From 1508ecfeae89659a1d8927e5ffefb8742cb318ef Mon Sep 17 00:00:00 2001
From: Vladimir Iakovlev <nvbn.rm@gmail.com>
Date: Wed, 14 Mar 2018 00:12:40 +0100
Subject: [PATCH] #N/A: Use mmap for sharing output in instant mode

---
 thefuck/const.py                    |  4 ++--
 thefuck/entrypoints/shell_logger.py | 19 +++++++++++++------
 thefuck/output_readers/read_log.py  | 23 +++++++++++------------
 3 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/thefuck/const.py b/thefuck/const.py
index 3f71d39..dc55a5a 100644
--- a/thefuck/const.py
+++ b/thefuck/const.py
@@ -76,8 +76,8 @@ CONFIGURATION_TIMEOUT = 60
 
 USER_COMMAND_MARK = u'\u200B' * 10
 
-LOG_SIZE = 1000
-
 LOG_SIZE_IN_BYTES = 1024 * 1024
 
+LOG_SIZE_TO_CLEAN = 10 * 1024
+
 DIFF_WITH_ALIAS = 0.5
diff --git a/thefuck/entrypoints/shell_logger.py b/thefuck/entrypoints/shell_logger.py
index 6c90365..3df3f76 100644
--- a/thefuck/entrypoints/shell_logger.py
+++ b/thefuck/entrypoints/shell_logger.py
@@ -1,19 +1,24 @@
 import array
 import fcntl
 from functools import partial
+import mmap
 import os
 import pty
 import signal
 import sys
 import termios
 import tty
-from ..logs import warn
+from .. import logs, const
 
 
 def _read(f, fd):
     data = os.read(fd, 1024)
-    f.write(data)
-    f.flush()
+    try:
+        f.write(data)
+    except ValueError:
+        f.move(0, const.LOG_SIZE_TO_CLEAN,
+               const.LOG_SIZE_IN_BYTES - const.LOG_SIZE_TO_CLEAN)
+        f.seek(const.LOG_SIZE_IN_BYTES - const.LOG_SIZE_TO_CLEAN)
     return data
 
 
@@ -61,10 +66,12 @@ def shell_logger(output):
 
     """
     if not os.environ.get('SHELL'):
-        warn("Shell logger doesn't support your platform.")
+        logs.warn("Shell logger doesn't support your platform.")
         sys.exit(1)
 
-    with open(output, 'wb') as f:
-        return_code = _spawn(os.environ['SHELL'], partial(_read, f))
+    fd = os.open(output, os.O_CREAT | os.O_TRUNC | os.O_RDWR)
+    os.write(fd, b'\x00' * const.LOG_SIZE_IN_BYTES)
+    buffer = mmap.mmap(fd, const.LOG_SIZE_IN_BYTES, mmap.MAP_SHARED, mmap.PROT_WRITE)
+    return_code = _spawn(os.environ['SHELL'], partial(_read, buffer))
 
     sys.exit(return_code)
diff --git a/thefuck/output_readers/read_log.py b/thefuck/output_readers/read_log.py
index 9262fa8..4da63e0 100644
--- a/thefuck/output_readers/read_log.py
+++ b/thefuck/output_readers/read_log.py
@@ -1,5 +1,7 @@
 import os
 import shlex
+import mmap
+import re
 try:
     from shutil import get_terminal_size
 except ImportError:
@@ -18,11 +20,6 @@ def _group_by_calls(log):
     script_line = None
     lines = []
     for line in log:
-        try:
-            line = line.decode()
-        except UnicodeDecodeError:
-            continue
-
         if const.USER_COMMAND_MARK in line or ps1_counter > 0:
             if script_line and ps1_counter == 0:
                 yield script_line, lines
@@ -53,13 +50,14 @@ def _get_script_group_lines(grouped, script):
 
 
 def _get_output_lines(script, log_file):
-    lines = log_file.readlines()[-const.LOG_SIZE:]
+    data = log_file.read().decode()
+    data = re.sub(r'\x00+$', '', data)
+    lines = data.split('\n')
     grouped = list(_group_by_calls(lines))
     script_lines = _get_script_group_lines(grouped, script)
-
     screen = pyte.Screen(get_terminal_size().columns, len(script_lines))
     stream = pyte.Stream(screen)
-    stream.feed(''.join(script_lines))
+    stream.feed('\n'.join(script_lines))
     return screen.display
 
 
@@ -91,10 +89,11 @@ def get_output(script):
         return None
 
     try:
-        with logs.debug_time(u'Read output from log'), \
-                open(os.environ['THEFUCK_OUTPUT_LOG'], 'rb') as log_file:
-            _skip_old_lines(log_file)
-            lines = _get_output_lines(script, log_file)
+        with logs.debug_time(u'Read output from log'):
+            fd = os.open(os.environ['THEFUCK_OUTPUT_LOG'], os.O_RDONLY)
+            buffer = mmap.mmap(fd, const.LOG_SIZE_IN_BYTES, mmap.MAP_SHARED, mmap.PROT_READ)
+            _skip_old_lines(buffer)
+            lines = _get_output_lines(script, buffer)
             output = '\n'.join(lines).strip()
             logs.debug(u'Received output: {}'.format(output))
             return output