From f0d3437f2e1fc9612e5a926d048a1ae3cd1e7a75 Mon Sep 17 00:00:00 2001
From: KunoiSayami <i@leanhe.dev>
Date: Tue, 23 May 2023 02:28:40 +0800
Subject: feat: Add read_helper.h

Signed-off-by: KunoiSayami <i@leanhe.dev>
---
 read_helper.h | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 read_helper.h

diff --git a/read_helper.h b/read_helper.h
new file mode 100644
index 0000000..311ebbb
--- /dev/null
+++ b/read_helper.h
@@ -0,0 +1,76 @@
+
+#ifndef LOCKFREE_READ_HELPER_H
+#define LOCKFREE_READ_HELPER_H
+
+#include <cassert>
+#include <cstdio>
+#include <random>
+#include <vector>
+#ifndef P_EFF
+#ifndef NDEBUG
+#define P_ERR(...) fprintf(stderr, __VA_ARGS__)
+#else
+#define P_ERR(...)
+#endif
+#endif
+
+class ReadHelper {
+  unsigned long long max_value = 0, min_value = 0x7fffffffff;
+
+  char const *filename;
+
+public:
+  ReadHelper(char const *filename) : filename(filename) {}
+  unsigned long long maxValue() const { return max_value; }
+  unsigned long long minValue() const { return min_value; }
+
+  std::vector<unsigned long long> population_vector;
+  inline void store_into_vector(unsigned long long value) {
+    if (max_value < value) {
+      max_value = value;
+    }
+    if (min_value > value) {
+      min_value = value;
+    }
+    population_vector.push_back(value);
+  }
+
+  static unsigned long randomRow(unsigned long max_value_) {
+    std::random_device randomDevice;
+    std::mt19937 mt19937(randomDevice());
+    std::uniform_int_distribution<std::mt19937::result_type> dst(0, max_value_);
+    return dst(mt19937);
+  }
+
+  void readFile(long sample_length, unsigned long &total_row,
+                unsigned long max_number) {
+    auto read_number = 0UL;
+    FILE *file = fopen(filename, "r");
+    assert(file);
+    P_ERR("Reading sample");
+    for (long long i;
+         read_number < max_number && fscanf(file, "%lld ", &i) != EOF;
+         store_into_vector(i))
+      read_number++;
+
+    if (total_row > 0) {
+      P_ERR("\rReading skip");
+      read_number = randomRow(total_row - sample_length - max_number - 256);
+      total_row = read_number;
+      // fprintf(stderr, "Skip %lu\n", read_number);
+      for (long long i; read_number > 0 && fscanf(file, "%lld ", &i) != EOF;)
+        read_number--;
+    }
+
+    P_ERR("\rReading population");
+    read_number = 0;
+
+    auto remain = sample_length + 256;
+    for (long long i; read_number < remain && fscanf(file, "%lld ", &i) != EOF;
+         store_into_vector(i))
+      read_number++;
+    fclose(file);
+    P_ERR("\r");
+  }
+};
+#endif
\ No newline at end of file
-- 
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