Handle corruption of JSON history file.

IPython/core/history.py

@@ -1,553 +1,556 b''
 """ History related magics and functionality """
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2010 The IPython Development Team.
 #
 #  Distributed under the terms of the BSD License.
 #
 #  The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 from __future__ import print_function
 
 # Stdlib imports
 import fnmatch
 import json
 import os
 import sys
 import threading
 import time
 
 # Our own packages
 import IPython.utils.io
 
 from IPython.utils.pickleshare import PickleShareDB
 from IPython.utils.io import ask_yes_no
 from IPython.utils.warn import warn
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 class HistoryManager(object):
     """A class to organize all history-related functionality in one place.
     """
     # Public interface
 
     # An instance of the IPython shell we are attached to
     shell = None
     # A list to hold processed history
     input_hist_parsed = None
     # A list to hold raw history (as typed by user)
     input_hist_raw = None
     # A list of directories visited during session
     dir_hist = None
     # A dict of output history, keyed with ints from the shell's execution count
     output_hist = None
     # String with path to the history file
     hist_file = None
     # PickleShareDB instance holding the raw data for the shadow history
     shadow_db = None
     # ShadowHist instance with the actual shadow history
     shadow_hist = None
     
     # Private interface
     # Variables used to store the three last inputs from the user.  On each new
     # history update, we populate the user's namespace with these, shifted as
     # necessary.
     _i00, _i, _ii, _iii = '','','',''
 
     # A set with all forms of the exit command, so that we don't store them in
     # the history (it's annoying to rewind the first entry and land on an exit
     # call).
     _exit_commands = None
     
     def __init__(self, shell):
         """Create a new history manager associated with a shell instance.
         """
         # We need a pointer back to the shell for various tasks.
         self.shell = shell
         
         # List of input with multi-line handling.
         self.input_hist_parsed = []
         # This one will hold the 'raw' input history, without any
         # pre-processing.  This will allow users to retrieve the input just as
         # it was exactly typed in by the user, with %hist -r.
         self.input_hist_raw = []
 
         # list of visited directories
         try:
             self.dir_hist = [os.getcwd()]
         except OSError:
             self.dir_hist = []
 
         # dict of output history
         self.output_hist = {}
 
         # Now the history file
         if shell.profile:
             histfname = 'history-%s' % shell.profile
         else:
             histfname = 'history'
         self.hist_file = os.path.join(shell.ipython_dir, histfname + '.json')
 
         # Objects related to shadow history management
         self._init_shadow_hist()
     
         self._i00, self._i, self._ii, self._iii = '','','',''
 
         self._exit_commands = set(['Quit', 'quit', 'Exit', 'exit', '%Quit',
                                    '%quit', '%Exit', '%exit'])
 
         # Object is fully initialized, we can now call methods on it.
         
         # Fill the history zero entry, user counter starts at 1
         self.store_inputs('\n', '\n')
 
     def _init_shadow_hist(self):
         try:
             self.shadow_db = PickleShareDB(os.path.join(
                                            self.shell.ipython_dir, 'db'))
         except UnicodeDecodeError:
             print("Your ipython_dir can't be decoded to unicode!")
             print("Please set HOME environment variable to something that")
             print(r"only has ASCII characters, e.g. c:\home")
             print("Now it is", self.ipython_dir)
             sys.exit()
         self.shadow_hist = ShadowHist(self.shadow_db, self.shell)
         
     def populate_readline_history(self):
         """Populate the readline history from the raw history.
 
         We only store one copy of the raw history, which is persisted to a json
         file on disk.  The readline history is repopulated from the contents of
         this file."""
 
         try:
             self.shell.readline.clear_history()
         except AttributeError:
             pass
         else:
             for h in self.input_hist_raw:
                 if not h.isspace():
                     for line in h.splitlines():
                         self.shell.readline.add_history(line)
 
     def save_history(self):
         """Save input history to a file (via readline library)."""
         hist = dict(raw=self.input_hist_raw, #[-self.shell.history_length:],
                     parsed=self.input_hist_parsed) #[-self.shell.history_length:])
         with open(self.hist_file,'wt') as hfile:
             json.dump(hist, hfile,
                       sort_keys=True, indent=4)
         
     def reload_history(self):
         """Reload the input history from disk file."""
 
         with open(self.hist_file,'rt') as hfile:
-            hist = json.load(hfile)
+            try:
+                hist = json.load(hfile)
+            except ValueError:    # Ignore it if JSON is corrupt.
+                return
             self.input_hist_parsed = hist['parsed']
             self.input_hist_raw = hist['raw']
             if self.shell.has_readline:
                 self.populate_readline_history()
         
     def get_history(self, index=None, raw=False, output=True):
         """Get the history list.
 
