From 5146ae275ee4faa3ed2acdee33cd04a9c6035d05 Mon Sep 17 00:00:00 2001
From: Daniel Langbein <daniel@systemli.org>
Date: Wed, 21 Jun 2023 19:16:25 +0200
Subject: [PATCH] feat: don't warn if value decreased

---
 src/de/p1st/monitor/logger.py             | 145 ++++++++++++++++------
 src/de/p1st/monitor/loggers/cpu.py        |  21 ++--
 src/de/p1st/monitor/loggers/drive.py      |  15 +--
 src/de/p1st/monitor/loggers/filesystem.py |  45 +++++--
 src/de/p1st/monitor/loggers/memory.py     |  17 +--
 src/de/p1st/monitor/loggers/network.py    |   6 +-
 src/de/p1st/monitor/loggers/swap.py       |  13 +-
 src/de/p1st/monitor/loggers/temp.py       |  13 +-
 src/de/p1st/monitor/main.py               |   4 +-
 src/de/p1st/monitor/string_conversion.py  |   2 +
 src/de/p1st/monitor/warn.py               |  50 ++++++--
 src/de/p1st/monitor/warn_data.py          |   8 ++
 12 files changed, 227 insertions(+), 112 deletions(-)
 create mode 100644 src/de/p1st/monitor/warn_data.py

diff --git a/src/de/p1st/monitor/logger.py b/src/de/p1st/monitor/logger.py
index 9bedf5f..892ad0c 100644
--- a/src/de/p1st/monitor/logger.py
+++ b/src/de/p1st/monitor/logger.py
@@ -1,10 +1,11 @@
 from pathlib import Path
 from abc import ABC, abstractmethod
 
-from de.p1st.monitor import csv_util
+from de.p1st.monitor import csv_util, datetime_util
 from de.p1st.monitor.cfg.logging_dir import logging_dir
 from de.p1st.monitor.string_conversion import to_string, from_string
 from de.p1st.monitor.warn import WarnMessage, WarnLevel
+from de.p1st.monitor.warn_data import WarnData
 
 
 # https://www.geeksforgeeks.org/abstract-classes-in-python/
@@ -15,7 +16,7 @@ class Logger(ABC):
                  warn_if_above: int | float = None,
                  critical_if_above: int | float = None,
                  ):
-        self.data: list[any] | None = None
+        self.data: list[any] = []
         # True if the data held by this object is already appended to the logfile.
         self.logged = False
 
@@ -29,7 +30,8 @@ class Logger(ABC):
                                 f' {critical_if_above}, {warn_if_above}')
         else:
             if warn_if_above is not None or critical_if_above is not None:
-                raise Exception('Either both, warn_if_above and critical_if_above, must be given, or both must be None.')
+                raise Exception(
+                    'Either both, warn_if_above and critical_if_above, must be given, or both must be None.')
         self.warn_if_above = warn_if_above
         self.critical_if_above = critical_if_above
 
@@ -49,41 +51,113 @@ class Logger(ABC):
 
     def check(self) -> WarnMessage:
         """
-        Checks the latest `self.warn_data_range` datasets for problems using `self.check_data()`.
+        Checks if `self.warn_threshold` or more of the latest `self.warn_data_range` datasets
+        contain values higher than `self.warn_if_above` in which case a warning (NORMAL or HIGH)
+        might be returned.
 
