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 X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B79D1C43331 for ; Fri, 6 Sep 2019 09:46:19 +0000 (UTC) Received: from dpdk.org (dpdk.org [92.243.14.124]) by mail.kernel.org (Postfix) with ESMTP id 7E829206A1 for ; Fri, 6 Sep 2019 09:46:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E829206A1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=dev-bounces@dpdk.org Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 90C6E1F2AD; Fri, 6 Sep 2019 11:46:14 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id 9179B1F2AD for ; Fri, 6 Sep 2019 11:46:12 +0200 (CEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1FC441570; Fri, 6 Sep 2019 02:46:12 -0700 (PDT) Received: from net-arm-c2400-02.shanghai.arm.com (net-arm-c2400-02.shanghai.arm.com [10.169.40.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A67CA3F59C; Fri, 6 Sep 2019 02:46:09 -0700 (PDT) From: Ruifeng Wang To: bruce.richardson@intel.com, vladimir.medvedkin@intel.com, olivier.matz@6wind.com Cc: dev@dpdk.org, stephen@networkplumber.org, konstantin.ananyev@intel.com, gavin.hu@arm.com, honnappa.nagarahalli@arm.com, dharmik.thakkar@arm.com, nd@arm.com, Ruifeng Wang Date: Fri, 6 Sep 2019 17:45:30 +0800 Message-Id: <20190906094534.36060-3-ruifeng.wang@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190906094534.36060-1-ruifeng.wang@arm.com> References: <20190822063457.41596-1-ruifeng.wang@arm.com> <20190906094534.36060-1-ruifeng.wang@arm.com> Subject: [dpdk-dev] [PATCH v2 2/6] lib/ring: add peek API X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" The peek API allows fetching the next available object in the ring without dequeuing it. This helps in scenarios where dequeuing of objects depend on their value. Signed-off-by: Dharmik Thakkar Signed-off-by: Ruifeng Wang Reviewed-by: Honnappa Nagarahalli Reviewed-by: Gavin Hu --- lib/librte_ring/rte_ring.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h index 2a9f768a1..d3d0d5e18 100644 --- a/lib/librte_ring/rte_ring.h +++ b/lib/librte_ring/rte_ring.h @@ -953,6 +953,36 @@ rte_ring_dequeue_burst(struct rte_ring *r, void **obj_table, r->cons.single, available); } +/** + * Peek one object from a ring. + * + * The peek API allows fetching the next available object in the ring + * without dequeuing it. This API is not multi-thread safe with respect + * to other consumer threads. + * + * @param r + * A pointer to the ring structure. + * @param obj_p + * A pointer to a void * pointer (object) that will be filled. + * @return + * - 0: Success, object available + * - -ENOENT: Not enough entries in the ring. + */ +__rte_experimental +static __rte_always_inline int +rte_ring_peek(struct rte_ring *r, void **obj_p) +{ + uint32_t prod_tail = r->prod.tail; + uint32_t cons_head = r->cons.head; + uint32_t count = (prod_tail - cons_head) & r->mask; + unsigned int n = 1; + if (count) { + DEQUEUE_PTRS(r, &r[1], cons_head, obj_p, n, void *); + return 0; + } + return -ENOENT; +} + #ifdef __cplusplus } #endif -- 2.17.1