1 files changed, 100 insertions, 0 deletions
diff --git a/lib/prserv/db.py b/lib/prserv/db.py
new file mode 100644
index 000000000..bbee9316b
--- /dev/null
+++ b/lib/prserv/db.py
@@ -0,0 +1,100 @@
+import logging
+import os.path
+import errno
+import sys
+import warnings
+import sqlite3
+
+try:
+    import sqlite3
+except ImportError:
+    from pysqlite2 import dbapi2 as sqlite3
+
+sqlversion = sqlite3.sqlite_version_info
+if sqlversion[0] < 3 or (sqlversion[0] == 3 and sqlversion[1] < 3):
+    raise Exception("sqlite3 version 3.3.0 or later is required.")
+
+class NotFoundError(StandardError):
+    pass
+
+class PRTable():
+    def __init__(self,cursor,table):
+        self.cursor = cursor
+        self.table = table
+
+        #create the table
+        self._execute("CREATE TABLE IF NOT EXISTS %s \
+                    (version TEXT NOT NULL, \
+                    checksum TEXT NOT NULL, \
+                    value INTEGER, \
+                    PRIMARY KEY (version,checksum));"
+                      % table)
+
+    def _execute(self, *query):
+        """Execute a query, waiting to acquire a lock if necessary"""
+        count = 0
+        while True:
+            try:
+                return self.cursor.execute(*query)
+            except sqlite3.OperationalError as exc:
+                if 'database is locked' in str(exc) and count < 500:
+                    count = count + 1
+                    continue
+                raise
+            except sqlite3.IntegrityError as exc:
+                print "Integrity error %s" % str(exc)
+                break
+
+    def getValue(self, version, checksum):
+        data=self._execute("SELECT value FROM %s WHERE version=? AND checksum=?;" % self.table,
+                           (version,checksum))
+        row=data.fetchone()
+        if row != None:
+            return row[0]
+        else:
+            #no value found, try to insert
+            self._execute("INSERT INTO %s VALUES (?, ?, (select ifnull(max(value)+1,0) from %s where version=?));" 
+                           % (self.table,self.table),
+                           (version,checksum,version))
+            data=self._execute("SELECT value FROM %s WHERE version=? AND checksum=?;" % self.table,
+                               (version,checksum))
+            row=data.fetchone()
+            if row != None:
+                return row[0]
+            else:
+                raise NotFoundError
+
+class PRData(object):
+    """Object representing the PR database"""
+    def __init__(self, filename):
+        self.filename=os.path.abspath(filename)
+        #build directory hierarchy
+        try:
+            os.makedirs(os.path.dirname(self.filename))
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise e
+        self.connection=sqlite3.connect(self.filename, timeout=5,
+                                          isolation_level=None)
+        self.cursor=self.connection.cursor()
+        self._tables={}
+
+    def __del__(self):
+        print "PRData: closing DB %s" % self.filename
+        self.connection.close()
+
+    def __getitem__(self,tblname):
+        if not isinstance(tblname, basestring):
+            raise TypeError("tblname argument must be a string, not '%s'" %
+                            type(tblname))
+        if tblname in self._tables:
+            return self._tables[tblname]
+        else:
+            tableobj = self._tables[tblname] = PRTable(self.cursor, tblname)
+            return tableobj
+
+    def __delitem__(self, tblname):
+        if tblname in self._tables:
+            del self._tables[tblname]
+        logging.info("drop table %s" % (tblname))
+        self.cursor.execute("DROP TABLE IF EXISTS %s;" % tblname)