From c370cdc123989308f0cf3497aa9fe120c4d9498d Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Mon, 22 Apr 2019 16:10:01 -0700
Subject: [PATCH] ircd::db: Lock writes after memtable sealed until flush to
 prevent rocksdb pthread use.

---
 ircd/db.cc | 59 +++++++++++++++++++++++++++++-------------------------
 1 file changed, 32 insertions(+), 27 deletions(-)

diff --git a/ircd/db.cc b/ircd/db.cc
index 28f47da1f..b9aabefb0 100644
--- a/ircd/db.cc
+++ b/ircd/db.cc
@@ -2630,26 +2630,20 @@ noexcept
 //
 
 void
-ircd::db::database::events::OnFlushCompleted(rocksdb::DB *const db,
-                                             const rocksdb::FlushJobInfo &info)
+ircd::db::database::events::OnMemTableSealed(const rocksdb::MemTableInfo &info)
 noexcept
 {
-	log::info
+	log::debug
 	{
-		log, "'%s': job:%d ctx:%lu flush ended writes[slow:%d stop:%d] seq[%zu -> %zu] %s '%s' `%s'",
+		log, "'%s': memory table sealed '%s' entries:%lu deletes:%lu",
 		d->name,
-		info.job_id,
-		info.thread_id,
-		info.triggered_writes_slowdown,
-		info.triggered_writes_stop,
-		info.smallest_seqno,
-		info.largest_seqno,
-		reflect(info.flush_reason),
 		info.cf_name,
-		info.file_path,
+		info.num_entries,
+		info.num_deletes
 	};
 
-	assert(info.thread_id == ctx::id(*ctx::current));
+	const ctx::uninterruptible::nothrow ui;
+	write_mutex.lock();
 }
 
 void
@@ -2657,6 +2651,8 @@ ircd::db::database::events::OnFlushBegin(rocksdb::DB *const db,
                                          const rocksdb::FlushJobInfo &info)
 noexcept
 {
+	assert(info.thread_id == ctx::id(*ctx::current));
+
 	log::info
 	{
 		log, "'%s': job:%d ctx:%lu flush start writes[slow:%d stop:%d] seq[%zu -> %zu] %s '%s'",
@@ -2671,7 +2667,30 @@ noexcept
 		info.cf_name,
 	};
 
+	const ctx::uninterruptible::nothrow ui;
+	write_mutex.unlock();
+}
+
+void
+ircd::db::database::events::OnFlushCompleted(rocksdb::DB *const db,
+                                             const rocksdb::FlushJobInfo &info)
+noexcept
+{
 	assert(info.thread_id == ctx::id(*ctx::current));
+	log::info
+	{
+		log, "'%s': job:%d ctx:%lu flush ended writes[slow:%d stop:%d] seq[%zu -> %zu] %s '%s' `%s'",
+		d->name,
+		info.job_id,
+		info.thread_id,
+		info.triggered_writes_slowdown,
+		info.triggered_writes_stop,
+		info.smallest_seqno,
+		info.largest_seqno,
+		reflect(info.flush_reason),
+		info.cf_name,
+		info.file_path,
+	};
 }
 
 void
@@ -2818,20 +2837,6 @@ noexcept
 	};
 }
 
-void
-ircd::db::database::events::OnMemTableSealed(const rocksdb::MemTableInfo &info)
-noexcept
-{
-	log::debug
-	{
-		log, "'%s': memory table sealed '%s' entries:%lu deletes:%lu",
-		d->name,
-		info.cf_name,
-		info.num_entries,
-		info.num_deletes
-	};
-}
-
 void
 ircd::db::database::events::OnColumnFamilyHandleDeletionStarted(rocksdb::ColumnFamilyHandle *const h)
 noexcept