[RFC PATCH 4/6] common/Throttle: FIFO throttler doesn't need to signal waiters when max changes

["Jim Schutt" <jaschut@xxxxxxxxxx>]

Only wait() and get() change the throttle max.

If there are no current waiters, the thread calling wait()/get()
doesn't need to signal itself.

If there are current waiters, the thread calling wait()/get() will
signal the oldest waiter in _wait() before sleeping, so the oldest
waiter always sees the new throttle limit immediately.

Signed-off-by: Jim Schutt <jaschut@xxxxxxxxxx>
---
 src/common/Throttle.h |    9 ++-------
 1 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/src/common/Throttle.h b/src/common/Throttle.h
index ca72060..2f74f4a 100644
--- a/src/common/Throttle.h
+++ b/src/common/Throttle.h
@@ -25,11 +25,6 @@ public:
   }
 
 private:
-  void _reset_max(int64_t m) {
-    if (m < max && !cond.empty())
-      cond.front()->SignalOne();
-    max = m;
-  }
   bool _should_wait(int64_t c) {
     return
       max &&
@@ -74,7 +69,7 @@ public:
       *sleep_seq = sseq;
     if (m) {
       assert(m > 0);
-      _reset_max(m);
+      max = m;
     }
     bool r = _wait(0);
     wseq++;
@@ -99,7 +94,7 @@ public:
       *sleep_seq = sseq;
     if (m) {
       assert(m > 0);
-      _reset_max(m);
+      max = m;
     }
     _wait(c);
     count += c;
-- 
1.7.1


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