From f70374f71fe4e715f6221d34aee268ed601b17b8 Mon Sep 17 00:00:00 2001
From: "Adam C. Emerson" <aemerson@redhat.com>
Date: Sat, 21 Nov 2020 19:34:07 -0500
Subject: [PATCH] rgw: Add LazyFIFO to keep from blasting an op-per-shard on
 startup

LazyFIFO opens the FIFO on first access.

Signed-off-by: Adam C. Emerson <aemerson@redhat.com>
(cherry picked from commit 1cc4a0a4e274700b4ae044db125a8cb3a64253a2)
Signed-off-by: Adam C. Emerson <aemerson@redhat.com>
---
 src/rgw/rgw_log_backing.h | 135 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 135 insertions(+)

diff --git a/src/rgw/rgw_log_backing.h b/src/rgw/rgw_log_backing.h
index ef2583c35b204..cd677764c5795 100644
--- a/src/rgw/rgw_log_backing.h
+++ b/src/rgw/rgw_log_backing.h
@@ -32,6 +32,8 @@
 namespace bc = boost::container;
 namespace bs = boost::system;
 
+#include "cls_fifo_legacy.h"
+
 /// Type of log backing, stored in the mark used in the quick check,
 /// and passed to checking functions.
 enum class log_type {
@@ -255,4 +257,137 @@ cursorgeno(std::optional<std::string_view> cursor) {
   }
 }
 
+class LazyFIFO {
+  librados::IoCtx& ioctx;
+  std::string oid;
+  std::mutex m;
+  std::unique_ptr<rgw::cls::fifo::FIFO> fifo;
+
+  int lazy_init(optional_yield y) {
+    std::unique_lock l(m);
+    if (fifo) return 0;
+    auto r = rgw::cls::fifo::FIFO::create(ioctx, oid, &fifo, y);
+    if (r) {
+      fifo.reset();
+    }
+    return r;
+  }
+
+public:
+
+  LazyFIFO(librados::IoCtx& ioctx, std::string oid)
+    : ioctx(ioctx), oid(std::move(oid)) {}
+
+  int read_meta(optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    return fifo->read_meta(y);
+  }
+
+  int meta(rados::cls::fifo::info& info, optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    info = fifo->meta();
+    return 0;
+  }
+
+  int get_part_layout_info(std::uint32_t& part_header_size,
+			   std::uint32_t& part_entry_overhead,
+			   optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    std::tie(part_header_size, part_entry_overhead)
+      = fifo->get_part_layout_info();
+    return 0;
+  }
+
+  int push(const ceph::buffer::list& bl,
+	   optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    return fifo->push(bl, y);
+  }
+
+  int push(ceph::buffer::list& bl,
+	   librados::AioCompletion* c,
+	   optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    fifo->push(bl, c);
+    return 0;
+  }
+
+  int push(const std::vector<ceph::buffer::list>& data_bufs,
+	   optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    return fifo->push(data_bufs, y);
+  }
+
+  int push(const std::vector<ceph::buffer::list>& data_bufs,
+	    librados::AioCompletion* c,
+	    optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    fifo->push(data_bufs, c);
+    return 0;
+  }
+
+  int list(int max_entries, std::optional<std::string_view> markstr,
+	   std::vector<rgw::cls::fifo::list_entry>* out,
+	   bool* more, optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    return fifo->list(max_entries, markstr, out, more, y);
+  }
+
+  int list(int max_entries, std::optional<std::string_view> markstr,
+	   std::vector<rgw::cls::fifo::list_entry>* out, bool* more,
+	   librados::AioCompletion* c, optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    fifo->list(max_entries, markstr, out, more, c);
+    return 0;
+  }
+
+  int trim(std::string_view markstr, bool exclusive, optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    return fifo->trim(markstr, exclusive, y);
+  }
+
+  int trim(std::string_view markstr, bool exclusive, librados::AioCompletion* c,
+	   optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    fifo->trim(markstr, exclusive, c);
+    return 0;
+  }
+
+  int get_part_info(int64_t part_num, rados::cls::fifo::part_header* header,
+		    optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    return fifo->get_part_info(part_num, header, y);
+  }
+
+  int get_part_info(int64_t part_num, rados::cls::fifo::part_header* header,
+		    librados::AioCompletion* c, optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    fifo->get_part_info(part_num, header, c);
+    return 0;
+  }
+
+  int get_head_info(fu2::unique_function<
+		      void(int r, rados::cls::fifo::part_header&&)>&& f,
+		    librados::AioCompletion* c,
+		    optional_yield y) {
+    auto r = lazy_init(y);
+    if (r < 0) return r;
+    fifo->get_head_info(std::move(f), c);
+    return 0;
+  }
+};
+
 #endif
-- 
2.39.5