From 32aeedbaf6584eb71126cbe92cb42e93b65d69d3 Mon Sep 17 00:00:00 2001
From: Douglas Rumbaugh <dbr4@psu.edu>
Date: Mon, 30 Oct 2023 14:47:35 -0400
Subject: Epoch/DynamicExtension: added cv to epoch retirement check

Instead of busy waiting on the active job count, a condition variable is
now used to wait for all active jobs to finish before freeing an epoch's
resources.
---
 include/framework/scheduling/Epoch.h | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

(limited to 'include/framework/scheduling/Epoch.h')

diff --git a/include/framework/scheduling/Epoch.h b/include/framework/scheduling/Epoch.h
index fe63c86..87463bd 100644
--- a/include/framework/scheduling/Epoch.h
+++ b/include/framework/scheduling/Epoch.h
@@ -62,6 +62,11 @@ public:
 
     void end_job() {
         m_active_jobs.fetch_add(-1);
+
+        if (m_active_jobs.load() == 0) {
+            std::unique_lock<std::mutex> lk(m_cv_lock);
+            m_active_cv.notify_all();  
+        }
     }
 
     size_t get_active_job_num() {
@@ -115,10 +120,35 @@ public:
         return epoch;
     }
 
+    /*
+     * 
+     */
+    bool retirable() {
+        /* if epoch is currently active, then it cannot be retired */
+        if (m_active) {
+            return false;
+        }
+
+        /* 
+         * if the epoch has active jobs but is not itself active, 
+         * wait for them to finish and return true. If there are 
+         * not active jobs, return true immediately 
+         */
+        while (m_active_jobs > 0) {
+            std::unique_lock<std::mutex> lk(m_cv_lock);
+            m_active_cv.wait(lk);
+        }
+
+        return true;
+    }
+
 private:
     Structure *m_structure;
     std::vector<Buffer *> m_buffers;
 
+    std::condition_variable m_active_cv;
+    std::mutex m_cv_lock;
+
     /*
      * The number of currently active jobs
      * (queries/merges) operating on this
@@ -126,5 +156,6 @@ private:
      * when this number is 0.
      */
     std::atomic<size_t> m_active_jobs;
+    bool m_active;
 };
 }
-- 
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