or have references, /// this method should return `0`, as it cannot have any heap allocated /// children. There is a shortcut macro for this implementation, [`known_size_of`](known_size_of), /// used like `known_deep_size!(0, (), u32, u64);` which generates the impls. /// /// The most common way to use this method, and how the derive works, /// is to call this method on each of the structs members and sum the /// results, which works as long as all members of the struct implement /// `DeepSizeOf`. /// /// To implement this for a collection type, you should sum the deep sizes of /// the items of the collection and then add the size of the allocation of the /// collection itself. This can become much more complicated if the collection /// has multiple separate allocations. /// /// Here is an example from the implementation of `DeepSizeOf` for `Vec<T>` /// ```rust, ignore /// # use deepsize::{DeepSizeOf, Context}; /// impl<T> DeepSizeOf for std::vec::Vec<T> where T: DeepSizeOf { /// fn deep_size_of_children(&self, context: &mut Context) -> usize { /// // Size of heap allocations for each child /// self.iter().map(|child| child.deep_size_of_children(context)).sum() /// + self.capacity() * std::mem::size_of::<T>() // Size of Vec's heap allocation /// } /// } /// ``` fn deep_size_of_children(&self, context: &mut Context) -> usize; } #[cfg(not(feature = "std"))] use alloc::collections::BTreeSet as GenericSet; #[cfg(feature = "std")] use std::collections::HashSet as GenericSet; /// The context of which references have already been seen. /// This should only be used in the implementation of the /// `deep_size_of_children` function, and (eventually, when this /// reaches 0.2) will not be able to be constructed, and only obtained /// from inside the function. /// /// Keeps track of the [`Arc`](std::sync::Arc)s, [`Rc`](std::rc::Rc)s, and references /// that have been visited, so that [`Arc`](std::sync::Arc)s and other references /// aren't double counted. /// /// Currently this counts each reference once, although there are arguments for /// only counting owned data and ignoring partial ownership, or for counting /// partial references such as Arc as its size divided by the strong reference count. /// /// [Github issue discussion here](https://github.com/dtolnay/request-for-implementation/issues/22) /// /// This must be passed between `deep_size_of_children` calls when /// recursing, so that references are not counted multiple timse. #[derive(Debug)] pub struct Context { /// A set of all [`Arc`](std::sync::Arc)s that have already been counted arcs: GenericSet<usize>, /// A set of all [`Rc`](std::sync::Arc)s that have already been counted rcs: GenericSet<usize>, } impl Context { /// Creates a new empty context for use in the `deep_size` functions fn new() -> Self { Self { arcs: GenericSet::new(), rcs: GenericSet::new(), } } /// Adds an [`Arc`](std::sync::Arc) to the list of visited [`Arc`](std::sync::Arc)s fn add_arc<T: ?Sized>(&mut self, arc: &alloc::sync::Arc<T>) { self.arcs.insert(&**arc as *const T as *const u8 as usize); } /// Checks if an [`Arc`](std::sync::Arc) is in the list visited [`Arc`](std::sync::Arc)s fn contains_arc<T: ?Sized>(&self, arc: &alloc::sync::Arc<T>) -> bool { self.arcs .contains(&(&**arc as *const T as *const u8 as usize)) } /// Adds an [`Rc`](std::rc::Rc) to the list of visited [`Rc`](std::rc::Rc)s fn add_rc<T: ?Sized>(&mut self, rc: &alloc::rc::Rc<T>) { self.rcs.insert(&**rc as *const T as *const u8 as usize); } /// Checks if an [`Rc`](std::rc::Rc) is in the list visited [`Rc`](std::rc::Rc)s /// Adds an [`Rc`](std::rc::Rc) to the list of visited [`Rc`](std::rc::Rc)s fn contains_rc<T: ?Sized>(&self, rc: &alloc::rc::Rc<T>) -> bool { self.rcs .contains(&(&**rc as *const T as *const u8 as usize)) } } impl<T> DeepSizeOf for alloc::vec::Vec<T> where T: DeepSizeOf, { /// Sums the size of each child object, and then adds the size of /// the unused capacity. /// /// ```rust /// use deepsize::DeepSizeOf; /// /// let mut vec: Vec<u8> = vec![]; /// for i in 0..13 { /// vec.push(i); /// } /// /// // The capacity (16) plus three usizes (len, cap, pointer) /// assert_eq!