From patchwork Wed Jun 5 19:41:20 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Dufresne X-Patchwork-Id: 20213 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id 1F198BDE6B for ; Wed, 5 Jun 2024 19:41:32 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id CEE2165445; Wed, 5 Jun 2024 21:41:30 +0200 (CEST) Received: from madrid.collaboradmins.com (madrid.collaboradmins.com [IPv6:2a00:1098:ed:100::25]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 0CC3E634CD for ; Wed, 5 Jun 2024 21:41:29 +0200 (CEST) Received: from nicolas-tpx395.lan (cola.collaboradmins.com [195.201.22.229]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: nicolas) by madrid.collaboradmins.com (Postfix) with ESMTPSA id 3E43337821B7; Wed, 5 Jun 2024 19:41:28 +0000 (UTC) From: Nicolas Dufresne To: libcamera-devel@lists.libcamera.org Cc: Nicolas Dufresne Subject: [PATCH v1] gstreamer: pool: Replace GstAtomicQueue with deque and mutex Date: Wed, 5 Jun 2024 15:41:20 -0400 Message-ID: <20240605194120.152960-1-nicolas@ndufresne.ca> X-Mailer: git-send-email 2.45.1 MIME-Version: 1.0 X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" From: Nicolas Dufresne The GstAtomicQueue only supports 2 threads, one pushing, and one popping. We pop and push on error cases and we may have multiple threads downstream returning buffer (using tee), which breaks this assumption. On top of which, the release function, that notify when the queue goes from empty to not-empty rely on a racy empty check. The downstream thread that does this check if effectively concurrent with our thread calling acquire(). Fix this by replacing the GstAtomicQueue with a std::deque, and protect access to that using the object lock. Bug: https://bugs.libcamera.org/show_bug.cgi?id=201 Signed-off-by: Nicolas Dufresne Reviewed-by: Kieran Bingham Acked-by: Jacopo Mondi --- src/gstreamer/gstlibcamerapool.cpp | 40 +++++++++++++++++++++++------- 1 file changed, 31 insertions(+), 9 deletions(-) diff --git a/src/gstreamer/gstlibcamerapool.cpp b/src/gstreamer/gstlibcamerapool.cpp index 9661c67a..0b1a5689 100644 --- a/src/gstreamer/gstlibcamerapool.cpp +++ b/src/gstreamer/gstlibcamerapool.cpp @@ -8,6 +8,7 @@ #include "gstlibcamerapool.h" +#include #include #include "gstlibcamera-utils.h" @@ -24,24 +25,41 @@ static guint signals[N_SIGNALS]; struct _GstLibcameraPool { GstBufferPool parent; - GstAtomicQueue *queue; + std::deque *queue; GstLibcameraAllocator *allocator; Stream *stream; }; G_DEFINE_TYPE(GstLibcameraPool, gst_libcamera_pool, GST_TYPE_BUFFER_POOL) +static GstBuffer * +gst_libcamera_pool_pop_buffer(GstLibcameraPool *self) +{ + GLibLocker lock(GST_OBJECT(self)); + GstBuffer *buf; + + if (self->queue->empty()) + return nullptr; + + buf = self->queue->front(); + self->queue->pop_front(); + + return buf; +} + static GstFlowReturn gst_libcamera_pool_acquire_buffer(GstBufferPool *pool, GstBuffer **buffer, [[maybe_unused]] GstBufferPoolAcquireParams *params) { GstLibcameraPool *self = GST_LIBCAMERA_POOL(pool); - GstBuffer *buf = GST_BUFFER(gst_atomic_queue_pop(self->queue)); + GstBuffer *buf = gst_libcamera_pool_pop_buffer(self); + if (!buf) return GST_FLOW_ERROR; if (!gst_libcamera_allocator_prepare_buffer(self->allocator, self->stream, buf)) { - gst_atomic_queue_push(self->queue, buf); + GLibLocker lock(GST_OBJECT(self)); + self->queue->push_back(buf); return GST_FLOW_ERROR; } @@ -64,9 +82,13 @@ static void gst_libcamera_pool_release_buffer(GstBufferPool *pool, GstBuffer *buffer) { GstLibcameraPool *self = GST_LIBCAMERA_POOL(pool); - bool do_notify = gst_atomic_queue_length(self->queue) == 0; + bool do_notify; - gst_atomic_queue_push(self->queue, buffer); + { + GLibLocker lock(GST_OBJECT(self)); + do_notify = self->queue->empty(); + self->queue->push_back(buffer); + } if (do_notify) g_signal_emit(self, signals[SIGNAL_BUFFER_NOTIFY], 0); @@ -75,7 +97,7 @@ gst_libcamera_pool_release_buffer(GstBufferPool *pool, GstBuffer *buffer) static void gst_libcamera_pool_init(GstLibcameraPool *self) { - self->queue = gst_atomic_queue_new(4); + self->queue = new std::deque(); } static void @@ -84,10 +106,10 @@ gst_libcamera_pool_finalize(GObject *object) GstLibcameraPool *self = GST_LIBCAMERA_POOL(object); GstBuffer *buf; - while ((buf = GST_BUFFER(gst_atomic_queue_pop(self->queue)))) + while ((buf = gst_libcamera_pool_pop_buffer(self))) gst_buffer_unref(buf); - gst_atomic_queue_unref(self->queue); + delete self->queue; g_object_unref(self->allocator); G_OBJECT_CLASS(gst_libcamera_pool_parent_class)->finalize(object); @@ -122,7 +144,7 @@ gst_libcamera_pool_new(GstLibcameraAllocator *allocator, Stream *stream) gsize pool_size = gst_libcamera_allocator_get_pool_size(allocator, stream); for (gsize i = 0; i < pool_size; i++) { GstBuffer *buffer = gst_buffer_new(); - gst_atomic_queue_push(pool->queue, buffer); + pool->queue->push_back(buffer); } return pool;