-        If at least `self.warn_threshold` problems are found,
-        then a WarnMessage with the highest reported WarnLevel is returned.
+        In details:
 
-        If at least one WarnLevel is above NORMAL,
-        then a WarnMessage is returned independent of the number of problems.
+        If the current value is above `self.critical_if_above`,
+        then a HIGH WarnMessage is returned.
+
+        If less than `self.warn_threshold` values are above `self.warn_if_above`,
+        then no warning is returned.
+
+        If the current value is lower than the previously logged one
+        and if during the previous check a warning was issued,
+        then no warning is returned.
+
+        Otherwise, a NORMAL WarnMessage is returned.
         """
-        datasets = self.get_datasets(self.warn_data_range)
-        warnings = [self.check_data(data) for data in datasets]
-        warnings = [warning for warning in warnings
-                    if not warning.level == WarnLevel.NONE]
+        datasets = self.get_datasets(self.warn_data_range + 1)
+        warn_datas = [self.get_warn_data(data) for data in datasets]
+        current_warn_data = warn_datas[-1]
 
-        if len(warnings) == 0:
+        # If current value is critical (or current warning is HIGH), directly return HIGH WarnMessage.
+        #
+        # -> As we don't want to send the same warning twice,
+        #    we check only if the current value is critical.
+        if isinstance(current_warn_data, WarnData):
+            if current_warn_data.value > self.critical_if_above:
+                return WarnMessage(WarnLevel.HIGH, datetime_util.now(), current_warn_data.message)
+        elif isinstance(current_warn_data, WarnMessage):
+            if current_warn_data.level > WarnLevel.NORMAL:
+                return current_warn_data
+        else:
+            raise ValueError()
+
+        current_warn_datas = warn_datas[-self.warn_data_range:]
+        curr_num_warnings, curr_highest_warning = self._get_num_warnings(current_warn_datas)
+
+        # Warning threshold not reached.
+        if curr_num_warnings < self.warn_threshold:
             return WarnMessage(WarnLevel.NONE)
-        # max() must not be called with an empty list.
-        highest_warn_level = max([warning.level for warning in warnings])
 
-        messages: list[str] = [warning.message for warning in warnings]
-        message = f'{len(warnings)} of the last {self.warn_data_range} datasets are above limits:\n\t' \
-                  + '\n\t'.join(messages)
+        previous_warn_datas = warn_datas[-self.warn_data_range - 1:-1]
+        prev_num_warnings, prev_highest_warning = self._get_num_warnings(previous_warn_datas)
 
-        if highest_warn_level > WarnLevel.NORMAL:
-            return WarnMessage(highest_warn_level, message)
-        if len(warnings) >= self.warn_threshold:
-            return WarnMessage(highest_warn_level, message)
-        return WarnMessage(WarnLevel.NONE)
+        # Don't send warning again if the current value decreased.
+        if prev_num_warnings >= self.warn_if_above:
+            previous_warn_data = warn_datas[-2]
+            if isinstance(current_warn_data, WarnData) \
+                    and isinstance(previous_warn_data, WarnData) \
+                    and current_warn_data.value <= previous_warn_data.value:
+                return WarnMessage(WarnLevel.NONE)
+
+        # Send warning.
+        warn_messages = self._get_warn_messages(current_warn_datas)
+        message = f'{curr_num_warnings} of the last {len(current_warn_datas)} datasets are above limits:\n\t' \
+                  + '\n\t'.join(warn_messages)
+        return WarnMessage(WarnLevel.NORMAL, datetime_util.now(), message)
+
+    def _get_num_warnings(self, warn_datas: list[WarnData | WarnMessage]) -> tuple[int, WarnLevel]:
+        """
+        @return: Number of warnings and the highest WarnLevel
+        """
+        num_warnings = 0
+        highest_warn_level = WarnLevel.NONE
+
+        for warn_data in warn_datas:
+            if isinstance(warn_data, WarnMessage):
+                highest_warn_level = max(highest_warn_level, warn_data.level)
+            elif isinstance(warn_data, WarnData):
+                if warn_data.value > self.critical_if_above:
+                    num_warnings += 1
+                    highest_warn_level = max(highest_warn_level, WarnLevel.HIGH)
+                elif warn_data.value > self.warn_if_above:
+                    num_warnings += 1
+                    highest_warn_level = max(highest_warn_level, WarnLevel.NORMAL)
+            else:
+                raise ValueError()
+
+        return num_warnings, highest_warn_level
+
+    def _get_warn_messages(self, warn_datas: list[WarnData | WarnMessage]) -> list[str]:
+        messages: list[str] = []
+
+        for warn_data in warn_datas:
+            if isinstance(warn_data, WarnMessage):
+                messages.append(warn_data.formatted_message())
+            elif isinstance(warn_data, WarnData):
+                if warn_data.value > self.critical_if_above:
+                    messages.append(
+                        WarnMessage(WarnLevel.HIGH, warn_data.date, warn_data.message).formatted_message())
+                elif warn_data.value > self.warn_if_above:
+                    messages.append(
+                        WarnMessage(WarnLevel.NORMAL, warn_data.date, warn_data.message).formatted_message())
+            else:
+                raise ValueError()
+
+        return messages
 