         Get the input and output history.
 
         Parameters
         ----------
         index : n or (n1, n2) or None
             If n, then the last entries. If a tuple, then all in
             range(n1, n2). If None, then all entries. Raises IndexError if
             the format of index is incorrect.
         raw : bool
             If True, return the raw input.
         output : bool
             If True, then return the output as well.
 
         Returns
         -------
         If output is True, then return a dict of tuples, keyed by the prompt
         numbers and with values of (input, output). If output is False, then
         a dict, keyed by the prompt number with the values of input. Raises
         IndexError if no history is found.
         """
         if raw:
             input_hist = self.input_hist_raw
         else:
             input_hist = self.input_hist_parsed
         if output:
             output_hist = self.output_hist
         n = len(input_hist)
         if index is None:
             start=0; stop=n
         elif isinstance(index, int):
             start=n-index; stop=n
         elif isinstance(index, tuple) and len(index) == 2:
             start=index[0]; stop=index[1]
         else:
             raise IndexError('Not a valid index for the input history: %r'
                              % index)
         hist = {}
         for i in range(start, stop):
             if output:
                 hist[i] = (input_hist[i], output_hist.get(i))
             else:
                 hist[i] = input_hist[i]
         if not hist:
             raise IndexError('No history for range of indices: %r' % index)
         return hist
 
     def store_inputs(self, source, source_raw=None):
         """Store source and raw input in history and create input cache
         variables _i*.
         
         Parameters
         ----------
         source : str
           Python input.
 
         source_raw : str, optional
           If given, this is the raw input without any IPython transformations
           applied to it.  If not given, ``source`` is used.
         """
         if source_raw is None:
             source_raw = source
             
         # do not store exit/quit commands
         if source_raw.strip() in self._exit_commands:
             return
         
         self.input_hist_parsed.append(source.rstrip())
         self.input_hist_raw.append(source_raw.rstrip())
         self.shadow_hist.add(source)
 
         # update the auto _i variables
         self._iii = self._ii
         self._ii = self._i
         self._i = self._i00
         self._i00 = source_raw
 
         # hackish access to user namespace to create _i1,_i2... dynamically
         new_i = '_i%s' % self.shell.execution_count
         to_main = {'_i': self._i,
                    '_ii': self._ii,
                    '_iii': self._iii,
                    new_i : self._i00 }
         self.shell.user_ns.update(to_main)
 
     def sync_inputs(self):
         """Ensure raw and translated histories have same length."""
         if len(self.input_hist_parsed) != len (self.input_hist_raw):
             self.input_hist_raw[:] = self.input_hist_parsed
 
     def reset(self):
         """Clear all histories managed by this object."""
         self.input_hist_parsed[:] = []
         self.input_hist_raw[:] = []
         self.output_hist.clear()
         # The directory history can't be completely empty
         self.dir_hist[:] = [os.getcwd()]
 
 class HistorySaveThread(threading.Thread):
     """This thread saves history periodically (the current default is once per
     minute), so that it is not lost in the event of a crash. It also allows the
     commands in the current IPython shell to be accessed in a newly started
     instance."""
     daemon = True
     
     def __init__(self, IPython_object, time_interval=60):
         threading.Thread.__init__(self)
         self.IPython_object = IPython_object
         self.time_interval = time_interval
         self.exit_now = threading.Event()
 
     def run(self):
         while True:
             self.exit_now.wait(self.time_interval)
             if self.exit_now.is_set():
                 break
             #print("Autosaving history...")   # DEBUG
             self.IPython_object.save_history()
             
     def stop(self):
         """Safely and quickly stop the autosave thread. This will not cause the
         history to be saved before stopping."""
         self.exit_now.set()
         self.join()
 
 def magic_history(self, parameter_s = ''):
     """Print input history (_i<n> variables), with most recent last.
     
