Add an optional compiled disk activities monitor to reduce the CPU usage (#38)

README.md

@@ -211,6 +211,15 @@ Please see `scripts/ugreen-leds.conf` for an example.
   systemctl enable ugreen-diskiomon
   ```
 
+- (_Optional_) To reduce the CPU usage of blinking LEDs when disks are active, you can enter the `scripts` directory and do the following things:
+  ```bash
+  # compile the disk activities monitor
+  g++ -std=c++17 -O2 blink-disk.cpp -o ugreen-blink-disk
+
+  # copy the binary file (the path can be changed, see BLINK_MON_PATH in ugreen-leds.conf)
+  cp ugreen-blink-disk /usr/bin
+  ```
+
 ## Disk Mapping
 
 To make the disk LEDs useful, we should map the disk LEDs to correct disk slots. First of all, we should highlight that using `/dev/sdX` is never a smart idea, as it may change at every boot.  

scripts/blink-disk.cpp

@@ -0,0 +1,73 @@
+#include <fstream>
+#include <thread>
+#include <vector>
+#include <iostream>
+#include <string>
+#include <chrono>
+
+int main(int argc, char *argv[]) {
+    if (argc < 4 || argc % 2 != 0) {
+        std::cerr << "Usage: " << argv[0] << " <sleep time (in second)>"
+            << " <block device 1> <led device 1> <block device 2> <led device 2>...\n";
+        return 1;
+    }
+
+    int num_devices = (argc - 2) / 2;
+    int sleep_time_ms = int(std::stod(argv[1]) * 1000);
+
+    std::vector<std::string> block_device_stat_paths;
+    std::vector<std::string> led_device_shot_paths;
+
+    for (int i = 0; i < num_devices; i++) {
+        std::string block_device = argv[2 + 2 * i];
+        std::string led_device = argv[3 + 2 * i];
+
+        block_device_stat_paths.push_back(
+                "/sys/block/" + block_device + "/stat");
+        led_device_shot_paths.push_back(
+                "/sys/class/leds/" + led_device + "/shot");
+    }
+
+    std::vector<bool> device_status(num_devices, true);
+    std::vector<std::string> old_lines(num_devices);
+
+    while (true) {
+        for (int i = 0; i < num_devices; i++) {
+
+            if (!device_status[i]) {
+                continue;
+            }
+
+            std::ifstream stat_file(block_device_stat_paths[i]);
+
+            if (!stat_file.is_open()) {
+                std::cerr << "Failed to open " << block_device_stat_paths[i] << "\n";
+                device_status[i] = false;
+                continue;
+            }
+
+            std::string line;
+            std::getline(stat_file, line);
+            stat_file.close();
+
+            if (line != old_lines[i]) {
+
+                std::ofstream led_file(led_device_shot_paths[i]);
+                if (!led_file.is_open()) {
+                    std::cerr << "Failed to open " << led_device_shot_paths[i] << "\n";
+                    device_status[i] = false;
+                    continue;
+                }
+
+                led_file << "1";
+                led_file.close();
+
+                old_lines[i] = std::move(line);
+            }
+        }
+
+        std::this_thread::sleep_for(std::chrono::milliseconds(sleep_time_ms));
+    }
+
+    return 0;
+}

scripts/ugreen-diskiomon

@@ -228,7 +228,7 @@ if [ "$CHECK_ZPOOL" = true ]; then
 
                     if [[ "${zpool_dev_state}" != "ONLINE" ]]; then
                         echo "$COLOR_ZPOOL_FAIL" > /sys/class/leds/$led/color
-                        echo Disk failure detected on /dev/$dev at $(date +%Y-%m-%d' '%H:%M:%S)
+                        echo Disk failure detected on /dev/$zpool_dev_name at $(date +%Y-%m-%d' '%H:%M:%S)
                     fi
 
                     # ==== To recover from an error, you should restart the script ====
@@ -316,8 +316,21 @@ fi
 disk_online_check_pid=$!
 
 # monitor disk activities
-declare -A diskio_data_rw
-while true; do
+BLINK_MON_PATH=${BLINK_MON_PATH:=/usr/bin/ugreen-blink-disk}
+if [ -f "${BLINK_MON_PATH}" ]; then
+
+    diskiomon_parameters() {
+        echo ${LED_REFRESH_INTERVAL}
+        for led in "${!devices[@]}"; do
+            echo ${devices[$led]} $led
+        done
+    }
+
+    ${BLINK_MON_PATH} $(diskiomon_parameters)
+
+else 
+    declare -A diskio_data_rw
+    while true; do
         for led in "${!devices[@]}"; do
 
             # if $dev does not exist, diskio_new_rw="", which will be safe
@@ -332,4 +345,5 @@ while true; do
 
         sleep ${LED_REFRESH_INTERVAL}s
 
-done
+    done
+fi

scripts/ugreen-leds.conf

@@ -20,6 +20,9 @@
 #           and fill the DISK_SERIAL array below (see the comments therein).
 MAPPING_METHOD=ata
 
+# The path of the compiled diskio monitor (OPTIONAL) 
+BLINK_MON_PATH=/usr/bin/ugreen-blink-disk
+
 # The serial numbers of disks (used only when MAPPING_METHOD=serial)
 # You need to record them before inserting to your NAS, and the corresponding disk slots.
 # If you have 4 disks, with serial numbers: SN1 SN2 SN3 SN4,