From 2aacdcd95feb16bdfdaa2c47662c2dca561bf81e Mon Sep 17 00:00:00 2001
From: Zygo Blaxell <bees@furryterror.org>
Date: Sun, 28 Jan 2018 23:08:50 -0500
Subject: [PATCH] time: add update_monotonic to RateEstimator

update_monotonic does not reset the counter if a new count is smaller than
earlier counts.  Useful when consuming an unsorted stream of eveent counts.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
---
 include/crucible/time.h |  3 +++
 lib/time.cc             | 11 +++++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/crucible/time.h b/include/crucible/time.h
index c788869..7261013 100644
--- a/include/crucible/time.h
+++ b/include/crucible/time.h
@@ -81,6 +81,9 @@ namespace crucible {
 		// Write count
 		void update(uint64_t new_count);
 
+		// Ignore counts that go backwards
+		void update_monotonic(uint64_t new_count);
+
 		// Read count
 		uint64_t count() const;
 
diff --git a/lib/time.cc b/lib/time.cc
index e7b4721..77a99ad 100644
--- a/lib/time.cc
+++ b/lib/time.cc
@@ -188,6 +188,17 @@ namespace crucible {
 		return update_unlocked(new_count);
 	}
 
+	void
+	RateEstimator::update_monotonic(uint64_t new_count)
+	{
+		unique_lock<mutex> lock(m_mutex);
+		if (m_last_count == numeric_limits<uint64_t>::max() || new_count > m_last_count) {
+			return update_unlocked(new_count);
+		} else {
+			return update_unlocked(m_last_count);
+		}
+	}
+
 	uint64_t
 	RateEstimator::count() const
 	{