     @abstractmethod
-    def check_data(self, data: list[any]) -> WarnMessage:
+    def get_warn_data(self, data: list[any]) -> WarnData | WarnMessage:
         """
-        Check the given data for problems.
-        Return a WarnLevel indicating how serious the problems are.
+        Calculate warn value from given data and return as part of `WarnData` object.
 
-        If there are no problems, return `WarnLevel.NONE`.
+        If the value can't be calculated, directly return a `WarnMessage` object.
+
+        @return Warn value; Message for normal warning; Message for critical warning
         """
         raise ValueError('Subclasses must implement this')
 
@@ -105,6 +179,8 @@ class Logger(ABC):
     def get_datasets(self, num: int) -> list[list[any]]:
         """
         Returns the last `num` datasets (including the current dataset).
+
+        The first row is the oldest, and the latest row is the current dataset.
         """
         if not self.logged and self.has_data():
             # We will append the current data manually.
@@ -130,18 +206,15 @@ class Logger(ABC):
 
         return data
 
-    def log(self, skip_if_no_data: bool = False) -> None:
+    def log(self) -> None:
         """
         Appends the current data (e.g. temperature of a sensor)
         to a logfile.
 
-        :param skip_if_no_data: Can be used to do nothing if no data is available. If one is sure to have called update() previously, this can be set to True.
         :raise Exception: If method is called but no data is available. Please do call update() first to avoid this!
         """
         if self.logged:
             return
-        if skip_if_no_data and not self.has_data():
-            return
 
         csv_util.write(file=self.get_log_file(), rows=[self.get_data_as_row()], header=self.data_schema())
         self.logged = True
@@ -151,12 +224,10 @@ class Logger(ABC):
         self.logged = False
 
     @abstractmethod
-    def read_data(self) -> list[any] | None:
+    def read_data(self) -> list[any]:
         """
         Collects current data (e.g. temperature of a sensor).
 
-        Might return None if sensor is detached / not available.
-
         :raise LoggerReadEx:
         """
         raise ValueError('Subclasses must implement this')
@@ -199,7 +270,7 @@ class Logger(ABC):
         ]
 
     def has_data(self) -> bool:
-        return self.data is not None
+        return len(self.data) > 0
 
     def get_data(self) -> list[any]:
         """
@@ -210,7 +281,9 @@ class Logger(ABC):
         else:
             raise ValueError(f'Data has not yet been read. {self.__str__()}')
 
-    def set_data(self, data: list[any] | None):
+    def set_data(self, data: list[any]):
+        if len(data) < 1:
+            raise ValueError()
         self.data = data
 
     def data_type_strs(self, data_schema: list[str] = None) -> list[str]:
diff --git a/src/de/p1st/monitor/loggers/cpu.py b/src/de/p1st/monitor/loggers/cpu.py
index fc5ec71..88a3d7b 100644
--- a/src/de/p1st/monitor/loggers/cpu.py
+++ b/src/de/p1st/monitor/loggers/cpu.py
@@ -7,7 +7,7 @@ import psutil
 from de.p1st.monitor import datetime_util
 
 from de.p1st.monitor.logger import Logger
-from de.p1st.monitor.warn import WarnMessage, WarnLevel
+from de.p1st.monitor.warn_data import WarnData
 
 
 class CPULogger(Logger):
@@ -24,17 +24,12 @@ class CPULogger(Logger):
                          critical_if_above)
         self.warn_if_above = warn_if_above
 
