From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49963C4321E for ; Fri, 2 Dec 2022 16:17:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233483AbiLBQRG (ORCPT ); Fri, 2 Dec 2022 11:17:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233975AbiLBQQa (ORCPT ); Fri, 2 Dec 2022 11:16:30 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 075DAD208B; Fri, 2 Dec 2022 08:16:07 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D90E562331; Fri, 2 Dec 2022 16:16:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 23525C43470; Fri, 2 Dec 2022 16:16:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669997766; bh=2kl4siMs2CiGNBXEZpLt5Bkk+dmVvKDxrC3ndkxJ8nE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eZzKRlTsLe+l4byy89diKfAYGW9gr1GxcrGfLMdowMTdFbapJswUpLyrVVyMFWbo8 nhk0YPlJgcqDriXywi2C7Zw8JuJ0jh9n7KlBk6lAjjY9uWjuYyugHjwLAYWpfCIy2p tb8LNf6EKbYFWQ4GBZheYuFM8j945A3k55dDEBHfKG2vylvqpfjaMlfnaUxPIHLiI/ r8xdzY2y2mmB0jH2VK+lP7AaSoB3Emt3gw5hdKF0ljfbx1QY+S7hYHofcUgW20htQo Dkx3NcXamstan9FGeYI+3ZA1htUUU0U3DA9f54Bgu+5XX29VRgOHHQBkbLctLQGDJC ugz2s0P5LHqXg== From: ojeda@kernel.org To: Miguel Ojeda , Wedson Almeida Filho , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev Subject: [PATCH v2 13/28] rust: alloc: add `Vec::try_with_capacity{,_in}()` constructors Date: Fri, 2 Dec 2022 17:14:44 +0100 Message-Id: <20221202161502.385525-14-ojeda@kernel.org> In-Reply-To: <20221202161502.385525-1-ojeda@kernel.org> References: <20221202161502.385525-1-ojeda@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: rust-for-linux@vger.kernel.org From: Miguel Ojeda Add `Vec::try_with_capacity()` and `Vec::try_with_capacity_in()` as the fallible versions of `Vec::with_capacity()` and `Vec::with_capacity_in()`, respectively. The implementations follow the originals and use the previously added `RawVec::try_with_capacity_in()`. In turn, `Vec::try_with_capacity()` will be used to implement the `CString` type (which wraps a `Vec`) in a later patch. Reviewed-by: Gary Guo Signed-off-by: Miguel Ojeda --- rust/alloc/raw_vec.rs | 1 - rust/alloc/vec/mod.rs | 89 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 89 insertions(+), 1 deletion(-) diff --git a/rust/alloc/raw_vec.rs b/rust/alloc/raw_vec.rs index c342f3843972..eb77db5def55 100644 --- a/rust/alloc/raw_vec.rs +++ b/rust/alloc/raw_vec.rs @@ -135,7 +135,6 @@ impl RawVec { /// Like `try_with_capacity`, but parameterized over the choice of /// allocator for the returned `RawVec`. - #[allow(dead_code)] #[inline] pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result { Self::try_allocate_in(capacity, AllocInit::Uninitialized, alloc) diff --git a/rust/alloc/vec/mod.rs b/rust/alloc/vec/mod.rs index 540787804cc2..8ac6c1e3b2a8 100644 --- a/rust/alloc/vec/mod.rs +++ b/rust/alloc/vec/mod.rs @@ -472,6 +472,48 @@ impl Vec { Self::with_capacity_in(capacity, Global) } + /// Tries to construct a new, empty `Vec` with the specified capacity. + /// + /// The vector will be able to hold exactly `capacity` elements without + /// reallocating. If `capacity` is 0, the vector will not allocate. + /// + /// It is important to note that although the returned vector has the + /// *capacity* specified, the vector will have a zero *length*. For an + /// explanation of the difference between length and capacity, see + /// *[Capacity and reallocation]*. + /// + /// [Capacity and reallocation]: #capacity-and-reallocation + /// + /// # Examples + /// + /// ``` + /// let mut vec = Vec::try_with_capacity(10).unwrap(); + /// + /// // The vector contains no items, even though it has capacity for more + /// assert_eq!(vec.len(), 0); + /// assert_eq!(vec.capacity(), 10); + /// + /// // These are all done without reallocating... + /// for i in 0..10 { + /// vec.push(i); + /// } + /// assert_eq!(vec.len(), 10); + /// assert_eq!(vec.capacity(), 10); + /// + /// // ...but this may make the vector reallocate + /// vec.push(11); + /// assert_eq!(vec.len(), 11); + /// assert!(vec.capacity() >= 11); + /// + /// let mut result = Vec::try_with_capacity(usize::MAX); + /// assert!(result.is_err()); + /// ``` + #[inline] + #[stable(feature = "kernel", since = "1.0.0")] + pub fn try_with_capacity(capacity: usize) -> Result { + Self::try_with_capacity_in(capacity, Global) + } + /// Creates a `Vec` directly from the raw components of another vector. /// /// # Safety @@ -617,6 +659,53 @@ impl Vec { Vec { buf: RawVec::with_capacity_in(capacity, alloc), len: 0 } } + /// Tries to construct a new, empty `Vec` with the specified capacity + /// with the provided allocator. + /// + /// The vector will be able to hold exactly `capacity` elements without + /// reallocating. If `capacity` is 0, the vector will not allocate. + /// + /// It is important to note that although the returned vector has the + /// *capacity* specified, the vector will have a zero *length*. For an + /// explanation of the difference between length and capacity, see + /// *[Capacity and reallocation]*. + /// + /// [Capacity and reallocation]: #capacity-and-reallocation + /// + /// # Examples + /// + /// ``` + /// #![feature(allocator_api)] + /// + /// use std::alloc::System; + /// + /// let mut vec = Vec::try_with_capacity_in(10, System).unwrap(); + /// + /// // The vector contains no items, even though it has capacity for more + /// assert_eq!(vec.len(), 0); + /// assert_eq!(vec.capacity(), 10); + /// + /// // These are all done without reallocating... + /// for i in 0..10 { + /// vec.push(i); + /// } + /// assert_eq!(vec.len(), 10); + /// assert_eq!(vec.capacity(), 10); + /// + /// // ...but this may make the vector reallocate + /// vec.push(11); + /// assert_eq!(vec.len(), 11); + /// assert!(vec.capacity() >= 11); + /// + /// let mut result = Vec::try_with_capacity_in(usize::MAX, System); + /// assert!(result.is_err()); + /// ``` + #[inline] + #[stable(feature = "kernel", since = "1.0.0")] + pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result { + Ok(Vec { buf: RawVec::try_with_capacity_in(capacity, alloc)?, len: 0 }) + } + /// Creates a `Vec` directly from the raw components of another vector. /// /// # Safety -- 2.38.1