Merge pull request #1 from dbrumbaugh/new-buffer

Initial Concurrency Implementation

1 files changed, 129 insertions, 0 deletions

diff --git a/include/framework/scheduling/FIFOScheduler.h b/include/framework/scheduling/FIFOScheduler.h
new file mode 100644
index 0000000..3ed4f49
--- /dev/null
+++ b/include/framework/scheduling/FIFOScheduler.h
@@ -0,0 +1,129 @@
+/*
+ * include/framework/scheduling/FIFOScheduler.h
+ *
+ * Copyright (C) 2023 Douglas B. Rumbaugh <drumbaugh@psu.edu> 
+ *
+ * Distributed under the Modified BSD License.
+ *
+ * This scheduler runs just concurrently, using a standard FIFO queue to
+ * determine which jobs to run next. If more jobs are scheduled than there
+ * are available threads, the excess will stall until a thread becomes
+ * available and then run in the order they were received by the scheduler.
+ *
+ * TODO: We need to set up a custom threadpool based on jthreads to support
+ * thread preemption for a later phase of this project. That will allow us
+ * to avoid blocking epoch transitions on long-running queries, or to pause
+ * reconstructions on demand.
+ */
+#pragma once
+
+#include <thread>
+#include <condition_variable>
+#include <chrono>
+#include "framework/scheduling/Task.h"
+#include "framework/scheduling/statistics.h"
+
+#include "ctpl/ctpl.h"
+#include "psu-ds/LockedPriorityQueue.h"
+
+namespace de {
+
+using namespace std::literals::chrono_literals;
+
+
+class FIFOScheduler {
+private:
+    static const size_t DEFAULT_MAX_THREADS = 8;
+
+public:
+    FIFOScheduler(size_t memory_budget, size_t thread_cnt)
+      : m_memory_budget((memory_budget) ? memory_budget : UINT64_MAX)
+      , m_thrd_cnt((thread_cnt) ? thread_cnt: DEFAULT_MAX_THREADS)
+      , m_used_memory(0)
+      , m_used_thrds(0)
+      , m_shutdown(false)
+    {
+        m_sched_thrd = std::thread(&FIFOScheduler::run, this);
+        m_sched_wakeup_thrd = std::thread(&FIFOScheduler::periodic_wakeup, this);
+        m_thrd_pool.resize(m_thrd_cnt);
+    }
+
+    ~FIFOScheduler() {
+        if (!m_shutdown.load()) {
+            shutdown();
+        }
+
+        m_sched_thrd.join();
+        m_sched_wakeup_thrd.join();
+    }
+
+    void schedule_job(std::function<void(void*)> job, size_t size, void *args, size_t type=0) {
+        std::unique_lock<std::mutex> lk(m_cv_lock);
+        size_t ts = m_counter.fetch_add(1);
+
+        m_stats.job_queued(ts, type, size);
+        m_task_queue.push(Task(size, ts, job, args, type, &m_stats));
+
+        m_cv.notify_all();
+    }
+
+    void shutdown() {
+        m_shutdown.store(true);
+        m_thrd_pool.stop(true);
+        m_cv.notify_all();
+    }
+
+    void print_statistics() {
+        m_stats.print_statistics();
+    }
+
+private:
+    psudb::LockedPriorityQueue<Task> m_task_queue;
+
+    size_t m_memory_budget;
+    size_t m_thrd_cnt;
+
+    std::atomic<bool> m_shutdown; 
+
+    std::atomic<size_t> m_counter;
+    std::mutex m_cv_lock;
+    std::condition_variable m_cv;
+
+    std::thread m_sched_thrd;
+    std::thread m_sched_wakeup_thrd;
+    ctpl::thread_pool m_thrd_pool;
+
+    std::atomic<size_t> m_used_thrds;
+    std::atomic<size_t> m_used_memory;
+
+    SchedulerStatistics m_stats;
+
+    void periodic_wakeup() {
+        do {
+            std::this_thread::sleep_for(10us);
+            m_cv.notify_all();
+        } while (!m_shutdown.load());
+    }
+
+    void schedule_next() {
+        assert(m_task_queue.size() > 0);
+        auto t = m_task_queue.pop();
+        m_stats.job_scheduled(t.m_timestamp);
+
+        m_thrd_pool.push(t);
+    }
+
+    void run() {
+        do {
+            std::unique_lock<std::mutex> cv_lock(m_cv_lock);
+            m_cv.wait(cv_lock);
+
+            while (m_task_queue.size() > 0 && m_thrd_pool.n_idle() > 0) {
+                schedule_next();
+            }
+        } while(!m_shutdown.load());
+    }
+
+};
+
+}