-    def check_data(self, data: list[any]) -> WarnMessage:
+    def get_warn_data(self, data: list[any]) -> WarnData:
         load_avg = data[1]
         message = f'CPU load avg of last {self.get_load_timespan()} minutes is at {load_avg}'
+        return WarnData(data[0], load_avg, message)
 
-        if load_avg > self.critical_if_above:
-            return WarnMessage(WarnLevel.HIGH, message)
-        if load_avg > self.warn_if_above:
-            return WarnMessage(WarnLevel.NORMAL, message)
-        return WarnMessage(WarnLevel.NONE)
-
-    def read_data(self) -> list[any] | None:
+    def read_data(self) -> list[any]:
         return [
             datetime_util.now(),
             self.get_load(self.get_load_timespan())
@@ -50,14 +45,13 @@ class CPULogger(Logger):
         return self.get_log_dir() / f'cpu_{self.get_load_timespan()}min.csv'
 
     @abstractmethod
-    def get_load_timespan(self) ->  Literal[1, 5, 15]:
+    def get_load_timespan(self) -> Literal[1, 5, 15]:
         raise ValueError('Subclasses must implement this')
 
     #
     # HELPERS
     #
 
-
     @staticmethod
     def get_load(minutes: Literal[1, 5, 15]) -> float:
         """
@@ -79,12 +73,17 @@ class CPULogger(Logger):
         # This value has been tested to be correct on my AMD Ryzen 4800H CPU.
         return psutil.getloadavg()[idx] / psutil.cpu_count()
 
+
 class CPULogger1(CPULogger):
     def get_load_timespan(self) -> Literal[1, 5, 15]:
         return 1
+
+
 class CPULogger5(CPULogger):
     def get_load_timespan(self) -> Literal[1, 5, 15]:
         return 5
+
+
 class CPULogger15(CPULogger):
     def get_load_timespan(self) -> Literal[1, 5, 15]:
         return 15
diff --git a/src/de/p1st/monitor/loggers/drive.py b/src/de/p1st/monitor/loggers/drive.py
index 4627869..9ad24ea 100644
--- a/src/de/p1st/monitor/loggers/drive.py
+++ b/src/de/p1st/monitor/loggers/drive.py
@@ -6,11 +6,13 @@ from de.p1st.monitor import datetime_util
 from de.p1st.monitor.exec_capture import execute_capture
 from de.p1st.monitor.logger import Logger
 from de.p1st.monitor.logger_ex import LoggerArgEx, LoggerReadEx
-from de.p1st.monitor.warn import WarnLevel, WarnMessage
+from de.p1st.monitor.warn_data import WarnData
+
 
 class BlkidException(Exception):
     pass
 
+
 class DriveLogger(Logger):
     def __init__(self, uuid: str = None,
                  device: Path = None,
@@ -44,17 +46,12 @@ class DriveLogger(Logger):
 
         self.warn_if_above = warn_if_above
 
-    def check_data(self, data: list[any]) -> WarnMessage:
+    def get_warn_data(self, data: list[any]) -> WarnData:
         temp = data[1]
         message = f'Temperature of {self.uuid} ist at {temp}'
+        return WarnData(data[0], temp, message)
 
