scroll by wheel

logFileModel.py

@@ -1,3 +1,4 @@
+import threading
 from typing import List
 import os
 from line import Line
@@ -6,27 +7,56 @@ from settings import Settings
 
 
 class LogFileModel:
+    _lock = threading.RLock()
+
     def __init__(self, file):
         self._file = file
 
-    def data(self, byte_offset:int, lines: int) -> List[Line]:
-        result : List[Line] = []
+    def data(self, byte_offset, scroll_lines, lines) -> List[Line]:
+        #print("data(%s, %s, %s)" % (byte_offset, scroll_lines, lines))
+        lines_before_offset: List[Line] = []
+        lines_after_offset: List[Line] = []
+        result: List[Line] = []
+        lines_to_find = lines  # + -1 * scroll_lines
 
-        # TODO handle lines longer than 4096 bytes
-        with open(self._file, 'r') as f:
-            offset = max(0, byte_offset - Settings.max_line_length())
-            offset = offset - offset % Settings.max_line_length() # align to blocks of 4kb
-            f.seek(offset)
-            while l := f.readline():
-                new_offset = f.tell()
-                if offset >= byte_offset:
-                    line = Line(offset, new_offset-1, l)
-                    result.append(line)
-                offset = new_offset
-                if len(result) >= lines:
-                    break
+        with self._lock:
+            # TODO handle lines longer than 4096 bytes
+            with open(self._file, 'rb') as f:
+                offset = min(byte_offset, self.byte_count())
+                offset = max(0, offset - Settings.max_line_length())
 
-        return result
+                #print("offset: %s" % (offset))
+
+                eof_reached = True
+                f.seek(offset)
+                while l := f.readline():
+                    new_offset = f.tell()
+                    line = Line(offset, new_offset, l.decode("utf8").replace("\r", "").replace("\n", ""))
+                    # print("%s %s" %(line.byte_offset(), line.line()))
+                    if offset < byte_offset:
+                        lines_before_offset.append(line)
+                    else:
+                        lines_after_offset.append(line)
+                    offset = f.tell()
+                    if len(lines_after_offset) >= lines_to_find:
+                        eof_reached = False
+                        break
+
+            if scroll_lines > 0:
+                result = result + lines_before_offset[-scroll_lines:]
+                result = result + lines_after_offset
+            elif eof_reached:
+                # we always return the number of requested lines even if we reach the end of the file
+                lines_to_return_from_before_offset = int(lines_to_find - len(lines_after_offset));
+                print(lines_to_return_from_before_offset)
+                if lines_to_return_from_before_offset > 0:
+                    result = result + lines_before_offset[-lines_to_return_from_before_offset:]
+                result = result + lines_after_offset
+            else:
+                result = result + lines_after_offset[-scroll_lines:]
+
+            #print("returning %s lines" % (len(result)))
+            return result
 
     def byte_count(self) -> int:
         return os.stat(self._file).st_size