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 49C18C47088 for ; Fri, 2 Dec 2022 16:17:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233099AbiLBQRG (ORCPT ); Fri, 2 Dec 2022 11:17:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233763AbiLBQQa (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 7CF9DE0741; Fri, 2 Dec 2022 08:16:04 -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 1B1A06232F; Fri, 2 Dec 2022 16:16:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7045DC433D6; Fri, 2 Dec 2022 16:16:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669997763; bh=BWxOvrWLIfwcfu7Jhuioqwg9jJ3x2xImME+v7sDyUfw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CiJAL/O5nYOueC3kMzcu/WJ9tWK+syLi//zvidOY+ZbCvng0QEwaqhkIBAOkYZ6tF YL7NSmDYhSNwX7NKIdzoWnnnLOayWhLxk5LTnuaailbdpw10e8uOH78PhaK2smqIS4 5O6UYG3YS36WY07VHR5UNR+/9chYtNBmz1vcrQ1X5fnQHX+efxhXGZaXwp0Xw6Rt4h Axq2gozL7rgL2B48BeL/4z44odbI4wGlHRgvS34zlMaD6xYL98ph7cOV/awkD30FfK C828xpj1c+5fimCjg/KdsMZuiszP93w3mdSfsQFlXETPlLbcQiLxJ8sOJVbgPziFlH aFWxShjqHeZKQ== 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 12/28] rust: alloc: add `RawVec::try_with_capacity_in()` constructor Date: Fri, 2 Dec 2022 17:14:43 +0100 Message-Id: <20221202161502.385525-13-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 the `RawVec::try_with_capacity_in()` constructor as the fallible version of `RawVec::with_capacity_in()`. The implementation follows the original. The infallible constructor is implemented in terms of the private `RawVec::allocate_in()` constructor, thus also add the private `RawVec::try_allocate_in()` constructor following the other. It will be used to implement `Vec::try_with_capacity{,_in}()` in the next patch. Reviewed-by: Gary Guo Signed-off-by: Miguel Ojeda --- rust/alloc/raw_vec.rs | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) diff --git a/rust/alloc/raw_vec.rs b/rust/alloc/raw_vec.rs index daf5f2da7168..c342f3843972 100644 --- a/rust/alloc/raw_vec.rs +++ b/rust/alloc/raw_vec.rs @@ -20,11 +20,11 @@ use crate::collections::TryReserveErrorKind::*; #[cfg(test)] mod tests; -#[cfg(not(no_global_oom_handling))] enum AllocInit { /// The contents of the new memory are uninitialized. Uninitialized, /// The new memory is guaranteed to be zeroed. + #[allow(dead_code)] Zeroed, } @@ -133,6 +133,14 @@ impl RawVec { Self::allocate_in(capacity, AllocInit::Uninitialized, alloc) } + /// 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) + } + /// Like `with_capacity_zeroed`, but parameterized over the choice /// of allocator for the returned `RawVec`. #[cfg(not(no_global_oom_handling))] @@ -203,6 +211,30 @@ impl RawVec { } } + fn try_allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Result { + // Don't allocate here because `Drop` will not deallocate when `capacity` is 0. + if mem::size_of::() == 0 || capacity == 0 { + return Ok(Self::new_in(alloc)); + } + + let layout = Layout::array::(capacity).map_err(|_| CapacityOverflow)?; + alloc_guard(layout.size())?; + let result = match init { + AllocInit::Uninitialized => alloc.allocate(layout), + AllocInit::Zeroed => alloc.allocate_zeroed(layout), + }; + let ptr = result.map_err(|_| AllocError { layout, non_exhaustive: () })?; + + // Allocators currently return a `NonNull<[u8]>` whose length + // matches the size requested. If that ever changes, the capacity + // here should change to `ptr.len() / mem::size_of::()`. + Ok(Self { + ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) }, + cap: capacity, + alloc, + }) + } + /// Reconstitutes a `RawVec` from a pointer, capacity, and allocator. /// /// # Safety -- 2.38.1