-        if temp > self.critical_if_above:
-            return WarnMessage(WarnLevel.HIGH, message)
-        if temp > self.warn_if_above:
-            return WarnMessage(WarnLevel.NORMAL, message)
-        return WarnMessage(WarnLevel.NONE)
-
-    def read_data(self)  -> list[any]:
+    def read_data(self) -> list[any]:
         return [
             datetime_util.now(),
             self.get_temp_from_device(self.device),
diff --git a/src/de/p1st/monitor/loggers/filesystem.py b/src/de/p1st/monitor/loggers/filesystem.py
index 28eed57..76a4263 100644
--- a/src/de/p1st/monitor/loggers/filesystem.py
+++ b/src/de/p1st/monitor/loggers/filesystem.py
@@ -1,12 +1,14 @@
+import math
 from pathlib import Path
 
 import psutil
-from de.p1st.monitor import datetime_util
+from de.p1st.monitor import datetime_util, csv_util
 from de.p1st.monitor.exec_capture import execute_capture
 
 from de.p1st.monitor.logger import Logger
 from de.p1st.monitor.logger_ex import LoggerArgEx, LoggerReadEx
 from de.p1st.monitor.warn import WarnLevel, WarnMessage
+from de.p1st.monitor.warn_data import WarnData
 
 
 class NotMounted(Exception):
@@ -81,22 +83,37 @@ class FilesystemLogger(Logger):
                 else:
                     raise LoggerReadEx(getattr(e, 'message', e))
 
-    def check_data(self, data: list[any]) -> WarnMessage:
-        if not self.mounted:
-            return WarnMessage(WarnLevel.NONE)
+    def export_data(self) -> Path:
+        data = self.get_all_datasets()
 
+        export_schema = self.data_schema()
+
+        # Filter rows where `Disk usage` is NAN.
+        export_data = [row for row in data
+                       if not math.isnan(row[1])]
+
+        export_file = self.get_log_file().parent.joinpath(self.get_log_file().name + '.exported.csv')
+        rows = [self.as_row(export_row, export_schema) for export_row in export_data]
+        csv_util.write(file=export_file, rows=rows, header=export_schema, recreate_file=True)
+        return export_file
+
+    def get_warn_data(self, data: list[any]) -> WarnData | WarnMessage:
         disk_usage = data[1]
+        if math.isnan(disk_usage):
+            if self.unmounted_ok:
+                return WarnMessage(WarnLevel.NONE)
+            else:
+                return WarnMessage(WarnLevel.HIGH, data[0], 'Disk is not mounted')
+
         message = f'Disk usage of {self.uuid} ist at {disk_usage}'
+        return WarnData(data[0], disk_usage, message)
 
-        if disk_usage > self.critical_if_above:
-            return WarnMessage(WarnLevel.HIGH, message)
-        if disk_usage > self.warn_if_above:
-            return WarnMessage(WarnLevel.NORMAL, message)
-        return WarnMessage(WarnLevel.NONE)
-
-    def read_data(self) -> list[any] | None:
+    def read_data(self) -> list[any]:
         if not self.mounted:
-            return None
+            return [
+                datetime_util.now(),
+                float('nan')
+            ]
 
         disk_usage: float = self.get_disk_usage(self.mountpoint)
         return [
@@ -105,6 +122,10 @@ class FilesystemLogger(Logger):
         ]
 
     def data_schema(self) -> list[str]:
+        """
+        If no disk usage value could be read (if a disk was unmounted),
+        NAN is stored as `Disk usage`.
+        """
         return ['datetime#Date', 'float#Disk usage']
 
     def get_log_file(self) -> Path:
diff --git a/src/de/p1st/monitor/loggers/memory.py b/src/de/p1st/monitor/loggers/memory.py
index 9135438..dfeb8cf 100644
--- a/src/de/p1st/monitor/loggers/memory.py
+++ b/src/de/p1st/monitor/loggers/memory.py
@@ -4,7 +4,7 @@ import psutil
 from de.p1st.monitor import datetime_util
 
 from de.p1st.monitor.logger import Logger
-from de.p1st.monitor.warn import WarnMessage, WarnLevel
+from de.p1st.monitor.warn_data import WarnData
 