     %history       -> print at most 40 inputs (some may be multi-line)\\
     %history n     -> print at most n inputs\\
     %history n1 n2 -> print inputs between n1 and n2 (n2 not included)\\
 
     By default, input history is printed without line numbers so it can be
     directly pasted into an editor.
 
     With -n, each input's number <n> is shown, and is accessible as the
     automatically generated variable _i<n> as well as In[<n>].  Multi-line
     statements are printed starting at a new line for easy copy/paste.
 
     Options:
 
       -n: print line numbers for each input.
       This feature is only available if numbered prompts are in use.
 
       -o: also print outputs for each input.
 
       -p: print classic '>>>' python prompts before each input.  This is useful
        for making documentation, and in conjunction with -o, for producing
        doctest-ready output.
 
       -r: (default) print the 'raw' history, i.e. the actual commands you typed.
       
       -t: print the 'translated' history, as IPython understands it.  IPython
       filters your input and converts it all into valid Python source before
       executing it (things like magics or aliases are turned into function
       calls, for example). With this option, you'll see the native history
       instead of the user-entered version: '%cd /' will be seen as
       'get_ipython().magic("%cd /")' instead of '%cd /'.
       
       -g: treat the arg as a pattern to grep for in (full) history.
       This includes the "shadow history" (almost all commands ever written).
       Use '%hist -g' to show full shadow history (may be very long).
       In shadow history, every index nuwber starts with 0.
 
       -f FILENAME: instead of printing the output to the screen, redirect it to
        the given file.  The file is always overwritten, though IPython asks for
        confirmation first if it already exists.
     """
 
     if not self.shell.displayhook.do_full_cache:
         print('This feature is only available if numbered prompts are in use.')
         return
     opts,args = self.parse_options(parameter_s,'gnoptsrf:',mode='list')
 
     # Check if output to specific file was requested.
     try:
         outfname = opts['f']
     except KeyError:
         outfile = IPython.utils.io.Term.cout  # default
         # We don't want to close stdout at the end!
         close_at_end = False
     else:
         if os.path.exists(outfname):
             if not ask_yes_no("File %r exists. Overwrite?" % outfname): 
                 print('Aborting.')
                 return
 
         outfile = open(outfname,'w')
         close_at_end = True
 
     if 't' in opts:
         input_hist = self.shell.history_manager.input_hist_parsed
     elif 'r' in opts:
         input_hist = self.shell.history_manager.input_hist_raw
     else:
         # Raw history is the default
         input_hist = self.shell.history_manager.input_hist_raw
             
     default_length = 40
     pattern = None
     if 'g' in opts:
         init = 1
         final = len(input_hist)
         parts = parameter_s.split(None, 1)
         if len(parts) == 1:
             parts += '*'
         head, pattern = parts
         pattern = "*" + pattern + "*"
     elif len(args) == 0:
         final = len(input_hist)-1
         init = max(1,final-default_length)
     elif len(args) == 1:
         final = len(input_hist)
         init = max(1, final-int(args[0]))
     elif len(args) == 2:
         init, final = map(int, args)
     else:
         warn('%hist takes 0, 1 or 2 arguments separated by spaces.')
         print(self.magic_hist.__doc__, file=IPython.utils.io.Term.cout)
         return
     
     width = len(str(final))
     line_sep = ['','\n']
     print_nums = 'n' in opts
     print_outputs = 'o' in opts
     pyprompts = 'p' in opts
     
     found = False
     if pattern is not None:
         sh = self.shell.history_manager.shadowhist.all()
         for idx, s in sh:
             if fnmatch.fnmatch(s, pattern):
                 print("0%d: %s" %(idx, s.expandtabs(4)), file=outfile)
                 found = True
     
     if found:
         print("===", file=outfile)
         print("shadow history ends, fetch by %rep <number> (must start with 0)",
               file=outfile)
         print("=== start of normal history ===", file=outfile)
         
     for in_num in range(init, final):
         # Print user history with tabs expanded to 4 spaces.  The GUI clients
         # use hard tabs for easier usability in auto-indented code, but we want
         # to produce PEP-8 compliant history for safe pasting into an editor.
         inline = input_hist[in_num].expandtabs(4).rstrip()+'\n'
 
