From 8b93821b9e87103a761f9bd6eea010843e6f4700 Mon Sep 17 00:00:00 2001
From: ZhuangYumin <zhuangyumin@sjtu.edu.cn>
Date: Sun, 3 Dec 2023 16:36:04 +0000
Subject: [PATCH] =?UTF-8?q?docs:=20=E4=BF=AE=E5=A4=8D=E4=BA=86drivearray?=
 =?UTF-8?q?=E5=8D=A0=E7=94=A8=E7=89=A9=E7=90=86=E5=86=85=E5=AD=98=E8=BF=87?=
 =?UTF-8?q?=E9=AB=98=E7=9A=84=E9=97=AE=E9=A2=98?=
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---
 backend/include/drivearray.hpp | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/backend/include/drivearray.hpp b/backend/include/drivearray.hpp
index 87fbd57..b504ee9 100644
--- a/backend/include/drivearray.hpp
+++ b/backend/include/drivearray.hpp
@@ -26,6 +26,8 @@ class DriveArray {
       ((info_len + 2) * sizeof(int) + kPageSize - 1) / kPageSize * kPageSize;
   std::stack<int> free_mem;
   int total_mem = 0;
+  const int kRefreshThreshold = 100;
+  unsigned int forced_refresh = 0;
   std::mutex mtx;
   void reallocate(bool include_resync = false) {
     size_t length_needed =
@@ -41,6 +43,11 @@ class DriveArray {
     virtual_mem = mmap(nullptr, file_length, PROT_READ | PROT_WRITE, MAP_SHARED,
                        file_descriptor, 0);
   }
+  void ForceRefresh() {
+    munmap(virtual_mem, file_length);
+    virtual_mem = mmap(nullptr, file_length, PROT_READ | PROT_WRITE, MAP_SHARED,
+                       file_descriptor, 0);
+  }
 
  public:
   DriveArray() = default;
@@ -86,6 +93,8 @@ class DriveArray {
     for (int i = 0; i < free_mem_cnt; i++) {
       free_mem.push(*(p++));
     }
+    madvise(virtual_mem + stk_data_begin, free_mem_cnt * sizeof(int),
+            MADV_FREE);
   }
 
   void initialise(std::string FN = "") {
@@ -109,11 +118,19 @@ class DriveArray {
   void get_info(int &tmp, int n) {
     if (n > info_len) return;
     tmp = *((int *)(virtual_mem) + n - 1);
+    if (++forced_refresh >= kRefreshThreshold) {
+      forced_refresh = 0;
+      ForceRefresh();
+    }
   }
 
   void write_info(int tmp, int n) {
     if (n > info_len) return;
     *((int *)(virtual_mem) + n - 1) = tmp;
+    if (++forced_refresh >= kRefreshThreshold) {
+      forced_refresh = 0;
+      ForceRefresh();
+    }
   }
 
   int write(T &t) {
@@ -131,14 +148,22 @@ class DriveArray {
     reallocate();
     void *data_begin = virtual_mem + raw_data_begin + sizeofT * (index - 1);
     std::memmove(data_begin, &t, sizeofT);
-    madvise(data_begin, sizeofT, MADV_DONTNEED);
+    madvise(data_begin, sizeofT, MADV_FREE);
+    if (++forced_refresh >= kRefreshThreshold) {
+      forced_refresh = 0;
+      ForceRefresh();
+    }
   }
 
   void read(T &t, const int index) {
     reallocate();
     void *data_begin = virtual_mem + raw_data_begin + sizeofT * (index - 1);
     std::memmove(&t, data_begin, sizeofT);
-    madvise(data_begin, sizeofT, MADV_DONTNEED);
+    madvise(data_begin, sizeofT, MADV_FREE);
+    if (++forced_refresh >= kRefreshThreshold) {
+      forced_refresh = 0;
+      ForceRefresh();
+    }
   }
 
   void Delete(int index) { free_mem.push(index); }