 
 class MemoryLogger(Logger):
@@ -13,7 +13,6 @@ class MemoryLogger(Logger):
                  warn_threshold: int = 1,
                  warn_data_range: int = 1,
                  ):
-
         # The space between memory is at `self.warn_if_above` and memory is full at `1.0`.
         buffer = 1 - warn_if_above
         critical_if_above = warn_if_above + 0.5 * buffer
@@ -23,20 +22,15 @@ class MemoryLogger(Logger):
                          critical_if_above)
         self.warn_if_above = warn_if_above
 
-    def check_data(self, data: list[any]) -> WarnMessage:
+    def get_warn_data(self, data: list[any]) -> WarnData:
         used_mb = data[1]
         total_available_mb = data[3]
         message = f'Memory usage ist at {used_mb} MB of {total_available_mb} MB'
 
         used = used_mb / total_available_mb
+        return WarnData(data[0], used, message)
 
-        if used > self.critical_if_above:
-            return WarnMessage(WarnLevel.HIGH, message)
-        if used > self.warn_if_above:
-            return WarnMessage(WarnLevel.NORMAL, message)
-        return WarnMessage(WarnLevel.NONE)
-
-    def read_data(self)  -> list[any]:
+    def read_data(self) -> list[any]:
         used_mb, free_mb, available_mb, total_mb = self.get_memory()
         used_and_cached_mb = total_mb - free_mb
         total_available_mb = used_mb + available_mb
@@ -48,7 +42,8 @@ class MemoryLogger(Logger):
         ]
 
     def data_schema(self) -> list[str]:
-        return ['datetime#Date', 'int#Used memory in MB', 'int#Used and cached in MB', 'int#Total available memory in MB']
+        return ['datetime#Date', 'int#Used memory in MB', 'int#Used and cached in MB',
+                'int#Total available memory in MB']
 
     def get_log_file(self) -> Path:
         return self.get_log_dir() / f'memory.csv'
diff --git a/src/de/p1st/monitor/loggers/network.py b/src/de/p1st/monitor/loggers/network.py
index 2d6c860..90dc598 100644
--- a/src/de/p1st/monitor/loggers/network.py
+++ b/src/de/p1st/monitor/loggers/network.py
@@ -54,7 +54,7 @@ class NetworkLogger(Logger):
         csv_util.write(file=export_file, rows=rows, header=export_schema, recreate_file=True)
         return export_file
 
-    def check_data(self, data: list[any]) -> WarnMessage:
+    def get_warn_data(self, data: list[any]) -> WarnMessage:
         return WarnMessage(WarnLevel.NONE)
 
     def data_schema(self) -> list[str]:
@@ -65,7 +65,7 @@ class NetworkLogger(Logger):
             'datetime#Boot date',
         ]
 
-    def read_data(self)  -> list[any]:
+    def read_data(self) -> list[any]:
         sent, received = self.get_net_usage()
         return [
             datetime_util.now(),
@@ -101,6 +101,7 @@ class NetworkLogger(Logger):
         epoch_seconds = psutil.boot_time()
         return datetime.fromtimestamp(epoch_seconds, tz=timezone.utc)
 
+
 def test():
     from de.p1st.monitor.cfg.singleton import init_cfg
     init_cfg()
@@ -109,5 +110,6 @@ def test():
     logger.update()
     logger.log()
 
