Piranha.py

   1
   2 import os, sys, getopt
   3 from os import path
   4
   5 import feedparser, sqlite3
   6 import PiranhaData
   7
   8 def version():
   9         return "0.1"
  10
  11 class Piranha:
  12         """Core class for managing a user's feeds, caching/accessing feed items, etc."""
  13
  14         def __init__( self, home=None ):
  15                 self._home = home
  16                 self._db = None
  17
  18                 self.check_home()
  19                 self.check_db()
  20
  21                 self._data = PiranhaData.PiranhaData( self.db() )
  22
  23         #### class management functions ####
  24
  25         def db( self, isolation=None ):
  26                 """Return a new cursor to the database.  This will connect to the database if needed."""
  27                 if isolation == None:
  28                         if self._db == None:
  29                                 db = sqlite3.connect( self._dbfile, isolation_level=isolation )
  30                                 self._db = db
  31                         else:
  32                                 db = self._db
  33                 else:
  34                         db = sqlite3.connect( self._dbfile, isolation_level=isolation )
  35
  36                 db.row_factory = sqlite3.Row
  37                 return db
  38         #end db()
  39
  40         def check_home( self ):
  41                 """Checks the existance of the user's Pirhanna directory and db file.
  42                 Creates both if they do not already exist."""
  43
  44                 if None == self._home:
  45                         self._home = path.join( path.expanduser("~"), ".piranha" )
  46                 self._dbfile = path.join( self._home, "piranha.db" )
  47
  48                 if not path.isdir( self._home ):
  49                         os.mkdir( self._home )
  50         #end check_home()
  51
  52         def check_db( self ):
  53                 """Check the internal schema of any sqlite databases to make sure they are the correct version."""
  54                 db = self.db()
  55                 cursor = db.cursor()
  56
  57                 # Check the existance of the config table
  58                 found = False
  59                 for row in cursor.execute( "select name from sqlite_master where type='table' and name='config'" ):
  60                         if row["name"] == "config":
  61                                 found = True
  62
  63                 # Create the config table if needed
  64                 if not found:
  65                         cursor.execute( "create table config( name text unique, ival int, rval real, tval text )" )
  66                         cursor.execute( "insert into config( name, ival ) values ( 'schema', 0 )" )
  67
  68                 # Check the database version
  69                 current = 0
  70                 latest = len(self._schema)
  71                 for row in cursor.execute( "select ival from config where name='schema'" ):
  72                         current = row["ival"]
  73
  74                 # Update the database as necessary
  75                 if current < latest:
  76                         lockdb = self.db("EXCLUSIVE")
  77                         while current < latest:
  78                                 try:
  79                                         lockdb.execute( self._schema[current] )
  80                                 except sqlite3.IntegrityError:
  81                                         lockdb.execute( "rollback" )
  82                                         raise
  83                                 current = current + 1
  84
  85                         lockdb.execute( "update config set ival=? where name='schema'", (latest,) )
  86                         lockdb.commit() #done
  87
  88                         # invalidate cached connection
  89                         self._db = None
  90         #end check_db()
  91
  92         """Basic schema for the piranha.db file."""
  93         _schema = [
  94                 '''create table category ( id integer primary key autoincrement, name text, parent integer )''',
  95                 '''create table feed ( id integer primary key autoincrement, category integer, url text unique, title text )''',
  96                 '''create table entry ( id integer primary key autoincrement, feed integer, sha1 text, status integer, stamp text, title text, author text, content blob )''',
  97                 '''create table tag ( id integer primary key autoincrement, name text unique )''',
  98                 '''create table tagged ( entry integer, tag integer )''',
  99                 ]
 100 #end Pirhanna
 101
 102 if __name__ == "__main__":
 103         """Piranha is a backend, so by default, do nothing."""
 104         pass