From 4ed95b7020bc57eec9685009e67ccd83af5d41e9 Mon Sep 17 00:00:00 2001
From: Calle Wilund <calle@cloudius-systems.com>
Date: Mon, 7 Sep 2015 15:29:05 +0200
Subject: [PATCH] Commitlog: Add sync_all_segments()

For #293 - allows explicit flush to disk (not close!) of all active segments
---
 db/commitlog/commitlog.cc | 18 ++++++++++++++----
 db/commitlog/commitlog.hh |  8 ++++++++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/db/commitlog/commitlog.cc b/db/commitlog/commitlog.cc
index 1abe4cf3bb..32bd68946f 100644
--- a/db/commitlog/commitlog.cc
+++ b/db/commitlog/commitlog.cc
@@ -184,6 +184,7 @@ public:
     future<sseg_ptr> new_segment();
     future<sseg_ptr> active_segment();
     future<> clear();
+    future<> sync_all_segments();
 
     scollectd::registrations create_counters();
 
@@ -824,17 +825,22 @@ void db::commitlog::segment_manager::discard_unused_segments() {
     }
 }
 
+future<> db::commitlog::segment_manager::sync_all_segments() {
+    return parallel_for_each(_segments, [this](sseg_ptr s) {
+        return s->sync().then([](sseg_ptr) {});
+    });
+}
+
 /*
  * Sync all segments, then clear them out. To ensure all ops are done.
  * (Assumes you have barriered adding ops!)
+ * Only use from tests.
  */
 future<> db::commitlog::segment_manager::clear() {
     logger.debug("Clearing all segments");
     flush_segments(true);
-    return do_until([this]() {return _segments.empty();}, [this]() {
-        auto s = _segments.front();
-        _segments.erase(_segments.begin());
-        return s->sync().then([](sseg_ptr) {});
+    return sync_all_segments().then([this] {
+       _segments.clear();
     });
 }
 /**
@@ -964,6 +970,10 @@ void db::commitlog::discard_completed_segments(const cf_id_type& id,
     _segment_manager->discard_completed_segments(id, pos);
 }
 
+future<> db::commitlog::sync_all_segments() {
+    return _segment_manager->sync_all_segments();
+}
+
 size_t db::commitlog::max_record_size() const {
     return _segment_manager->max_mutation_size - segment::entry_overhead_size;
 }
diff --git a/db/commitlog/commitlog.hh b/db/commitlog/commitlog.hh
index 1fad3811e6..ed3350e29f 100644
--- a/db/commitlog/commitlog.hh
+++ b/db/commitlog/commitlog.hh
@@ -222,6 +222,14 @@ public:
 
     const config& active_config() const;
 
+    /**
+     * Issues disk sync on all (allocating) segments. I.e. ensures that
+     * all data written up until this call is indeed on disk.
+     * _However_, if you issue new "add" ops while this is executing,
+     * those can/will be missed.
+     */
+    future<> sync_all_segments();
+
     future<std::vector<descriptor>> list_existing_descriptors() const;
     future<std::vector<descriptor>> list_existing_descriptors(const sstring& dir) const;