         if pattern is not None and not fnmatch.fnmatch(inline, pattern):
             continue
             
         multiline = int(inline.count('\n') > 1)
         if print_nums:
             print('%s:%s' % (str(in_num).ljust(width), line_sep[multiline]),
                   file=outfile)
         if pyprompts:
             print('>>>', file=outfile)
             if multiline:
                 lines = inline.splitlines()
                 print('\n... '.join(lines), file=outfile)
                 print('... ', file=outfile)
             else:
                 print(inline, end='', file=outfile)
         else:
             print(inline, end='', file=outfile)
         if print_outputs:
             output = self.shell.history_manager.output_hist.get(in_num)
             if output is not None:
                 print(repr(output), file=outfile)
 
     if close_at_end:
         outfile.close()
 
 
 def magic_hist(self, parameter_s=''):
     """Alternate name for %history."""
     return self.magic_history(parameter_s)
 
 
 def rep_f(self, arg):
     r""" Repeat a command, or get command to input line for editing
 
     - %rep (no arguments):
     
     Place a string version of last computation result (stored in the special '_'
     variable) to the next input prompt. Allows you to create elaborate command
     lines without using copy-paste::
     
         $ l = ["hei", "vaan"]       
         $ "".join(l)        
         ==> heivaan        
         $ %rep        
         $ heivaan_ <== cursor blinking    
     
     %rep 45
     
     Place history line 45 to next input prompt. Use %hist to find out the
     number.
     
     %rep 1-4 6-7 3
     
     Repeat the specified lines immediately. Input slice syntax is the same as
     in %macro and %save.
     
     %rep foo
     
     Place the most recent line that has the substring "foo" to next input.
     (e.g. 'svn ci -m foobar').    
     """
     
     opts,args = self.parse_options(arg,'',mode='list')
     if not args:
         self.set_next_input(str(self.shell.user_ns["_"]))
         return
 
     if len(args) == 1 and not '-' in args[0]:
         arg = args[0]
         if len(arg) > 1 and arg.startswith('0'):
             # get from shadow hist
             num = int(arg[1:])
             line = self.shell.shadowhist.get(num)
             self.set_next_input(str(line))
             return
         try:
             num = int(args[0])
             self.set_next_input(str(self.shell.input_hist_raw[num]).rstrip())
             return
         except ValueError:
             pass
         
         for h in reversed(self.shell.input_hist_raw):
             if 'rep' in h:
                 continue
             if fnmatch.fnmatch(h,'*' + arg + '*'):
                 self.set_next_input(str(h).rstrip())
                 return
         
     try:
         lines = self.extract_input_slices(args, True)
         print("lines", lines)
         self.run_cell(lines)
     except ValueError:
         print("Not found in recent history:", args)
         
 
 _sentinel = object()
 
 class ShadowHist(object):
     def __init__(self, db, shell):
         # cmd => idx mapping
         self.curidx = 0
         self.db = db
         self.disabled = False
         self.shell = shell
     
     def inc_idx(self):
         idx = self.db.get('shadowhist_idx', 1)
         self.db['shadowhist_idx'] = idx + 1
         return idx
         
     def add(self, ent):
         if self.disabled:
             return
         try:
             old = self.db.hget('shadowhist', ent, _sentinel)
             if old is not _sentinel:
                 return
             newidx = self.inc_idx()
             #print("new", newidx) # dbg
             self.db.hset('shadowhist',ent, newidx)
         except:
             self.shell.showtraceback()
             print("WARNING: disabling shadow history")
             self.disabled = True
     
     def all(self):
         d = self.db.hdict('shadowhist')
         items = [(i,s) for (s,i) in d.iteritems()]
         items.sort()
         return items
 
     def get(self, idx):
         all = self.all()
         
         for k, v in all:
             if k == idx:
                 return v
 
 
 def init_ipython(ip):
     ip.define_magic("rep",rep_f)        
     ip.define_magic("hist",magic_hist)            
     ip.define_magic("history",magic_history)
 
     # XXX - ipy_completers are in quarantine, need to be updated to new apis
     #import ipy_completers
     #ipy_completers.quick_completer('%hist' ,'-g -t -r -n')