+
 if __name__ == '__main__':
     test()
diff --git a/src/de/p1st/monitor/loggers/swap.py b/src/de/p1st/monitor/loggers/swap.py
index 610c241..4fe7333 100644
--- a/src/de/p1st/monitor/loggers/swap.py
+++ b/src/de/p1st/monitor/loggers/swap.py
@@ -5,6 +5,7 @@ from de.p1st.monitor import datetime_util
 
 from de.p1st.monitor.logger import Logger
 from de.p1st.monitor.warn import WarnMessage, WarnLevel
+from de.p1st.monitor.warn_data import WarnData
 
 
 class SwapLogger(Logger):
@@ -13,7 +14,6 @@ class SwapLogger(Logger):
                  warn_threshold: int = 1,
                  warn_data_range: int = 1,
                  ):
-
         # The space between swap is at `self.warn_if_above` and swap is full at `1.0`.
         buffer = 1 - warn_if_above
         critical_if_above = warn_if_above + 0.5 * buffer
@@ -23,21 +23,16 @@ class SwapLogger(Logger):
                          critical_if_above)
         self.warn_if_above = warn_if_above
 
-    def check_data(self, data: list[any]) -> WarnMessage:
+    def get_warn_data(self, data: list[any]) -> WarnData | WarnMessage:
         used_mb = data[1]
         total_mb = data[2]
         message = f'Swap usage ist at {used_mb} MB of {total_mb} MB'
 
         if used_mb == 0 and total_mb == 0:
-            return WarnMessage(WarnLevel.HIGH, 'Swap is not enabled')
+            return WarnMessage(WarnLevel.HIGH, data[0], 'Swap is not enabled')
 
         usage = used_mb / total_mb
-
-        if usage > self.critical_if_above:
-            return WarnMessage(WarnLevel.HIGH, message)
-        if usage > self.warn_if_above:
-            return WarnMessage(WarnLevel.NORMAL, message)
-        return WarnMessage(WarnLevel.NONE)
+        return WarnData(data[0], usage, message)
 
     def read_data(self) -> list[any]:
         used_mb, total_mb = self.get_swap()
diff --git a/src/de/p1st/monitor/loggers/temp.py b/src/de/p1st/monitor/loggers/temp.py
index de4ff59..0efa033 100644
--- a/src/de/p1st/monitor/loggers/temp.py
+++ b/src/de/p1st/monitor/loggers/temp.py
@@ -5,7 +5,7 @@ import psutil
 from de.p1st.monitor import datetime_util
 from de.p1st.monitor.logger import Logger
 from de.p1st.monitor.logger_ex import LoggerReadEx
-from de.p1st.monitor.warn import WarnMessage, WarnLevel
+from de.p1st.monitor.warn_data import WarnData
 
 
 class TempLogger(Logger):
@@ -26,15 +26,10 @@ class TempLogger(Logger):
 
         self.warn_if_above = warn_if_above
 
-    def check_data(self, data: list[any]) -> WarnMessage:
+    def get_warn_data(self, data: list[any]) -> WarnData:
         temp = data[1]
         message = f'Temperature of {self.name} {self.label} ist at {temp}'
-
-        if temp > self.critical_if_above:
-            return WarnMessage(WarnLevel.HIGH, message)
-        if temp > self.warn_if_above:
-            return WarnMessage(WarnLevel.NORMAL, message)
-        return WarnMessage(WarnLevel.NONE)
+        return WarnData(data[0], temp, message)
 
     def read_data(self) -> list[any]:
         return [
@@ -60,7 +55,7 @@ class TempLogger(Logger):
         :return: Temperature in celsius
         """
         data = psutil.sensors_temperatures(fahrenheit=False)
-        if not self.name in data:
+        if self.name not in data:
             raise LoggerReadEx(f'Sensor {self.name} not found')
         for i in data[self.name]:
             if i.label == self.label:
diff --git a/src/de/p1st/monitor/main.py b/src/de/p1st/monitor/main.py
index df05697..e130577 100755
--- a/src/de/p1st/monitor/main.py
+++ b/src/de/p1st/monitor/main.py
@@ -54,9 +54,7 @@ def log():
         except LoggerReadEx as e:
             logger_read_exs.append(e)
             continue
-        # After logger.update() there might still be no data
-        #   Example: FilesystemLogger if partition is not mounted (and unmounted_ok is True)
-        logger.log(skip_if_no_data=True)
+        logger.log()
         if logger.check().print().is_warning():
             logger_warnings += 1
 