(vec.deep_size_of(), 16 + 24); /// ``` /// With allocated objects: /// ```rust /// use deepsize::DeepSizeOf; /// /// let mut vec: Vec<Box<u64>> = vec![]; /// for i in 0..13 { /// vec.push(Box::new(i)); /// } /// /// // The capacity (16?) * size (8) plus three usizes (len, cap, pointer) /// // and length (13) * the allocated size of each object /// assert_eq!(vec.deep_size_of(), 24 + vec.capacity() * 8 + 13 * 8); /// ``` fn deep_size_of_children(&self, context: &mut Context) -> usize { self.iter() .map(|child| child.deep_size_of_children(context)) .sum::<usize>() + self.capacity() * size_of::<T>() // Size of unused capacity } } impl<T> DeepSizeOf for alloc::collections::VecDeque<T> where T: DeepSizeOf, { /// Sums the size of each child object, and then adds the size of /// the unused capacity. /// /// ```rust /// use deepsize::DeepSizeOf; /// use std::collections::VecDeque; /// /// let mut vec: VecDeque<u8> = VecDeque::new(); /// for i in 0..12 { /// vec.push_back(i); /// } /// vec.push_front(13); /// /// // The capacity (15?) plus four usizes (start, end, cap, pointer) /// assert_eq!(vec.deep_size_of(), vec.capacity() * 1 + 32); /// ``` /// With allocated objects: /// ```rust /// use deepsize::DeepSizeOf; /// use std::collections::VecDeque; /// /// let mut vec: VecDeque<Box<u64>> = VecDeque::new(); /// for i in 0..12 { /// vec.push_back(Box::new(i)); /// } /// vec.push_front(Box::new(13)); /// /// // The capacity (15?) * size (8) plus four usizes (start, end, cap, pointer) /// // and length (13) * the allocated size of each object /// assert_eq!(vec.deep_size_of(), 32 + vec.capacity() * 8 + 13 * 8); /// ``` fn deep_size_of_children(&self, context: &mut Context) -> usize { // Deep size of children self.iter() .map(|child| child.deep_size_of_children(context)) .sum::<usize>() + self.capacity() * size_of::<T>() // Size of Vec's heap allocation } } impl<T> DeepSizeOf for alloc::collections::LinkedList<T> where T: DeepSizeOf, { /// Sums the size of each child object, assuming the overhead of /// each node is 2 usize (next, prev) /// /// ```rust /// use deepsize::DeepSizeOf; /// use std::collections::LinkedList; /// /// let mut list: LinkedList<u8> = LinkedList::new(); /// for i in 0..12 { /// list.push_back(i); /// } /// list.push_front(13); /// /// assert_eq!(list.deep_size_of(), std::mem::size_of::<LinkedList<u8>>() /// + 13 * 1 + 13 * 2 * 8); /// ``` fn deep_size_of_children(&self, context: &mut Context) -> usize { self.iter().fold(0, |sum, child| { sum + size_of_val(child) + child.deep_size_of_children(context) + size_of::<usize>() * 2 // overhead of each node }) } } #[cfg(feature = "std")] impl<K, V, S> DeepSizeOf for std::collections::HashMap<K, V, S> where K: DeepSizeOf + Eq + std::hash::Hash, V: DeepSizeOf, S: std::hash::BuildHasher, { // How much more overhead is there to a hashmap? The docs say it is // essentially just a Vec<Option<(u64, K, V)>>; // For the old implementation of HashMap: // fn deep_size_of_children(&self, context: &mut Context) -> usize { // self.iter().fold(0, |sum, (key, val)| { // sum + key.deep_size_of_children(context) + val.deep_size_of_children(context) // }) + self.capacity() * size_of::<Option<(u64, K, V)>>() // } // For the hashbrown implementation of HashMap: fn deep_size_of_children(&self, context: &mut Context) -> usize { self.iter().fold(0, |sum, (key, val)| { sum + key.deep_size_of_children(context) + val.deep_size_of_children(context) }) + self.capacity() * size_of::<(K, V)>() // Buckets would be the more correct value, but there isn't // an API for accessing that with hashbrown. // I believe that hashbrown's HashTable is represented as // an array of (K, V), with control bytes at the start/end // that mark used/uninitialized buckets (?) } } #[cfg(feature = "std")] impl<K, S> DeepSizeOf for std::collections::HashSet<K, S> where K: DeepSizeOf + Eq + std::hash::Hash, S: std::hash::BuildHasher, { fn deep_size_of_children(&self, context: &mut Context) -> usize { // self.iter() // .fold(0, |sum, item| sum + item.deep_size_of_children(context)) // + self.capacity() * size_of::<Option<(u64, K, ())>>() self.iter() .fold(0, |sum, key| sum + key.deep_size_of_children(context)) + self.capacity() * size_of::<K>() } } // A btree node has 2*B - 1 (K,V) pairs and (usize, u16, u16) // overhead, and an internal btree node additionally has 2*B // `usize` overhead. // A node can contain between B - 1 and 2*B - 1 elements, so // we assume it has the midpoint 3/2*B - 1. // Constants from rust's source: // https://doc.rust-lang.org/src/alloc/collections/btree/node.rs.html#43-45 const BTREE_B: usize = 6; const BTREE_MIN: usize = 2 * BTREE_B - 1; const BTREE_MAX: usize = BTREE_B - 1; #[cfg(feature = "std")] impl<K: Ord + DeepSizeOf, V: DeepSizeOf> DeepSizeOf for std::collections::BTreeMap<K, V> { fn deep_size_of_children(&self, context: &mut Context) -> usize { let element_size = self.iter().fold(0, |sum, (k, v)| { sum + k.deep_size_of_children(context) + v.deep_size_of_children(context) }); let overhead = size_of::<(usize, u16, u16, [(K, V); BTREE_MAX], [usize; BTREE_B])>(); element_size + self.len() * overhead * 2 / (BTREE_MAX + BTREE_MIN) } } #[cfg(feature = "std")] impl<K: Ord + DeepSizeOf> DeepSizeOf for std::collections::BTreeSet<K> { fn deep_size_of_children(&self, context: &mut Context) -> usize { let element_size = self .iter() .fold(0, |sum, item| sum + item.deep_size_of_children(context)); let overhead = size_of::<(usize, u16, u16, [K; BTREE_MAX], [usize; BTREE_B])>(); element_size + self.len() * overhead * 2 / (BTREE_MAX + BTREE_MIN) } } impl<T> DeepSizeOf for alloc::boxed::Box<T> where T: DeepSizeOf + ?Sized, { fn deep_size_of_children(&self, context: &mut Context) -> usize { let val: &T = &*self; size_of_val(val) + val.deep_size_of_children(context) } } impl<T> DeepSizeOf for alloc::sync::Arc<T> where T: DeepSizeOf + ?Sized, { fn deep_size_of_children(&self, context: &mut Context) -> usize { if context.contains_arc(self) { 0 } else { context.add_arc(self); let val: &T = &*self; // Size of the Arc, size of the value, size of the allocations of the value size_of_val(val) + val.deep_size_of_children(context) } } } impl<T> DeepSizeOf for alloc::rc::Rc<T> where T: DeepSizeOf + ?Sized, { fn deep_size_of_children(&self, context: &mut Context) -> usize { if context.contains_rc(self) { 0 } else { context.add_rc(self); let val: &T = &*self; size_of_val(val) + val.deep_size_of_children(context) } } } // References aren't owned; should they count? impl<T> DeepSizeOf for &T where T: DeepSizeOf + ?Sized, { fn deep_size_of_children(&self, _context: &mut Context) -> usize { 0 // if context.contains_ref(&self) { // 0 // } else { // context.add_ref(&self); // size_of_val(*self) + (*self).deep_size_of_children(context) // } } } impl<T> DeepSizeOf for &mut T where T: DeepSizeOf + ?Sized, { fn deep_size_of_children(&self, _context: &mut Context) -> usize { 0 } } impl<T> DeepSizeOf for [T] where T: DeepSizeOf, { fn deep_size_of_children(&self, context: &mut Context) -> usize { self.iter() .map(|child| child.deep_size_of_children(context)) .sum() } }