diff --git a/src/de/p1st/monitor/string_conversion.py b/src/de/p1st/monitor/string_conversion.py
index 88edb6a..4bae2ca 100644
--- a/src/de/p1st/monitor/string_conversion.py
+++ b/src/de/p1st/monitor/string_conversion.py
@@ -17,8 +17,10 @@ def data_types() -> dict[str, dict[str, Callable[[any], any]]]:
         'datetime': {'to': datetime_util.to_str, 'from': datetime_util.from_str},
     }
 
+
 def to_string(v: any, type_str: str) -> str:
     return data_types()[type_str]['to'](v)
 
+
 def from_string(v: str, type_str: str) -> any:
     return data_types()[type_str]['from'](v)
diff --git a/src/de/p1st/monitor/warn.py b/src/de/p1st/monitor/warn.py
index 0a8648e..dda402a 100644
--- a/src/de/p1st/monitor/warn.py
+++ b/src/de/p1st/monitor/warn.py
@@ -1,7 +1,9 @@
 from __future__ import annotations
 import sys
+from datetime import datetime
 from enum import Enum
 from functools import total_ordering
+from typing import TextIO
 
 
 # https://docs.python.org/3/library/functools.html#functools.total_ordering
@@ -24,26 +26,54 @@ class WarnLevel(Enum):
 
 
 class WarnMessage:
-    def __init__(self, level: WarnLevel, message: str = None):
+    def __init__(self, level: WarnLevel, date: datetime = None, message: str = None):
+        """
+        @param level:
+        @param date: Required, except if `WarnLevel.NONE` given.
+        @param message: Required, except if `WarnLevel.NONE` given.
+        """
         self.level = level
+        self.date = date
         self.message = message
 
+        if self.level != WarnLevel.NONE:
+            if self.date is None:
+                raise ValueError()
+            if self.message is None:
+                raise ValueError()
+        if self.level == WarnLevel.NONE:
+            if self.date is not None:
+                raise ValueError()
+            if self.message is not None:
+                raise ValueError()
+
     def is_warning(self) -> bool:
         return self.level > WarnLevel.NONE
 
-    def print(self, default_message: str = 'Warning!') -> WarnMessage:
+    def print(self) -> WarnMessage:
         """
         return: self
         """
-        message = default_message if self.message is None else self.message
-
         if self.level == WarnLevel.NONE:
             pass
-        elif self.level == WarnLevel.LOW:
-            print(message)
-        elif self.level == WarnLevel.NORMAL:
-            print(message, file=sys.stderr)
-        elif self.level == WarnLevel.HIGH:
-            print(f'[CRITICAL] {message}', file=sys.stderr)
+        else:
+            print(self.formatted_message(), file=self.file())
 
         return self
+
+    def formatted_message(self) -> str:
+        return self.prefix() + self.message
+
+    def prefix(self) -> str:
+        if self.level == WarnLevel.NONE:
+            raise ValueError()
+        if self.level > WarnLevel.HIGH:
+            return f'[CRITICAL] {self.date}: '
+        return f'{self.date}:'
+
+    def file(self) -> TextIO:
+        if self.level == WarnLevel.NONE:
+            raise ValueError()
+        if self.level >= WarnLevel.NORMAL:
+            return sys.stderr
+        return sys.stdout
diff --git a/src/de/p1st/monitor/warn_data.py b/src/de/p1st/monitor/warn_data.py
new file mode 100644
index 0000000..8fd8a1a
--- /dev/null
+++ b/src/de/p1st/monitor/warn_data.py
@@ -0,0 +1,8 @@
+from typing import NamedTuple
+from datetime import datetime
+
+
+class WarnData(NamedTuple):
+    date: datetime
+    value: int | float
+    message: str